[Federal Register Volume 90, Number 215 (Monday, November 10, 2025)]
[Proposed Rules]
[Pages 50766-50811]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-19812]
[[Page 50765]]
Vol. 90
Monday,
No. 215
November 10, 2025
Part II
Environmental Protection Agency
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40 CFR Part 82
Protection of Stratospheric Ozone: Listing of Substitutes Under the
Significant New Alternatives Policy Program in Refrigeration and Air
Conditioning and Fire Suppression; Proposed Rule
Federal Register / Vol. 90 , No. 215 / Monday, November 10, 2025 /
Proposed Rules
[[Page 50766]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 82
[EPA-HQ-OAR-2024-0503; FRL-12207-01-OAR]
RIN 2060-AW45
Protection of Stratospheric Ozone: Listing of Substitutes Under
the Significant New Alternatives Policy Program in Refrigeration and
Air Conditioning and Fire Suppression
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: Pursuant to the U.S. Environmental Protection Agency's
Significant New Alternatives Policy program, this action proposes to
list several substitutes as acceptable, subject to use conditions, for
residential and light commercial air conditioning and heat pumps,
chillers, household refrigerators and freezers, motor vehicle air
conditioning, and fire suppression and explosion protection. This
action also proposes to update use conditions for substitutes
previously listed for certain air conditioning end-uses and for water
coolers.
DATES: Comments must be received on or before December 26, 2025 unless
a public hearing is held. If a public hearing is held, comments on this
notice of proposed rulemaking must be received on or before date 30
days after date of public hearing. Public hearing: Any party requesting
a public hearing must notify the contact listed in the FOR FURTHER
INFORMATION CONTACT section, which is Emily Maruyama at email address:
[email protected] by 5 p.m. Eastern Daylight Time on or before
November 17, 2025. If a public hearing is held, it will take place on
or around November 25, 2025. Please refer to the SUPPLEMENTARY
INFORMATION section for additional information on the public hearing.
ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2024-0503 by any of the following methods:
Federal Rulemaking Portal: https://www.regulations.gov
(our preferred method). Follow the online instructions for submitting
comments.
Email: [email protected]. Include Docket ID No. EPA
HQ-OAR-2024-0503 in the subject line of the message.
Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Air and Radiation Docket, Mail Code 28221T, 1200 Pennsylvania
Avenue NW, Washington, DC 20460.
Hand Delivery or Courier: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operations are 8:30 a.m. to 4:30 p.m.,
Monday-Friday (except Federal Holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov, including personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document. For
information on EPA Docket Center services, please visit us online at
https://www.epa.gov/dockets.
If a public hearing is requested on or before November 17, 2025,
the EPA will post an update at https://www.epa.gov/snap. The EPA does
not intend to publish a document in the Federal Register announcing
updates. The public hearing will be held on or around November 25,
2025. Information on the hearing including the time and URL will be
posted at EPA's Stratospheric Ozone website at https://www.epa.gov/snap. Refer to the section titled, Public Participation for additional
information.
FOR FURTHER INFORMATION CONTACT: For information about this proposed
rule, contact Emily Maruyama, Stratospheric Protection Division, Office
of Atmospheric Protection (Mail Code 6205A), Environmental Protection
Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460; telephone
number: (202) 564-2809; email address: [email protected]. Notices
and rulemakings under the EPA's Significant New Alternatives Policy
(SNAP) program are available on the EPA's SNAP website at https://www.epa.gov/snap/snap-regulations.
SUPPLEMENTARY INFORMATION:
Preamble acronyms and abbreviations. Throughout this preamble the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:
2-BTP--2-bromo-3,3,3-trifluoropropene
AC--Air Conditioning
AIHA--American Industrial Hygiene Association
AIM--American Innovation and Manufacturing
ANSI--American National Standards Institute
APU--Auxiliary Power Unit
ASHRAE--American Society of Heating, Refrigerating and Air-
Conditioning Engineers
ASTM--American Society for Testing and Materials
BTMS--Battery Thermal Management Systems
CAA--Clean Air Act
CAS Reg. No.--Chemical Abstracts Service Registry Identification
Number
CBI--Confidential Business Information
CFC--Chlorofluorocarbon
CFR--Code of Federal Regulations
CMAQ--Community Multiscale Air Quality
CO2--Carbon Dioxide
CRP--Cooperative Research Program
DIY--Do it yourself
DOT--United States Department of Transportation
EEAP--Environmental Effects Assessment Panel
EPA--United States Environmental Protection Agency
ER&R--Emissions Reduction and Reclamation
EV--Exchange Value
FMEA--Failure Mode and Effects Analysis
FR--Federal Register
GHG--Greenhouse Gas
GSHP--Ground-Source Heat Pump
HC--Hydrocarbon
HCFC--Hydrochlorofluorocarbon
HCFO--Hydrochlorofluoroolefin
HCR--Hydrocarbon Refrigerant
HD--Heavy-Duty
HDOH--Heavy-Duty On-Highway
HFC--Hydrofluorocarbon
HFO--Hydrofluoroolefin
ICF--ICF International, Inc.
IEC--International Electrotechnical Commission
IPCC--Intergovernmental Panel on Climate Change
IPR--Industrial Process Refrigeration
IRC--International Residential Code
LD--Light-Duty
LFL--Lower Flammability Limit
LMDV--Light- and Medium-Duty Vehicle
MIR--Maximum Incremental Reactivity
MVAC--Motor Vehicle Air Conditioning or Motor Vehicle Air
Conditioner
MY--Model Year
NAAQS--National Ambient Air Quality Standard
NAICS--North American Industrial Classification System
NCEL--New Chemical Exposure Limit
NFPA--National Fire Protection Association
NRTL--Nationally Recognized Testing Laboratory
ODP--Ozone Depletion Potential
ODS--Ozone-Depleting Substances
OECD--Organisation for Economic Co-operation and Development
OEL--Occupational Exposure Limit
OEM--Original Equipment Manufacturer
OMB--United States Office of Management and Budget
OSHA--United States Occupational Safety and Health Administration
PBI--Proprietary Business Information
PEL--Permissible Exposure Limit
PFAS--Per- and Polyfluoroalkyl Substances
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PFC--Perfluorocarbon
PMN--Pre-Manufacture Notice
PMS--Pantone[supreg] Matching System
PPE--Personal Protective Equipment
ppm--Parts Per Million
PRA--Paperwork Reduction Act
PTAC--Packaged Terminal Air Conditioner
PTHP--Packaged Terminal Heat Pump
RAL--``Reichs-Ausschu[szlig] f[uuml]r Lieferbedingungen und
G[uuml]tesicherung,'' Germany's National Commission for Delivery
Terms and Quality Assurance
RCRA--Resource Conservation and Recovery Act
RFA--Regulatory Flexibility Act
RfC--Reference Concentration
SAE--SAE International, previously known as the Society of
Automotive Engineers
SDS--Safety Data Sheet
SIP--State Implementation Plan
SNAP--Significant New Alternatives Policy
SNUR--Significant New Use Rule
TEAP--Technology and Economic Assessment Panel
TFA--Trifluoroacetic Acid
TLV--Threshold Limit Value
TWA--Time Weighted Average
UL--UL, formerly known as Underwriters Laboratories, Inc.
UMRA--Unfunded Mandates Reform Act
VOC--Volatile Organic Compounds
VRF--Variable Refrigerant Flow
WEEL--Workplace Environmental Exposure Limit
WMO--World Meteorological Organization
WSHP--Water-Source Heat Pump
Table of Contents
I. Executive Summary
A. Purpose of the Regulatory Action
B. Summary of the Major Provisions of the Regulatory Action
II. Public Participation
A. Written Comments
B. Participation in Virtual Public Hearing
C. Public Access to Voluntary Consensus Safety Standards
III. General Information
A. Does this action apply to me?
B. What action is the Agency proposing to take?
C. What is the Agency's authority for taking this action?
D. What are the guiding principles of the SNAP program and what
are the SNAP criteria for evaluating substitutes?
IV. Residential and Light Commercial Air Conditioning and Heat Pumps
A. What is the EPA proposing in this action?
B. Background on Residential and Light Commercial AC and Heat
Pumps
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
D. What are the refrigerants the EPA is proposing to list as
acceptable in the residential and light commercial AC and heat pumps
end-use and how do they compare to other refrigerants in this end-
use?
E. What are the refrigerants for which the EPA is proposing to
update use conditions and how do they compare to other refrigerants
in the residential and light commercial AC and heat pumps end-use?
F. What use conditions is the EPA proposing in this action for
new and updated listings in this residential and light commercial AC
and heat pumps end-use?
G. What additional information is the EPA including in these
proposed listings?
V. Household Refrigerators and Freezers
A. What is the EPA proposing in this action?
B. Background on Household Refrigerators and Freezers
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
D. What is HCR 4141 and how does it compare to other
refrigerants in the household refrigerators and freezers end-use?
E. What use conditions is the EPA proposing in this action for
the new listing for HCR 4141 in new household refrigerators and
freezers?
F. What additional information is the EPA including in this
proposed listing?
VI. Water Coolers
A. What is the EPA proposing in this action?
B. Background on Water Coolers
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
D. What is R-290 and how does it compare to other refrigerants
in the water coolers end-use?
E. What use conditions is the EPA proposing in this action for
the updated listing for R-290 in new water coolers?
F. What additional information is the EPA including in this
proposed listing?
VII. Chillers
A. What is the EPA proposing in this action?
B. Background on Centrifugal Chillers and Positive Displacement
Chillers
C. What are the ASHRAE classifications for refrigerant
flammability and toxicity?
D. What is R-516A and how does it compare to other refrigerants
in the centrifugal chillers and positive displacement chillers end-
uses?
E. What use conditions is the EPA proposing in this action for
the new listing for R-516A in new centrifugal chillers and positive
displacement chillers?
F. What additional information is the EPA including in this
proposed listing?
VIII. Motor Vehicle Air Conditioning
A. What is the EPA proposing in this action?
B. Background on Motor Vehicle Air Conditioning
C. What are the ASHRAE classifications for refrigerant
flammability and toxicity used in MVACs?
D. What are refrigerants HFO-1234yf, R-444A, R-453A, R-456A, and
R-480A and how do they compare to other refrigerants in the same
end-use?
E. What use conditions is the EPA proposing in this action that
apply to proposed listings in this end-use?
F. Modification of ``unacceptability'' Listing Applicable to
Flammable Refrigerants in MVAC
G. Modifications to MVAC SNAP Requirements
IX. Fire Suppression and Explosion Protection
A. What is the EPA proposing in this action?
B. Background on Total Flooding Fire Suppression
C. What is 2-BTP/CO2 and how does it compare to other
fire suppressants in the same end-use?
D. What use conditions is the EPA proposing?
E. Why is the EPA proposing these specific use conditions?
F. What Additional Information Is the EPA Including in This
proposed listing?
X. On Which Topics Is the EPA Specifically Requesting Comment?
A. Residential and Light Commercial AC and Heat Pumps, Household
Refrigerators and Freezers, and Water Coolers
B. Chillers
C. Motor Vehicle Air Conditioning
D. Fire Suppression and Explosion Protection
XI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
I. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act
XII. References
I. Executive Summary
A. Purpose of the Regulatory Action
The EPA is proposing new and revised listings after our evaluation
of human health and environmental information for certain substitutes
under Clean Air Act (CAA) section 612, Significant New Alternatives
Policy (SNAP) program. The Agency is proposing action on these new
listings in the refrigeration and air conditioning (AC), and fire
suppression and explosion protection sectors based on the information
that the EPA has included in the docket. This proposed action would
provide new refrigerant and fire suppressant options in specific uses,
thereby increasing flexibility for industry. It also would revise
certain existing requirements under the SNAP program to allow for
greater consistency and compatibility with current industry
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safety standards such as those for AC equipment and for water coolers.
B. Summary of the Major Provisions of the Regulatory Action
This action proposes to list new alternatives as well as to revise
use conditions for existing alternatives for the refrigeration and AC
sector and to list a new alternative for the fire suppression and
explosion protection sector. Specifically, the EPA is proposing to:
Update existing use conditions for hydrofluorocarbon
(HFC)-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A in
residential and light commercial AC and heat pumps;
List the hydrocarbon refrigerant (HCR) blend HCR 4141,
hydrofluoroolefin (HFO)-1234ze(E), and the HFO/HFC blend R-516A as
acceptable, subject to use conditions, in residential and light
commercial AC and heat pumps;
List HCR 4141 as acceptable, subject to use conditions, in
household refrigerators and freezers;
Update existing use conditions for R-290 in water coolers;
List R-516A as acceptable, subject to use conditions, in
positive displacement chillers and centrifugal chillers;
List HFO-1234yf as acceptable, subject to use conditions,
in retrofit light- and medium-duty vehicle (LMDV) motor vehicle air
conditioning (MVAC), in new MVACs on buses, and in new MVACs in heavy-
duty on-highway (HDOH) vehicles;
List the blend R-444A as acceptable, subject to use
conditions, in retrofit LMDV MVACs and retrofit heavy-duty (HD) pickup
trucks and van MVACs (complete and incomplete);
List the blend R-456A as acceptable, subject to use
conditions, in retrofit LMDV MVACs, retrofit HD pickup trucks and van
MVACs (complete and incomplete), retrofit HDOH MVACs, and retrofit
MVACs on buses and trains;
List the blend R-480A as acceptable, subject to use
conditions, in retrofit LMDV MVACs, retrofit MVACs on HD pickup trucks
and vans (complete and incomplete), retrofit HDOH MVACs, and retrofit
MVACs on buses and trains;
List the blend R-453A as acceptable, subject to use
conditions, in retrofit MVACs on buses and trains; and
List 2-bromo-3,3,3-trifluoropropene/carbon dioxide (2-BTP/
CO2) as acceptable, subject to use conditions, as a total
flooding agent in fire suppression for use in normally unoccupied
spaces onboard aircraft including engine nacelles, auxiliary power
units (APUs), and cargo bays.
In summary, the common use conditions proposed for new household
refrigerators and freezers, residential and light commercial AC and
heat pumps, water coolers, and chillers are as follows:
(1) These refrigerants may be used only in new equipment, designed
specifically and clearly identified for use with the refrigerant. None
of these substitutes may be used as a conversion or ``retrofit''
refrigerant for existing equipment.
(2) These refrigerants must be used with warning labels on the
equipment and packaging that are similar to or match verbatim those
required by the relevant Underwriters Laboratories (UL) standard.
(3) Equipment must be marked with distinguishing red color-coded
hoses and piping to indicate use of a flammable refrigerant and marked
service ports, pipes, hoses, and other devices through which the
refrigerant is serviced.
Additional use conditions specific to particular end-uses also
apply and are discussed with each proposed listing. The regulatory text
of the proposed listings, including the proposed use conditions and
further information, appears in tables in the docket for this
rulemaking under the title ``Proposed Regulatory Text for SNAP Rule
27.'' All proposed new listings appear in proposed appendix Z of 40
Code of Federal Regulations (CFR) part 82, subpart G. The proposed
updated listings for HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-
290, and R-441A in residential and light commercial AC and heat pumps
and for R-290 in new water coolers appear as proposed changes in
appendix R, appendix W, and appendix V of 40 CFR part 82, subpart G.
II. Public Participation
A. Written Comments
Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2024-
0503 at https://www.regulations.gov (our preferred method), or the
other methods identified in the ADDRESSES section. Once submitted,
comments cannot be edited or removed from the docket. The EPA may
publish any comment received to its public docket. Do not submit to the
EPA's docket at https://www.regulations.gov any information you
consider to be Confidential Business Information (CBI), Proprietary
Business Information (PBI), or other information whose disclosure is
restricted by statute. Multimedia submissions (audio, video, etc.) must
be accompanied by a written comment. The written comment is considered
the official comment and should include discussion of all points you
wish to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (i.e., on the web,
cloud, or other file sharing system). Please visit https://www.epa.gov/dockets/commenting-epa-dockets for additional submission methods; the
full EPA public comment policy; information about CBI, PBI, or
multimedia submissions; and general guidance on making effective
comments.
B. Participation in Virtual Public Hearing
The EPA may hold a virtual public hearing if the agency receives a
request to hold one. Any party requesting a public hearing must notify
the contact listed in the FOR FURTHER INFORMATION CONTACT section,
which is Emily Maruyama at email address: [email protected] by 5
p.m. Eastern Daylight Time on or before November 17, 2025. If a virtual
public hearing is held, it will take place on or around November 25,
2025 and further information will be provided on the EPA's
Stratospheric Ozone website at https://www.epa.gov/snap.
The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule. Each
commenter will have 3-5 minutes to provide oral testimony. The EPA
encourages commenters to provide a copy of their oral testimony
electronically by emailing it to [email protected]. The EPA also
recommends submitting the text of your oral comments as written
comments to the rulemaking docket EPA-HQ-OAR-2024-0503. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral comments and
supporting information presented at the public hearing. The EPA may ask
clarifying questions during the oral presentations but will not respond
to the presentations at that time.
Please note that any updates made to any aspect of the hearing are
posted online at https://www.epa.gov/snap. While the EPA expects the
hearing to go forward as set forth above, please monitor our website or
contact Emily Maruyama, 202-564-2809, [email protected] to
determine if there are any updates. The EPA does
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not intend to publish a document in the Federal Register announcing
updates.
C. Public Access to Voluntary Consensus Safety Standards
The EPA is proposing to incorporate by reference the American
National Standards Institute/American Society of Heating, Refrigerating
and Air-Conditioning Engineers (ANSI/ASHRAE) Standard 15-2024, ``Safety
Standard for Refrigeration Systems'' (hereafter ``ASHRAE 15-2024'') in
the use conditions for one refrigerant proposed to be listed for use in
chillers. The standard concerns the safe design, construction,
installation, and operation of refrigeration systems. This standard is
available at https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources and may be purchased by mail at: 180
Technology Parkway NW, Peachtree Corners, Georgia 30092; by telephone:
1-800-527-4723 in the United States or Canada. ASHRAE 15-2024 and
ASHRAE 34-2024 are available as a bundle costing $178.00 for an
electronic copy or hard copy. The cost of obtaining this standard is
not a significant financial burden for equipment manufacturers or for
those selling, installing, and servicing the equipment. Therefore, the
ASHRAE standard the EPA is proposing to incorporate by reference is
reasonably available.
As one of two co-proposed options for use conditions for listings
in the residential and light commercial AC and heat pumps, household
refrigerators and freezers, and water coolers end-uses, the EPA
proposes to incorporate by reference several industry safety standards
from UL. The EPA is also proposing to incorporate by reference an
industry safety standard from UL in the use conditions for one
refrigerant proposed to be listed for use in chillers. The 2022
revision of the standard UL 60335-2-40, ``Household And Similar
Electrical Appliances--Safety--Part 2-40: Particular Requirements for
Electrical Heat Pumps, Air-Conditioners and Dehumidifiers'' (hereafter
``UL 60335-2-40''), 4th edition, December 15, 2022 is available at:
https://www.shopulstandards.com/ProductDetail.aspx?UniqueKey=43802, and
may be purchased by mail at: COMM 2000, 151 Eastern Avenue,
Bensenville, IL 60106; Email: [email protected]; Telephone: 1-
888-853-3503 in the United States or Canada (other countries dial 1-
415-352-2178); internet address: https://ulstandards.ul.com or https://www.shopulstandards.com. The cost of the 2022 revision to UL 60335-2-40
is $521 for an electronic copy and $652 for a hard copy.
The 2024 revision of the standard UL 60335-2-24, ``Household And
Similar Electrical Appliances--Safety--Part 2-24: Particular
Requirements for Refrigerating Appliances, Ice-Cream Appliances and
Ice-Makers,'' (hereafter ``UL 60335-2-24''), 3rd edition, July 29,
2022, and revisions through February 29, 2024, is available at: https://www.shopulstandards.com/ProductDetail.aspx?productId=UL60335-2-24_3_S_20220729. It may be purchased by mail, email, or telephone as
described in the previous paragraph for UL 60335-2-40. The cost of the
2024 revision to the 3rd edition of UL 60335-2-24 is $555 for an
electronic copy and $694 for a hard copy.
The February 2024 revision of the standard UL 399, ``Drinking Water
Coolers'' (hereafter ``UL 399''), 8th edition, March 30, 2017, and
revisions through February 28, 2024, is available at: https://www.shopulstandards.com/ProductDetail.aspx?productId=UL399_8_S_20170330. It may be purchased by
mail, email, or telephone as described in the previous paragraphs for
UL 60335-2-40 and UL 60335-2-24. The cost of the February 2024 revision
to the 8th edition of UL 399 is $798 for an electronic copy and $998
for a hard copy.
UL also offers a subscription service to the Standards
Certification Customer Library that allows unlimited access to their
standards and related documents. The cost of obtaining these standards
is not a significant financial burden for equipment manufacturers and
purchase is not necessary for those selling, installing, and servicing
the equipment. Therefore, the UL standards the EPA is proposing to
incorporate by reference are reasonably available.
III. General Information
A. Does this action apply to me?
The following list identifies regulated entities that may be
affected by this rule and their respective North American Industrial
Classification System (NAICS) codes:
New Single-Family Housing Construction (except For-Sale
Builders) (236115).
Commercial and Institutional Building Construction
(236220).
Plumbing, Heating, and Air Conditioning Contractors
(238220).
All Other Basic Organic Chemical Manufacturing (325199).
Air Conditioning and Warm Air Heating Equipment and
Commercial and Industrial Refrigeration Equipment Manufacturing
(333415).
Aircraft Manufacturing (336411).
Motor Vehicle Manufacturing (3361).
Motor Vehicle Parts Manufacturing (3363).
Refrigeration Equipment and Supplies Merchant Wholesalers
(423740).
Recyclable Material Merchant Wholesalers (423930).
Convenience Stores (445120).
General Automotive Repair (811111).
Appliance Repair and Maintenance (811412).
Fire Protection (922160).
This list is not intended to be exhaustive, but rather to provide a
guide for readers regarding entities likely to be affected by this
action. To determine whether your facility, company, business, or
organization could be affected by this action, you should carefully
examine the regulations at 40 CFR part 82, subpart G, and the proposed
revisions. If you have questions regarding the applicability of this
action to a particular entity, consult the person listed in the FOR
FURTHER INFORMATION CONTACT section.
B. What action is the Agency proposing to take?
The EPA is proposing to list new alternatives for the refrigeration
and AC sector and for the fire suppression and explosion protection
sector. The Agency also proposes to revise use conditions for existing
alternatives for the refrigeration and AC sector and list a new
alternative for the fire suppression and explosion protection sector.
C. What is the Agency's authority for taking this action?
This action is based upon the EPA's authority under CAA section
612. The SNAP program implements CAA section 612. The first SNAP
rulemaking was promulgated in 1994, and set forth the framework for the
program in addition to finalizing listings for a number of alternatives
as acceptable. Since that time, EPA has issued 26 final rules and 39
Federal Register notices under the SNAP program. Several major
provisions of CAA section 612 are as follows:
CAA section 612(c) requires the EPA to promulgate rules making it
unlawful to ``replace any class I [(chlorofluorocarbon (CFC), halon,
carbon tetrachloride, methyl chloroform, methyl bromide,
hydrobromofluorocarbon, and chlorobromomethane)] or class II
[(hydrochlorofluorocarbon (HCFC))] substance with any substitute
substance which the Administrator determines
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may present adverse effects to human health or the environment, where
the Administrator has identified an alternative to such replacement
that (1) reduces the overall risk to human health and the environment;
and (2) is currently or potentially available.'' CAA section 612(c)
requires the EPA to publish a list of the substitutes that it finds to
be unacceptable for specific uses and to publish a corresponding list
of acceptable substitutes for specific uses. Since its inception, the
SNAP program has continually responded to petitions and submissions
using either a rulemaking or notice to convey listing decisions.
CAA section 612(d) grants the right to any person to petition the
Administrator to add a substance to, or delete a substance from, the
lists published in accordance with section 612(c).
CAA section 612(e) directs the EPA to require ``any person who
produces a chemical substitute for a class I substance . . . to notify
the [Agency] not less than 90 days before new or existing chemicals are
introduced into interstate commerce for significant new use as
substitutes for a class I substance.'' The producer must also provide
the Agency with the producer's unpublished health and safety studies on
such substitutes.
The regulations for the SNAP program are promulgated at 40 CFR part
82, subpart G, and the Agency's process for reviewing SNAP submissions
is described in regulations at 40 CFR 82.180. Under these rules, the
Agency identified five types of listing decisions: acceptable;
acceptable, subject to use conditions; acceptable, subject to narrowed
use limits; unacceptable; and pending. Use conditions and narrowed use
limits are both considered ``use restrictions.'' Substitutes that are
deemed acceptable with no use restrictions (no use conditions or
narrowed use limits) can be used for all applications within the
relevant end-uses in the sector. After reviewing a substitute, the
Agency may determine that a substitute is acceptable if certain
conditions in the way that the substitute is used are met to minimize
risks to human health and the environment. The EPA describes such
substitutes as ``acceptable, subject to use conditions.'' \1\ For some
substitutes, the Agency may permit a narrowed range of use within an
end-use or sector. For example, the Agency may limit the use of a
substitute to certain end-uses or specific applications within an
industry sector. The EPA describes these substitutes as ``acceptable
subject to narrowed use limits.'' \2\ Under the narrowed use limit,
users intending to adopt these substitutes ``must ascertain that other
alternatives are not technically feasible.'' \3\ CAA section 612 and
the EPA regulations do not allow the introduction of substitutes on the
``unacceptable'' list into interstate commerce unless and until the
effective date of a final rule that changes an unacceptable listing to
acceptable, acceptable subject to use conditions, or acceptable subject
to narrowed use limits.
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\1\ 40 CFR 82.180(b)(2).
\2\ 40 CFR 82.180(b)(3).
\3\ Id.
---------------------------------------------------------------------------
Many SNAP listings include ``comments'' or ``further information''
to provide additional information on substitutes. Since this additional
information is not part of the regulatory decision under SNAP, these
statements are not binding for use of the substitute under the SNAP
program. The EPA encourages users of substitutes to apply all
statements in the ``Further Information'' column in their use of these
substitutes. Regulatory requirements so listed may be binding under
other regulatory programs (e.g., worker protection regulations
promulgated by United States Occupational Safety and Health
Administration (OSHA) or Department of Transportation (DOT)
requirements for transport of flammable gases). In many instances, the
information simply refers to sound operating practices that have
already been identified in existing industry and/or building codes or
safety standards. Thus, many of the statements, if adopted, would not
require the affected user to make significant changes in existing
operating practices.
The ``Further Information'' column also does not necessarily
include all other legal obligations pertaining to the manufacture, use,
handling, and disposal of the listed substitute. Flammable refrigerants
being recovered or otherwise disposed of from commercial or industrial
air conditioning equipment are likely to be considered hazardous waste
under the Resource Conservation and Recovery Act (RCRA).\4\ Lower
flammability ignitable spent refrigerants that are recycled for reuse
can follow alternative safety standards under 40 CFR part 266, subpart
Q, instead of the full RCRA Subtitle C hazardous waste requirements.
---------------------------------------------------------------------------
\4\ 40 CFR parts 260-270.
---------------------------------------------------------------------------
For additional information on the SNAP program, visit the EPA's
SNAP website at https://www.epa.gov/snap. The lists of acceptable
substitutes for Ozone-Depleting Substances (ODS) in all industrial
sectors are available at https://www.epa.gov/snap/snap-substitutes-sector. For more information on the Agency's process for administering
the SNAP program or criteria for evaluation of substitutes, refer to
the initial SNAP rulemaking, codified at 40 CFR part 82, subpart G.\5\
SNAP decisions and the appropriate Federal Register (FR) citations can
be found at https://www.epa.gov/snap/snap-regulations. Substitutes
listed as unacceptable; acceptable, subject to narrowed use limits; or
acceptable, subject to use conditions, are also listed in the
appendices of 40 CFR part 82, subpart G.
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\5\ See 59 FR 13044; March 18, 1994.
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D. What are the guiding principles of the SNAP program and what are the
SNAP criteria for evaluating substitutes?
The guiding principles of the SNAP program are described in the
preamble to the first SNAP rule.\6\ These principles, reiterated and
described in many subsequent SNAP rulemakings, are:
---------------------------------------------------------------------------
\6\ Ibid.
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1. Evaluate substitutes within a comparative risk framework: The
SNAP program evaluates the risk of substitutes compared to available or
potentially available substitutes which the new substitutes are
intended to replace.
2. Do not require that substitutes be risk free to be found
acceptable: Substitutes found to be acceptable must not pose
significantly greater risk than other substitutes, but they do not have
to be risk free.
3. Restrict those substitutes that are significantly worse: The EPA
does not intend to restrict a substitute if it has only marginally
greater risk.
4. Evaluate risks by use: Central to SNAP's evaluations is the
intersection between the characteristics of the substitute itself and
its specific end-use application.
5. Provide the regulated community with information as soon as
possible.
6. Do not endorse products manufactured by specific companies.
7. Defer to other environmental regulations when warranted: In some
cases, the EPA and other federal agencies have developed extensive
regulations under other sections of the CAA or other statutes that
address potential environmental or human health effects that may result
from the use of certain substitutes. The SNAP program takes existing
regulations under other programs into account when reviewing
substitutes.
[[Page 50771]]
In making decisions regarding whether a substitute is acceptable or
unacceptable, and whether substitutes present risks that are lower than
or comparable to risks from other substitutes that are currently or
potentially available in the end-uses under consideration, the EPA
examines the following criteria in 40 CFR 82.180(a)(7): ``(i)
atmospheric effects and related health and environmental impacts; (ii)
general population risks from ambient exposure to compounds with direct
toxicity and to increased ground-level ozone; (iii) ecosystem risks;
(iv) occupational risks; (v) consumer risks; (vi) flammability; and
(vii) cost and availability of the substitute.'' To enable the EPA to
assess these criteria, we require submitters to include various
information including but not limited to ozone depletion potential
(ODP), flammability, and the potential for human exposure. The EPA
applies the same criteria to all evaluations; however, the Agency
notes, for different sectors, the relevance of the factors may vary.
For example, for the fire suppression sector, flammability would be
considered differently than for the other sectors.
To assess atmospheric effects, the EPA uses both the ODP of class I
and class II ODS in appendix A of 40 CFR part 82, subpart A and where
appropriate the exchange values for HFCs listed in the American
Innovation and Manufacturing (AIM) Act and codified at 40 CFR part 84,
subpart A. For both ODP and exchange values, there are equivalent
values listed in Montreal Protocol on Substances that Deplete the Ozone
Layer (Montreal Protocol) annexes.\7\ For substitute compounds without
these values, the Agency uses information provided in the World
Meteorological Organization (WMO) 2022 assessment,\8\ and other
relevant sources. For chemical blends, such as the fire suppressant
blend proposed as acceptable in this document, the EPA calculates
atmospheric effects values as a mass weighted average of each component
of the blend.
---------------------------------------------------------------------------
\7\ https://ozone.unep.org/treaties/montreal-protocol/montreal-protocol-substances-deplete-ozone-layer.
\8\ WMO, Scientific Assessment of Ozone Depletion: 2022, GAW
Report No. 278, 509 pp.; WMO: Geneva, 2022. Available at: https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022.pdf. (WMO, 2022).
---------------------------------------------------------------------------
In a future notice and comment rulemaking, the EPA plans to revisit
the criteria used for these evaluations particularly regarding
atmospheric effects. The EPA acknowledges that there is an important
relationship between ODS and HFCs. Therefore, this future rulemaking
may be combined with other relevant proposals in order to consider the
provisions regarding substitutes under CAA Title VI and the AIM Act
subsection (i) paragraph (5) holistically. The Agency is not proposing
or seeking comment on these topics in this rulemaking.
The SNAP program uses exposure assessments to estimate
concentration levels of substitutes to which workers, consumers, the
general population, and environmental receptors may be exposed over a
determined period of time. These assessments are based on personal
monitoring data or area sampling data if available. Exposure
assessments may be conducted for many types of releases including: (1)
releases in the workplace and in homes; (2) releases to ambient air and
surface water; (3) releases from the management of solid wastes.
The SNAP program uses toxicity data to assess the possible health
and environmental effects of exposure to substitutes. We use broad
health-based criteria such as: (1) Permissible Exposure Limits (PELs)
for occupational exposure; (2) inhalation reference concentrations
(RfCs) for noncarcinogenic effects on the general population; and (3)
cancer slope factors for carcinogenic risk to members of the general
population. When considering risks in the workplace, if OSHA has not
issued a PEL for a compound, the EPA then considers Recommended
Exposure Limits from the National Institute for Occupational Safety and
Health, Workplace Environmental Exposure Limits (WEELs) set by the
American Industrial Hygiene Association (AIHA), or Threshold Limit
Values (TLVs) set by the American Conference of Governmental Industrial
Hygienists. If limits for occupational exposure or exposure to the
general population are not already established, then the EPA derives
these values following the Agency's peer reviewed guidelines. Exposure
information is combined with toxicity information to explore any basis
for concern. Toxicity data are used with existing EPA guidelines to
develop health-based limits for interim use in these risk
characterizations.
The SNAP program examines flammability as a safety concern for
workers and consumers. The EPA assesses flammability risk using data
on: (1) flash point and flammability limits (e.g., OSHA flammability/
combustibility classifications); (2) data on testing of blends with
flammable components; (3) test data on flammability in consumer
applications conducted by independent laboratories; and (4) information
on flammability risk mitigation techniques.
The SNAP program also examines other potential environmental
impacts such as ecotoxicity and local air quality impacts. A compound
that is likely to be discharged to water may be evaluated for impacts
on aquatic life. Some substitutes are volatile organic compounds (VOC).
The EPA also notes whenever a potential substitute is considered a
hazardous or toxic air pollutant (under CAA sections 112(b) and 202(l))
or hazardous waste under the RCRA subtitle C regulations.
The EPA also notes that the U.S. government has not adopted a
single definition of per- and polyfluoroalkyl substances (PFAS) and has
not included HFCs, HFOs, 2-BTP, or trifluoroacetic acid (TFA) in any
PFAS-related restrictions. There also is no consensus definition of
PFAS as a class of chemicals, and different definitions can result in
more or fewer chemicals being classified as PFAS. There are several
HFCs and HFOs, among other chemicals such as 2-BTP and TFA, that are
defined as PFAS by some states and other jurisdictions. The EPA is not
proposing or seeking comment on any definitions of PFAS in this
rulemaking.
As described above, the proposed listing decisions consider whether
substitutes present risks that are lower than or comparable to risks
from other substitutes that are currently or potentially available in
the end-uses under consideration. The EPA does not assume any
substitute is risk free.
IV. Residential and Light Commercial Air Conditioning and Heat Pumps
A. What is the EPA proposing in this action?
The EPA is proposing to list R-516A and HFO-1234ze(E) as
acceptable, subject to use conditions, for use in all applications
under the residential and light commercial AC and heat pumps end-use.
The EPA is also proposing to list HCR 4141 as acceptable, subject to
use conditions, for use in self-contained room AC, a limited subset of
equipment covered by this end-use.
SNAP use conditions are designed to ensure that refrigerants are
listed for specific end-uses and in a way that mitigates risks to human
health and the environment. The use conditions proposed for these new
listings are discussed in Section IV.F. They include a requirement that
these refrigerants be used in new equipment only and specific
requirements for warning labels and markings. The EPA is also co-
proposing two options for an additional use condition related to
equipment
[[Page 50772]]
certification or industry safety standard requirements. These options
are described in detail in Section IV.F.4. One option would incorporate
by reference a new edition of the safety standard for this end-use. The
second option would require residential and light commercial AC and
heat pump equipment to be certified to a U.S. industry consensus safety
standard by an organization that is recognized as a Nationally
Recognized Testing Laboratory (NRTL).
The proposed regulatory text for listings using the third-party
certification option can be found in the docket for this rulemaking
under the title ``Proposed Regulatory Text for SNAP Rule 27'' in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Third-Party Certification Option (co-proposed as an alternative to
Section III).'' The proposed regulatory text for listings using the
incorporate by reference option can be found in the docket for this
rulemaking under the title ``Proposed Regulatory Text for SNAP Rule
27'' in the section ``Proposed revisions to Appendices R, V, W, and new
Appendix Z--Incorporate by Reference Option.'' If one of the use
condition options is finalized, the EPA would publish corresponding
finalized listings for R-516A, HCR 4141, and HFO-1234ze(E) in new
residential and light commercial AC and heat pump equipment in appendix
Z of 40 CFR part 82, subpart G.
The EPA is also proposing to update use conditions for the
previously listed refrigerants HFC-32, R-452B, R-454A, R-454B, R-454C,
R-457A, R-290, and R-441A for use in the residential and light
commercial AC and heat pumps end-use. Information on the previous
listing locations and the existing use conditions for these
refrigerants can be found in Section IV.E.
The EPA proposes that the same use conditions described previously
in this section for the new listings in this end-use would also apply
to these updated listings. The EPA is also co-proposing the same two
options for a use condition related to equipment certification or
industry safety standard requirements. For these updated listings, the
EPA intends to finalize one of these co-proposed options along with an
appropriate transition period to provide manufacturers with opportunity
for a smooth transition between the existing and updated use
conditions. Throughout Sections IV. and VI. in this document, the term
``updated use conditions'' refers to the set of use conditions being
proposed that would apply to new equipment manufactured after the
effective date of a final rule. The updated use conditions would
neither apply to nor affect equipment manufactured before the effective
date of the final rule. All the proposed use conditions are described
in detail in Section IV.F. The EPA would update the existing listings
for these substitutes in the following locations:
HFC-32 in new residential and light commercial AC and heat
pumps--self-contained room AC only in appendix R of 40 CFR part 82,
subpart G;
HFC-32 in new residential and light commercial AC and heat
pumps excluding self-contained room AC in appendix W of 40 CFR part 82,
subpart G;
R-452B, R-454A, R-454B, R-454C, and R-457A in new
residential and light commercial AC and heat pumps in appendix W of 40
CFR part 82, subpart G; and
R-290 and R-441A in new residential and light commercial
AC and heat pumps--self-contained room AC only in appendix R of 40 CFR
part 82, subpart G.
This proposal would also add listing numbers to each row in the
end-use column of appendix W in the table ``Refrigerants--Substitutes
Acceptable Subject to Use Conditions.'' Additionally, this proposal
would fix a typographical error in appendix R and appendix V where the
name of a standard was written as ``UL 60355-2-89'' instead of ``UL
60335-2-89'' in the ``Further information'' column. These formatting
and typographical edits would not substantively change any listings in
the tables and would improve clarity and readability.
B. Background on Residential and Light Commercial AC and Heat Pumps
The residential and light commercial AC and heat pumps end-use
includes equipment for cooling air in individual rooms, single-family
homes, and small commercial buildings. Heat pumps are equipment types
that offer both air heating and cooling options for such locations.
This end-use differs from commercial comfort AC, which uses chillers to
cool water that is then circulated to cool air throughout a large
commercial building, such as an office building or hotel. This end-use
includes both self-contained and split systems. Self-contained systems
include some rooftop AC units (e.g., those ducted to supply conditioned
air to multiple spaces) and many types of room ACs, including packaged
terminal air conditioners (PTACs), packaged terminal heat pumps
(PTHPs), window AC units, portable room AC units, and wall-mounted
self-contained ACs, designed for use in a single room. The EPA refers
to the variety of self-contained equipment for cooling a single room
using the phrase ``residential and light commercial AC and heat pumps--
self-contained room AC,'' irrespective of whether they are air
conditioners, providing space cooling, or heat pumps that can either
heat or cool a space. Split systems include ducted and non-ducted mini-
splits (which might also be designed for use in a single room), multi-
splits and variable refrigerant flow (VRF) systems, and ducted unitary
splits. Water-source and ground-source heat pumps (WSHPs/GSHPs) often
are packaged systems similar to self-contained equipment but could be
applied with the condenser separated from the other components similar
to split systems. Examples of equipment for residential and light
commercial AC and heat pumps include:
Unitary AC or unitary split systems, also called central
air conditioners: These systems include an outdoor unit with a
condenser and a compressor, refrigerant lines, an indoor unit with an
evaporator, and ducts to carry cooled air throughout a building.
Central heat pumps are similar but offer the choice to either heat or
cool the indoor space.
Multi-split and mini-split air conditioners and heat
pumps: Multi-split systems include one or more outdoor unit(s) with a
condenser and compressor, and multiple indoor units, each of which is
connected to the outdoor unit by refrigerant lines. Mini-split systems
are similar to multi-split systems, but they have only a single outdoor
unit and a single indoor unit, and they cool a single room. Non-ducted
multi-splits and mini-splits provide cooled or heated air directly from
the indoor unit rather than providing the air through ducts.
Rooftop AC units: These are units that combine the
compressor, condenser, and evaporator in a single package and may
contain additional components for filtration and dehumidification. Most
units also include dampers to control air intake. Rooftop AC units cool
or heat outside air that is then delivered to the space directly
through the ceiling or a duct network. Rooftop AC units are common in
small commercial buildings such as a single store in a mall with no
indoor passageways between stores (e.g., a ``strip-mall''). They can
also be set up in an array to provide cooling or heating throughout a
larger commercial establishment such as a department store or
supermarket.
[[Page 50773]]
Window air conditioners: These are self-contained units
that fit in a window with the condenser extending outside the window.
PTACs and PTHPs: These are self-contained units that
consist of a separate, un-encased combination of heating and cooling
assemblies mounted through a wall. PTACs and PTHPs are intended for use
in a single room and use no ducts to carry cooled air and no external
refrigerant lines. Typical applications include motel or dormitory air
conditioners.
Portable room air conditioners: These are self-contained
units that usually have wheels and are designed to be moved easily from
room to room. They may contain an exhaust hose that can be placed
through a window or door to eject heat to the outside.
WSHPs and GSHPs: These are similar to unitary split
systems except that, when in cooling mode, heat is ejected from the
condenser through a second circuit rather than directly with outside
air. The second circuit transfers the heat to the ground, ground water,
or another body of water such as a lake. Water is used for this
transfer, but brine can be used if temperatures would risk freezing.
Some systems can perform heating in a similar matter with the
refrigerant circuit running in reverse. Regardless, the term ``heat
pump'' is most often used.
Unless specified, all these types of AC and heat pump equipment
would be subject to the listing decisions under this rule for the
identified substitutes. Of these types of equipment, window air
conditioners, PTACs, PTHPs, rooftop AC units, portable room air
conditioners, and often GSHPs and WSHPs are self-contained equipment
with the condenser, compressor, evaporator, and tubing all within a
single unit casing. In contrast, unitary split systems, multi-split
systems, and mini-split systems have an outdoor condenser that is
separate from an indoor unit. Compared to these split systems, self-
contained equipment typically has smaller charge sizes, fewer locations
that are prone to leak, and is less likely to require servicing by a
technician. These types of AC and heat pump equipment, both self-
contained and split systems, typically fall under the scope of UL
60335-2-40.
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
ASHRAE 34-2024 assigns a safety group for each refrigerant, which
consists of two to three alphanumeric characters (e.g., A2L or B1).\9\
The initial character indicates the toxicity, and the numeral, with or
without suffix letter, denotes the flammability. ASHRAE classifies
Class A refrigerants as refrigerants for which toxicity has not been
identified at concentrations less than or equal to 400 parts per
million (ppm) by volume, based on data used to determine threshold
limit value-time-weighted average (TLV-TWA) or consistent indices.
Class B signifies refrigerants for which there is evidence of toxicity
at concentrations below 400 ppm by volume, based on data used to
determine TLV-TWA or consistent indices.
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\9\ ASHRAE, 2024b. ANSI/ASHRAE Standard 34-2024: Designation and
Safety Classification of Refrigerants.
---------------------------------------------------------------------------
ASHRAE 34-2024 also assigns refrigerants a flammability class of 1,
2, 2L, or 3. Tests for flammability are conducted in accordance with
American Society for Testing and Materials (ASTM) E681 using a spark
ignition source at 140 [deg]F (60 [deg]C) and 14.7 psia (101.3 kPa).
The flammability class ``1'' is given to refrigerants that, when
tested, show no flame propagation. The flammability class ``2'' is
given to refrigerants that, when tested, exhibit flame propagation,
have a heat of combustion less than 19,000 kJ/kg (8,169 BTU/lb), and
have a lower flammability limit (LFL) greater than 0.10 kg/m\3\. The
flammability class ``2L'' is given to refrigerants that meet the
requirements of the ``2'' class and have a maximum burning velocity of
10 cm/s or lower when tested in dry air at 73.4 [deg]F (23.0 [deg]C)
and 14.7 psia (101.3 kPa). Throughout this document, refrigerants in
the flammability class of ``2L'' are referred to as lower flammability
refrigerants. The flammability class ``3'' is given to refrigerants
that, when tested, exhibit flame propagation and either have a heat of
combustion of 19,000 kJ/kg (8,169 BTU/lb) or greater or have an LFL of
0.10 kg/m\3\ or lower. Throughout this document, refrigerants in the
flammability class of ``3'' are referred to as higher flammability
refrigerants.\10\ Flammability for refrigerant blends are designated
based on the worst case of formulation for flammability and the worst
case of fractionation for flammability determined for the blend.
Information about refrigerant safety groups is consistent with that in
prior rules under the SNAP program. See Section II.A.2. of SNAP Rule 26
\11\ for more detail. Using these safety groups, HFO-1234ze(E), HFC-32
and the refrigerant blends R-452B, R-454A, R-454B, R-454C, R-457A, and
R-516A are in the A2L Safety Group, while R-290, R-441A, and the
components of HCR 4141 are in the A3 Safety Group.
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\10\ To see a diagram depicting these classifications, see SNAP
Rule 26, 89 FR 50417; June 13, 2024.
\11\ See 89 FR 50410; June 13, 2024.
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D. What are the refrigerants the EPA is proposing to list as acceptable
in the residential and light commercial AC and heat pumps end-use and
how do they compare to other refrigerants in this end-use?
The EPA is proposing to list HCR 4141, HFO-1234ze(E), and R-516A as
acceptable, subject to use conditions, for this end-use. HCR 4141 is a
higher flammability refrigerant blend with each component in the A3
Safety Group. HFO-1234ze(E) and R-516A are lower flammability
refrigerants, both in the A2L Safety Group. HCR 4141 is a blend of the
saturated hydrocarbons (HCs) isobutane (R-600a), n-butane (R-600), and
propane (R-290); the percentages of each component in the blend are
claimed as CBI. The respective Chemical Abstracts Service Registry
Identification Numbers (CAS Reg. Nos.) of R-600a, R-600, and R-290 are
75-28-5, 106-97-8, and 74-98-6. HFO-1234ze(E), also known by the trade
names ``Solstice[supreg] ze and Solstice[supreg] 1234ze,'' is also
known as trans-1,3,3,3-tetrafluoroprop-1-ene (CAS Reg. No. 29118-24-9).
R-516A, also known by the trade name ``Forane[supreg] 516A,'' is a
blend consisting of 77.5 percent HFO-1234yf (also known as 2,3,3,3-
tetrafluoroprop-1-ene, CAS Reg. No. 754-12-1), 14 percent HFC-152a
(also known as 1,1-difluoroethane, CAS Reg. No. 75-37-6), and 8.5
percent HFC-134a (also known as 1,1,1,2-tetrafluoroethane, CAS Reg. No.
811-97-2).
Redacted submissions and supporting documentation for HCR 4141,
HFO-1234ze(E), and R-516A are provided in the docket. The EPA performed
a risk screening assessment to examine the human health and
environmental risks of each of these substitutes which are available in
the docket.\12\ \13\ \14\
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\12\ ICF, 2025a. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: HCR 4141.
\13\ ICF, 2025b. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: HFO-1234ze(E) (Solstice[supreg] ze, Solstice[supreg]
1234ze).
\14\ ICF, 2025c. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-516A (Forane[supreg] 516A).
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Environmental information: The specific atmospheric effects values
can be found in the individual risk screens for HCR 4141, HFO-
1234ze(E), and R-
[[Page 50774]]
516A. These were determined consistent with the source information
noted in Section III.C. above as well as using the methodology for
determining values for blends of chemicals (i.e., determined by the
percentage of each component). HFO-1234ze(E) and the components of R-
516A--HFC-134a, HFC-152a, and HFO-1234yf--are excluded from the EPA's
regulatory definition of VOC \15\ addressing the development of State
Implementation Plans (SIPs) to attain and maintain the National Ambient
Air Quality Standards (NAAQS).\16\
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\15\ 40 CFR 51.100(s).
\16\ 40 CFR 51.100(s) states that ``any compound of carbon''
which ``participates in atmospheric photochemical reactions'' is
considered a VOC unless expressly excluded in that provision based
on a determination of ``negligible photochemical reactivity'' when
compared to ethane's photochemical reactivity.
---------------------------------------------------------------------------
HCR 4141 is a blend of saturated HCs, all of which fall under the
EPA's regulatory definition of VOC \17\ for the purpose of developing
SIPs to attain and maintain the NAAQS. The maximum incremental
reactivities (MIRs) \18\ of the components of this blend are as high or
higher and more reactive than that of ethane (MIR of 0.26 g
O3/g ethane), which the EPA uses as a threshold to determine
whether substances may have negligible photochemical reactivity in the
lower atmosphere (troposphere). The MIR of the blend HCR 4141 is
expected to be less than that of R-600a (MIR of 1.23 g O3/g
isobutane) and R-290 (MIR of 0.49 g O3/g propane). The EPA
has previously listed R-290 as acceptable, subject to use conditions,
in residential and light commercial AC and heat pumps--self-contained
room AC.
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\17\ 40 CFR 51.100(s).
\18\ MIR values are from ``Development of the SAPRC-07 Chemical
Mechanism and Updated Ozone Reactivity Scales,'' Report to the
California Air Resources Board by William P.L. Carter. Revised
January 27, 2010. (Carter, 2010).
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The EPA has previously performed air quality modeling on various
scenarios to determine whether emissions of HC refrigerants could have
a significant impact on local air quality, particularly in certain
cities with challenges in achieving attainment of the NAAQS for ground-
level ozone. The EPA prepared an analysis in 2014 \19\ and a follow-on
analysis in 2016 \20\ to evaluate the potential impact of the use of HC
refrigerants on ground-level ozone concentrations in the United States.
These analyses estimated refrigerant emissions from refrigeration and
AC equipment which were all assumed to contain propylene, R-600a, R-
290, and/or the HC blends R-441A and R-443A under different scenarios.
The EPA concluded that potential emissions of saturated HC refrigerants
used in refrigeration and AC equipment, such as R-290 and R-600a, do
not have a significant impact on local air quality and would not have a
greater overall impact on human health and the environment than other
acceptable refrigerants, even if their market share grew much greater
than anticipated.\21\
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\19\ ICF, 2014. Assessment of the Potential Impact of
Hydrocarbon Refrigerants on Ground Level Ozone Concentrations.
February, 2014.
\20\ ICF, 2016. Additional Follow-on Assessment of the Potential
Impact of Hydrocarbon Refrigerants on Ground Level Ozone
Concentrations. September, 2016.
\21\ ICF, 2014.
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The analysis evaluated HC refrigerant in the following end-uses:
cold storage warehouses, chillers, residential and light commercial AC
and heat pumps, and specific small, self-contained refrigeration and
air-conditioning units. The EPA considered it possible that HC
refrigerants may be used in those end-uses because either SNAP had
received applications for HCs in these end-uses or UL standards that
specifically address higher flammability refrigerants existed for these
end-uses, showing industry interest in using HC refrigerants. The
scenarios for these end-uses were modeled to consider whether they were
or were not exempted from the CAA section 608 venting prohibition.\22\
The HC emissions used for these scenarios were estimated based on the
EPA's Vintaging Model, and their potential contributions to ozone
concentrations were assessed using the EPA's Community Multiscale Air
Quality (CMAQ) model.
---------------------------------------------------------------------------
\22\ ICF, 2016.
---------------------------------------------------------------------------
CMAQ modeling was performed for the Atlanta, Houston, and Los
Angeles regions, due to their distinctive geographic settings and
chronic high levels of ground-level ozone. Their ozone concentrations
were used to estimate and scale for national emission estimates. Ozone
concentrations due to HC refrigerant emissions were compared to 70 ppb
for the purposes of illustrating that even under a worst-case scenario,
the projected impacts on ground-level ozone would be small.\23\ We
found that even if all the HC refrigerants in appliances in end-uses
listed as acceptable, subject to use conditions, and listed as
acceptable in previous rules were to be emitted, as well as two
unsaturated HC refrigerants that the EPA ultimately listed as
unacceptable in certain end-uses, there would be a worst-case impact of
less than 0.15 ppb for ground-level ozone in the Los Angeles area.\24\
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\23\ The current NAAQS for ozone and other photochemical
oxidants is 0.070 ppm, as the fourth-highest daily maximum 8-hour
concentration, averaged across three consecutive years. The level of
the NAAQS, 0.070 ppm, is equivalent to 70 ppb.
\24\ ICF, 2016. Op cit.
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In 2022, the EPA conducted a more recent air quality analysis,
which considered additional end-uses and recently listed acceptable
refrigerants (e.g., R-1150 [ethylene] in very low temperature
refrigeration). This analysis did not include the refrigerants
propylene and R-443A due to the EPA's listing of these refrigerants as
unacceptable in certain end-uses, citing their potential for local air
quality impacts.\25\ The analysis utilized updated models and projected
future impacts out to 2040.\26\ The EPA found that the revised air
quality models showed slightly greater impacts compared to our 2014 and
2016 analyses when using the same refrigerants in the same end-uses.
For example, when looking at a worst-case scenario where the most
reactive HC refrigerant analyzed, propylene, was used broadly in all
refrigeration and AC end-uses, the largest incremental amount of
O3 generated was 7.80 ppb in the 2016 analysis, which
increased to 8.62 ppb in the 2022 analysis. Changes to the CMAQ model,
more updated refrigerant emissions estimates from the EPA's Vintaging
Model, as well as the longer time-period considered, resulted in the
changes in impacts. However, the 2022 analysis also included analyses
that accounted for updates in the SNAP listings since the prior
analysis. In the 2022 analysis scenarios that estimated emissions if HC
refrigerants then listed as acceptable, subject to use conditions,
reached 100 percent market penetration in the end-uses in SNAP Rule 25,
the worst-case increase in ground-level ozone in Los Angeles was 0.012
ppb, in Houston was 0.009 ppb, and in Atlanta was 0.006 ppb. Unlike the
2016 analysis, the 2022 analysis only examined impacts of propylene in
the worst-case scenario and did not otherwise model propylene or the
propylene blend R-443A in the more reasonable scenarios, as those
refrigerants were listed as unacceptable in SNAP Rule 21.\27\ Because
propylene and R-443A had a much higher potential impact on local air
quality than the saturated HCs, removing propylene and R-443A from the
modeling resulted in lower projected impacts on local air quality in
the 2022 analysis compared to the 2016 analysis in the more reasonable
scenarios. The
[[Page 50775]]
EPA considers the 2022 modeling to further support the Agency's earlier
conclusions in 2015 and 2016 that use of saturated HCs as refrigerants
would not result in a significant increase in ground-level ozone.
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\25\ See SNAP Rule 21, 81 FR 86778; December 1, 2016.
\26\ ICF, 2022. Additional Assessment of the Potential Impact of
Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. May
2022.
\27\ See 81 FR 86778; December 1, 2016.
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HCR 4141 is a blend of saturated HCs. The potential of this
refrigerant blend to form ground-level ozone, as determined by the MIRs
of its components, is expected to be less than that of R-600a or the
blend R-441A, and greater than that of R-290, as mentioned earlier in
this section. The EPA is proposing to list HCR 4141 as acceptable,
subject to use conditions, for use in household refrigerators and
freezers, where other HC refrigerants with comparable MIRs are listed
as acceptable, subject to use conditions, and for use in residential
and light commercial AC and heat pumps--self-contained room AC. Thus,
the EPA considers the potential impacts of HCR 4141 on local air
quality, as well as the overall risk to human health and the
environment, to be no greater than that of other substitutes available
and already listed as acceptable in the same end-uses.
Flammability information: HCR 4141 has higher flammability, with
all its components having an ASHRAE flammability classification of 3.
HFO-1234ze(E) and R-516A have lower flammability, with an ASHRAE
flammability classification of 2L.
Toxicity and exposure data: HFO-1234ze(E) and R-516A have an ASHRAE
toxicity classification of A (lower toxicity). HCR 4141 has not yet
been reviewed by ASHRAE's committee that develops the ASHRAE 34
standard, ``Refrigerant Designation and Safety Classification;''
however, its components all have an ASHRAE toxicity classification of
A.
Potential health effects of exposure to these substitutes include
drowsiness or dizziness. The substitutes may also irritate the skin or
eyes or cause frostbite. At sufficiently high concentrations, the
substitutes may cause irregular heartbeat. The substitutes could cause
asphyxiation if air is displaced by vapors in a confined space. These
potential health effects are common to many refrigerants.
The AIHA has established WEELs of 1,000 ppm as an 8-hr TWA for HFC-
134a and HFC-152a and 500 ppm as an 8-hr TWA for HFO-1234yf. ASHRAE has
adopted an Occupational Exposure Limit (OEL) of 800 ppm as an 8-hr TWA
for HFO-1234ze(E). ASHRAE also has adopted an OEL of 590 ppm as an 8-hr
TWA for R-516A.\28\ ASHRAE has adopted OELs of 1,000 ppm for each of
the components of HCR 4141. The EPA anticipates that users can meet the
AIHA WEELs and ASHRAE OELs and address potential health risks by
following requirements and recommendations in the manufacturers' safety
data sheets (SDSs), the proposed use conditions, and other safety
precautions common to the refrigeration and AC industry.
---------------------------------------------------------------------------
\28\ ANSI/ASHRAE Standard 34-2024. Designation and Safety
Classification of Refrigerants.
---------------------------------------------------------------------------
Comparison to other substitutes in this end-use: The atmospheric
effects for HCR 4141, HFO-1234ze(E), and R-516A are overall better than
or comparable to many of the substitutes currently listed as acceptable
in this end-use such as R-290, R-457A, R-454C, R-454A, R-454B, or R-
513A. More specifically, for new residential and light commercial AC
and heat pump applications, R-516A, HFO-1234ze(E), and HCR 4141 have
better than or comparable profiles to other acceptable substitutes
already listed in this end-use such as R-457A, R-454C, R-454A, R-454B,
R-513A, and HFC-32. The EPA acknowledges that the atmospheric effects
of ammonia absorption, acceptable in this end-use, may be lower than R-
516A, HFO-1234ze(E), and HCR 4141; however, the EPA is unaware of any
ammonia absorption systems that are being used in the United States for
this end-use. Other regulations also may limit the use of ammonia
absorption; therefore, the SNAP program does not consider this
substitute to be available or potentially available for new equipment
in the affected applications. Furthermore, as noted above, the EPA does
not intend to restrict a substitute if it has only marginally greater
risk. The EPA does not consider the atmospheric effects of these three
substitutes to be significantly greater and the Agency recognizes that
they can provide an additional option for situations where other
refrigerants are not viable, such as for use in split-systems and
equipment requiring larger charge sizes, or where equipment using other
generally available alternatives may be restricted in some
jurisdictions. For new residential and light commercial AC and heat
pumps--self-contained room AC, the atmospheric effects of HCR 4141 are
comparable to or lower than that of other acceptable substitutes in
this end-use category such as HFC-32, R-290, R-441A, and R-454B.
Toxicity risks of use, determined by the likelihood of exceeding
the exposure limit of these refrigerants in this end-use, are evaluated
in the previously referenced risk screens. The toxicity risks of using
HCR 4141, HFO-1234ze(E), and R-516A are comparable to or lower than
toxicity risks of other available substitutes in the same end-use.\29\
Toxicity risks of the proposed refrigerants can be minimized by use
consistent with the proposed use conditions and best industry
practices.
---------------------------------------------------------------------------
\29\ See previous listing decisions for information regarding
the toxicity of other available alternatives (see https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps).
---------------------------------------------------------------------------
The flammability risks associated with HCR 4141, HFO-1234ze(E), and
R-516A in this end-use, determined by the likelihood of exceeding their
respective LFLs, are evaluated in the risk screens referenced earlier
in this section. While these refrigerants are more flammable than
available, acceptable A1 refrigerants in the same end-use, this risk
can be minimized by use consistent with the proposed use conditions, as
well as recommendations in the manufacturers' SDS and other safety
precautions common in the refrigeration and AC industry. The
flammability risks of these refrigerants are comparable to or less than
other available lower flammability (e.g., HFC-32, R-454B) or higher
flammability refrigerants (e.g., R-290) that the EPA has previously
listed as acceptable, subject to use conditions. The EPA is proposing
use conditions that mitigate human health and environmental risks
associated with the flammability of these alternatives so that they
will not pose greater overall risk than other acceptable substitutes in
this end-use category.
The EPA is proposing to list R-516A, HCR 4141, and HFO-1234ze(E) as
acceptable, subject to use conditions. Given the wide range of
applications for residential and light commercial AC and heat pumps,
not all refrigerants listed as acceptable under SNAP will be suitable
for the full range of equipment in this end-use. This proposal would
provide additional refrigerant options for the full range of
residential and light commercial AC and heat pump equipment.
E. What are the refrigerants for which the EPA is proposing to update
use conditions and how do they compare to other refrigerants in the
residential and light commercial AC and heat pumps end-use?
The EPA is proposing to update the use conditions for eight
previously listed refrigerants in the residential and light commercial
AC and heat pumps end-use. The EPA previously listed HFC-32, R-452B, R-
454A, R-454B, R-454C, and R-457A as acceptable, subject to use
conditions, for use in all residential and light commercial AC and heat
pump applications, and R-290 and R-441A as acceptable, subject to use
[[Page 50776]]
conditions, for use in residential and light commercial AC and heat
pumps--self-contained room AC.
R-290 is a HC refrigerant with three carbons and the formula
C3H8. R-441A is a HC blend \30\ consisting of 55
percent R-290, 36 percent R-600, six percent R-600a, and three percent
R-170 (ethane) by weight. R-290 and R-441A are higher flammability
refrigerants in the A3 Safety Group.
---------------------------------------------------------------------------
\30\ The EPA notes that under the SNAP program, we review and
list refrigerants with specific compositions (59 FR 13044; March 18,
1994). To the extent possible, we follow ASHRAE's designations for
refrigerants. Blends of refrigerants must be reviewed separately.
For example, we consider each blend of R-290 with R-600a to be a
different and unique refrigerant, and each would require separate
submission, review and listing. Thus, blends of the refrigerants
that we are listing as acceptable, subject to use conditions, in
this rule are not acceptable.
---------------------------------------------------------------------------
HFC-32 is also known as difluoromethane. R-452B, also known by the
trade names ``OpteonTM XL 55,'' and ``Solstice[supreg]
L41y,'' is a blend consisting of 67 percent by weight HFC-32; seven
percent HFC-125, also known as 1,1,1,2,2-pentafluoroethane; and 26
percent HFO-1234yf. R-457A, also known by the trade name
``Forane[supreg] 457A,'' is a blend consisting of 18 percent HFC-32, 12
percent HFC-152a, and 70 percent HFO-1234yf. R-454A, also known by the
trade name ``OpteonTM XL 40,'' is a blend consisting of 35
percent HFC-32 and 65 percent HFO-1234yf. R-454B, also known by the
trade names ``OpteonTM XL 41'' and ``Puron
AdvanceTM,'' is a blend consisting of 68.9 percent HFC-32
and 31.1 percent HFO-1234yf. R-454C, also known by the trade name
``OpteonTM XL 20,'' is a blend consisting of 21.5 percent
HFC-32 and 78.5 percent HFO-1234yf. R-457A, also known by the trade
name ``Forane[supreg] 457A,'' is a blend consisting of 70 percent HFO-
1234yf, 18 percent HFC-32, and 12 percent HFC-152a.
HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A are lower
flammability refrigerant blends in the A2L Safety Group. Additional
information on the refrigerants and their components can be found in
the docket for this rulemaking under the title ``Section IV.E.
Information on Refrigerants and Their Components--Residential and Light
Commercial AC and Heat Pumps.''
Redacted submissions and supporting documentation for HFC-32, R-
452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A are provided in
the docket. The EPA performed updated risk screening for two proposed
updated A2L listings, R-454C and R-457A, and one proposed updated A3
listing, R-441A, to examine the human health and environmental risks of
these substitutes and to evaluate the impact of applying the 4th
edition of UL 60335-2-40. The EPA chose these three representative
substitutes which had the most conservative (lowest) LFLs and most
conservative short- and long-term exposure limits among the group of
refrigerants proposed for updated use conditions. These representative
refrigerants were selected because it was presumed that substances with
higher LFLs and exposure limits that were modeled for the same
scenarios and end-uses would also pass the risk screens. The EPA
proposes to conclude from these comparisons that while some calculated
concentrations changed due to different assumptions and requirements,
the refrigerants still could be used without exceeding the LFL and
therefore did not increase flammability or exposure risks compared to
the EPA's previous risk screens that assumed equipment followed UL
60335-2-40, 3rd edition. Thus, the risk screens demonstrated no greater
overall risk to human health and the environment than other
refrigerants being used when considering the impact of the co-proposed
use conditions requiring use that meets the requirements of UL 60335-2-
40, 4th edition. These risk screens are available in the docket.\31\
\32\ \33\
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\31\ ICF, 2025e. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-441A.
\32\ ICF, 2025f. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-454C (OpteonTM XL20).
\33\ ICF, 2025g. Risk Screen on Substitutes in Residential and
Light Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-457A (Forane[supreg] 457A).
---------------------------------------------------------------------------
Environmental information: The specific atmospheric effects values
can be found in the individual risk screens for HFC-32, R-290, R-441A,
R-452B, R-454A, R-454B, R-454C, and R-457A. These were determined
consistent with the source information noted in Section III.C. above
(e.g., CAA, the AIM Act) as well as using the methodology used for
determining values for blends of chemicals (i.e., determined by the
percentage of each component).
The refrigerant blends R-452B, R-454A, R-454B, R-454C, and R-457A
are made up of the components HFC-125, HFC-32, HFC-152a, and HFO-
1234yf. R-441A is made up of HC components and R-290 is a neat HC
refrigerant.
The components of the refrigerant blends, HFC-125, HFO-1234yf, HFC-
152a, and HFC-32, are excluded from the EPA's regulatory definition of
VOC \34\ for the purpose of addressing the development of SIPs to
attain and maintain the NAAQS. See Section IV.D. for discussion of air
quality analysis that was performed, which the EPA used to evaluate
potential air quality impacts due to emissions of R-290, R-441A, and
other HC refrigerants that are VOC under the EPA's regulatory
definition of VOC.\35\ The EPA has also established certain exemptions
to the CAA section 608 venting prohibition, as listed in 40 CFR
82.154(a)(1), and none of those exemptions apply to HFC-32, R-452B, R-
454A, R-454B, R-454C, or R-457A. The EPA previously exempted R-290 and
R-441A in self-contained room air conditioners for residential and
light commercial AC and heat pumps from the venting prohibition under
CAA section 608(c)(2), finding that such venting, release, or disposal
does not pose a threat to the environment.\36\ The EPA is not proposing
to change either of these decisions and is not reopening them for
comment.
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\34\ 40 CFR 51.100(s).
\35\ Id.
\36\ See 80 FR 19454; April 10, 2015.
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Flammability information: HFC-32, R-452B, R-454A, R-454B, R-454C,
and R-457A have lower flammability, with an ASHRAE flammability
classification of 2L. R-290 and R-441A have higher flammability, with
an ASHRAE flammability classification of 3.
Toxicity and exposure data: HFC-32, R-290, R-441A, R-452B, R-454A,
R-454B, R-454C, and R-457A have an ASHRAE toxicity classification of A
(lower toxicity). Potential health effects of exposure to these
substitutes include drowsiness or dizziness. The substitutes may also
irritate the skin or eyes or cause frostbite. At sufficiently high
concentrations, the substitutes may cause irregular heartbeat. The
substitutes could cause asphyxiation if air is displaced by vapors in a
confined space. These potential health effects are common to many
refrigerants.
The AIHA has established WEELs of 1,000 ppm as an 8-hr TWA for HFC-
32, HFC-125, HFC-134a, and HFC-152a and 500 ppm as an 8-hr TWA for HFO-
1234yf. ASHRAE also has adopted OELs of 1,000, 1,000, 870, 690, 850,
620, and 650 ppm as an 8-hr TWA for R-290, R-441A, R-452B, R-454A, R-
454B, R-454C, and R-457A, respectively.\37\ The EPA anticipates that
users can meet the AIHA WEELs and ASHRAE OELs and address potential
health risks by following requirements and recommendations in the
manufacturers'
[[Page 50777]]
SDS, the proposed use conditions, and other safety precautions common
to the refrigeration and AC industry.
---------------------------------------------------------------------------
\37\ OELs are those in ASHRAE 34-2024, ``Designation and Safety
Classification of Refrigerants.''
---------------------------------------------------------------------------
Comparison to other substitutes in this end-use: The atmospheric
effects for HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and
R-457A are overall better than or comparable to many of the substitutes
currently listed as acceptable. For new residential and light
commercial AC and heat pump applications (the full category), HFC-32,
R-452B, R-454A, R-454B, R-454C, and R-457A have comparable or higher
individual values than some other substitutes listed as acceptable in
part of this end-use such as R-290 and ammonia absorption and lower
values than other acceptable substitutes listed in this end-use (e.g.,
the exchange value of HFC-32 is lower than HFC-134a, R-407C, and R-
410A). However, the EPA is unaware of any ammonia absorption systems
being used in the United States for this end-use and due to its
flammability, R-290 is listed as acceptable for use in self-contained
room AC only and is not an available substitute for any of the other
end-uses within the sector. As noted above, the EPA does not intend to
restrict a substitute if it has only marginally greater risk. The EPA
does not consider the atmospheric effects of these proposed substitutes
to be significantly greater than other acceptable substitutes and the
Agency recognizes that they can provide an additional option for
situations where other refrigerants are not viable.
Toxicity risks of HFC-32, R-290, R-441A, R-452B, R-454A, R-452B, R-
454C, and R-457A in this end-use, determined by the likelihood of
exceeding their respective exposure limits, are evaluated in the
previously referenced risk screens. The toxicity risks of using HFC-32,
R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A are
comparable to or lower than toxicity risks of other available
substitutes in the same end-use.\38\ Toxicity risks of the proposed
refrigerants can be minimized by use consistent with the proposed use
conditions and best industry practices.
---------------------------------------------------------------------------
\38\ See previous listing decisions for information regarding
the toxicity of other available alternatives (https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps).
---------------------------------------------------------------------------
The flammability risks of HFC-32, R-290, R-441A, R-452B, R-454A, R-
454B, R-454C, and R-457A in this end-use, determined by the likelihood
of exceeding their respective LFLs, are evaluated in the previously
referenced risk screens. While these refrigerants may pose greater
flammability risk than other available substitutes in the same end-use,
this risk can be minimized by use consistent with the proposed use
conditions, as well as recommendations in the manufacturers' SDS and
other safety precautions common in the refrigeration and AC industry.
The EPA is proposing use conditions that maintain the low potential
risk associated with the flammability of these alternatives so that
they will not pose greater overall risk than other acceptable
substitutes in this end-use category. A full discussion of the proposed
use conditions may be found in Section IV.F.
While R-290 and R-441A have higher flammability than many
substitutes listed as acceptable in this end-use, the proposed updated
use conditions would reduce the potential risk associated with the
flammability of these alternatives so that they would not pose greater
overall risk than other acceptable substitutes in this end-use. The
proposed substitutes HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A
would provide additional options for situations where other
refrigerants are not viable, such as for use in split-systems or
equipment requiring larger charge sizes, or where equipment using other
generally available alternatives may be restricted in some
jurisdictions.
The EPA proposes to find that updating the use conditions for the
existing listings for HFC-32, R-452B, R-454A, R-454B, R-454C, and R-
457A as acceptable, subject to use conditions, for use in all types of
residential and light commercial AC and heat pumps and for R-290 and R-
441A in residential and light commercial AC and heat pumps--self-
contained room AC, is appropriate to maintain a broad list of
acceptable substitutes available for the full range of applications
under this end-use and to continue safe use of these refrigerants.
These updated listings would help establish and maintain an equal
playing field for substitutes used in the market.
HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A
are currently listed as acceptable, subject to use conditions, for use
in the residential and light commercial AC and heat pumps end-use. The
EPA is not proposing to move any of these listings to any other listing
category (e.g., unacceptable). Rather, the EPA is proposing to update
the use conditions because the industry consensus safety standards that
were incorporated by reference at the time of the listing have since
been either updated \39\ or superseded.\40\
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\39\ UL 60335-2-40.
\40\ UL 484.
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This list provides a summary of the existing listings for each
refrigerant in the residential and light commercial AC and heat pumps
end-use that the EPA is proposing to update:
HFC-32 is listed as acceptable, subject to use conditions,
in all new residential and light commercial AC and heat pump
applications. The current use conditions incorporate by reference UL
60335-2-40, 3rd edition. Previous listings for this refrigerant in this
end-use and detailed information on the use conditions, listing
decision, and rationale for these previous listings can be found in
SNAP Rule 19,\41\ SNAP Rule 23,\42\ and SNAP Rule 25.\43\
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\41\ See 80 FR 19454; April 10, 2015.
\42\ See 86 FR 24444; May 6, 2021.
\43\ See 88 FR 26382; April 28, 2023.
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R-452B, R-454A, R-454B, R-454C, and R-457A are listed as
acceptable, subject to use conditions, in all new residential and light
commercial AC and heat pump applications. The current use conditions
incorporate by reference UL 60335-2-40, 3rd edition. Previous listings
for these refrigerants in this end-use and detailed information on the
use conditions, listing decision, and rationale for these previous
listings can be found in SNAP Rule 23.\44\
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\44\ See 86 FR 24444; May 6, 2021.
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R-290 and R-441A are listed as acceptable, subject to use
conditions, in new residential and light commercial AC and heat pumps--
self-contained room AC only. The current use conditions incorporate by
reference Supplement SA and Appendices B through F of the 8th edition
of UL 484. Previous listings for these refrigerants in this end-use and
detailed information on the use conditions, listing decision, and
rationale for these previous listings can be found in SNAP Rule 19.\45\
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\45\ See 80 FR 19454; April 10, 2015.
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F. What use conditions is the EPA proposing in this action for new and
updated listings in this residential and light commercial AC and heat
pumps end-use?
The proposed use conditions described in this section would apply
to newly listed refrigerants HCR 4141, HFO-1234ze(E), and R-516A in
this end-use and to previously listed refrigerants HFC-32, R-452B, R-
454A, R-454B, R-454C, R-457A, R-290, and R-441A in this end-use. For
these eight previously listed refrigerants, the proposed use conditions
would apply to new equipment manufactured after the effective date of
the final rule. The proposed updated use conditions would neither apply
to nor affect equipment
[[Page 50778]]
manufactured before the effective date of the final rule.
Many of the proposed use conditions described in this section
mirror the SNAP program's historical approach to requirements for lower
flammability and higher flammability refrigerants. For example, the
proposed use condition related to use only in new equipment is
consistent with previously listed lower flammability and higher
flammability refrigerants in this end-use. The proposed use conditions
related to labels and markings are very similar to previous
requirements for lower and higher flammability refrigerants in this
end-use, with a few changes to better align the EPA's requirements with
updated industry consensus safety standards. The co-proposed option
that would incorporate by reference UL 60335-2-40 described in Section
IV.F.4.a. would simply update the required safety standard to the
latest edition in a manner consistent with the EPA's historical
practice of incorporating portions of or entire industry consensus
safety standards by reference. The other co-proposed option described
in Section IV.F.4.b., while different than the EPA's historical
practice, would address situations where agency regulations require
adherence to editions of industry consensus safety standards that have
been updated and replaced subsequent to the issuance of a final rule.
The EPA is proposing to remove the existing use conditions specific
to refrigerant charge size limits for R-290, R-441A, R-452B, R-454A, R-
454B, R-454C, and R-457A in residential and light commercial AC and
heat pump applications. SNAP Rule 19 \46\ included a specific use
condition for R-290 and R-441A in self-contained room AC for
refrigerant charge size limits based on cooling capacity and type of
equipment. SNAP Rule 23 \47\ included a specific use condition for R-
452B, R-454A, R-454B, R-454C, and R-457A in all residential and light
commercial AC and heat pump applications for charge size based on UL
60335-2-40 and the room size where the equipment is used. The EPA is
not proposing to eliminate charge size restrictions. Rather, the EPA is
co-proposing two use condition options related to equipment
certification or industry consensus safety standards, which both
include requirements to ensure that equipment is designed using safe
refrigerant charge sizes. The EPA is proposing to rely on the charge
size restrictions inherent in that proposed requirement rather than
duplicate charge size restrictions in a separate use condition. The EPA
proposes the following use conditions:
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\46\ See 80 FR 19454; April 10, 2015.
\47\ See 86 FR 24444; May 6, 2021.
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1. New Equipment Only; Not Intended for Use as a Retrofit Alternative
The EPA is proposing that all refrigerants covered by this action
in the residential and light commercial AC and heat pumps end-use,
including the applicable applications (e.g., unitary split AC systems,
mini-splits, and heat pumps), may be used only in new equipment
designed to address concerns unique to lower and higher flammability
refrigerants. In other words, none of these substitutes may be used as
a conversion or ``retrofit'' refrigerant for existing equipment. These
lower and higher flammability refrigerants were not submitted under the
SNAP program to be used in retrofitted equipment, and no information
was provided on how to address hazards if they were to be used in
equipment that was designed for nonflammable refrigerants.
2. Labels
The EPA is proposing to require labels for residential and light
commercial AC and heat pump equipment. These labels would need to be
permanently attached at the locations provided. The following text
would be required for residential and light commercial AC and heat pump
equipment containing an A2L refrigerant that is proposed to be listed
in this rule:
a. On the outside of the equipment: ``WARNING--Risk of Fire.
Flammable Refrigerant Used. To Be Repaired Only by Trained Service
Personnel. Do Not Puncture Refrigerant Tubing.''
b. On the outside of the equipment: ``WARNING--Risk of Fire.
Dispose of Properly in Accordance with Federal or Local Regulations.
Flammable Refrigerant Used.''
c. On the inside of the equipment near the compressor: ``WARNING--
Risk of Fire. Flammable Refrigerant Used. Consult Repair Manual/Owner's
Guide Before Attempting to Service This Product. All Safety Precautions
Must be Followed.''
d. For any equipment pre-charged at the factory, on the equipment
packaging: ``WARNING--Risk of Fire due to Flammable Refrigerant Used.
Follow Handling Instructions Carefully in Compliance with National
Regulations''
e. On the indoor unit near the nameplate: A label stating the
minimum installation height (if applicable), in m and ft, and the
minimum room area (operating or storage), in m\2\ and ft\2\. These
values shall be calculated according to a U.S. industry consensus
safety standard for AC and heat pump equipment.
f. On the outside of non-fixed equipment, such as portable air
conditioners and window air conditioners and heat pumps: ``WARNING--
Risk of Fire--Store in a well ventilated room without continuously
operating flames or other potential ignition.''
g. For fixed equipment such as packed terminal air conditioners,
packaged terminal heat pumps, rooftop units, and split air
conditioners: ``WARNING--Risk of Fire--Auxiliary devices which may be
ignition sources shall not be installed in the ductwork, other than
auxiliary devices listed for use with the specific appliance. See
instructions.''
The EPA has previously stated that it would be difficult to see
warning labels with the minimum lettering height requirement for A2L
refrigerants of \1/8\ inch as required by the UL standard. Therefore,
as in previous rules,\48\ the EPA is proposing that the minimum height
for lettering be \1/4\ inch (6.4 mm) as opposed to \1/8\ inch, which
would make it easier for technicians, consumers, retail storeowners,
first responders, and those disposing of the appliance to view the
warning labels. Other than the proposed label under paragraph e, the
text of the labels is similar or verbatim in language to those required
by the 4th edition of UL 60335-2-40. They are also aligned with
labeling requirements for A2L refrigerants in previous SNAP Rules 23
\49\ and 25.\50\
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\48\ See 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
\49\ See 86 FR 24444, May 6, 2021.
\50\ See 88 FR 26382, April 28, 2023.
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The proposed label under paragraph e describes the required content
of a label rather than exact language that the label would need to
contain. The same change is being proposed for one of the labels for
equipment using A3 refrigerants, see paragraph l, later in this
section. This proposed change would allow the EPA's use conditions to
remain consistent with the requirements of the latest edition of UL
60335-2-40 while giving flexibility for the use condition to remain
applicable even if the third-party certification option described in
Section IV.F.4.b. is finalized, and the UL standard is not incorporated
by reference. This proposed change is intended to avoid potential
conflict between the regulatory requirements and the industry safety
standards if the specific requirements in those standards are changed.
The EPA is also proposing labels for residential and light
commercial AC and
[[Page 50779]]
heat pump equipment using A3 refrigerants proposed in this rule. The
following text would need to be permanently attached at the locations
provided:
h. On the outside of the equipment: ``DANGER--Risk of Fire or
Explosion. Flammable Refrigerant Used. To Be Repaired Only by Trained
Service Personnel. Do Not Puncture Refrigerant Tubing.''
i. On the outside of the equipment: ``WARNING--Risk of Fire or
Explosion. Dispose Of Properly in Accordance with Federal or Local
Regulations. Flammable Refrigerant Used.''
j. On the inside of the equipment near the compressor: ``DANGER--
Risk of Fire or Explosion. Flammable Refrigerant Used. Consult Repair
Manual/Owner's Guide Before Attempting to Service This Product. All
Safety Precautions Must Be Followed.''
k. For any equipment pre-charged at the factory, on the equipment
packaging: ``DANGER--Risk of Fire or Explosion due to Flammable
Refrigerant Used. Follow Handling Instructions Carefully in Compliance
with National Regulations.''
l. On an indoor unit near the nameplate: A label stating the
minimum installation height (if applicable), in m and ft, and the
minimum room area (operating or storage), in m\2\ and ft\2\. These
values shall be calculated according to a U.S. industry consensus
safety standard for AC and heat pump equipment.
m. On the outside of non-fixed equipment, such as portable air
conditioners and window air conditioners and heat pumps: ``WARNING--
Risk of Fire or Explosion--Store in a well ventilated room without
continuously operating flames or other potential ignition.''
The EPA is proposing that the minimum height for lettering be at
least \1/4\ inch (6.4 mm), consistent with the labeling requirements
for A3 refrigerants under the 4th edition of UL 60335-2-40. This text
size makes it easier for technicians, consumers, retail storeowners,
first responders, and those disposing the appliance to view the warning
labels. The text of the proposed labels is similar or verbatim in
language to those that required by the 4th edition of UL 60335-2-40.
This proposed text differs from that in SNAP Rule 19 \51\ for A3
refrigerants in this end-use. For example, the proposed labels under
paragraphs k and m do not currently exist as use conditions for R-290
and R-441A but are consistent with the latest labeling requirements for
A3 refrigerants under the 4th edition of UL 60335-2-40. Additionally,
the proposed labels under paragraphs i and j use the words ``WARNING''
and ``DANGER'' in lieu of ``CAUTION.'' The EPA proposes these updates
to the labeling requirements to be consistent with the 4th edition of
UL 60335-2-40 and with the SNAP labeling requirements for other higher
flammability refrigerants. The EPA proposes to find that using a common
set of labels would aid in compliance, especially for a manufacturer
that uses more than one of these refrigerants or produces both self-
contained room ACs and heat pumps and other types of residential and
light commercial AC and heat pumps. The labels for residential and
light commercial AC and heat pump equipment using A3 refrigerants are
listed in paragraphs a through f in appendices R and Z in the proposed
regulatory text for the A3 listings in this end-use. The proposed
regulatory text can be found in the docket for this rulemaking under
the title ``Proposed Regulatory Text for SNAP Rule 27'' in the sections
``Proposed revisions to Appendices R, V, W, and new Appendix Z--
Incorporate by Reference Option'' and ``Proposed revisions to
Appendices R, V, W, and new Appendix Z--Third-Party Certification
Option (co-proposed as an alternative to Section III).'' The proposed
labeling requirements are identical in both sections.
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\51\ See 80 FR 19454; April 10, 2015.
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3. Color-Coded Hoses and Piping
The EPA is proposing to require that equipment have distinguishing
red (Pantone[supreg] Matching System [PMS] #185 or ``Reichs-
Ausschu[szlig] f[uuml]r Lieferbedingungen und G[uuml]tesicherung,''
[RAL] 3020 from Germany's National Commission for Delivery Terms and
Quality Assurance) color-coded hoses and piping to indicate use of a
flammable refrigerant. The equipment would need to have red marked
service ports, pipes, hoses, and other devices through which the
refrigerant is serviced. This color would need to be present at all
service ports and where service puncturing or otherwise creating an
opening from the refrigerant circuit to the atmosphere might be
expected. Markings would need to extend at least one inch (25 mm) from
the servicing port and would need to be replaced if removed. The EPA
has applied this proposed use condition in past actions for lower and
higher flammability refrigerants.\52\ The EPA is proposing that such
markings apply to both A2L and A3 refrigerants to establish a common,
familiar, and standard means of identifying the use of a lower or
higher flammability refrigerant. Being able to immediately identify the
use of a lower or higher flammability refrigerant would reduce the risk
of a technician using sparking equipment or otherwise having an
ignition source nearby. The AC and refrigeration industry currently
uses red-colored hoses and piping as means for identifying the use of a
lower or higher flammability refrigerant based on previous SNAP
listings. Likewise, distinguishing coloring is used elsewhere to
indicate an unusual and potentially dangerous situation, for example in
the use of orange-insulated wires in hybrid electric vehicles.
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\52\ See 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
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The use of color-coded hoses and piping would be in addition to the
proposed use of warning labels. Having two such warning methods is
reasonable and consistent with other general industry practices. This
approach is the same as in our previous rules on A2L and A3
refrigerants.\53\
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\53\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 88 FR 26382, April 28, 2023.
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4. Use Condition Options Related to Equipment Certification or Industry
Safety Standard Requirements
The EPA is co-proposing two options for a use condition related to
equipment certification or industry safety standard requirements. Under
the first option, the EPA would incorporate by reference a new edition
of the industry consensus safety standard for this end-use. Under the
second option, the EPA would require residential and light commercial
AC and heat pump equipment to be certified by an organization that is
recognized as an NRTL to a U.S. industry consensus safety standard that
is designed to allow for safe use of flammable refrigerants and
mitigates risks such that the listed refrigerants can be used in a
manner that does not pose a greater overall risk to human health and
the environment than other substitutes in this end-use.
a. Incorporate by Reference UL 60335-2-40, 4th Edition Option
Since 2008, the EPA has listed numerous A2, A2L, and A3
refrigerants as acceptable, subject to use conditions, addressing use
of lower and higher flammability refrigerants in end-uses where the EPA
has determined it is necessary to mitigate risks. Most often, the EPA
has relied in part on incorporating by reference industry consensus
safety standards to ensure these risks are mitigated. Industry
consensus safety standards are developed in cooperation with parties
with an interest in participating in the
[[Page 50780]]
development or use of the standard. For example, UL uses a process
where experts with various interests, including manufacturers,
government agencies, and academia, come together to agree on the safety
requirements for a product, resulting in a standard that reflects a
collective consensus on best practices for safety. These standards are
typically under continuous maintenance, meaning that they are updated
and superseded by newer editions. This often means that regulations and
safety standards are out of step; and thus, the EPA often updates its
regulations to incorporate the newer version of the standard. The
revision cycle for the 4th edition of UL 60335-2-40, including final
recirculation, concluded with its publication on December 15, 2022.
Under this first option, the EPA is proposing to set a use
condition consistent with the latest version of UL standards through
incorporation by reference. Thus, the EPA proposes to list new
refrigerants and update existing listings for refrigerants in the
relevant end-use covered by this action with a use condition that these
refrigerants may be used only in equipment that meets all requirements
in UL 60335-2-40, 4th edition. This option continues the practice of
updating regulations to align with newer editions of standards.
Specifically, the EPA is proposing to update the condition to meet
all requirements listed in UL 60335-2-40, 3rd edition, ``Household and
Similar Electrical Appliances--Safety--Part 2-40: Particular
Requirements for Electrical Heat Pumps, Air Conditioners and
Dehumidifiers,'' dated November 1, 2019 (for A2L refrigerants), or
Supplement SA and Appendices B through F of UL Standard 484 8th
edition, ``Room Air Conditioners,'' dated August 2, 2012 (for R-290 and
R-441A), with the proposed condition to meet all requirements listed in
the 4th edition of UL 60335-2-40, ``Household and Similar Electrical
Appliances--Safety--Part 2-40: Particular Requirements for Electrical
Heat Pumps, Air Conditioners and Dehumidifiers,'' dated December 15,
2022. This proposed use condition incorporating the 4th edition would
apply to new equipment manufactured after the effective date of any
final action. In cases where this rule includes requirements that are
different than those of UL 60335-2-40 (e.g., font size), the EPA is
proposing that the requirements of this rule apply.
UL 60335-2-40 applies to the SNAP applications of window unit room
air conditioners, PTACs and PTHPs, portable air conditioners, central
air conditioners, non-ducted AC systems, packaged rooftop units, WSHPs,
GSHPs, and other products. This UL standard indicates that refrigerant
charges greater than a specific amount (called ``m3'' in the UL
standard and based on the refrigerant's LFL) are beyond its scope and
that national safety standards might apply, such as ANSI or ASHRAE
15.2. Because the EPA has not evaluated such situations, this proposal
only covers residential and light commercial AC and heat pump equipment
that fits within the scope of the UL standard.
UL 60335-2-40 was developed in an open and consensus-based
approach, with the assistance of experts in the refrigeration and AC
industry as well as experts involved in assessing the safety of
products. Participants of the UL 60335-2-40 consensus standard process
reviewed results of testing on equipment for flammability risk in
residential applications and evaluated the relevant scientific studies.
Further, UL has developed safety standards for construction and system
design, markings, and performance tests concerning refrigerant leakage,
ignition of switching components, surface temperature of parts, and
component strength after being scratched. Aspects of system
construction and design, including charge size, ventilation, and
installation space, and greater detail on markings, are discussed later
in this section. While similar safety standards exist from other
bodies, such as the International Electrotechnical Commission (IEC), we
are proposing in this option to use specific UL standards that are most
applicable and used by U.S. manufacturers. The EPA used this approach
in previous SNAP rules concerning lower and higher flammability
refrigerants.\54\
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\54\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------
The EPA has evaluated the revisions and proposes to find that
construction and use of equipment in accordance with the 4th edition
would not pose greater overall risk to human health and the environment
than use in accordance with the 3rd edition. The 4th edition makes
changes that address potential hazards of flammable refrigerants
including refined requirements for leak detection systems to
accommodate various methods, increase robustness and reliability, and
account for deviation and drift over the system life cycle.
The requirements in UL 60335-2-40 would reduce the risk to workers
and consumers. Incorporating the latest edition of the UL standard as a
use condition would also reduce conflict between federal regulations,
building codes, and other authorities that require compliance with the
latest version of the UL standard. This section summarizes relevant
aspects of UL 60335-2-40 for information only and is not meant to be a
complete review of the standard or how it is applied.
UL 60335-2-40 limits the amount of refrigerant allowed in each type
of appliance based on several factors explained in that standard. The
EPA is proposing to require charge size limits for each of the proposed
refrigerants by equipment type in accordance with UL 60335-2-40, 4th
edition. Annex GG of the standard provides the charge limits,
ventilation requirements, and requirements for secondary circuits. The
standard specifies requirements for installation space of an appliance
(i.e., room floor area) and/or ventilation or other requirements which
are determined according to the refrigerant charge used in the
appliance, the installation location, and the type of ventilation of
the location or of the appliance. Within Annex GG, table GG.1DV
provides guidance on how to apply the requirements to address the
potential flammability hazards of flammable refrigerants.
UL 60335-2-40, 4th edition also contains new specific requirements
for determining releasable charge. As opposed to total refrigerant
charge, which is the actual refrigerant charge of a single
refrigerating system, releasable charge is the mass of refrigerant that
can be released into the indoor space from a refrigerating system in
the event of a leak. While accounting for releasable charge results in
larger total refrigerant charges allowed under the 4th edition when
compared to the 3rd edition, the EPA proposes to find that the
mitigation requirements in the 4th edition of the standard, such as
leak detection systems and safety shutoff valves, effectively reduce
risk and address the hazards of flammable refrigerants even at larger
total charge sizes.
UL 60335-2-40, 4th edition contains provisions for safety
mitigation that were developed to ensure the safe use of flammable
refrigerants over a range of appliances. In general, as larger charge
sizes are used, more stringent mitigation requirements apply. In
certain applications, refrigerant detection systems (as described in
Annex LL, Refrigerant detection systems for A2L refrigerants),
refrigerant sensors (as described in Annex MM, Refrigerant sensor
location confirmation test), and safety alarms are required. The 4th
edition includes significantly improved requirements for refrigerant
detection systems, including clarified sensor
[[Page 50781]]
location requirements and better test methods for leak simulation
tests.
Where mechanical ventilation (i.e., fans) is required in accordance
with Annex GG, it must be initiated by a separate refrigerant detection
system either as part of the appliance or installed separately. In a
room with no mechanical ventilation, Annex GG provides requirements for
openings to rooms based on several factors including the charge size
and the room area. The minimum opening is intended to be sufficient so
that natural ventilation would reduce the risk of using a flammable
refrigerant. The standard also includes specific requirements for split
system appliances covering construction, instruction manuals, and
allowable charge sizes, mechanical ventilation, safety alarms, and shut
off valves for A2L refrigerants.
In addition to Annex GG and table GG.1DV, UL 60335-2-40 has a
requirement for the maximum charge for an appliance using an A2L
refrigerant, such as HFC-32, HFO-1234ze(E), R-452B, R-454A, R-454B, R-
454C, R-457A, and R-516A. The 4th edition sets more comprehensive
requirements on A2L refrigerants than the 3rd edition, and the EPA
proposes to consider these additional safety mechanisms, including
charge size limitations, to be more protective of human health and the
environment. If the appliance is a portable appliance, a non-fixed
factory-sealed single package, or a cord-connected appliance, which may
be periodically or seasonally relocated (excluding servicing) by the
end user, there are no additional requirements for room area,
ventilation, or other risk mitigation if the charge is sufficiently
small--under three times the LFL. Additional requirements exist for
charge sizes exceeding three times the LFL.
For A3 refrigerants, including R-290, R-441A, and HCR 4141, UL
60335-2-40 requires a maximum charge of three times the LFL for an
appliance that is a portable appliance, a non-fixed factory-sealed
single package, or a cord-connected appliance which may be periodically
or seasonally relocated (excluding servicing) by the end user. For
example, for R-290 this maximum charge for non-fixed appliances would
be 114 g.
The EPA compared the effect that requirements from previous
standards (UL 484 and UL 60335-2-40, 3rd edition) versus UL 60335-2-40,
4th edition, would have on the results of the EPA's comparative risk
screens, which are included in the docket. The EPA conducted updated
risk screening on two proposed A2L listings and one proposed A3
listing, which had the most conservative (lowest) LFLs and most
conservative short- and long-term exposure limits among the proposed
alternatives. As discussed in Section IV.E., these risk screens
demonstrated that use of these refrigerants in the residential and
light commercial AC and heat pumps end-use would not pose greater
overall risk to human health and the environment than other
refrigerants being used when considering the impact of the co-proposed
use condition requiring use that meets the requirements of UL 60335-2-
40, 4th edition.
As discussed earlier in this section, the EPA is proposing to
remove the existing use conditions specific to refrigerant charge size
limits for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in
residential and light commercial AC and heat pump applications. Rather
than duplicate charge size restrictions in a separate use condition,
the EPA is proposing to rely on the charge size restrictions inherent
in the requirements of UL 60335-2-40, 4th edition. Consistent with
previous listings for other lower and higher flammability refrigerants
in this end-use, the EPA is not proposing to include a use condition
related to adherence to ASHRAE 15 or ASHRAE 15.2. As discussed in this
section, the 4th edition of UL 60335-2-40 includes changes from the 3rd
edition that specifically address the potential flammability hazards of
lower and higher flammability refrigerants. The EPA proposes to find
that these refrigerants can be used safely provided the use conditions
in this proposed rule are followed, including compliance with the 4th
edition of UL 60335-2-40. The EPA recognizes that in certain clauses,
UL 60335-2-40 refers to ASHRAE 15 and ASHRAE 15.2 for compliance. We
also note that other authorities might impose additional requirements,
such as the adoption of ASHRAE 15 and 15.2 in building codes, that
would provide an additional layer of safety above what the EPA is
proposing to require under SNAP.
Under this incorporate by reference option, all three of the new
refrigerant listings and the eight updated refrigerant listings
proposed for this end-use would include the use conditions described in
Sections IV.F.1., IV.F.2., and IV.F.3., as well as a use condition that
the refrigerant may only be used in equipment that meets all the
requirements of UL 60335-2-40, 4th edition.
The EPA performed assessments to examine the human health and
environmental risks of each of these substitutes. These assessments are
available in the docket.\55\ The proposed regulatory text for new and
updated listings under this option can be found in the docket under the
title ``Proposed Regulatory Text for SNAP Rule 27'' in the section
``Proposed revisions to Appendices R, V, W, and new Appendix Z--
Incorporate by Reference Option.''
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\55\ See in section XII., ``References'': ICF, 2025a; ICF,
2025b; ICF, 2025c; ICF, 2025e; ICF, 2025f; and ICF, 2025g.
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b. Third-Party Certification Option
As noted elsewhere, in recent rulemakings for listings of lower and
higher flammability refrigerants, the EPA has incorporated by reference
portions of or entire industry consensus safety standards as use
conditions for SNAP listings. The Agency recognizes that these
standards are under continuous maintenance, meaning that they are
updated and superseded by newer editions. This often means that
regulations and safety standards are out of step; and thus, the EPA
often updates its regulations to incorporate the newer version of the
standard and to avoid directing regulated entities to editions of
standards that have been updated and replaced subsequent to the
issuance of a final rule. This is time-consuming, increases
administrative burden, and there is often time between the issuance of
a new edition of a standard and a later revised regulation which could
result in confusion for the regulated community as well as slowing down
adoption of revised requirements based upon the most recent science and
industry experience.
This approach also may result in the EPA's requirements including
sections of standards that are not needed to address the flammability
risks of refrigerants. For example, UL 60335-2-40 includes certain
tests that apply to all parts of the equipment, not just to the
refrigerating system, and specifications about leakage current and
electrical strength, which are not needed specifically to address
flammability of refrigerants. Therefore, the EPA is proposing another
option to streamline use conditions and to maintain consistency with
the latest version of the relevant standards. This option allows for
the EPA to address flammability risks while recognizing that a specific
edition of a relevant standard applicable for the residential and light
commercial AC and heat pumps end-use may be replaced by a later
edition. This option is described in this Section IV.F.4.b.
Under this potential option, the EPA proposes that all residential
and light commercial AC and heat pump
[[Page 50782]]
equipment using the refrigerants listed in this rulemaking would need
to be certified by an OSHA-recognized NRTL to a U.S. industry consensus
safety standard that is designed to allow for safe use of flammable
refrigerants in residential and light commercial AC and heat pump
equipment, and mitigates risks such that the listed refrigerants can be
used in a manner that does not pose a greater overall risk to human
health and the environment than other substitutes in this end-use. For
listings in this end-use under this option, the EPA is proposing
replacing the practice of incorporating by reference portions of or
entire industry consensus safety standards with a use condition that
relies on NRTLs certifying equipment to a U.S. industry consensus
safety standard that mitigates risks. The industry consensus safety
standard would need to be designed for use in the United States and be
consistent with best industry safety practices (e.g., UL 60335-2-40).
The EPA proposes that an industry consensus safety standard used to
meet this use condition would need to contain requirements for:
Refrigerant charge sizes and risk mitigation measures that
are designed to allow for safe use of flammable refrigerants (e.g.,
refrigerant detection systems, ventilation to maintain refrigerant
concentrations below the LFL in the case of a leak); and
Markings that communicate the risks.
Definitions and requirements for the OSHA NRTL Program can be found
at 29 CFR 1910.7. The term ``NRTL'' means an organization recognized by
OSHA in accordance with appendix A to 29 CFR 1910.7, and which tests
for safety, lists or labels or accepts equipment or materials, and
meets the criteria described in 29 CFR 1910.7. Any testing agency or
organization considering itself to meet the definition of an NRTL as
specified in Sec. 1910.7 may apply for OSHA recognition.
While the EPA is proposing reliance on certification by these
NRTLs, the EPA is not opening OSHA's regulations at 29 CFR 1910.7 for
comment, including definitions or requirements, nor is the EPA seeking
comment on the OSHA program itself. For listings in this end-use under
this option, the EPA is proposing a use condition based on
certification by NRTLs instead of incorporation by reference of
portions of or entire industry consensus safety standards. In addition
to meeting the requirements laid out above, the U.S. industry consensus
safety standard used to meet this requirement would also need to be
deemed an appropriate test standard and approved by OSHA. The NRTL
Program regulation at 29 CFR 1910.7(c) sets forth the criteria for
determining whether a test standard is appropriate. An appropriate test
standard is a document which specifies the safety requirements for
specific equipment or class of equipment and is (1) recognized in the
United States as a safety standard providing an adequate level of
safety; (2) compatible with and maintained current with periodic
revisions of applicable national codes and installation standards; and
(3) developed by a standards developing organization under a method
providing for input and consideration of views of industry groups,
experts, users, consumers, governmental authorities, and others having
broad experience in the safety field involved; or (4) in lieu of
paragraphs (c) (1), (2), and (3), the standard is currently designated
as an ANSI safety-designated product standard or an ASTM test standard
used for evaluation of products or materials. The various procedures
for approval of appropriate test standards are found in the OSHA NRTL
Program Policies, Procedures, and Guidelines CPL-01-00-004 (Program
Directive). NRTLs and a list of appropriate test standards that are
recognized by OSHA are publicly available, and updated periodically, on
OSHA's website.\56\
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\56\ https://www.osha.gov/nationally-recognized-testing-laboratory-program/current-list-of-nrtls and https://www.osha.gov/nationally-recognized-testing-laboratory-program/list-standards.
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As discussed earlier in Section IV.F.4.a., industry consensus
safety standards are developed in cooperation with parties with an
interest in participating in the development or use of the standard.
The EPA has confidence in this safety standards development process, as
it relies on consensus built by the industry. For example, UL uses a
process where experts with various interests, including manufacturers,
government agencies, and academia, come together to agree on the safety
requirements for a product, resulting in a standard that reflects a
collective consensus on best practices for safety.
One example of an appropriate test standard for equipment in the
residential and light commercial AC and heat pumps end-use is UL 60335-
2-40. UL 60335-2-40 was developed in an open and consensus-based
approach. The EPA proposes to view this standard as one example of a
U.S. industry consensus safety standard that could be used to meet this
requirement, as the requirements of the standard align with the levels
of safety that the EPA expects in terms of mitigating risks to human
health and the environment. As mentioned in Sections IV.D. and IV.E.,
the EPA performed risk screening assessments to examine the human
health and environmental risks of the refrigerants being proposed in
this action for this end-use. These risk screens demonstrated that use
of these refrigerants in the residential and light commercial AC and
heat pumps end-use consistent with the latest edition of UL 60335-2-40
would not pose greater overall risk to human health and the environment
than other acceptable substitutes for new equipment in this end-use.
One potential downside of this third-party certification option is
that future revisions could be made to OSHA-recognized appropriate test
standards that do not align with the SNAP program's criteria for
mitigating risks to human health and the environment. However, the EPA
already monitors the development and revision process for industry
consensus safety standards that apply to equipment in the residential
and light commercial AC and heat pumps end-use and other end-uses. If
this option is finalized, the EPA would continue monitoring these
standards, and if revisions are made to industry safety standards that
impact their alignment with the SNAP program's risk mitigation
criteria, the EPA would raise concerns and could revisit and propose
changes to refrigerant listing categories and/or use conditions through
rulemaking.
OSHA recognizes NRTLs at the organizational-level as opposed to the
laboratory-level. Therefore, the laboratory that performs the equipment
testing would need to be part of an NRTL that is recognized by OSHA and
have the necessary equipment and training required to test to a
specific standard that would be most applicable to the equipment
applications in this section.
OSHA requires all electrical equipment used in the workplace to be
tested and certified by an NRTL or otherwise determined to be
``acceptable'' as defined in 29 CFR 1910.399. The EPA is proposing that
equipment in the residential and light commercial AC and heat pumps
end-use using the refrigerants proposed in this action would need to be
certified to a U.S. industry consensus safety standard by an OSHA-
recognized NRTL. In accordance with Annex B of the OSHA NRTL Program
Directive and section 4 of ISO/IEC 17065:2012, NRTLs shall maintain
registration of a certification mark with the U.S. Patent and Trademark
Office, and an NRTL's procedures shall require clients to apply the
NRTL's registered certification mark
[[Page 50783]]
to the certified equipment to signify that the equipment is certified
by an NRTL and complies with the requirements of an appropriate safety
test standard. In addition, the test standard(s), certification
category, or a symbol or code that identifies the test standard(s) to
which the unit is certified shall be shown adjacent to the NRTL's mark.
These markings provide users with evidence that the equipment complies
with applicable safety test standard requirements and is safe for use.
The EPA is not proposing to establish specific requirements or
protocols for laboratories because OSHA already has established such
requirements and performs detailed reviews of equipment certification
entities. OSHA's review of NRTLs includes a thorough evaluation of
application materials, assessments of the organization's programs and
facilities, publication of findings in the Federal Register, response
to public comments, and announcement of a final decision on NRTLs. OSHA
also performs ongoing evaluations of NRTLs and responds to safety
concerns that occur in the field. Because NRTLs must be recognized to
test to a specific safety standard, all of the requirements of that
particular safety standard are adopted by the NRTL, which is similar to
SNAP's current use condition approach for HFC-32, R-452B, R-454A, R-
454B, R-454C, R-457A, R-290, and R-441A that incorporates by reference
a particular safety standard.
By not incorporating by reference a specific edition of a relevant
safety standard in this use condition option, the EPA intends to
increase efficiencies by not having to propose a new rule each time a
safety standard is updated and to leverage OSHA's NRTL Program. The EPA
does not expect this option to pose significant additional burden on
manufacturers or NRTLs because most manufacturers of residential and
light commercial AC and heat pump equipment have their equipment
certified by an NRTL already. Manufacturers that do not already certify
their equipment through an OSHA-recognized NRTL would need to do so
beginning two years after the effective date of the final rule.
The EPA is aware of three entities, UL, Intertek, and CSA Group,
that are currently NRTLs and test and certify equipment to industry
consensus safety standards for equipment in the residential and light
commercial AC and heat pumps end-use. The EPA understands there may be
additional entities now or in the future.
As noted previously, the current SNAP regulations incorporate by
reference UL 60335-2-40, 3rd edition, which is no longer the latest
edition of a standard that is publicly available and applicable to this
end-use. OSHA regulations do not specify specific editions of
standards. Rather, an NRTL recognized for an ANSI-approved test
standard may use either the latest proprietary version or the latest
ANSI version of the standard, regardless of which version appears in
its list of test standards on OSHA's web page for the NRTL. When an
NRTL applies to be recognized to test to a particular standard, they
must submit the specific standard to which they aim to test. If an NRTL
is found to be testing and certifying equipment to a standard they are
not recognized for, OSHA may act.
As discussed earlier in this section, the EPA is proposing to
remove the existing use conditions specific to refrigerant charge size
limits for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in
residential and light commercial AC and heat pump applications. Rather
than duplicating charge size restrictions in a separate use condition,
the EPA is proposing to rely on the charge size restrictions inherent
in the process of getting residential and light commercial AC and heat
pump equipment certified by an NRTL to an industry consensus safety
standard that is designed to allow for safe use of flammable
refrigerants.
Under this third-party certification option, all three of the new
refrigerant listings and eight updated refrigerant listings proposed
for this end-use would include the use conditions described in Sections
IV.F.1., IV.F.2., and IV.F.3. There would also be a condition that
equipment be certified by an OSHA-recognized NRTL to a U.S. industry
consensus safety standard that is designed to allow for safe use of
flammable refrigerants in residential and light commercial AC and heat
pump equipment.
The EPA performed an assessment to examine the human health and
environmental risks of each of the proposed new substitutes. These
assessments are available in the docket.\57\ As discussed in Section
IV.E., the EPA also conducted updated analyses for three representative
substitutes for the updated listings to evaluate the health and safety
implications of designing and using AC equipment in accordance with the
latest edition of UL 60335-2-40, which the EPA proposes to view as one
example of a U.S. industry consensus safety standard that could be used
to meet this third-party certification requirement. These analyses
found that use of these proposed refrigerants in accordance with this
standard would not pose greater overall risk to human health and the
environment than other acceptable substitutes for new equipment in this
end-use. These assessments are available in the docket.\58\ Proposed
regulatory text for these new and updated listings under this potential
option can be found in the docket under the title ``Proposed Regulatory
Text for SNAP Rule 27'' in the section ``Proposed revisions to
Appendices R, V, W, and new Appendix Z--Third-Party Certification
Option (co-proposed as an alternative to Section III).''
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\57\ See in section XII., ``References'': ICF, 2025a; ICF,
2025b; and ICF, 2025c.
\58\ See in section XII., ``References'': ICF, 2025e; ICF,
2025f; and ICF, 2025g.
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5. When would the use conditions take effect?
For the newly listed refrigerants in this end-use, the use
conditions would take effect on the effective date of a final rule
based upon this proposal. For the refrigerants for which the EPA is
proposing to update use conditions in this end-use, the EPA is
proposing to allow regulated entities to follow either the existing use
conditions or the proposed updated use conditions from the effective
date of a final rule until two years after the effective date of the
final rule.
If the EPA finalizes the third-party certification option,
equipment manufactured between the effective date of the final rule and
two years after that effective date could follow either the existing
use conditions that include use of either UL 60335-2-40, 3rd edition
\59\ or the updated use conditions that would include certification of
equipment by an OSHA-recognized NRTL. The updated use conditions would
neither apply to nor affect equipment manufactured before the effective
date of the final rule.
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\59\ Or UL 484, 8th edition for R-290 and R-441A.
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G. What additional information is the EPA including in these proposed
listings?
For all proposed listings in this end-use, the EPA is including
recommendations, found in the ``Further Information'' column of the
proposed listings, to protect personnel from the risks of using
flammable refrigerants. Similar to our previous listings of flammable
refrigerants, the EPA is including information on the OSHA requirements
at 29 CFR part 1910, proper ventilation, personal protective equipment
(PPE), fire extinguishers, use of spark-proof tools
[[Page 50784]]
and equipment designed for flammable refrigerants, and training.
If the third-party certification option described in Section
IV.F.4.b. is finalized, the EPA would also include a sentence in the
``Further Information'' column stating that the EPA views UL 60335-2-40
to be an example of an appropriate U.S. industry consensus safety
standard that mitigates risks.
Since this additional information is not part of the regulatory
decision under SNAP, these statements are not binding for use of the
substitute under the SNAP program. While the statements in the
``Further Information'' column are not legally binding under the SNAP
program, the EPA encourages users of substitutes to apply all
statements in the ``Further Information'' column in their use of these
substitutes.
V. Household Refrigerators and Freezers
A. What is the EPA proposing in this action?
The EPA is proposing to list HCR 4141 as acceptable, subject to use
conditions, for use in new household refrigerators and freezers. The
EPA would list HCR 4141 in a table in the new appendix Z of 40 CFR part
82, subpart G.
The EPA is proposing several use conditions for the use of HCR 4141
in the household refrigerators and freezers end-use. SNAP use
conditions are designed to ensure that refrigerants are listed for
specific end-uses and in a way that mitigates risks to human health and
the environment. In summary, the EPA is co-proposing two options for
use conditions to address flammability risks of the refrigerant HCR
4141 in household refrigerators and freezers similar to the two options
discussed in Section IV.F.4. for the residential and light commercial
AC and heat pumps end-use. The key difference between the two options
in the household refrigerators and freezers end-use and the two options
in the residential and light commercial AC and heat pumps end-use is
the industry safety standard that the EPA would incorporate by
reference or would describe as being a relevant industry consensus
safety standard for third-party certification. In the household
refrigerators and freezers end-use the relevant U.S. industry consensus
safety standard that addresses safe use of flammable refrigerant is UL
60335-2-24, ``Household and Similar Electrical Appliances--Safety--Part
2-24: Particular Requirements for Refrigerating Appliances, Ice-Cream
Appliances and Ice-Makers,'' rather than UL 60335-2-40.
Under both options, the EPA proposes the same use conditions that
would restrict the use of the refrigerant HCR 4141 to new equipment
that is specifically designed for that refrigerant and that would
require warning labels and markings on equipment to inform consumers,
technicians, and first responders of potential flammability hazards.
Those common use conditions are described in Section V.E.
The two co-proposed options take two different potential approaches
to proposed use conditions addressing design safety requirements for
household refrigerators and freezers and in particular, charge size.
These options are described in detail in Sections V.E.4.a. and V.E.4.b.
Section V.E.4.a. describes an option in which the EPA would incorporate
by reference UL 60335-2-24, 3rd edition, including testing and charge
sizes. Section V.E.4.b. describes an option in which the EPA would
require household refrigerators and freezers to be certified to a U.S.
industry consensus safety standard such as UL 60335-2-24 by an
organization that OSHA recognizes as an NRTL. The EPA will consider
comments and available information and could finalize either of these
two co-proposals.
The common use conditions are described in Sections V.E.1., V.E.2.,
and V.E.3. The use condition option requiring household refrigerators
and freezers using HCR 4141 to meet a specific edition of UL 60335-2-24
is described in Section V.E.4.a. The option for a use condition
requiring third-party certification of household refrigerators and
freezers using HCR 4141 is described in Section V.E.4.b.
The proposed regulatory text for this listing using the third-party
certification option appears in the docket for this rulemaking under
the title ``Proposed Regulatory Text for SNAP Rule 27'' in the section
``Proposed revisions to Appendices R, V, W, and new Appendix Z--Third-
Party Certification Option (co-proposed as an alternative to Section
III).'' The proposed regulatory text for this listing using the
incorporate by reference option can be found in the docket for this
rulemaking under the title ``Proposed Regulatory Text for SNAP Rule
27'' in the section ``Proposed revisions to Appendices R, V, W, and new
Appendix Z--Incorporate by Reference Option.'' If one of the use
condition options is finalized, the EPA would publish a corresponding
finalized listing for HCR 4141 in new household refrigerators and
freezers in appendix Z of 40 CFR part 82, subpart G.
B. Background on Household Refrigerators and Freezers
Household refrigerators, freezers, and combination refrigerators
and freezers are intended primarily for residential use, although they
may be used outside the home (e.g., workplace kitchen pantries). The
designs and refrigeration capacities of equipment vary widely. This
equipment is composed of three main categories: household freezers only
offer storage space at freezing temperatures, household refrigerators
only offer storage space at non-freezing temperatures, and products
with both a refrigerator and freezer in a single unit which are most
common and are referred to as combination refrigerators and freezers.
Small refrigerated household appliances (e.g., chilled kitchen drawers,
wine coolers, mini-fridges, stand-alone ice makers, home ice cream
makers) are also within this end-use. In addition, refrigerators or
freezers that are designed for consumer, but not commercial or
professional, use and that are merely situated on a moving vehicle
(e.g., personal vehicle, recreational vehicle, or boat for leisure
purposes) are within the scope of the household refrigerators and
freezers end-use for purposes of the SNAP program. These uses are
within the scope of the relevant U.S. industry safety standard, UL
60335-2-24. Throughout this document, we refer to all these uses with
the phrase ``household refrigerators and freezers.'' Refrigerators or
freezers in a commercial kitchen such as onboard a cruise ship or on
aircraft are not household refrigerators or freezers for purposes of
the SNAP program and such equipment is outside the scope of UL 60335-2-
24. Household refrigerators and freezers have all refrigeration
components integrated, and for the smallest types, the refrigeration
circuit is entirely brazed or welded. These systems are charged with
refrigerant at the factory and typically require only an electricity
supply to begin operation.
ASHRAE's Handbook of Refrigeration provides an overview of food
preservation regarding household refrigerators and freezers. Generally,
a storage temperature between 32 and 39 [deg]F (0 to 3.9 [deg]C) is
desirable for preserving fresh food. Humidity and higher or lower
temperatures are more suitable for certain foods and beverages. Wine
chillers, for example, are frequently used for storing wine, and have
slightly higher optimal temperatures from 45 to 65 [deg]F (7.2 to 18.3
[deg]C). Freezers and combination refrigerators and freezers that are
designed to store food for long durations
[[Page 50785]]
have temperatures below 8 [deg]F (-13.3 [deg]C) and are designed to
hold temperatures near 0 to 5 [deg]F (-17.7 to -15 [deg]C). In single-
door refrigerators, the optimum conditions for food preservation are
typically warmer than this because food storage is not intended for
long-term storage.
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
See Section IV.C. for information on ASHRAE groups for refrigerant
flammability and toxicity.
D. What is HCR 4141 and how does it compare to other refrigerants in
the household refrigerators and freezers end-use?
HCR 4141 is a blend of the saturated HCs R-600a, R-600, and R-290,
all of which are higher flammability refrigerants having an ASHRAE
safety group of A3; the percentage of each component in the blend is
claimed as CBI. See Section IV.D. for environmental information,
flammability information, and toxicity and exposure information on HCR
4141. The redacted submission and supporting documentation for HCR 4141
in household refrigerators and freezers are provided in the docket. The
EPA performed a risk screening assessment to examine the human health
and environmental risks of this substitute which also is available in
the docket.\60\
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\60\ ICF, 2025h. Risk Screen on Substitutes in Household
Refrigerators and Freezers (New Equipment); Substitute: HCR 4141.
---------------------------------------------------------------------------
Comparison to other substitutes in the household refrigerators and
freezers end-use: The specific atmospheric effects values can be found
in the individual risk screen for HCR 4141. The values were determined
consistent with the source information noted in Section III.C. above
(e.g., CAA; the AIM Act; WMO, 2022) as well as using the methodology
for determining values for blends of chemicals (i.e., determined by the
percentage of each component). The EPA compared HCR-4141 to other A3
refrigerants listed as acceptable subject to use conditions for the
same end-use. The MIR of the blend HCR 4141 is expected to be less than
that of R-600a (MIR of 1.23 g O3/g isobutane) and greater
than that of R-290 (MIR of 0.49 g O3/g propane). The MIR of
HCR 4141 is greater than that of compounds that have been excluded from
the EPA's regulatory definition of VOC \61\ addressing the development
of SIPs to attain and maintain the NAAQS, such as HFC-152a.
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\61\ 40 CFR 51.100(s).
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The EPA's risk screen for HCR 4141 in new household refrigerators
and freezers \62\ found that HCR 4141 can be used without exceeding its
recommended OEL of 1,000 ppm (8-hr TWA); thus, the toxicity risks of
HCR 4141 are comparable to those of other acceptable substitutes in new
household refrigerators and freezers, which also are used without
exceeding their OELs.
---------------------------------------------------------------------------
\62\ ICF, 2025h. Op. cit.
---------------------------------------------------------------------------
Although we noted that the flammability of HCR 4141 may be greater
than that of other available substitutes that have ASHRAE 1, 2 or 2L
flammability classifications in the same end-use, we found its
flammability risk to be not significant even under worst-case
assumptions in this end-use when following the proposed use
conditions.\63\ Further, its flammability risk is comparable to that of
other A3 refrigerants that the EPA has previously listed as acceptable
in this end-use. We note that flammability risk can be minimized by use
consistent with industry safety standards such as UL 60335-2-24--which
would be required by the proposed use conditions--as well as
recommendations in the manufacturers' SDS and other safety precautions
common in the refrigeration and air conditioning industry. The proposed
use conditions for household refrigerators and freezers would maintain
low potential risk associated with the flammability of this alternative
so that it would not pose greater overall risk than other acceptable
substitutes in this end-use.
---------------------------------------------------------------------------
\63\ ICF, 2025h. Op. cit.
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E. What use conditions is the EPA proposing in this action for the new
listing for HCR 4141 in new household refrigerators and freezers?
The proposed use conditions described in this section would apply
to new household refrigerators and freezers using HCR 4141. Many of the
proposed use conditions mirror the SNAP program's historical approach
to requirements for flammable refrigerants in this end-use. The
proposed use condition related to use in new equipment only is
consistent with previously listed higher flammability refrigerants in
this end-use. The proposed use conditions related to labels and
markings are very similar to what has previously been required by SNAP
for higher flammability refrigerants in this end-use, with a few
updates made specifically to better align the EPA requirements with
updated industry safety standards. A use condition option that proposes
to incorporate by reference the latest edition of UL 60335-2-24 is
consistent with the EPA's historical practice for listing flammable
refrigerants in this end-use. The other co-proposed option, while
different from the EPA's historical practice of incorporating portions
of or entire industry consensus safety standards by reference, would
address situations where the EPA's regulations require adherence to
editions of industry consensus safety standards that have been updated
and replaced subsequent to the issuance of a final rule. The EPA
proposes the following use conditions:
1. New Equipment Only; Not Intended for Use as a Retrofit Alternative
The EPA is proposing that HCR 4141 may be used only in new
equipment designed specifically and clearly identified for the
refrigerant. In other words, this substitute must not be used as a
conversion or ``retrofit'' \64\ refrigerant for existing equipment
designed for another refrigerant. The EPA has established this same
requirement for other A3 refrigerants in this end-use and in certain
other refrigeration and AC end-uses, such as vending machines, retail
food refrigeration--stand-alone units, and very low temperature
refrigeration. This requirement is intended to ensure that equipment
using a higher flammability refrigerant is specifically designed to
address flammability risks.
---------------------------------------------------------------------------
\64\ Sometimes conversion refrigerant substitutes are
inaccurately referred to as ``drop in'' replacements.
---------------------------------------------------------------------------
2. Labels
The EPA is proposing to require labeling of household refrigerators
and freezers using HCR 4141. The following markings, or the equivalent,
would need to be provided and be permanent:
a. ``DANGER--Risk of fire or explosion. Flammable refrigerant used.
Do not use mechanical devices to defrost refrigerator. Do not puncture
refrigerant tubing.'' This marking would need to be located on or near
any evaporators that can be contacted by the consumer.
b. ``DANGER--Risk of fire or explosion. Flammable refrigerant used.
To be repaired only by trained service personnel. Use only
manufacturer-authorized service parts. Any repair equipment used must
be designed for flammable refrigerants. Follow all manufacturer repair
instructions. Do not puncture refrigerant tubing.'' This marking would
need to be located near the machine compartment.
c. ``CAUTION \65\--Risk of fire or explosion. Dispose of
refrigerator
[[Page 50786]]
properly in accordance with the applicable federal or local
regulations. Flammable refrigerant used.'' This marking would need to
be located on the exterior of the refrigeration equipment.
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\65\ The word ``CAUTION'' may be substituted with the word
``WARNING.''
---------------------------------------------------------------------------
d. ``CAUTION \66\--Risk of fire or explosion due to puncture of
refrigerant tubing; follow handling instructions carefully. Flammable
refrigerant used.'' This marking would need to be located near all
exposed refrigerant tubing.
---------------------------------------------------------------------------
\66\ The word ``CAUTION'' may be substituted with the word
``WARNING.''
---------------------------------------------------------------------------
Both the 3rd and 2nd editions of UL 60335-2-24 have required labels
with the above text as a hazard warning on refrigerated equipment that
uses a flammable refrigerant. The 3rd edition of UL 60335-2-24 has
revised two requirements in the 2nd edition concerning warning labels.
The first change was that one marking would no longer be required that
stated, ``CAUTION--Risk of fire or explosion. Flammable refrigerant
used. Consult repair manual/owner's guide before attempting to service
this product. All safety precautions must be followed.'' The EPA also
would not require this marking in the proposed use conditions.
The second change to the labels in the 3rd edition of UL 60335-2-24
is that the height of the letters on the warning labels have changed
from no less than 6.4 mm (\1/4\ inch) to no less than 3.2 mm (\1/8\
inch), with the signal words ``DANGER,'' ``WARNING,'' and ``CAUTION''
being no less than 5.0 mm (0.2 inch). This would be a smaller font size
that would allow for smaller labels that would be more convenient for
manufacturers to apply. The EPA is instead proposing that the label
text size be no less than 6.4 mm (\1/4\ inch) to allow for greater
visibility for technicians, consumers, recyclers, and first responders.
The larger font size is also consistent with the font size that the EPA
has previously required for these labels in other SNAP rules for
refrigeration or AC equipment using flammable refrigerants.
3. Color-Coded Hoses and Piping
The EPA is proposing to require that equipment have distinguishing
red (PMS #185 or RAL 3020) color-coded hoses and piping to indicate use
of a flammable refrigerant. This color would need to be present at all
service ports and other parts of the system where service puncturing or
other actions creating an opening from the refrigerant circuit to the
atmosphere might be expected, would need to extend a minimum of one
inch (25 mm) in both directions from such locations, and would need to
be replaced if removed. The EPA has applied this proposed use condition
in past actions for flammable refrigerants.\67\
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\67\ See 86 FR 24444, May 6, 2021, and 88 FR 26382, April 28,
2023.
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Red markings are a requirement of the 3rd edition of UL 60335-2-24.
The standard allows for an exception if the labels are visible when a
technician attempts to access a process tube. In addition, the 3rd
edition of UL 60335-2-24 calls for red markings but does not specify
any particular shade of red. The EPA's proposal would not allow for
this exception and is specifying particular shades of red, as in
previous rules.
4. Use Condition Options Related to Equipment Certification or Industry
Safety Standard Requirements
The EPA is co-proposing two options for a use condition related to
equipment certification or industry safety standard requirements for
equipment that uses HCR 4141 in household refrigerators and freezers.
Under the first option, the EPA would incorporate by reference a new
edition of the safety standard for this end-use. Under the second
option, the EPA would require household refrigerators and freezers to
be certified by an organization that is recognized as an NRTL to a U.S.
industry consensus safety standard that is designed to allow for safe
use of flammable refrigerants in household refrigerators and freezers.
This is the same proposed approach discussed in Section IV.F.4.a.
For the most recent listings of flammable refrigerants used in
household refrigerators and freezers, the EPA addressed design elements
to reduce flammability risks by incorporating by reference the 2nd
edition of UL 60335-2-24, ``Household and Similar Electrical
Appliances--Safety--Part 2-24: Particular Requirements for
Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers.'' \68\
The EPA is co-proposing an option to incorporate by reference UL 60335-
2-24, 3rd edition (dated July 29, 2022, with revisions through February
29, 2024). As discussed in Section IV.F.4.b., the Agency recognizes
that certain standards, including UL 60335-2-24, are under continuous
maintenance, meaning that they are updated and superseded by newer
editions. This often means that regulations and safety standards are
out of step. Therefore, the EPA is proposing another option to
streamline use conditions and to maintain consistency with the most
current version of the relevant standards. This potential option is
discussed in Section V.E.4.b.
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\68\ Dated April 28, 2017. See 83 FR 38969; August 8, 2018.
---------------------------------------------------------------------------
Each co-proposal in Sections IV.F.4.a. and IV.F.4.b. would include
certain use conditions in addition to the common use conditions in
Sections V.E.1., V.E.2., and V.E.3. (i.e., for use in new equipment
only, labels, and color-coded hoses and piping). The use conditions for
HCR 4141 would apply to household refrigerators and freezers
manufactured on and after the effective date of the final rule. The use
conditions would be in a new appendix Z of 40 CFR part 82, subpart G.
a. Incorporate by Reference UL 60335-2-24, 3rd Edition Option
In this first co-proposal, the EPA proposes that the refrigerant
HCR 4141 may be used only in equipment that meets all the requirements
in UL 60335-2-24.\69\ The EPA has set a similar requirement for the use
of R-290, R-600a, and R-441A in household refrigerators and
freezers,\70\ where the Agency's regulations require that those
refrigerants be used only in equipment meeting the requirements of the
2nd edition \71\ of UL 60335-2-24, rather than the 3rd edition of that
standard. In this proposed new listing for HCR 4141 in new household
refrigerators and freezers, the EPA would incorporate by reference the
standard UL 60335-2-24, ``Safety Requirements for Household and Similar
Electrical Appliances, Part 2: Particular Requirements for
Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers.'' \72\
This safety standard establishes requirements for the evaluation of
household and similar electrical appliances, and safe use of flammable
refrigerants. The EPA previously incorporated by reference UL 60335-2-
24, 2nd edition for R-290, R-441A, and R-600a in our most recent rule
on flammable refrigerants in household refrigerators and freezers.\73\
This proposal would incorporate by reference the latest edition and
revisions to that safety standard. Where the rule includes requirements
that are different than those of UL 60335-2-24 (e.g., font size), the
EPA is proposing that the appliance would need to meet the requirements
of the rule. UL 60335-2-24 establishes requirements for the evaluation
of household and similar electrical appliances and the safe use of
[[Page 50787]]
A2, A2L, or A3 refrigerants. The charge size limit for each separate
refrigerant circuit (i.e., compressor, condenser, evaporator, and
refrigerant piping) is 150 grams (5.3 ounces), remaining the same in
the 3rd edition as in the 2nd edition.
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\69\ 3rd edition, July 29, 2022, with revisions through February
29, 2024.
\70\ See 83 FR 38969; August 8, 2018, and appendix R of 40 CFR
part 82, subpart G.
\71\ 2nd edition of UL 60335-2-24 dated April 28, 2017.
\72\ 3rd edition, July 29, 2022, with revisions through February
29, 2024.
\73\ See 83 FR 38969; August 8, 2018.
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Both the 2nd and 3rd editions require testing of refrigeration
appliances containing flammable refrigerants, including leakage tests,
temperature and scratch tests, and heat testing requirements to address
the hazards due to ignition of leaked refrigerant by potential ignition
sources associated with the appliance. These tests are intended, among
other things, to ensure that any leaks will result in concentrations
well below the LFL, and that potential ignition sources will not be
able to create temperatures high enough to start a fire. Specifically,
the leakage test ensures that refrigerant concentrations do not reach
or exceed 75 percent of the LFL inside any internal or external
electrical component compartments. Appliances that comply with UL
60335-2-24 have passed appropriate ignition or leakage tests as
stipulated in the standard. In addition, UL 60335-2-24, 3rd edition,
includes labels and markings, as discussed in Sections V.E.2. and
V.E.3. UL standard 60335-2-24 was developed using a consensus-based
approach developed in cooperation with parties with an interest in
participating in the development or use of the standard. For example,
UL uses a process where experts with various interests, including
manufacturers, experts in assessing the safety of products, government
agencies, and academia, come together to agree on the safety
requirements for a product, resulting in a standard that reflects a
collective consensus on best practices for safety. While similar
standards exist from other bodies such as the IEC, we are proposing in
this option to use specific UL standards that are most applicable and
used by U.S. manufacturers. The EPA used this approach in previous SNAP
rules concerning lower and higher flammability refrigerants.\74\ UL
standard 60335-2-24 was developed using a consensus-based approach
developed in cooperation with parties with an interest in participating
in the development or use of the standard. For example, UL uses a
process where experts with various interests, including manufacturers,
experts in assessing the safety of products, government agencies, and
academia, come together to agree on the safety requirements for a
product, resulting in a standard that reflects a collective consensus
on best practices for safety. While similar standards exist from other
bodies such as the IEC, we are proposing in this option to rely on
specific UL standards that are most applicable and used by U.S.
manufacturers. The approach of incorporating a UL standard by reference
is the same as that in our previous rules on flammable
refrigerants.\75\
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\74\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
\75\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.
---------------------------------------------------------------------------
Under this incorporate by reference option, this listing would
include the use conditions described in Sections V.E.1., V.E.2., and
V.E.3. as well as a use condition that the refrigerant may only be used
in equipment that meets all the requirements of UL 60335-2-24, 3rd
edition.
The EPA performed an assessment to examine the human health and
environmental risks of HCR 4141 in household refrigerators and
freezers. This assessment is available in the docket.\76\ The proposed
regulatory text for this new listing under this option can be found in
the docket under the title ``Proposed Regulatory Text for SNAP Rule
27'' in the section ``Proposed revisions to Appendices R, V, W, and new
Appendix Z--Incorporate by Reference Option.''
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\76\ ICF, 2025h. Risk Screen on Substitutes in Household
Refrigerators and Freezers (New Equipment); Substitute: HCR 4141.
2025.
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b. Third-Party Certification Option
Under this second co-proposal, the EPA is proposing a use condition
where all household refrigerators and freezers using HCR 4141 must be
certified by an OSHA-recognized NRTL to a U.S. industry consensus
safety standard that is designed to allow for safe use of flammable
refrigerants in household refrigerators and freezers and mitigates
risks such that the listed refrigerant can be used in a manner that
does not pose a greater overall risk to human health and the
environment than other substitutes in this end-use. The industry
consensus safety standard must be designed for use in the United States
and be consistent with best industry safety practices.\77\ For further
detail on requirements of applicable industry consensus safety
standards that the EPA proposes to find necessary to sufficiently
mitigate risks, see Section IV.F.4.b. While the EPA is proposing
reliance on certification by these NRTLs, the EPA is not opening OSHA's
regulations at 29 CFR 1910.7 for comment, including definitions or
requirements, nor is the EPA seeking comment on the OSHA program
itself. For further information on OSHA's NRTL Program, see Section
IV.F.4.b.
---------------------------------------------------------------------------
\77\ e.g., UL 60335-2-24.
---------------------------------------------------------------------------
By not incorporating by reference a specific edition of a relevant
safety standard in this use condition option, the EPA intends to
increase efficiencies by not having to propose a new rule each time a
standard is updated and to leverage OSHA's NRTL Program. The EPA does
not expect this option to pose significant additional burden on
manufacturers or NRTLs because most manufacturers of household
refrigerators and freezers have their equipment certified by an NRTL
already. Manufacturers that do not already certify their equipment
through an OSHA-recognized NRTL would need to do so beginning two years
after the effective date of the final rule.
Under this third-party certification option, the listing would
include the use conditions described in Sections V.E,1., V.E.2., and
V.E.3. as well as a use condition that equipment be certified by an
OSHA-recognized NRTL to a U.S. industry consensus safety standard that
is designed to allow for safe use of flammable refrigerants in
household refrigerators and freezers. The EPA proposes that the use
conditions for HCR 4141 in new household refrigerators and freezers
would apply on the effective date of the final rule.
The EPA performed an assessment to examine the human health and
environmental risks of HCR 4141 in household refrigerators and
freezers. This assessment is available in the docket.\78\ Proposed
regulatory text for the new listing for HCR 4141 in household
refrigerators and freezers under this option can be found in the docket
under the title ``Proposed Regulatory Text for SNAP Rule 27'' in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Third-Party Certification Option (co-proposed as an alternative to
Section III).''
---------------------------------------------------------------------------
\78\ ICF, 2025h.
---------------------------------------------------------------------------
F. What additional information is the EPA including in this proposed
listing?
The ``Further Information'' column of the proposed listing for HCR
4141 in household refrigerators and freezers includes applicable OSHA
requirements at 29 CFR part 1910, suggestions on ventilation and PPE,
appropriate type of fire extinguisher (Class B), and suggestions for
technicians. Among the suggestions for technicians are the appropriate
type of tools and equipment to use for servicing, conditions for
[[Page 50788]]
release of refrigerant if it is not recovered, and a recommendation
that only technicians specifically trained in handling of flammable
refrigerants service equipment containing the refrigerant.
The ``Further Information'' column of the listing for HCR 4141
under the third-party certification option would be the same as under
the incorporation by reference of UL 60335-2-24 option.\79\ In
addition, because the EPA would not require use of UL 60335-2-24 in a
use condition under the third-party certification option, the Agency
would include a recommendation to follow the latest edition of UL
60335-2-24 or similar industry safety standard. While the statements in
the ``Further Information'' column are not legally binding under the
SNAP program, the EPA encourages users of HCR 4141 to apply all
statements in the ``Further Information'' column in their use of this
substitute.
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\79\ See section V.E.4.
---------------------------------------------------------------------------
VI. Water Coolers
A. What is the EPA proposing in this action?
The EPA is proposing to update use conditions for the previously
listed refrigerant R-290 for use in water coolers. The EPA listed R-290
as acceptable, subject to use conditions, in new water coolers in SNAP
Rule 21.\80\ The industry consensus safety standard that was
incorporated by reference at the time of the original listing has since
been updated. The EPA is not proposing to move this listing from
acceptable, subject to use conditions, to any other listing category
(e.g., unacceptable).
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\80\ See 81 FR 86778; December 1, 2016.
---------------------------------------------------------------------------
The proposed updated use conditions include a requirement that R-
290 be used in new equipment only, specific requirements for warning
labels, and specific requirements for markings. As with some other
listings in this rule, the EPA is co-proposing two options for an
additional use condition related to equipment certification or industry
safety standard requirements for R-290 in water coolers. The EPA
intends to finalize one of these co-proposed options along with an
appropriate transition period to provide manufactures with opportunity
for a smooth transition between the existing use conditions and the
updated use conditions. Throughout this section, the term ``updated use
conditions'' refers to the set of use conditions being proposed that
would apply to new equipment manufactured after the effective date of
the final rule. The updated use conditions would neither apply to nor
affect equipment manufactured before the effective date of the final
rule.
The proposed regulatory text for this listing can be found in the
docket for this rulemaking under the title ``Proposed Regulatory Text
for SNAP Rule 27'' in the section ``Proposed revisions to Appendices R,
V, W, and new Appendix Z--Incorporate by Reference Option'' and in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Third-Party Certification Option (co-proposed as an alternative to
Section III).'' If one of the use condition options is finalized, the
EPA would publish a corresponding finalized listing for R-290 in water
coolers in appendix V to 40 CFR part 82, subpart G.
B. Background on Water Coolers
Water coolers are self-contained refrigerated units providing
chilled water for drinking. They may or may not feature detachable
containers of water. These devices are extensively used in homes,
workplaces, public facilities, and warehouses typically employing a
compact refrigeration system to chill water. Many models are self-
contained, incorporating either bottle-fed or point-of-use water
sources.
C. What are the ASHRAE groups for refrigerant flammability and
toxicity?
See Section IV.C. for information on ASHRAE groups for refrigerant
flammability and toxicity.
D. What is R-290 and how does it compare to other refrigerants in the
water coolers end-use?
See Section IV.E. for information about R-290 and its
environmental, flammability, and toxicity and exposure impacts.
Redacted supporting documentation for R-290 in water coolers is
provided in the docket. The EPA performed a risk screening assessment
to examine the human health and environmental risks of R-290 in water
coolers which also is available in the docket.\81\
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\81\ ICF, 2025i. Risk Screen on Substitutes in Water Coolers
(New Equipment); Substitute: Propane (R-290). 2025.
---------------------------------------------------------------------------
Environmental information: See Section IV.D. for discussion of the
EPA's analysis of potential air quality impacts due to emissions of R-
290 and other HC refrigerants that are VOCs under EPA's regulatory
definition of VOC.\82\ The analysis showed relatively minimal air
quality impacts of R-290 released to the atmosphere from the end-uses
where it is already listed as acceptable, subject to use conditions,
including water coolers. The EPA therefore concluded that R-290 does
not have a greater overall impact on human health and the environment
based on its effects on local air quality than other refrigerants
listed as acceptable in the same end-uses.
---------------------------------------------------------------------------
\82\ 40 CFR 51.100(s).
---------------------------------------------------------------------------
The EPA previously exempted R-290 in water coolers from the venting
prohibition under CAA section 608(c)(2), finding that such venting,
release, or disposal does not pose a threat to the environment.\83\ The
EPA is not proposing to change either of these decisions and is not
reopening them for comment.
---------------------------------------------------------------------------
\83\ See 81 FR 86778; December 1, 2016; 40 CFR
82.154(a)(1)(viii).
---------------------------------------------------------------------------
Flammability information: R-290 exhibits higher flammability than
other alternatives in this end-use and has an ASHRAE flammability
classification of 3.
Toxicity and exposure data: R-290 has an ASHRAE toxicity
classification of A (lower toxicity).
Comparison to other acceptable substitutes in the water coolers
end-use: The atmospheric effects values can be found in the individual
risk screen for R-290. These were determined consistent with the source
information noted in Section III.C. above. Other acceptable substitutes
for the water coolers end-use include R-480A, R-513A, HFC-134a, R-404A,
and R-507A. The atmospheric effects for R-290 are better than or
comparable to other listed substitutes. R-290 has an ODP of 0, which is
lower than or identical to the ODPs of other alternatives in this end-
use.
R-290 is a VOC, unlike the other substitutes listed in this end-
use. However, because of the relatively minimal air quality impacts of
R-290 if it is released to the atmosphere from the end-uses where it is
listed as acceptable, subject to use conditions, even in a worst-case
scenario, the EPA has previously concluded that R-290 does not have a
greater overall impact on human health and the environment based on its
effects on local air quality than other refrigerants listed as
acceptable in the same end-use. When used in this end-use, workplace
and consumer exposure to R-290 is not expected to exceed relevant
exposure limits. Thus, R-290 does not pose significantly greater
toxicity risks than other acceptable refrigerants in this end-use.
The flammability risks of R-290 in this end-use, determined by the
likelihood of exceeding the LFL, are evaluated in the risk screen
previously referenced. Other acceptable substitutes
[[Page 50789]]
in this end-use category, including R-404A and HFC-134a, have an ASHRAE
flammability class of 1. The proposed updated use conditions reduce the
potential risk associated with the flammability of this alternative so
it would not pose greater overall risk than other acceptable
substitutes in this end-use. Updating the use conditions for this
refrigerant would enable it to continue to be available and used safely
in the industry. This proposed revised listing under SNAP would provide
greater flexibility to use R-290, while maintain safe use in this end-
use.
The EPA previously found R-290 acceptable, subject to use
conditions, in new water coolers in SNAP Rule 21.\84\ Those
requirements are codified in appendix V of 40 CFR part 82, subpart G.
The EPA provided information on the environmental and health properties
of R-290 and the various substitutes available at that time for use in
this end-use. The EPA's risk screen for R-290 in water coolers is
available in the docket for that previous rulemaking.\85\
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\84\ See 81 FR 86778; December 1, 2016.
\85\ EPA-HQ-OAR-2015-0663.
---------------------------------------------------------------------------
The existing use conditions for R-290 in water coolers address safe
use of this higher flammability refrigerant and include incorporation
by reference of Supplement SB to UL 399, 7th edition, a requirement
that the refrigerant only be used in new equipment that is designed
specifically and clearly identified for the refrigerant, a requirement
that the charge size not exceed 60 grams per refrigerant circuit in the
water cooler, and requirements for markings and warning labels on
equipment using the refrigerant to inform consumers and technicians of
potential flammability hazards.
Without appropriate use conditions, the flammability risk posed by
this refrigerant would be higher than nonflammable refrigerants because
individuals may not be aware that their actions could potentially cause
a fire, and because the refrigerant could be used in existing equipment
that has not been designed specifically to minimize flammability risks.
Our assessment and listing decisions in SNAP Rule 21 \86\ found that
with the use conditions, the use of this substitute, including the risk
due to flammability, does not present a greater overall risk in the
end-use than other substitutes that are currently or potentially
available for that same end-use. The EPA has not updated the use
conditions for R-290 in water coolers since 2016.
---------------------------------------------------------------------------
\86\ See 81 FR 86778; December 1, 2016.
---------------------------------------------------------------------------
In the Notice of Proposed Rulemaking for SNAP Rule 21, the EPA
proposed 150 g of R-290 as the charge size limit.\87\ This proposed
charge size was greater than the 60 g charge size limit in the 7th
edition of UL 399. Based upon the EPA's initial risk screen prepared
for that rulemaking, a worst-case release of an entire charge of 150 g
of R-290 in a small room could result in exceeding the LFL. The release
of a charge of 120 g, as well as the 60 g charge limit in the 7th
edition of UL 399, would not result in exceeding the LFL. Based upon
public comment, the EPA revised its risk screen and finalized a 60 g
charge limit to be consistent with the 60 g limit in the 7th edition of
UL 399.
---------------------------------------------------------------------------
\87\ See 81 FR 22810; April 18, 2016.
---------------------------------------------------------------------------
Based on additional risk screening and in response to a request
from a manufacturer of water coolers, the EPA now proposes to find that
the larger charge size of 130 g in the 8th edition of UL 399 with
revisions through February 28, 2024, can be used safely through
proposed, updated use conditions to address flammability risks.
E. What use conditions is the EPA proposing in this action for the
updated listing for R-290 in new water coolers?
The use conditions that currently apply to R-290 in the water
coolers end-use incorporate by reference an industry consensus safety
standard \88\ that has been updated since the listing decision was
finalized. Similar to Section IV.F. for updated use conditions in the
residential and light commercial AC and heat pumps end-use, the EPA is
proposing to update the listing for R-290 in the water coolers end-use
so that the use conditions reflect updated industry safety standards.
---------------------------------------------------------------------------
\88\ UL 399, 7th edition.
---------------------------------------------------------------------------
Many of the proposed use conditions described in this section
mirror existing use conditions. A use condition option described that
proposes to incorporate by reference the latest edition of UL 399 is
consistent with the EPA's historical practice for listing flammable
refrigerants in this end-use. The other co-proposed option, while
different from the EPA's historical practice of incorporating portions
of or entire industry consensus safety standards by reference, would
address situations where the EPA regulations require adherence to
editions of industry consensus safety standards that have been updated
and replaced subsequent to the issuance of a final rule. The EPA
proposes the following use conditions:
1. New Equipment Only; Not Intended for Use as a Retrofit Alternative
The EPA is proposing that R-290 may be used only in new equipment
designed specifically and clearly identified for the refrigerant. In
other words, this refrigerant must not be used as a conversion or
``retrofit'' refrigerant for existing equipment designed for another
refrigerant. This is an existing use condition for R-290 in water
coolers and the EPA is only addressing use of R-290 in new equipment
which can be properly designed for higher flammability refrigerants.
2. Labels
The EPA is proposing to require labeling of water coolers using R-
290. The following statements would need to be attached on labels at
the locations provided and be permanent:
a. On or near any evaporators that the user can contact: ``DANGER--
Risk of Fire or Explosion. Flammable Refrigerant Used. Do Not Puncture
Refrigerant Tubing.''
b. On the inside of the water cooler near the compressor/condenser
compartment: ``DANGER--Risk of Fire or Explosion. Flammable Refrigerant
Used. To Be Repaired Only by Trained Service Personnel. Do Not Puncture
Refrigerant Tubing.''
c. On the inside of the water cooler near the compressor/condenser
compartment: ``CAUTION--Risk of Fire or Explosion. Flammable
Refrigerant Used. Consult Instruction Manual/Repair Manual/Owner's
Guide Before Attempting to Install or Service This Product. All Safety
Precautions Must be Followed.''
d. On the outside of the water cooler: ``CAUTION--Risk of Fire or
Explosion. Dispose of Properly in Accordance With Federal Or Local
Regulations. Flammable Refrigerant Used.''
e. Near all exposed tubing: ``CAUTION--Risk of Fire or Explosion
Due To Puncture Of Refrigerant Tubing; Follow Handling Instructions
Carefully. Flammable Refrigerant Used.''
The proposed text of the labels is verbatim in language to those
required by the section SB6.1.1 through SB6.1.5 of Supplement SB of
both the 7th and 8th editions of UL 399. As required in section SB6.1.1
of both the 7th and 8th editions of UL 399, the minimum height for
lettering must be \1/4\ inch (6.4 mm) for all these labels, making it
easy for technicians, consumers, retail storeowners, first responders,
and those disposing the appliance to view the warning labels. These
requirements are also aligned with previous labeling requirements for
A3 refrigerants in
[[Page 50790]]
SNAP Rule 21.\89\ Under both the use condition options proposed and
discussed in Sections VI.E.4.a. and VI.E.4.b., the proposed listing
would maintain this use condition for labels.
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\89\ See 81 FR 86778; December 1, 2016.
---------------------------------------------------------------------------
3. Color-Coded Hoses and Piping
An existing use condition for R-290 in water coolers is that they
must have distinguishing red (PMS #185) color-coded pipes, hoses, or
other devices through which the refrigerant passes, to indicate the use
of a flammable refrigerant. This color must be applied at all service
ports and other parts of the system where service puncturing or other
actions creating an opening from the refrigerant circuit to the
atmosphere might be expected and must extend a minimum of one inch (25
mm) in both directions from such locations. If removed, these markings
also shall be replaced. These markings are the same as those required
in section SB6.1.6 of Supplement SB to the 7th and 8th editions of UL
399, although the exact wording of those requirements is slightly
different (e.g., states ``refrigerant tubing or other devices through
which the refrigerant is intended to be serviced''). The EPA proposes
that this same use condition continue to apply. This would be the case
either for the incorporate by reference option described in Section
VI.E.4.a. or for the third-party certification option described in
Section VI.E.4.b.
4. Use Condition Options Related to Equipment Certification or Industry
Safety Standard Requirements
In the initial listing of R-290 as acceptable, subject to use
conditions, for use in water coolers, the EPA set two use conditions
that relate to charge size and risk mitigation: (1) limiting the
maximum charge of R-290 to 60 g in each refrigerant circuit and (2)
requiring that water coolers using R-290 must meet all requirements of
Supplement SB to the 7th edition of UL 399, dated August 22, 2008, with
all revisions through October 18, 2013. Supplement SB to the 7th
edition of UL 399 set a maximum refrigerant charge size of 2 ounces or
60 g for class 3 (higher flammability) refrigerants and other
requirements such as construction requirements, performance testing,
and marking requirements.
The latest revision to the 8th edition of UL 399 issued in February
2024 allows up to 130 g of A3 refrigerants, including R-290, in water
coolers. The Agency's most recent risk screening finds that R-290 may
be used safely in new water coolers in accordance with the 8th edition
of UL 399 and a charge size of up to 130 g of R-290 to mitigate
flammability risks.
These water coolers are factory charged with R-290 by the
manufacturer. The risk of fire is minimal if water coolers meet the
provisions of the 8th edition of UL 399 and have a charge size of R-290
no greater than 130 g. Water coolers containing R-290 should not be
installed in enclosed areas and water coolers containing R-290 that are
installed in lobbies or locations of egress (e.g., hallways) and would
need to have a charge size no greater than three times the LFL, or 114
g of R-290, as stated in standards such as ASHRAE 15 and UL 399. Water
coolers installed in locations with adequate space and/or ventilation
in accordance with the EPA recommendations and requirements, industry
consensus safety standards, and the installation and maintenance
manuals for equipment using R-290, are unlikely to pose flammability
risk and human health risk to end-users, personnel, or the general
population when the proposed use conditions are followed. Thus, the EPA
proposes to find that updating the charge size and being consistent
with the 8th edition of UL 399 to address flammability risks from use
of R-290 in water coolers is appropriate to protect against such risks.
EPA is proposing to update the condition to follow Supplement SB of
the 7th edition of UL 399 and remove the existing, separate use
condition to use a charge size of R-290 of no greater than 60 g.
Supplement SB contains specific safety criteria for water coolers using
flammable refrigerants such as R-290. These requirements, including
testing to meet safety standards, are designed to mitigate risks
associated with flammable refrigerants. EPA proposes to find that the
requirements in the 8th edition of UL 399, including the larger charge
size of 130 g, allow R-290 to be used in a manner that sufficiently
addresses flammability risks.
The EPA is co-proposing two options for a use condition related to
equipment certification or industry safety standard requirements for
the use of R-290 in water coolers. Section VI.E.4.a. describes an
option in which the EPA would incorporate by reference a new edition of
the industry consensus safety standard for this end-use. Section
VI.E.4.b. describes an option in which the EPA would require water
coolers to be certified by an organization that is recognized as an
NRTL to a U.S. industry consensus safety standard that is designed to
allow for safe use of flammable refrigerants and mitigates risks such
that R-290 can be used in a manner that does not pose a greater overall
risk to human health and the environment than other substitutes in this
end-use.
a. Incorporate by Reference UL 399, 8th Edition Option
For background on the SNAP program's recent approach to identifying
use conditions for lower and higher flammability refrigerants, refer to
Section IV.F.4.a. In this first co-proposed option, the EPA proposes
that R-290 only be used in water coolers that meet all the requirements
listed in Supplement SB of UL 399, 8th edition. The EPA is proposing to
incorporate by reference Supplement SB of UL 399, ``Standard for
Safety: Drinking Water Coolers,'' 8th edition, March 30, 2017, with
revisions through February 28, 2024, which establishes requirements for
the evaluation of household and similar electrical appliances, and safe
use of flammable refrigerants. Where the rule requirements are
different than those of UL 399, the EPA is proposing that the appliance
would need to meet the requirements of the rule.
UL 399 establishes requirements for the evaluation of water coolers
and the safe use of refrigerants with a flammability classification of
A2, A2L, or A3. This section summarizes relevant requirements of UL 399
for information only and is not meant to be a complete review of the
standard or how it is applied.
The EPA has evaluated the revisions to the standard published in
the 8th edition and finds that construction and use of water coolers in
accordance with the 8th edition would not pose greater overall risk to
human health and the environment when compared to use in accordance
with the 7th edition. The charge size limit for each separate
refrigerant circuit (i.e., compressor, condenser, evaporator, and
refrigerant piping) is 130 grams (4.6 ounces), which is more than the
60 g limit in the 7th edition.
Both the 7th and 8th editions of UL 399 require testing of water
coolers containing flammable refrigerants, including leakage tests,
temperature and scratch tests, and heat testing requirements to address
the hazards due to ignition of leaked refrigerant by potential ignition
sources associated with the appliance. These tests are intended, among
other things, to ensure that any leaks will result in concentrations
well below the LFL, and that potential ignition sources will not be
able to create temperatures high enough to start a fire. Water coolers
that comply with UL 399 have passed
[[Page 50791]]
appropriate ignition or leakage tests as stipulated in the standard.
Passing the leakage test ensures that refrigerant concentrations in the
event of a leak do not reach or exceed 75 percent of the LFL inside any
internal or external electrical component compartments. In addition,
the 8th edition of UL 399 includes hazard warning labels and markings
to make users, technicians, first responders, and others aware of
flammability hazards. UL 399 was developed in an open and consensus-
based approach, with the assistance of experts in the refrigeration and
AC industry as well as experts involved in assessing the safety of
products. More information about the way in which UL standards are
developed can be found in Section IV.F.4.a. While similar standards
exist from other bodies, we are proposing in this option to rely on
specific UL standards that are most applicable and used by U.S.
manufacturers. The EPA expects that there would be greater consistency
for industry to move from an edition of a UL standard to another
edition of the same UL standard than to change to a different standard
from a different standards setting organization. This approach has also
been taken in recent SNAP rules concerning lower and higher
flammability refrigerants.\90\
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\90\ See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10,
2015; 81 FR 86778, December 1, 2016; 86 FR 24444, May 6, 2021; 88 FR
26382, April 28, 2023.
---------------------------------------------------------------------------
The EPA recognizes that in certain clauses, UL 399 refers to ASHRAE
15 for compliance. Consistent with previous listings for other
flammable refrigerants in this end-use, the EPA is not proposing to
include a use condition related to adherence to ASHRAE 15. The EPA
proposes to find that these refrigerants can be used safely provided
the use conditions in this proposed rule are followed, including
compliance with the 8th edition of UL 399.
As stated in Section VI.A., the EPA is proposing to update the use
conditions for the listing of R-290 for use in new water coolers. The
updated use conditions would apply to equipment manufactured after the
effective date of the final rule. The updated use conditions would
neither apply to nor affect equipment manufactured before the effective
date of the final rule.
Under this incorporate by reference option, the updated refrigerant
listing would include the use conditions described in Sections VI.E.1.,
VI.E.2., and VI.E.3. as well as a use condition that the refrigerant
may only be used in equipment that meets all the requirements of
Supplement SB of UL 399, 8th edition.
The EPA has conducted updated analysis to evaluate the
environmental, health, and safety implications of designing and using
water coolers using R-290 in accordance with UL 399, 8th edition and
found that design and use in accordance with the 8th edition allows for
safe use of R-290. This assessment is available in the docket.\91\ The
proposed regulatory text for the updated listing under this option can
be found in the docket under the title ``Proposed Regulatory Text for
SNAP Rule 27'' in the section ``Proposed revisions to Appendices R, V,
W, and new Appendix Z--Incorporate by Reference Option.''
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\91\ ICF, 2025i. Risk Screen on Substitutes in Water Coolers
(New Equipment); Substitute: Propane (R-290).
---------------------------------------------------------------------------
b. Third-Party Certification Option
As explained in Section IV.F.4.b., the EPA is co-proposing a second
use condition option to address flammability risks while recognizing
that a specific edition of a relevant industry consensus safety
standard applicable for the water coolers end-use may be replaced by a
later edition. For listings in this end-use under this option, the EPA
is proposing a use condition that relies on NRTLs certifying equipment
to a U.S. industry consensus safety standard that mitigates risks.
Under this option, the EPA proposes that all new water coolers
using R-290 would need to be certified by an OSHA-recognized NRTL to a
U.S. industry consensus safety standard that is designed to allow for
safe use of flammable refrigerants in water coolers and mitigates risks
such that the listed refrigerant can be used in a manner that does not
pose a greater overall risk to human health and the environment than
other substitutes in this end-use. Under this option, the EPA would
remove the use condition that incorporates by reference Supplement SB
of the 7th edition of UL 399 for new equipment manufactured after the
effective date of a final rule and instead require certification of
equipment to a U.S. industry consensus safety standard by an NRTL. By
not incorporating by reference a specific edition of a relevant safety
standard, the EPA intends to increase efficiencies by avoiding
questions about whether it should propose a new rule each time a
standard is updated and to leverage OSHA's NRTL Program.\92\
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\92\ Definitions and requirements for the OSHA NRTL Program can
be found at 29 CFR 1910.7.
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The industry consensus safety standard used to meet this proposed
requirement would need to be designed for use in the United States and
be consistent with best industry safety practices (e.g., UL 399). The
EPA proposes to view UL 399 as one example of a U.S. industry consensus
safety standard that could be used to meet this requirement, as the
requirements of the standard align with the levels of safety that the
EPA expects in terms of mitigating risks to human health and the
environment. As discussed in Section VI.E.4.a., the EPA has evaluated
the latest edition of UL 399 and finds that use of R-290 in water
coolers consistent with this standard would not pose greater overall
risk to human health and the environment than other acceptable
substitutes in this end-use.
The certification process confirms that the design, manufacture,
and operation of the water coolers meet industry safety standards such
as UL 399 for higher flammability refrigerants including R-290. This
includes ensuring refrigerant containment and mitigating risks
associated with pressure and electrical safety, among other things.
The EPA is not proposing to establish specific requirements or
protocols for laboratories because OSHA already has established such
requirements and performs detailed reviews of equipment certification
entities. More information about OSHA's review of NRTLs and the NRTL
Program can be found in Section IV.F.4.b.
While the EPA is proposing reliance on certification by these
NRTLs, the EPA is not opening OSHA's regulations at 29 CFR 1910.7 for
comment, including definitions or requirements, nor is the EPA seeking
comment on the OSHA program itself.
The EPA does not expect this option to pose significant additional
burden on manufacturers or NRTLs because most manufacturers of water
coolers have their equipment certified by an NRTL already.
Manufacturers that do not already certify their equipment through an
OSHA-recognized NRTL would need to do so beginning two years after the
effective date of the final rule.
For further explanation about this co-proposed option, refer to the
information provided in Section IV.F.4.b.
Under this third-party certification option, the updated listing
for R-290 in water coolers would include the use conditions described
in Sections VI.E.1., VI.E.2., and VI.E.3. as well as a use condition
that equipment be certified by an OSHA-recognized NRTL to a U.S.
[[Page 50792]]
industry consensus safety standard that is designed to allow for safe
use of flammable refrigerants in water coolers. The updated use
conditions would apply to equipment manufactured after the effective
date of the final rule. The updated use conditions would neither apply
to nor affect equipment manufactured before the effective date of the
final rule.
The EPA performed an assessment to examine the human health and
environmental risks of R-290 in water coolers. This assessment is
available in the docket.\93\ Proposed regulatory text for the revised
listing for R-290 in water coolers under this option can be found in
the docket for this rulemaking under the title ``Proposed Regulatory
Text for SNAP Rule 27'' in the section ``Proposed revisions to
Appendices R, V, W, and new Appendix Z--Third-Party Certification
Option (co-proposed as an alternative to Section III).''
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\93\ ICF, 2025i.
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5. When would the use conditions take effect?
The EPA is proposing to allow regulated entities to follow either
the existing use conditions or the proposed updated use conditions from
the effective date of the final rule until two years after that
effective date.
If the EPA finalizes the third-party certification option,
equipment manufactured between the effective date of a final rule and
two years after the effective date of a final rule could follow either
the existing use conditions (including the 7th edition of UL 399, the
60 g limit, and the existing labeling and marking requirements) or the
updated use conditions that would include certification of equipment by
an OSHA-recognized NRTL. The updated use conditions would neither apply
to nor affect equipment manufactured before the effective date of the
final rule.
F. What additional information is the EPA including in this proposed
listing?
The EPA would retain the additional information provided in the
existing listing for R-290 in water coolers in the ``Further
Information'' column of the regulatory text, to protect personnel and
users from the risks of using flammable refrigerants. Similar to our
previous listings of flammable refrigerants, the EPA is including
information on the OSHA requirements at 29 CFR part 1910, proper
ventilation, PPE, fire extinguishers, use of spark-proof tools and
equipment designed for flammable refrigerants, and training.
Under the third-party certification option, the EPA would also
include a sentence in stating that the EPA views UL 399 to be an
example of an appropriate U.S. industry consensus safety standard that
mitigates risks.
Since this additional information is not part of the regulatory
decision under SNAP, these statements are not binding for use of the
substitute under the SNAP program. While the statements in the
``Further Information'' column are not legally binding under the SNAP
program, the EPA encourages users of R-290 to apply all statements in
the ``Further Information'' column in their use of these substitutes.
VII. Chillers
A. What is the EPA proposing in this action?
The EPA is proposing to list R-516A as acceptable, subject to use
conditions, for use in the centrifugal chillers and positive
displacement chillers end-uses. This proposed listing for R-516A
applies to all compressor types of chillers, i.e., centrifugal and
positive displacement (including reciprocating, screw, scroll, and
rotary) chillers. The proposed listing is for comfort cooling
applications of such chillers under the EPA's proposed use conditions,
including but not limited to use in commercial comfort AC.
The proposed use conditions for chillers are similar to those
finalized for other lower flammability refrigerants in these end-
uses.\94\ The proposed use conditions include a requirement that R-516A
be used in new equipment only, specific requirements for warning
labels, specific requirements for markings, and requirements that the
refrigerant be used only in chiller equipment that meets all the
requirements of UL 60335-2-40 and ASHRAE 15-2024. See Section VII.E.
for further discussion on the requirements of this standard that the
EPA is incorporating by reference.
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\94\ See 88 FR 26382; April 28, 2023, and appendix X to 40 CFR
part 82, subpart G.
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The regulatory text of the proposed decision appears in the docket
under the title ``Proposed Regulatory Text for SNAP Rule 27'' in the
section ``Proposed revisions to Appendices R, V, W, and new Appendix
Z--Incorporate by Reference Option'' and in the section ``Proposed
revisions to Appendices R, V, W, and new Appendix Z--Third-Party
Certification Option (co-proposed as an alternative to Section III).''
The text for this listing is identical in both sections. This text
would be codified in appendix Z of 40 CFR part 82, subpart G. The
proposed regulatory text contains listing decisions for the proposed
end-uses. The EPA notes that there may be other legal obligations
pertaining to the manufacture, use, handling, and disposal of the
proposed refrigerants that are not included in the information listed
in the tables (e.g., CAA section 608(c)(2) venting prohibition or DOT
requirements for transport of flammable gases). Flammable refrigerants
being recovered or otherwise disposed of from chillers are likely to be
hazardous waste under RCRA (40 CFR parts 260-270). Lower flammability
ignitable spent refrigerants, including R-516A, that are recycled for
reuse can follow alternative standards under 40 CFR part 266, subpart
Q, instead of the full RCRA Subtitle C hazardous waste requirements.
B. Background on Centrifugal Chillers and Positive Displacement
Chillers
A chiller is a type of equipment using refrigerant that typically
cools water or a brine solution, which is then pumped to fan coil units
or other air handlers to cool the air that is supplied to the occupied
spaces transferring the heat to the water. The heat absorbed by the
water can then be used for heating purposes and/or can be transferred
directly to the air (air-cooled), to a cooling tower or body of water
(water-cooled), or through evaporative coolers (evaporative-cooled). A
chiller or a group of chillers could similarly be used for district
cooling where the chiller plant cools water or another fluid that is
then pumped to multiple locations being served such as several
different buildings within the same complex. Chillers may also be used
to maintain operating temperatures in various types of buildings, for
example, in data centers, server farms, and agricultural and food
operations. This proposal applies to chillers that are covered by UL
60335-2-40 and ASHRAE 15-2024. EPA understands that the UL standard
applies to chillers used for comfort cooling. The EPA is not proposing
to list R-516A in chillers used in other applications such as IPR
(e.g., chillers used to cool process streams in industrial
applications) and industrial process air conditioning (e.g., chillers
used for comfort cooling of operators or climate control and for
protecting process equipment in industrial buildings).
Centrifugal chillers utilize a centrifugal compressor in a vapor-
compression refrigeration cycle. Centrifugal chillers are typically
used for commercial comfort AC, although other uses, that we are not
proposing here, do exist. Centrifugal chillers tend to be used in
larger buildings such as
[[Page 50793]]
office buildings, hotels, arenas, convention halls, and airport
terminals.
Positive displacement chillers are those that utilize positive
displacement compressors such as reciprocating, screw, scroll, or
rotary types in a vapor-compression refrigeration cycle. Positive
displacement chillers are applied in similar situations as centrifugal
chillers, again primarily for commercial comfort AC, except they tend
to be used for smaller capacity needs such as in mid- and low-rise
buildings.
C. What are the ASHRAE classifications for refrigerant flammability and
toxicity?
See Section IV.C. for information on ASHRAE classifications for
refrigerant flammability and toxicity.
D. What is R-516A and how does it compare to other refrigerants in the
centrifugal chillers and positive displacement chillers end-uses?
R-516A is a lower flammability refrigerant blend in the A2L Safety
Group. See Section IV.D. for information on the chemical components of
R-516A as well as environmental information, flammability information,
and toxicity and exposure information on R-516A. The redacted
submission and supporting documentation for R-516A is provided in the
docket. The EPA performed a risk screening assessment to examine the
human health and environmental risks of this substitute which also is
available in the docket.\95\
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\95\ ICF, 2025j. Risk screen on Substitutes in Chillers (New
Equipment); Substitute: R-516A (Forane[supreg] 516A).
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Comparison to other substitutes in the centrifugal chillers and
positive displacement chillers end-uses: The specific atmospheric
effects values can be found in the individual risk screen for R-516A.
These were determined consistent with the source information noted in
Section III.C. above (e.g., CAA, the AIM Act) as well as using the
methodology for determining values for blends of chemicals (i.e.,
determined by the percentage of each component). The atmospheric
effects for R-516A are overall better than or comparable to many of the
substitutes currently listed as acceptable in this end-use such R-454C,
R-454A, R-454B, HFC-32, R-452B, R-514A, R-1224yd(Z), HFO-1234yf, and
HFO-1234ze. Furthermore, as noted above, the EPA does not intend to
restrict a substitute if it has only marginally greater risk.
Toxicity risks of use, determined by the likelihood of exceeding
the exposure limit of the refrigerant in these end-uses, are evaluated
in the previously referenced risk screen. The toxicity risks of using
R-516A are comparable to or lower than toxicity risks of other
available substitutes in the same end-uses.\96\ Toxicity risks of the
proposed refrigerants can be minimized by use consistent with the
proposed use conditions and best industry practices.
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\96\ See previous listing decisions for information regarding
the toxicity of other available alternatives (https://www.epa.gov/snap/substitutes-chillers).
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The flammability risks associated with R-516A in these end-uses,
determined by the likelihood of exceeding their respective LFLs, are
evaluated in the previously referenced risk screen. In conclusion,
while this refrigerant may pose greater flammability risk than other
available substitutes in the same end-uses, this risk can be minimized
by use consistent with the proposed use conditions, as well as
recommendations in the manufacturers' SDS and other safety precautions
common in the refrigeration and AC industry. The EPA is proposing use
conditions that mitigate human health and environmental risks
associated with the flammability of these alternatives so that they
would not pose greater overall risk than other acceptable substitutes
in these end-uses.
Given the wide range of applications for centrifugal chillers and
positive displacement chillers, not all refrigerants listed as
acceptable under SNAP will be suitable for the range of equipment in
these end-uses. To provide additional options to ensure the
availability of substitutes for the full range of comfort cooling
chillers, the EPA is proposing the new listing for R-516A.
E. What use conditions is the EPA proposing in this action for the new
listing for R-516A in new centrifugal chillers and positive
displacement chillers?
The proposed use conditions described in this section would apply
to new centrifugal chillers and new positive displacement chillers
using R-516A. In summary, these use conditions are:
1. New equipment only; not intended for use as a retrofit
alternative: The EPA is proposing that this refrigerant may be used
only in new equipment designed to address concerns unique to flammable
refrigerants. None of these substitutes may be used as a conversion or
``retrofit'' refrigerant for existing equipment.
2. UL Standard: This refrigerant may be used only in chiller
equipment that meets all requirements listed in the 4th edition, dated
December 15, 2022, of the standard UL 60335-2-40, ``Household and
Similar Electrical Appliances--Safety--Part 2-40: Particular
Requirements for Electrical Heat Pumps, Air Conditioners and
Dehumidifiers.'' In cases where this rule includes requirements
different than those of the 4th edition of UL 60335-2-40, the EPA is
proposing that the appliance would need to meet the requirements of the
rule.
3. ASHRAE Standard: This refrigerant may be used only in chillers
that meet all requirements listed in ASHRAE 15-2024. ASHRAE 15-2024 is
the latest version of the ASHRAE 15 standard. In cases where the rule
includes requirements different than those of ASHRAE 15-2024, the EPA
is proposing that the appliance would need to meet the requirements of
the rule. The EPA is also proposing that in cases where similar
requirements of ASHRAE 15-2024 and UL 60335-2-40 differ, the more
stringent or conservative condition would apply unless superseded by
the final rule.
4. Labels: The EPA is proposing that this refrigerant may be used
only in equipment with appropriate warning labels. These warning labels
are identical to those proposed as use conditions for A2L refrigerants
as detailed in Section IV.F.2., other than the proposed label under
paragraph for non-fixed equipment since chillers for comfort cooling
are typically fixed equipment. These labels are similar or verbatim in
language to those required by UL 60335-2-40. The warning labels would
need to be provided in letters no less than 6.4 mm (\1/4\ inch) high
and would need to be permanent.
5. Color-coded hoses and piping: The EPA is proposing to require
that equipment have distinguishing red (PMS #185 or RAL 3020) color-
coded hoses and piping to indicate use of a flammable refrigerant. The
equipment would need to have marked service ports, pipes, hoses, and
other devices through which the refrigerant is serviced. Markings would
need to extend at least one inch (25 mm) from the servicing port and
would need to be replaced if removed. This requirement is identical to
the requirement proposed as a use condition for A2Ls as detailed in
Section IV.F.3.
UL 60335-2-40 applies to chillers used for comfort cooling, among
other things. A summary of the requirements of UL 60335-2-40 as they
affect the refrigerants and end-uses in this proposal can be found in
Section IV.F.4.a.
UL 60335-2-40, 4th edition indicates that refrigerant charges
greater than a specific amount (called ``m3'' in the UL
[[Page 50794]]
standard and based on the refrigerant's LFL) are beyond its scope and
that national standards apply, such as ASHRAE 15-2024. Given that
either UL 60335-2-40 or ASHRAE 15-2024 would apply, depending on the
charge size of the equipment, the EPA is proposing adherence to both
standards as use conditions for chillers. Where similar requirements of
ASHRAE 15-2024 and UL 60335-2-40 differ, the EPA is proposing that the
more stringent or conservative condition would apply unless superseded
by this rule.
The EPA is proposing that new chillers using R-516A would need to
adhere to ASHRAE 15-2024, ``Safety Standard for Refrigeration
Systems,'' including all addenda published by the date of this
proposal. Where the requirements specified in this rule and ASHRAE 15-
2024 are different, the requirements of this rule would apply. The EPA
understands that ASHRAE 15-2024 was published early to align the
standard with the model code revision cycle. Incorporating by reference
ASHRAE 15-2024 would align the SNAP requirements with the latest
industry best practices and model code requirements.
The 2024 edition of ASHRAE 15 incorporates ASHRAE 15-2022 and
Addenda a, b, c, e, f, g, h, i, l, m, o, p, q, r, t, v, w, and ab. Most
addenda to the 2022 edition address some aspect of flammable
refrigerant use. Key changes include updated best practices for
handling, transport, and storage of flammable refrigerants, and the
installing, servicing, and decommissioning of equipment containing
flammable refrigerants. ASHRAE 15-2024 provides information regarding
machinery rooms including revised ventilation requirements in machinery
rooms, information on what types of equipment are generally expected to
be in a machinery room, types of equipment and materials that should
not be located in a machinery room, and authorized personnel
requirements for accessing a machinery room.
This section summarizes relevant aspects of ASHRAE 15-2024 for
information only and is not meant to be a complete review of the
standard or how it is applied. ASHRAE 15-2024 specifies requirements
for refrigeration systems based on the safety group of the refrigerant
used, the type of occupancy in the location where the system is used,
and whether refrigerant-containing parts of the system enter the space
or ductwork such that leakage in the space is deemed ``probable.''
``High-probability'' installations are those where leaks or failures
result in refrigerant entering occupied space. Occupancies are divided
into six classifications: institutional, public assembly, residential,
commercial, large mercantile, and industrial. Examples of these include
jails, theaters, apartment buildings, office buildings, shopping malls,
and chemical plants, respectively.
Sections 7.2 and 7.3 of ASHRAE 15-2024 determine the maximum amount
of refrigerant allowed in the system. Section 7.4 provides an option to
locate equipment outdoors or in a machinery room constructed and
maintained under conditions specified in the standard. Section 7.6
addresses A2L refrigerants when used for human comfort in ``high-
probability'' systems, including requirements for nameplates, labels,
refrigerant detection systems (under certain conditions), airflow
initiation, activation of safety shutoff valves, other actions if a
rise in refrigerant concentration is detected, and other restrictions.
ASHRAE 15 undergoes regular revision cycles with publication of
periodic addenda and is typically updated and republished every three
years. While the EPA is proposing to incorporate ASHRAE 15-2024 and all
addenda published by the date of this proposal, there may be additional
changes to ASHRAE 15-2024 by the time the EPA issues a final rule.
Because the EPA would not have reviewed those changes, the EPA is not
proposing to incorporate by reference any addenda or other changes made
to ASHRAE 15-2024 after the date of the publication of this proposed
rule.
F. What additional information is the EPA including in this proposed
listing?
The EPA is providing additional information related to this
proposed listing, found in the ``Further Information'' column of the
regulatory text, to protect personnel from the risks of using a lower
flammability refrigerant such as R-516A. Similar to our previous
listings of lower flammability refrigerants, the EPA is including
information on the OSHA requirements at 29 CFR part 1910, proper
ventilation, PPE, fire extinguishers, use of spark-proof tools and
equipment designed for flammable refrigerants, and training. Since this
additional information is not part of the regulatory decision under
SNAP, these statements are not binding for use of the substitute under
the SNAP program. While the statements in the ``Further Information''
column are not legally binding under the SNAP program, the EPA
encourages users of substitutes to apply all statements in the
``Further Information'' column in their use of these substitutes.
VIII. Motor Vehicle Air Conditioning
A. What is the EPA proposing in this action?
The EPA is proposing to list HFO-1234yf as acceptable, subject to
use conditions, for use in new MVACs in HDOH vehicles and buses.
The EPA is proposing for retrofit equipment the following listings:
HFO-1234yf, R-444A, R-456A, and R-480A as acceptable,
subject to use conditions, for retrofit of LMDV MVACs;
R-444A, R-456A, and R-480A as acceptable, subject to use
conditions, for retrofit of MVACs in HD pickup trucks and vans (both
complete and incomplete);
R-456A and R-480A as acceptable, subject to use
conditions, for retrofit of HDOH MVACs; and
R-453A, R-456A, and R-480A as acceptable, subject to use
conditions, for retrofit of MVACs in buses and trains.
The proposed retrofit listings would allow for retrofits of CFC-12
or HCFC-22 MVACs as well as for retrofits of MVACs using any of the
refrigerants the SNAP program lists as acceptable, including HFC-134a
and HFO-1234yf. None of these substitutes have been listed for retrofit
applications previously, and with the exception of HFO-1234yf, none
have been listed for use in MVACs previously.
The EPA also is proposing to modify the unacceptable listing of
flammable refrigerants in MVACs to exclude R-444A and HFO-1234yf when
used in retrofit equipment. These two refrigerants are lower
flammability and are being proposed as acceptable, subject to use
conditions, as retrofits in MVAC in this action.
The EPA is proposing to consider certain stand-alone battery
thermal management systems (BTMS) on electric HD and nonroad vehicles
as part of the MVAC end-use under the SNAP program. Refrigerants listed
for use in MVACs in a given vehicle type would also be acceptable for
use in BTMS onboard those vehicle types.
Finally, the EPA is proposing non-substantive changes to existing
listings to reduce redundancy and improve clarity. The EPA is proposing
to consolidate several listings for HFO-1234yf in appendix B of 40 CFR
part 82, subpart G that share the same use conditions. For example, the
EPA proposes to consolidate the listings for HFO-1234yf in five types
of nonroad equipment that share the same use conditions into a single
row. The EPA
[[Page 50795]]
is also proposing to reformat and clarify the existing listings for
refrigerants in the table titled ``Refrigerants--Unacceptable
Substitutes'' in appendix B of 40 CFR part 82, subpart G, by publishing
the end-use for each row. The EPA is also proposing to number each row
in the tables titled ``Refrigerants--Acceptable Subject to Use
Conditions,'' ``Refrigerants--Acceptable Subject to Narrowed Use
Conditions,'' and ``Refrigerants--Unacceptable Substitutes'' in
appendix B of 40 CFR part 82, subpart G.
B. Background on Motor Vehicle Air Conditioning
The SNAP program uses the term MVAC broadly to describe a wide
variety of non-stationary air conditioning systems that provide
passenger comfort cooling for LMDVs, HD vehicles, nonroad vehicles,
buses, and trains. The SNAP MVAC end-use includes systems that may also
be subject to other CAA regulatory programs, including for example,
where those systems fit within the regulatory definition of ``MVAC''
under 40 CFR 82.32,\97\ or the definition of an ``MVAC-like appliance''
\98\ or ``appliance'' under 40 CFR 82.152, or both.
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\97\ As defined in 40 CFR 82.32, Motor vehicle air conditioners
means mechanical vapor compression refrigeration equipment used to
cool the driver's or passenger's compartment of any motor vehicle.
This definition is not intended to encompass the hermetically sealed
refrigeration systems used on motor vehicles for refrigerated cargo
and the air conditioning systems on passenger buses using HCFC-22
refrigerant. See also 40 CFR 82.152 (defining MVAC to mean ``any
appliance that is a motor vehicle air conditioner as defined in
subpart B of 40 CFR part 82'').
\98\ As defined in 40 CFR 82.152 MVAC-like appliance means a
mechanical vapor compression, open-drive compressor appliance with a
full charge of 20 pounds or less of refrigerant used to cool the
driver's or passenger's compartment of off-road vehicles or
equipment. This includes, but is not limited to, the air-
conditioning equipment found on agricultural or construction
vehicles. This definition is not intended to cover appliances using
R-22 refrigerant.
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To appropriately evaluate human health and environmental risks, the
SNAP program considers the type of vehicle in which the proposed
alternative would be used. The EPA is proposing listings for
refrigerants used in MVACs in LMDVs (e.g., common passenger vehicles
such as sedans, small pickup trucks, and sport utility vehicles),
complete and incomplete HD pickup trucks and vans (e.g., large
passenger vehicles such as large pickup trucks or vans), HDOH vehicles
(e.g., vocational or commercial vehicles such as tractor-trailers and
box trucks), buses, and trains.
MVACs across all vehicle types are typically charged during vehicle
manufacture apart from incomplete HD vehicles. Incomplete HD vehicles
are modified by secondary manufacturers and may involve the
installation of additional AC or refrigeration equipment--for example,
AC for the rear compartment of an ambulance or van.
The class I ODS refrigerant, CFC-12 was the refrigerant
historically used in MVACs for passenger vehicles and trucks. HFC-134a,
amongst other substitutes, was listed as acceptable for use in new and
retrofit MVACs, including light-duty (LD) vehicles, in the initial SNAP
rulemaking.\99\ Since then, the EPA has listed additional alternatives
for MVACs as acceptable, subject to use conditions, for use in new
LMDV, including HFO-1234yf, HFC-152a, and carbon dioxide (R-744).
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\99\ See 59 FR 13044; March 18, 1994.
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HFO-1234yf is the predominant refrigerant used in new LMDVs that
are manufactured and imported in the United States. Older vehicles
continue to use HFC-134a and in some cases, CFC-12. HFC-134a is the
predominant refrigerant used in new HDOH and bus MVACs. The Class II
ODS refrigerant HCFC-22 was historically used in buses and trains while
newer buses and passenger trains often use HFC-134a or R-407C.
As noted above, the EPA considers other relevant regulatory
programs when developing listing decisions and use conditions. For
example, CAA section 609 and implementing regulations in 40 CFR part
82, subpart B address the repair and servicing of MVACs as well as
technician training and certification. CAA section 608 and implementing
regulations in 40 CFR part 82, subpart F restrict the sale of
refrigerant and address disposal and other activities involving MVACs
that are not regulated under CAA section 609.
The EPA notes that by considering the regulatory requirements that
already exist consistent with the SNAP program's guiding principles,
the EPA has been able to limit the use conditions the Agency would have
otherwise considered particularly for retrofits. Under CAA section 609
and its implementing regulations, no person may perform any service on
an MVAC that involves refrigerant for consideration (i.e., payment or
bartering) without properly using \100\ refrigerant recovery,
recycling, and recharging equipment approved by the EPA or an EPA-
approved independent standards organization. Individuals not accepting
payment (also known as do-it-yourselfers or DIYers) are exempt from the
certification requirements. The regulations under CAA section 609
prohibit refrigerant recovered from an MVAC to be recharged into an
MVAC, including the MVAC it was extracted from, unless it has been
recycled.\101\ Recycling may be done through the use of EPA-approved
equipment that recovers and subsequently recycles refrigerant before
returning it to an MVAC. Alternatively, when using EPA-approved
recover-only equipment the refrigerant must be sent offsite for
reclamation as described in the definition of ``properly using.'' While
there are circumstances in which refrigerant recovered from MVACs is
sent offsite to be reclaimed,\102\ onsite recovery, recycling, and
recharging of single-component MVAC refrigerants is currently the most
common practice.
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\100\ As defined in 40 CFR 82.32(e)(1) properly using means
using equipment in conformity with the regulations set forth in
subpart B of 40 CFR part 82, including but not limited to the
prohibitions and required practices set forth in 40 CFR 82.34, and
the recommended service procedures and practices for the containment
of refrigerant set forth in 40 CFR 82.36(a) and appendices A, B, C,
D, E, and F to that subpart, as applicable. In addition, this term
includes operating the equipment in accordance with the
manufacturer's guide to operation and maintenance and using the
equipment only for the controlled substance for which the machine is
designed. For equipment that extracts and recycles refrigerant,
properly using also means to recycle refrigerant before it is
returned to an MVAC or MVAC-like appliance, including to the MVAC or
MVAC-like appliances from which the refrigerant was extracted. For
equipment that only recovers refrigerant, properly using includes
the requirement to recycle the refrigerant onsite or send the
refrigerant off-site for reclamation.
\101\ 40 CFR 82.34(d)(1).
\102\ As defined in 40 CFR 82.152, reclaim means to reprocess
recovered refrigerant to all of the specifications in appendix A to
subpart F of 40 CFR part 82 (based on AHRI Standard 700-2016,
Specifications for Refrigerants) that are applicable to that
refrigerant and to verify that the refrigerant meets these
specifications using the analytical methodology prescribed in
section 5 of appendix A of this subpart.
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The EPA's regulatory approach under CAA sections 609 and 612 for
MVACs seeks to mitigate refrigerant mixing and refrigerant emissions
while accommodating the practice of onsite recycling. SNAP program
requirements in appendix D of 40 CFR part 82, subpart G include
specifications for unique fittings,\103\ labeling of retrofit MVACs,
and a prohibition against ``topping off'' an MVAC that uses
[[Page 50796]]
another refrigerant. Together with the CAA section 609 requirement to
use certified servicing equipment, these provisions minimize
refrigerant mixing and cross contamination while allowing for onsite
recovery, recycling, and recharging.
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\103\ A unique set of fittings is required for each refrigerant
approved for use in MVACs under the SNAP program. These fittings are
attachment points on the service ports of the MVAC itself, on all
recovery and recycling equipment, on large refrigerant containers,
and taps on small cans of refrigerant. The unique set of fittings
for each refrigerant prevents the accidental mixing of different
refrigerants. This helps protect the purity of the refrigerant. An
adapter may not be used to make a fitting compatible with a
refrigerant for which it was not intended.
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This framework for onsite refrigerant recycling relies on industry
safety standards for refrigerant purity and the use of EPA-approved
recover, recycle, and recharge equipment. For example, SAE
International, previously known as the Society of Automotive Engineers
(SAE) establishes requirements (e.g., SAE J2843) for equipment used to
recycle HFO-1234yf. The EPA did not change this framework in the 2024
Emissions Reduction and Reclamation (ER&R) final rule.\104\ Subsection
(h)(2)(B) of the AIM Act states that a ``regulated substance used as a
refrigerant that is recovered shall be reclaimed before the regulated
substance is sold or transferred to a new owner, except where the
recovered regulated substance is sold or transferred to a new owner
solely for the purposes of being reclaimed or destroyed.'' As discussed
in that rule, the EPA did not propose or establish requirements
implementing subsection (h)(2)(B) for MVAC servicing facilities that
currently reclaim or recycle recovered MVAC refrigerant. The EPA
recognized the longstanding practice of onsite recovery and recycling
to relevant MVAC safety standards (e.g., SAE J2099) and that industry
plans to develop relevant safety standards for recover, recycle, and
recharge equipment for MVAC refrigerant blends, including those
proposed in this action. As discussed in the ER&R final rule, the
Agency intends to propose regulations for this sector after it has
clarity on the development of such a safety standard and its likely
content. Additionally, the EPA may need to consider potential
approaches for recycling and/or reclaiming MVAC refrigerant blends,
which may include HFCs and/or substitutes for HFCs, particularly given
that refrigerant blends are currently not used in MVACs.\105\
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\104\ 89 FR 82862; October 11, 2024.
\105\ 89 FR 82827; October 11, 2024.
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Lastly, the EPA has received inquiries regarding the use of BTMS in
HD and nonroad vehicles. In some cases, BTMS in these vehicle types may
be separate from the AC systems that cool the passenger cabins of these
vehicles. The EPA is proposing to consider these BTMS on HD and nonroad
vehicles to be MVAC under the SNAP program. Thus, refrigerants listed
as acceptable in MVACs in a given vehicle type would also be acceptable
for use in BTMS in that same vehicle type. This interpretation would
also mean that use conditions applicable to refrigerants in MVACs would
apply to these refrigerants when used in BTMS. Requirements may
include, but are not limited to, use of unique service port fittings,
labeling, and compliance with industry safety standards. Note that this
proposed interpretation would only apply to the SNAP program and would
not change the treatment of MVACs under other EPA regulatory
programs.\106\
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\106\ e.g., the 609 program or the Technology Transitions rules.
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In written correspondence, the EPA has previously said that
``stand-alone'' BTMS falls under other SNAP end-uses depending on the
equipment configuration, such as non-mechanical heat transfer. However,
upon further consideration, the EPA is proposing the aforementioned
interpretation to ensure consistency in how BTMS are classified and
clarity about what substitutes are acceptable.
The EPA is basing this proposed interpretation on similarities in
risk profiles between BTMS and traditional MVACs that primarily provide
comfort cooling for passengers. Both may be subject to collisions at
high speeds, vibrations, and vehicle occupants who spend prolonged
periods of time in the enclosed passenger cabin. Substitutes listed as
acceptable for use in MVAC have already been screened taking these risk
factors into consideration. Substitutes listed in other SNAP end-uses
that predominantly consider use cases in stationary equipment would not
have considered these factors and may not be appropriate for use in
BTMS.
Further, the standard setting bodies are the same for both
traditional MVACs and BTMS in HD and nonroad vehicles. HD and nonroad
vehicles typically follow standards set by SAE, and the EPA understands
that SAE is currently researching alternative refrigerants and
technologies to improve and optimize electric vehicle thermal
management systems. The EPA expects that SAE would apply existing
standards or would develop new standards to BTMS systems.
Finally, this interpretation aligns the SNAP classification of
stand-alone BTMS in HD and nonroad vehicles with the program's
treatment of combined BTMS/passenger cooling systems that are common in
LMDVs. SNAP has consistently treated combined systems as MVAC.
Classifying stand-alone BTMS as any other end-use under SNAP would
subject these systems to a different slate of acceptable refrigerants
and different use conditions that have not been evaluated for use in
vehicles, which would create inconsistency and lack of clarity. The
EPA's proposed interpretation means that stand-alone BTMS systems will
have an analogous slate of alternatives and use conditions as combined
systems across different vehicle types. This proposed interpretation
would clearly identify acceptable refrigerants for use in BTMS in HD
and nonroad vehicles, providing clarity for industry about the
refrigerants acceptable in this application.
C. What are the ASHRAE classifications for refrigerant flammability and
toxicity used in MVACs?
ASHRAE 34-2024 categorizes HFO-1234yf and R-444A as being in the
A2L Safety Group and R-453A, R-456A, and R-480A in the A1 Safety Group.
Refer to Section IV.C. for a description of the ASHRAE classifications
for refrigerant flammability and toxicity.
The SNAP program has listed flammable refrigerants as unacceptable
in MVAC end-uses for both new and retrofit equipment, with the
exception of HFO-1234yf and HFC-152a in new MVACs under the use
conditions in appendix B of 40 CFR part 82, subpart G. Within the SNAP
program, unacceptable substitutes may not be used unless and until the
listing has been revised to acceptable, which we expect would involve
the substitute undergoing a risk assessment and the necessary reviews
by the SNAP program, generally including a notice and comment
rulemaking.
This action proposes to list HFO-1234yf, as acceptable, subject to
use conditions, in new MVACs in HDOH vehicles and buses, and as a
retrofit for LMDV MVACs. The EPA understands that the submitter intends
to market HFO-1234yf as a retrofit for other listed substitutes for
LMDVs, specifically HFC-134a. The EPA conducted risk screens for these
end-uses and proposes to find HFO-1234yf acceptable, subject to use
conditions, for these end-uses. Similarly, the EPA conducted risk
screens of R-444A as a retrofit in LMDV and HD pickup trucks and vans,
and proposes to find it acceptable, subject to use conditions, in these
end-uses. The EPA proposes to amend the restrictions on flammable
refrigerants in MVACs to include these listings.\107\
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\107\ See section VIII.F.
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[[Page 50797]]
D. What are refrigerants HFO-1234yf, R-444A, R-453A, R-456A, and R-480A
and how do they compare to other refrigerants in the same end-use?
1. How do HFO-1234yf, R-444A, R-456A, and R-480A compare to other
refrigerants for retrofit in the LDMV MVAC end-use?
The EPA is proposing to list HFO-1234yf, R-444A, R-456A, and R-480A
as acceptable, subject to use conditions, for retrofit of LMDV MVACs.
HFO-1234yf is also known as R-1234yf or 2,3,3,3-
tetrafluoropropene.\108\ R-444A is a refrigerant blend consisting of 12
percent HFC-32 (also known as difluoromethane or methylene fluoride;
CAS Reg. No. 75-10-5), 5 percent HFC-152a (also known as 1,1-
difluoroethane; CAS Reg. No. 75-37-6), and 83 percent HFO-1234ze(E)
(also known as trans-1,3,3,3-tetrafluoroprop-1-ene; CAS Reg. No. 29118-
24-9). R-456A is a refrigerant blend consisting of 6 percent HFC-32, 45
percent HFC-134a (also known as 1,1,1,2-tetrafluoroethane; CAS Reg. No.
811-97-2), and 49 percent HFO-1234ze(E). R-480A is a refrigerant blend
consisting of 5 percent R-744 (CAS Reg. No. 124-38-9), 86 percent HFO-
1234ze(E), and 9 percent HFC-227ea (also known as 1,1,1,2,3,3,3-
heptafluoropropane; CAS Reg. No. 431-89-0).
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\108\ CAS Reg. No. 754-12-1.
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Redacted submissions and supporting documentation for these four
proposed refrigerants are provided in the docket. The EPA performed
risk screening assessments to examine the human health and
environmental risks of each of these substitutes which also are
available in the docket.109 110 111 112
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\109\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty and Medium-Duty Vehicles) (Retrofit
Equipment); Substitute: HFO-1234yf (Solstice[supreg] yf or
Solstice[supreg] 1234yf). 2025. (ICF, 2025k).
\110\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty Vehicles, Medium-Duty Vehicles, and Heavy-
Duty Vehicles) (Retrofit Equipment); Substitute: R-444A
(Klea[supreg] 444A). 2025. (ICF, 2025l).
\111\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty Vehicles, Medium-Duty Vehicles, and Heavy-
Duty Vehicles) (Retrofit Equipment); Substitute: R-456A
(Klea[supreg] 456A). 2025. (ICF, 2025m).
\112\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty Vehicles, Medium-Duty Vehicles, and Heavy-
Duty Vehicles) (Retrofit Equipment); Substitute: R-480A (RS-20).
2025. (ICF, 2025n).
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Environmental information: The specific atmospheric effects values
can be found in the individual risk screens for HFO-1234yf, R-444A,
R456A, and R-480A. These were determined consistent with the source
information noted in Section III.C. above (e.g., CAA, the AIM Act) as
well as using the methodology for determining values for blends of
chemicals (i.e., determined by the percentage of each component).
HFO-1234yf and the components of R-444A, R-456A, and R-480A are
excluded from the EPA's regulatory definition of VOC \113\ for the
purpose of addressing the development of SIPs to attain and maintain
the NAAQS.
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\113\ 40 CFR 51.100(s).
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HFO-1234yf and HFC-134a (a component of R-453A and R-456A) can
break down into TFA in the atmosphere. HFO-1234yf is almost completely
transformed into TFA, while the yield of TFA from HFC-134a is estimated
to be 7 to 20 percent.\114\ For more information on TFA, see the
response to comments section of SNAP Rule 26.\115\
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\114\ EEAP, 2023. Environmental Effects of Stratospheric Ozone
Depletion, UV Radiation, and Interactions with Climate Change. 2022
Assessment Report. UNEP, Environmental Effects Assessment Panel.
March, 2023. Available at: https://ozone.unep.org/system/files/documents/EEAP-2022-Assessment-Report-May2023.pdf.
\115\ See 88 FR 50457-8.
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Flammability information: R-456A and R-480A are nonflammable
refrigerant blends (ASHRAE flammability classification 1). Of the
components of R-456A, HFC-134a is nonflammable, while HFC-32 and HFO-
1234ze(E) are classified as A2L refrigerants. Of the components of R-
480A, R-744 and HFC-227ea are nonflammable, while HFO-1234ze(E) is
classified as an A2L refrigerant. Based on their ASHRAE safety group as
A1, these refrigerants will not propagate a flame, and use of these
refrigerants is not expected to pose flammability risk in LMDV MVACs.
HFO-1234yf and R-444A are lower flammability refrigerants (ASHRAE
flammability classification 2L). HFO-1234yf and R-444A may pose greater
flammability risk than nonflammable substitutes in retrofit LMDV MVACs.
The flammability risk, determined by the likelihood of exceeding their
respective LFLs, are evaluated in the risk screens referenced in this
section. The EPA is proposing to determine that these substitutes may
be used safely since flammability risk can be mitigated by use
consistent with the proposed labeling requirements in appendix D of 40
CFR part 82, subpart G, recommendations in the manufacturers' SDS, and
other safety precautions common in the refrigeration and AC industry.
The flammability characteristics of HFO-1234yf make the risk of
ignition low. HFO-1234yf requires an open flame to ignite, such as a
match or a cigarette lighter, because of its relatively high minimum
ignition energy of greater than 5,000 mJ.\116\ HFO-1234yf has an LFL of
62,000 ppm,\117\ and has a low burning velocity \118\ compared to
refrigerants with flammability classification of 2 such as HFC-152a
\119\ or with flammability classification of 3 such as HC
refrigerants.\120\ As a result of these flammability characteristics,
HFO-1234yf is difficult to ignite, and is generally unable to propagate
a flame once ignited (i.e., flames resulting from HFO-1234yf put
themselves out).
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\116\ B. Minor, D. Herrmann, and B. Gravell. (111g) Flammability
Characteristics of Low GWP Refrigerant HFO-1234yf. AIChE 2009 Spring
Meeting & 5th Global Congress on Process Safety. Available online
at: https://proceedings.aiche.org/conferences/aiche-spring-meeting-and-global-congress-on-process-safety/2009/proceeding/paper/111g-flammability-characteristics-low-gwp-refrigerant-hfo-1234yf. Minor
et al., 2009.
\117\ Manufacturer's Safety Data Sheet for HFO-1234yf.
Honeywell, 23 May 2019. Also see Minor et al., 2009.
\118\ A2L refrigerants have a burning velocity of less than 0.1
meters/second, per International Standards Organization 817 and
ASHRAE 34-2024. HFO-1234yf has a burning velocity of 0.015m/s, per
Minor et al., 2009.
\119\ The burning velocity of HFC-152a is measured at
approximately 0.236 m/s. Kenji Takizawa, Akifumi Takahashi, Kazuaki
Tokuhashi, Shigeo Kondo, and Akira Sekiya. Burning velocity
measurement of fluorinated compounds by the spherical-vessel method,
Combustion and Flame, Volume 141, Issue 3, Pages 298-307, 2005.
Available online at https://doi.org/10.1016/j.combustflame.2005.01.009. Takizawa et al., 2005.
\120\ The burning velocity of R-290 is at least 0.4 m/s,
depending on temperature and pressure. M. Metghalchi and J.C. Keck.
Laminar Burning Velocity of Propane-Air Mixtures at High Temperature
and Pressure. Combustion And Flame 38: 143-154 (1980). Available
online at: https://james-keck-memorial-collection.unibs.it/JCKeck-papers/MetghalchiKeck-CombustionFlame-38-143-1980.pdf. Metghalchi
and Keck, 1980.
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Under this proposal, HFO-1234yf could be used to retrofit MVACs
originally designed for an A1 refrigerant. The EPA considered if this
could create additional flammability risk distinct from its use in a
new MVAC that is specifically designed with mitigation measures to use
a flammable refrigerant. The original submission for HFO-1234yf in new
vehicles included analyses that evaluated the flammability and toxicity
risks of HFO-1234yf in MVACs that were originally designed for HFC-
134a. The vehicles in these analyses did not feature any design changes
to address potential flammability. In this way, MVACs used in the
original analysis were analogous to vehicles that would be retrofit
under this proposal.\121\
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\121\ Gradient Corporation, 2008. Risk Assessment For
Alternative Refrigerant HFO-1234yf. (Phase I) Prepared for the
Society of Automotive Engineers (SAE) Cooperative Research Project
150.
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These analyses consisted of reports published in 2008, 2009, and
2013 from the SAE Cooperative Research Program (CRP). The 2008 report
found that the
[[Page 50798]]
increased flammability risk of HFO-1234yf in a vehicle designed for use
with HFC-134a is well below those commonly accepted by the general
public.\122\ A revised 2009 report found that the risks of HFO-1234yf
were low overall, and somewhat less than the toxicity risks posed by R-
744.\123\ The submitter of HFO-1234yf provided these analyses to the
EPA to support the EPA's original consideration of HFO-1234yf in new
vehicles, and the EPA based its listing of acceptability in part on the
findings of these analyses. The Agency concluded that the risks of HFO-
1234yf are comparable to or less than the risks from other available or
potentially available alternatives in this end-use that the EPA had
already listed or proposed as acceptable (e.g., HFC-152a, HFC-134a, and
R-744).\124\
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\122\ Gradient Corporation, 2008. Risk Assessment for
Alternative Refrigerant HFO-1234yf. Confidential report prepared for
SAE International Cooperative Research Program 1234. February 2008.
\123\ Gradient Corporation, 2009. Risk Assessment for
Alternative Refrigerants HFO-1234yf and R-744 (CO2).
Confidential report prepared for SAE International Cooperative
Research Program 1234. December 17, 2009.
\124\ See 76 FR 17491; March 29, 2011.
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SAE revised its assessment of HFO-1234yf and released a
supplemental report in 2013 that contained two new fault tree analyses
that included additional ``worst-case scenarios.'' \125\ The report
revised the probability of a vehicle fire due to ignition of HFO-1234yf
in a system featuring no design changes compared to an HFC-134a system
to about 3 x 10-12 events per hour of vehicle operation.
This probability remains extremely remote and is several orders of
magnitude below other commonly accepted risks, including the
probability of dying during a plane trip (7 x 10-8), the
probability of being in a police-reported vehicle collision (4 x
10-5), and the probability of a vehicle fire due to any
cause (1 x 10-6).
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\125\ Gradient Corporation, 2013a. Additional Risk Assessment of
Alternative Refrigerant R-1234yf. Confidential report prepared for
SAE International Cooperative Research Program 1234-4. July 24,
2013.
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The submitter of HFO-1234yf in retrofit LMDV MVACs provided an
updated fault tree analysis that evaluated the additional risk
associated with use of HFO-1234yf specifically in retrofit applications
and the EPA considered this new analysis in our review of HFO-
1234yf.\126\ The analysis only considered scenarios that increased the
flammability risk in a retrofit (such as increased risk of mechanical
fan failure and electrical fires and less consistent presence and
deployment of airbags) and did not consider scenarios that reduced the
flammability risk in a retrofit (such as the larger cabin size in older
vehicles that would be retrofit). The overall estimated risk was about
8 x 10-12 events per operating hour, which is similar to the
risk of vehicle fire due to HFO-1234yf ignition in new MVAC equipment
(5 x 10-12 events per operating hour).\127\ The actual
increased risk is likely lower than this, as the evaluation only
considered circumstances that would increase the probability of a
vehicle fire and did not consider circumstances that would reduce the
probability.
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\126\ Gradient Corporation, 2023a. Retrofit Analysis Letter.
Prepared for Honeywell International. September 26, 2023.
\127\ Gradient Corporation, 2009. Risk Assessment for
Alternative Refrigerants HFO-1234yf and R-744 (CO2).
Confidential report prepared for SAE International Cooperative
Research Program 1234. December 17, 2009.
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The EPA conducted a risk screen for HFO-1234yf use in retrofit
LMDVs. The risk screen found that concentrations of HFO-1234yf did
exceed the LFL in the passenger compartment under certain worst-case
scenarios but remained well below the LFL in more realistic industry
consortium field testing. For example, using a simple box model,
combining the highest ratio of refrigerant charge to observed passenger
compartment size with a catastrophic release of 60 percent of the
charge in 60 seconds resulted in a maximum instantaneous charge of
172,000 ppm, compared to an LFL of 62,000 ppm. However, analysis using
the more accurate technique of computational fluid dynamics modeling
found the instantaneous concentration of HFO-1234yf to vary from 65,000
ppm to 34,000 ppm. The industry consortium field testing found a
maximum instantaneous concentration of HFO-1234yf of 29,774 ppm when a
vehicle's full charge was released.\128\
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\128\ ICF, 2025k.
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The EPA's original risk analysis of HFO-1234yf for use in new LMDVs
also identified scenarios in which concentrations exceeded the LFL. The
EPA listed HFO-1234yf as acceptable, subject to use conditions, in new
LMDVs leveraging this risk analysis.\129\ In the EPA's original
listing, the Agency stated that it found that the use of HFO-1234yf in
new passenger vehicle and LD truck MVACs, subject to the use conditions
adopted in that listing, does not present a greater overall risk to
human health and the environment compared to the currently approved
MVAC alternatives or as compared to R-744.\130\ The EPA has also
subsequently listed R-744 as acceptable, subject to use conditions, in
new LMDV MVACs.
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\129\ ICF 2009 Risk Screen on Substitutes for CFC-12 in Motor
Vehicle Air Conditioning: Substitute: HFO-1234yf. (ICF, 2009).
\130\ See SNAP Rule 16, 76 FR 17488; March 29, 2011.
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Finally, HFO-1234yf in new LMDV MVACs has been widely adopted since
being listed in 2012. In MY2023, the share of new LMDVs sold in the
United States with HFO-1234yf reached 97 percent.\131\ Even with its
broad use, the EPA is not aware of any real-world instances in which
HFO-1234yf has ignited and caused a vehicle fire, which further
augments the record for this refrigerant. R-444A is also an A2L
refrigerant. The EPA understands that the submitter of this refrigerant
intends to market it to be used as a retrofit in MVACs, including those
charged with HFO-1234yf. Based on review of materials available in the
docket, the EPA is proposing to determine that R-444A is acceptable,
subject to use conditions, for use in retrofit LMDV MVACs because the
flammability risk associated with such use is low and is comparable to
the flammability risk associated with the same use of HFO-1234yf.\132\
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\131\ U.S. EPA, 2024. EPA Automotive Trends Report: Greenhouse
Gas Emissions, Fuel Economy, and Technology since 1975. US EPA.
November, 2024.
\132\ Gradient Corporation, 2013b. Risk Assessment for
Alternative Refrigerants R-445A and R-1234yf. Phase III. Prepared
for SAE International MRB CRP. December 30, 2013. See Appendix B,
Fault Trees for R-1234yf and Appendix C, Fault Trees for R-444A.
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Similar to HFO-1234yf, the EPA conducted a risk screen of R-444A
which identified certain scenarios in which concentrations exceed the
LFL of R-444A. Using a simple box model, combining the highest ratio of
refrigerant charge to observed passenger compartment size with a
catastrophic release of 60 percent of the charge in 60 seconds resulted
in a maximum instantaneous charge of 140,200 ppm, compared to an LFL of
82,000 ppm. However, analysis using computational fluid dynamics
modeling found the instantaneous concentration of HFO-1234yf to vary
from 40,000 ppm to 76,000 ppm, which are below the LFL of R-444A.
Further, the EPA's evaluation of flammability risks of R-444A in
retrofit LMDV MVACs included a fault-tree analysis that evaluated the
risk of a vehicle occupant being exposed to a flame resulting from R-
444A ignition. This analysis found that risk to be slightly lower than
the risk of an occupant being exposed to a flame resulting from HFO-
1234yf ignition.\133\
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\133\ Id.
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SAE J1661 currently provides guidance on how to retrofit a vehicle
originally charged with CFC-12 to HFC-
[[Page 50799]]
134a. The EPA anticipates that SAE would develop an analogous standard
or revise this standard for retrofitting vehicles using newer
refrigerants, including those proposed as acceptable, subject to use
conditions, for retrofitting in this proposal. Following such standards
may further reduce the flammability risk associated with retrofitting
MVACs, which is already expected to be extremely small in magnitude.
Given the findings of the evaluation materials available in the
docket and, in the case of HFO-1234yf, its widespread adoption without
documented flammability issues, the EPA is proposing that HFO-1234yf
and R-444A may be safely used for retrofit of LMDV MVACs.
The other refrigerants that the EPA is proposing to list for
retrofit of LMDV MVACs, R-456A and R-480A, are both nonflammable
(ASHRAE classification of A1) and thus are comparable to or lower in
their flammability risks than other acceptable substitutes for the same
uses.
Toxicity information: Toxicity risk, determined by the likelihood
of exceeding the exposure limits in these end-uses, are evaluated in
the previously referenced risk screens. HFO-1234yf, R-444A, R-456A, and
R-480A are lower toxicity (ASHRAE toxicity group A) refrigerants or
refrigerant blends. ASHRAE has adopted OELs for these refrigerants of
500 ppm, 850 ppm, 900 ppm, and 900 ppm, respectively. The toxicity
risks of using the proposed refrigerants in retrofit LMDV MVACs are
comparable to or lower than that of other available substitutes in the
same end-use, including HFC-134a and HFO-1234yf.\134\ Toxicity risks of
the proposed refrigerants can be mitigated by use consistent with
applicable industry safety standards, recommendations in the
manufacturers' SDS, and other safety precautions common in the
refrigeration and AC industry.
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\134\ See previous listing decisions for information regarding
the toxicity of other available alternatives. (https://www.epa.gov/snap/substitutes-motor-vehicle-air-conditioning).
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HFO-1234yf is subject to a significant new use rule (SNUR) under 40
CFR 721.10182(a). Significant new uses under this requirement include:
(A) Use other than as a refrigerant: in MVAC systems in new
passenger cars and vehicles (as defined in 40 CFR 82.32(c) and (d)), in
stationary and transport refrigeration, or in stationary AC.
(B) Commercial use other than: in passenger cars and vehicles in
which the original charging of MVAC systems with the pre-manufacture
notice (PMN) substance was done by the motor vehicle original equipment
manufacturer (OEM), in stationary and transport refrigeration, or in
stationary AC.
(C) Use in consumer products other than products used to recharge
the MVAC systems in passenger cars and vehicles in which the original
charging of MVAC systems with the PMN substance was done by the motor
vehicle OEM.
Use in all MVAC end-uses, except for when originally charged with
HFO-1234yf, would fall under (B) or (C) as commercial or consumer use
to recharge an MVAC in which the original charging of the MVAC was with
a substance other than HFO-1234yf. The EPA considers retrofitting a
vehicle to use HFO-1234yf that was not originally charged by the OEM
with HFO-1234yf to be a significant new use of HFO-1234yf under this
SNUR. Significant new uses require the chemical producer to submit a
significant new use notice to the EPA for review of a substance before
introducing the substance into interstate commerce in the significant
new use.
Comparison to other substitutes in these end-uses: The specific
atmospheric effects values can be found in the individual risk screens
for R-444A, R-456A, and R-480A. These were determined consistent with
the source information noted in Section III.C. above (e.g., CAA, the
AIM Act) as well as using the methodology for determining values for
blends of chemicals (i.e., determined by the percentage of each
component). The atmospheric effects for HFO-1234yf, R-444A, R456A, and
R-480A are overall better than or comparable to many of the substitutes
currently listed as acceptable in this end-use, such as HFC-134a and
HFC-152a. The EPA acknowledges that the atmospheric effects of one
substitute, HFO-1234yf, may be lower than the three blends; however,
the EPA is proposing to list R-444A, R-456A, and R-480A for retrofit
use only where HFC-134a is the only available substitute currently
listed as acceptable for retrofit of LMDV MVACs. Furthermore, as noted
above, the EPA does not intend to restrict a substitute if it has only
marginally greater risk. The EPA's analysis found that the effects on
human health and the environment associated with retrofitting LMDV
MVACs with the proposed alternatives are comparable to one another, and
much lower than that of HFC-134a.\135\
---------------------------------------------------------------------------
\135\ The EPA is aware that the submitters of HFO-1234yf, R-
456A, and R-480A are likely to market these substitutes to retrofit
MVACs originally charged with HFC-134a.
---------------------------------------------------------------------------
The EPA is aware that the submitter of R-444A may market this
substitute to retrofit MVACs originally charged with HFO-1234yf. The
submitter provided information and analysis on R-444A which posits that
the overall environmental impact of this substance used in retrofits
for LMDV MVAC is comparable to that of HFO-1234yf. According to the
submitter, this is because R-444A is expected to leak less and slower
than HFO-1234yf due to its higher viscosity, and because R-444 has a
slightly higher coefficient of performance, which allows R-444A MVACs
to cool a given amount with less fuel. These improvements in leakage
rate and efficiency may offset atmospheric effects of R-444A so that
when it is used to retrofit MVACs originally charged with HFO-1234yf,
its overall environmental effect is comparable to that of HFO-1234yf.
The analysis supports the submitter's conclusion, that when evaluated
using a more wholistic approach, the use of R-444A is unlikely to have
a greater overall environmental impact.
The EPA's risk screens for HFO-1234yf, R-444A, R-456A, and R-480A
in LMDV MVACs found that these substitutes can be used without
exceeding their recommended OELs of 500 ppm (8-hr OEL), 900 ppm (8-hr
OEL), 850 ppm (8-hr OEL), and 900 ppm (8-hr OEL) respectively; thus,
the toxicity risks of these refrigerants are comparable to those of
other acceptable substitutes in MVACs, which also are used without
exceeding their OELs.136 137 138 139
---------------------------------------------------------------------------
\136\ ICF, 2025k.
\137\ ICF, 2025l.
\138\ ICF, 2025m.
\139\ ICF, 2025n.
---------------------------------------------------------------------------
R-480A and R-456A are nonflammable refrigerants. The flammability
of HFO-1234yf and R-444A may be greater than that of other available
substitutes in the same end-use that have an ASHRAE flammability
classification of 1. The EPA's analysis of the flammability risks of
HFO-1234yf and R-444A found that when used in accordance with the
proposed use conditions, these A2L refrigerants may be safely used in
this end-use without presenting additional adverse effects to human
health and the environment than other alternatives. HFO-1234yf has been
used for over a decade in new LMDV MVACs without any reported harm or
incidences of fire. R-444A is also an
[[Page 50800]]
A2L refrigerant with a similar flammability profile. We note that
flammability risk can be minimized by use consistent with applicable
industry safety standards as well as recommendations in the
manufacturers' SDS and other safety precautions common in the MVAC
industry and any difference in flammability can be addressed by the
existing labeling requirements in appendix D of 40 CFR part 82, subpart
G.\140\
---------------------------------------------------------------------------
\140\ Described in section VIII.E.1.
---------------------------------------------------------------------------
These proposed refrigerants provide additional retrofit options and
would not pose additional adverse effects to human health or the
environment when used in accordance with existing and proposed
requirements and as intended by the submitter. To provide additional
options for the full range of MVACs, the EPA is proposing the listings
for HFO-1234yf, R-444A, R-456A, and R-480A as acceptable, subject to
use conditions, for retrofit of LMDV MVACs.
2. How do R-444A, R-456A, and R-480A compare to other refrigerants
for retrofit in the HD pickup trucks and HD vans MVAC end-uses?
The EPA is proposing to list R-444A, R-456A, and R-480A as
acceptable, subject to use conditions, for retrofit of HD pickup trucks
and HD van MVACs (complete and incomplete). Information about R-444A,
R-456A, and R-480A and their components is described in Section
VIII.D.1. Environmental, flammability, and toxicity information about
these proposed substitutes are also described in Section VIII.D.1. and
does not differ between end-uses.
Redacted submissions and supporting documentation for R-456A and R-
480A are provided in the docket. The EPA performed a risk screening
assessment to examine the human health and environmental risks of each
of these substitutes in these end-uses which also are available in the
docket.141 142 143
---------------------------------------------------------------------------
\141\ ICF, 2025l.
\142\ ICF, 2025m.
\143\ ICF, 2025n.
---------------------------------------------------------------------------
Comparison to other substitutes in these end-uses: The Agency
understands that these substitutes will be marketed as retrofit options
for different refrigerants, including HFC-134a and HFO-1234yf. HFC-134a
is the only available refrigerant listed as acceptable for retrofit of
MVACs in HD pickup trucks and vans, and HFO-1234yf is the primary
refrigerant used in new HD pickup truck and van MVACs. For a comparison
of the flammability, health, and environmental characteristics of these
refrigerants to one another and to HFO-1234yf and HFC-134a, refer to
Section VIII.D.1.
These proposed refrigerants provide additional retrofit options and
would not pose additional adverse effects to human health or the
environment when used in accordance with existing and proposed
requirements and as intended by the submitter. To provide additional
options for the full range of MVACs, the EPA is proposing the listings
for R-444A, R-456A, and R-480A as acceptable, subject to use
conditions, for retrofit of HD pickup truck and van MVACs.
3. How do HFO-1234yf, R-456A, and R-480A compare to other
refrigerants in the HDOH MVAC end-use?
The EPA is proposing to list HFO-1234yf as acceptable, subject to
use conditions, in new HDOH MVACs. The EPA is also proposing to list R-
456A and R-480A for use in retrofit of HDOH MVACs. Environmental and
toxicity information and information about the components of these
proposed substitutes is described in Section VIII.D.1. and does not
differ between end-uses.
Redacted submissions and supporting documentation for HFO-1234yf,
R-456A, and R-480A are provided in the docket. The EPA performed a risk
screening assessment to examine the human health and environmental
risks of each of these substitutes which also are available in the
docket.144 145 146
---------------------------------------------------------------------------
\144\ ICF, 2025o. Risk Screen on Substitutes in Motor Vehicle
Air Conditioning (Heavy-Duty On-Highway (HDOH) Vehicles) (New
Equipment); Substitute: HFO-1234yf (Solstice[supreg] yf or
Solstice[supreg] 1234yf). 2025.
\145\ ICF, 2025m.
\146\ ICF, 2025n.
---------------------------------------------------------------------------
Flammability information: Flammability information about R-456A and
R-480A is described in Section VIII.D.1. and does not differ between
end-uses. HFO-1234yf is a lower flammability refrigerant with an ASHRAE
classification of 2L. The EPA's risk screen found that concentrations
of HFO-1234yf in this end-use could exceed the LFL in feasible worst-
case scenarios. As discussed in Section VIII.D.1., HFO-1234yf is
difficult to ignite and, in the event of ignition, flames are unlikely
to propagate.
The EPA reviewed risk assessments for HFO-1234yf from the submitter
in addition to developing its own risk screen. Fault tree analysis for
use of HFO-1234yf in HDOH MVACs, which is included in the docket,
demonstrates that even in worst-case scenarios, risk probabilities are
relatively small. The fault tree analysis determined that the risk of
exposure to a vehicle fire due to HFO-1234yf ignition was 2.8 x
10-9 per vehicle engine hour (non-collision) and 2 x
10-14 per vehicle engine hour (collision).\147\ This risk is
equal to or below other risks in HDOH MVAC applications including: risk
of an HD truck or bus experiencing a serious collision (1 x
10-5 per vehicle engine hour),\148\ risk of a highway fire
in a freight road transport vehicle (2 x 10-6 per vehicle
engine hour), and the acceptable risk for road vehicles in the ISO
26262 standard ``Road vehicles--Functional safety'' (1 x
10-9 per vehicle engine hour).\149\ The risk of a fire
occurring in a new HDOH MVAC that uses HFO-1234yf is sufficiently small
in magnitude so as to not be substantive; therefore, the EPA is
proposing to list HFO-1234yf as acceptable, subject to use conditions,
in new HDOH MVACs.
---------------------------------------------------------------------------
\147\ Id.
\148\ ``Engine hour'' is the terminology used in this fault tree
analysis. Engine hour is synonymous with ``operating hour.''
\149\ Gradient Corporation. 2023b. Gradient Risk Analysis for
Heavy-Duty On-Highway Vehicles. 2023. (Gradient HDOH risk analysis,
2023b).
---------------------------------------------------------------------------
The worst-case flammability scenario that the EPA modelled for HDOH
MVACs was for class 7 or 8 tractors. The probability of occupant
exposure to a refrigerant leak from a class 7 or 8 HDOH tractor during
use may be higher than in other MVACs due to the nature of how these
vehicle types are used. For example, occupants of class 7 and 8
tractors may spend protracted lengths of time in the passenger cabin
and may be sleeping or living in the vehicle. The EPA's review of a
fault tree analysis of HFO-1234yf for use in new HDOH vehicles found
that the flammability risks were not substantively different from that
of HFO-1234yf in other MVAC end-uses or from that of other substitutes
that the EPA has listed as acceptable (e.g., R-744). Additionally, when
HFO-1234yf is ignited in real-world tests it is unable to propagate a
flame due to its high minimum ignition energy, its relatively high LFL,
and its lower burning velocity.\150\ These risks may be mitigated by
use in accordance with the proposed use conditions and recommendations
in the manufacturers' SDS, and other safety precautions common in the
refrigeration and AC industry.
---------------------------------------------------------------------------
\150\ Id.
---------------------------------------------------------------------------
Comparison to other substitutes in these end-uses: The EPA is
proposing to list HFO-1234yf as acceptable, subject to use conditions,
in new HDOH vehicles and to list R-456A and R-480A as acceptable,
subject to use conditions, for retrofit of HDOH MVACs. HFC-134a is the
principal refrigerant currently acceptable for use in new HDOH
vehicles, and the only refrigerant acceptable for retrofit of HDOH
MVACs. For a comparison of the flammability,
[[Page 50801]]
health, and environmental characteristics of these refrigerants to one
another and to HFC-134a, refer to Section VIII.D.1.
HFO-1234yf has a higher flammability risk than other substitutes
available in HDOH MVACs. Flammability risk in HDOH vehicles may be
higher than in other vehicle types due to the charge size to cabin
volume ratio and the fact that drivers may spend prolonged periods in
the vehicle with the engine running. However, as noted earlier, the
risk of HFO-1234yf ignition in HDOH MVACs is sufficiently remote to not
be substantively different from the risk of HFO-1234yf ignition in
other MVAC applications.
We note that while the flammability of HFO-1234yf may be greater
than that of other available substitutes in the same end-use, this risk
can be minimized by use consistent with recommendations in the
manufacturers' SDS and other guidance, the proposed use conditions, and
other safety precautions common in the MVAC industry. Any difference in
flammability can be addressed by the proposed use conditions described
in Section VIII.E.1. Further, HFO-1234yf has lower environmental risks
than other substitutes acceptable in this end-use.
These proposed refrigerants would not pose additional adverse
effects to human health or the environment when used in accordance with
the proposed use conditions and existing requirements and as intended
by the submitter. These proposed listings would provide additional
options to promote the availability of refrigerants for the full range
of MVACs, thereby lowering overall risk to human health and the
environment.
4. How do HFO-1234yf, R-453A, R-456A, and R-480A compare to other
refrigerants in the bus and train MVAC end-uses?
The EPA is proposing to list HFO-1234yf as acceptable, subject to
use conditions, in new bus MVACs. The EPA is also proposing to list R-
453A, R-456A, and R-480A as acceptable, subject to use conditions, for
retrofit of bus and train MVACs. Information about the components of R-
456A and R-480A is described in Section VIII.D.1. and does not differ
between end-uses.
R-453A is a refrigerant blend consisting of 20 percent HFC-32, 20
percent HFC-125 (also known as pentafluoroethane; CAS Reg. No. 354-33-
6), 53.8 percent HFC-134a, 5 percent HFC-227ea, 0.6 percent R-600 (CAS
Reg. No. 75-28-5), and 0.6 percent R-601a (also known as isopentane;
CAS Reg. No. 78-78-4).
Redacted submissions and supporting documentation for HFO-1234yf,
R-453A, R-456A, and R-480A are provided in the docket. The EPA
performed a risk screening assessment to examine the human health and
environmental risks of each of these substitutes which also are
available in the docket.151 152 153 154 155
---------------------------------------------------------------------------
\151\ ICF, 2025s.
\152\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Buses) (New and Retrofit Equipment); Substitute: HFO-
1234yf (Solstice[supreg] yf or Solstice[supreg] 1234yf). 2025. (ICF,
2025p).
\153\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning--Buses and Passenger Rail (Retrofit Equipment);
Substitute: R-453A (RS-70). 2025. (ICF, 2025q).
\154\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Buses and Passenger Rail) (Retrofit Equipment);
Substitute: R-456A (Klea[supreg] 456A). 2025. (ICF, 2025r).
\155\ ICF. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Retrofit Equipment); Substitute: R-480A (RS-20). 2025.
(ICF, 2025s).
---------------------------------------------------------------------------
Environmental information: Environmental information about HFO-
1234yf, R-456A, and R-480A is described in Section VIII.D.1. and does
not differ between end-uses.
The specific atmospheric effects values of R-453A can be found in
the individual risk screen for R-453A. These were determined consistent
with the source information noted in Section III.C. above (e.g., CAA,
the AIM Act) as well as using the methodology for determining values
for blends of chemicals (i.e., determined by the percentage of each
component). The atmospheric effects of R-453A are comparable to or
lower than other acceptable refrigerants used in retrofits of MVACs for
buses and trains, such as HFC-134a. Components of R-453A making up 98.6
percent of the composition are excluded from the EPA's regulatory
definition of VOC \156\ for the purpose of addressing the development
of SIPs to attain and maintain the NAAQS. The remaining two components,
R-600 and R-601a, are VOCs under that definition. The reactivity of
these two compounds in the lower atmosphere is not significantly
different than that of other saturated HCs that the EPA has evaluated
and the total amount of these two compounds used as refrigerants is
significantly lower than that of other saturated HCs that the EPA has
evaluated for potential impacts on local air quality.\157\
---------------------------------------------------------------------------
\156\ 40 CFR 51.100(s).
\157\ See section IV.D. for a discussion of the EPA's analyses
of air quality impacts of HC refrigerants.
---------------------------------------------------------------------------
Flammability information: R-453A is a nonflammable blend. Based on
this blend's ASHRAE classification as an A1 refrigerant, use of this
refrigerant is not expected to pose flammability risk. Flammability
information about R-456A and R-480A is described in Section VIII.D.1.
and does not differ between end-uses.
HFO-1234yf is a lower flammability (ASHRAE classification of 2L)
refrigerant. Although HFO-1234yf is more flammable than other
refrigerants currently available in the new buses MVAC end-use, the
EPA's risk screen of HFO-1234yf in this end-use found that
concentrations of HFO-1234yf in the passenger cabin of buses did not
exceed the LFL even in the feasible worst-case scenarios. To further
mitigate flammability risk, the EPA is proposing use conditions as
discussed in Section VIII.E.
Toxicity information: Toxicity information about HFO-1234yf, R-
456A, and R-480A is found in Section VIII.D.1.
R-453A is a lower-toxicity (ASHRAE classification A) refrigerant
blend. The toxicity risks of using R-453A for retrofit of bus and train
MVACs are comparable to or lower than toxicity risks of other available
substitutes in the same end-use, including HFC-134a. Toxicity risks of
the proposed refrigerants can be mitigated by use consistent with
applicable industry safety standards; recommendations in the
manufacturers' SDS; and other safety precautions common in the
refrigeration and AC industry.
HFO-1234yf is subject to a SNUR under 40 CFR 721.10182(a).
Significant new uses under this requirement include:
(A) Use other than as a refrigerant: in MVACs in new passenger cars
and vehicles (as defined in 40 CFR 82.32(c) and (d)), in stationary and
transport refrigeration, or in stationary AC.
(B) Commercial use other than: in passenger cars and vehicles in
which the original charging MVACs with the PMN substance was done by
the motor vehicle OEM, in stationary and transport refrigeration, or in
stationary AC.
(C) Use in consumer products other than products used to recharge
MVACs in passenger cars and vehicles in which the original charging of
MVACs with the PMN substance was done by the motor vehicle OEM.
This use of HFO-1234yf in new bus MVACs would fall under (A) and
thus would not be a significant new use.
Comparison to other substitutes in these end-uses: The EPA is
proposing to list HFO-1234yf as acceptable, subject to use conditions,
in new bus MVACs, and R-453A, R-456A, and R-480A as acceptable, subject
to use conditions, for retrofits of bus and train MVACs.
[[Page 50802]]
Buses historically used HCFC-22, a class II ODS, in MVACs. HFC-
134a, HCFC-22, and R-407C historically have been the most used
refrigerants in new bus and train MVACs, and HFC-134a and R-407C are
the acceptable refrigerants most often used for retrofit of bus and
train MVACs.\158\ For a comparison of the environmental, health, and
safety characteristics of HFO-1234yf, R-456A, and R-480A to HFC-134a
and to one another, refer to Section VIII.D.1.
---------------------------------------------------------------------------
\158\ Newly produced class I and II ODS including HCFC-22 cannot
be used in manufacturing new MVACs per the statutory prohibition in
CAA section 605.
---------------------------------------------------------------------------
As stated above, the specific atmospheric effects values can be
found in the individual risk screen for R-453A. The atmospheric effects
for R-453A are overall better than or comparable to other refrigerants
currently available in this end-use including HCFC-22, HFC-134a, R-
407A, and R-407C. R-453A may be used without exceeding its OEL of 1,000
ppm; therefore, its toxicity risks are comparable to other substitutes
available in this end-use.\159\ R-453A is nonflammable with an ASHRAE
flammability classification of 1; therefore, its flammability risks are
comparable to other acceptable refrigerants in this end-use.
---------------------------------------------------------------------------
\159\ ICF, 2025q.
---------------------------------------------------------------------------
The EPA is aware that the submitter of R-453A may market this
substitute to retrofit bus and train MVACs charged with HCFC-22, a
class II ODS. Some refrigerants already listed as acceptable for
retrofits in MVACs for buses and trains (e.g., HFC-134a) operate at a
lower pressure range than HCFC-22. These refrigerants may not be
practical to use when retrofitting equipment originally charged with
HCFC-22. Listing R-453A as acceptable, subject to use conditions, would
provide a high-pressure alternative that is practical for retrofitting
bus and train MVACs originally designed for HCFC-22. The EPA's analysis
found that when used as intended by the submitter to retrofit bus and
train MVACs originally charged with HCFC-22, and in accordance with the
proposed use conditions described in Section VIII.E.4., this
refrigerant does not pose increased risk to human health or the
environment.
This proposed listing of R-453A, R-456A, and R-480A would allow for
buses and trains currently using ozone-depleting HCFC-22, which has
been phased out under the CAA, to be retrofitted to non-ozone depleting
alternatives.
The EPA is proposing to list HFO-1234yf as acceptable, subject to
use conditions, in new bus MVACs. HFO-1234yf, an A2L refrigerant, is
more flammable than other refrigerants currently available in this end-
use; however, the EPA's risk screen of HFO-1234yf in this end-use found
that concentrations of HFO-1234yf that leaked in the passenger cabin
did not exceed its LFL in worst-case scenarios. Thus, use of HFO-1234yf
in this end-use does not result in greater flammability risk than other
acceptable substitutes for new bus MVACs. Additionally, buses are
maintained by technicians in workplace settings as part of fleets.
These technicians are trained and have experience working with
flammable substances, using safe practices in locations such as repair
garages that have sufficient ventilation and other safeguards that can
mitigate flammability risk. The risk associated with flammability in
this application may be mitigated by use consistent with
recommendations in the manufacturers' SDS and other guidance, the
proposed use conditions in Section VIII.E.3., and other safety
precautions common in the MVAC industry.
The proposed refrigerants can provide additional options and would
not pose additional adverse effects to human health or the environment
when used in accordance with the proposed use conditions and existing
requirements and as intended by the submitter. All the refrigerants
proposed in this rule in this end-use have better or comparable
atmospheric effect values and toxicity. Any difference in flammability
can be addressed by the proposed use conditions described in Section
VIII.E.3. Furthermore, as noted above, the EPA does not intend to
restrict a substitute if it has only marginally greater risk. The EPA
does not consider any of these substitutes to pose significantly
greater risks than other acceptable substitutes.
To provide additional options to promote the availability of
refrigerants for the full range of MVACs, thereby lowering overall risk
to human health and the environment, the EPA is proposing the listings
for HFO-1234yf as acceptable, subject to use conditions, in new bus
MVACs and for R-453A, R-456A, and R-480A as acceptable, subject to use
conditions, for use for retrofit of bus and train MVACs.
E. What use conditions is the EPA proposing in this action that apply
to proposed listings in this end-use?
1. What use conditions is the EPA proposing for HFO-1234yf, R-444A,
R-456A, and R-480A for retrofit of MVACs in LMDVs, for R-444A, R-456A,
and R-480A for retrofit of MVACs in HD pickup trucks and vans, and for
R-456A and R-480A for retrofit of MVACs in HDOH MVACs; and what
existing requirements apply to these refrigerants?
Appendix D of 40 CFR part 82, subpart G specifies requirements for
unique fittings for new and retrofit MVAC listings, specifies
information that must appear on a new label when a retrofit is
performed, and outlines requirements for how the retrofit is completed
including specifications for how unique fittings must be applied when
performing a retrofit. The requirements for labeling, unique fittings,
and the performance of the retrofit would apply to all proposed
acceptability listings for MVAC retrofits in this action. The EPA is
proposing minor adjustments to these retrofit specifications and
labeling requirements. These existing requirements and proposed
amendments are described fully in Section VIII.G.
The requirements for labeling and for service port conversion
assemblies would minimize the risk of mixing refrigerant by serving as
a mechanical barrier to inadvertent refrigerant mixing and ensuring
that technicians are aware of the contents of the MVAC. Refrigerant
that differs from its initial composition may compromise the purity of
the refrigerant supply and the practice of onsite recovery, recycling,
and recharging common in the MVAC sector. For additional discussion of
onsite recovery, recycling, and recharging in MVACs, refer to Section
VIII.B. For discussion of the environmental risks of refrigerant
mixing, refer to Section VIII.D.1. Existing use conditions under
appendix D of 40 CFR part 82, subpart G would mitigate the
environmental risks associated with mixing refrigerants.
In the case of HFO-1234yf and R-444A, the requirement to include a
label would mitigate flammability risk by ensuring that technicians are
aware that the MVAC contents is flammable.
The EPA is proposing specifications for unique fittings for R-444A,
R-456A, and R-480A when used to retrofit MVACs in LMDVs, HD pickup
trucks and vans, and HDOH vehicles. The specifications of these
fittings, along with the unique fittings proposed for the high and low
side service ports and 30-lb cylinders, would be added to appendix B of
40 CFR part 82, subpart G. These proposed specifications can be found
in the docket for this rulemaking under the title ``Proposed Regulatory
Text for SNAP Rule 27.''
The EPA's SNAP program has a longstanding approach of requiring
unique fittings for use with each
[[Page 50803]]
refrigerant in MVACs. Appendix D of 40 CFR part 82, subpart G requires
that each refrigerant be used with a set of fittings that is unique to
that refrigerant. This is intended to prevent cross contamination of
different refrigerants, preserve the purity of recycled refrigerants,
and ultimately to avoid venting of refrigerant consistent with
requirements under CAA section 608(c), codified at 40 CFR 82.154(a). In
the 1996 SNAP Rule requiring the use of unique fittings on all
refrigerants submitted for use in MVACs, the EPA urged industry to
develop mechanisms to ensure that the venting prohibition under CAA
section 608(c) and the implementing regulations at 40 CFR 82.154 are
observed.\160\ The EPA has issued multiple SNAP rules requiring the use
of fittings unique to a refrigerant for use on ``containers of the
refrigerant, on can taps, on recover, recycle, and recharge equipment,
and on all [motor vehicle] air conditioning system service ports.''
\161\
---------------------------------------------------------------------------
\160\ See 61 FR 54032; October 16, 1996.
\161\ See appendix D of 40 CFR part 82, subpart G.
---------------------------------------------------------------------------
The manufacturer of R-444A and R-456A has stated that they intend
to use fittings for small cans of refrigerant that are the same as the
fittings previously assigned to R-416A and Freeze 12. The EPA is
proposing use of these fittings, even though they previously were
assigned to R-416A and Freeze 12, because the EPA listed those
refrigerants as unacceptable in SNAP Rule 20.\162\ Thus, the EPA
presumes that the fittings corresponding to R-416A and Freeze 12 are no
longer in use and may be available to be used with other refrigerants.
Permitting the use of smaller fittings previously assigned to
refrigerants that are no longer in use would be less burdensome than
requiring development of other, likely large fittings.
---------------------------------------------------------------------------
\162\ See 80 FR 42870; July 20, 2015.
---------------------------------------------------------------------------
Currently, there are no approved recover, recycle, and recharge
equipment or industry safety standards for the refrigerant blends in
this end-use.\163\ The EPA is aware that the submitters of these blends
are working with SAE and equipment manufacturers. In the future, the
EPA could pursue a notice and comment rulemaking under CAA 609 to
potentially incorporate new or revised industry standards, amongst
other things. In the absence of certified equipment and industry safety
standards, these refrigerants may be inappropriately mixed or released.
Mixing refrigerant may also lead directly to release due to certain
mixtures having higher pressures than either component alone. Thus,
pressure-sensitive components, such as air purge devices on recycling
machines and relief devices on MVACs, may be activated by these
mixtures, venting the refrigerant to the atmosphere. Inappropriately
mixed refrigerants are also less attractive for the aftermarket because
they are difficult to separate and return to the AHRI-700 purity
standard.
---------------------------------------------------------------------------
\163\ i.e., R-444A, R-456A, and R-480A.
---------------------------------------------------------------------------
Until certified equipment and relevant safety standards are
developed, only recovery-only machines may be used to recover the
refrigerant blends proposed for use in MVACs, consistent with
requirements under CAA section 609. Recovery-only machines would allow
for the refrigerants to be recovered (but not recycled or recharged)
onsite and subsequently sent for reclamation. Development of industry
safety standards and machines would allow for technicians to recover,
recycle, and recharge these newer refrigerants onsite within the same
framework as the currently listed refrigerants and would prevent
inappropriate mixing of these refrigerants. Further, the EPA expects
that the companies selling refrigerants intended to be used as
retrofits would make appropriate unique fittings and refrigerant labels
available to certified technicians and DIYers to allow them to conduct
a retrofit in a manner that meets requirements under the CAA.
The EPA acknowledges that DIYers would not have the appropriate
equipment to recover the original refrigerant from the MVAC prior to
performing a retrofit. Instead, DIYers would likely need to bring their
vehicles to a service shop or other facility to have the existing
refrigerant recovered before the retrofit. Further, DIYers may not know
how to prevent or fix leaks in an MVAC and may add additional
refrigerant to the existing charge (i.e., topping-off). DIYers also are
less likely to be trained to safely handle flammable refrigerant
compared to technicians working in professional settings.
The EPA considered, but is not proposing, restricting retrofits of
MVACs using these refrigerants in LMDVs, HD pickup trucks and vans, and
HDOH vehicles to professional settings. The EPA considered this
alternative as it may mitigate adverse effects to human health and the
environment resulting from the release of these refrigerants, and
because technicians in professional settings likely would be better
able to handle flammable refrigerants for the reasons stated above.
However, the EPA views existing regulatory requirements, such as those
under CAA section 609, and the proposed use conditions as sufficient in
addressing these concerns. As proposed, compliance with the use
conditions should prevent knowingly venting or otherwise releasing
refrigerants and allow for DIYers to retrofit their MVACs.
2. What use conditions is the EPA proposing for HFO-1234yf for use
in new HDOH and bus MVACs; and what existing requirements apply to this
refrigerant?
These proposed use conditions are designed to ensure that HDOH and
bus MVACs using HFO-1234yf operate safely under normal and foreseeable
conditions while mitigating risks associated with refrigerant leakage
and flammability.
The EPA is proposing that the MVAC connections (e.g., any points
where components of an MVAC join together) either be located outside of
the airflow path of the passenger cabin or be designed to prevent leaks
into the passenger cabin. This requirement currently applies to use of
HFO-1234yf in new passenger vehicles.\164\ This use condition would
further mitigate flammability risks associated with leaks of HFO-1234yf
into the passenger cabin.
---------------------------------------------------------------------------
\164\ New passenger vehicles charged with HFO-1234yf are subject
to a use condition that they follow all requirements of SAE standard
J639, which includes this requirement.
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The EPA is also proposing that the manufacturer of MVACs and
vehicles (i.e., the OEM) to conduct and keep records of a Failure Mode
and Effects Analysis (FMEA), a type of risk assessment, for at least
three years from the date of creation. SAE J1739 \165\ provides
applicable guidance. The EPA understands it is standard industry
practice to perform the FMEA and to keep it on file while the vehicle
is in production and for several years afterwards. Note that the EPA is
not proposing to establish specific requirements or protocols for
conducting and recording an FMEA, nor is the EPA requiring that
manufacturers follow SAE J1739. This use condition currently applies to
use of HFO-1234yf in new passenger vehicles, and as previously noted,
HDOH vehicles have large charge sizes and drivers may frequently spend
prolonged periods in the passenger cabin. The requirement to conduct
FMEAs and retain them for three years would serve to identify and
address flammability risks associated with system failures.
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\165\ SAE J1739, ``Potential Failure Mode and Effects Analysis
(FMEA) Including Design FMEA, Supplemental FMEA-MSR, and Process
FMEA''. Dated January 2021.
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The EPA currently requires that new MVACs charged with HFO-1234yf
on other vehicle types (including LMDVs
[[Page 50804]]
and nonroad vehicles) comply with all requirements of SAE J639, and the
EPA understands that most HDOH vehicles typically follow this standard.
The EPA considered, but is not proposing, a requirement that new MVACs
in bus and HDOH vehicles comply with all requirements of SAE J639.
Instead, the EPA is proposing the aforementioned use conditions which
mirror the safety requirements associated with HFO-1234yf in SAE J639.
The use conditions as currently proposed would apply similar safety
requirements to HFO-1234yf when used in bus and HDOH vehicles without
incorporating a standard by reference. Several other refrigerants
proposed in this rule do not have associated standards that may be
incorporated by reference. Further, the EPA understands that buses may
not typically follow SAE J639, and this standard may not be appropriate
for equipment in this end-use. This approach as currently proposed
establishes similar safety requirements while maintaining parity
between the refrigerants proposed in this rule.
Existing requirements in appendix D of 40 CFR part 82, subpart G
require that this substitute be used with unique service port fittings.
Service port fittings for HFO-1234yf were previously established and
are identified in appendix B of 40 CFR part 82, subpart G. For
additional discussion of this requirement, refer to Section VIII.E.1.
EPA is proposing to require a label on the MVAC of new bus and HDOH
vehicles that use HFO-1234yf. The label would have the following
characteristics:
The label must include the statement ``This refrigerant is
FLAMMABLE. Take appropriate precautions.''
The label must be large enough to be easily read and must
be permanent.
The label must be affixed to the system over information
related to the previous refrigerant, in a location not normally
replaced during vehicle repair.
Testing of labels must meet ANSI/UL 969-1991.
This proposed use condition would mitigate flammability risk
associated with HFO-1234yf by ensuring that technicians are aware that
the contents of the MVAC is flammable. For discussion of the
flammability risk associated with HFO-1234yf, refer to Section
VIII.D.3. These requirements mirror existing requirements for flammable
refrigerants when used in retrofit MVACs.
3. What use conditions is the EPA proposing for R-453A, R-456A, and
R-480A for retrofit of MVAC in buses and trains; and what existing
requirements apply to this refrigerant?
These proposed use conditions for R-453A, R-456A, and R-480A for
retrofit of MVAC in buses and trains are designed to ensure that buses
and trains operate safely under normal and foreseeable conditions.
The EPA is proposing that the labeling requirements in paragraph 2
of appendix D of 40 CFR part 82, subpart G apply to these listings in
buses and trains. Labeling requirements ensure that technicians are
aware of the MVAC contents, thereby promoting proper refrigerant
handling, preventing the inadvertent mixing of refrigerant, and
preventing waste and refrigerant emissions during servicing. The EPA is
proposing minor adjustments to these provisions. For a full discussion
see Section VIII.G.
Existing technician certification requirements under CAA sections
608 and 609 apply to the retrofit of AC appliances on buses. Buses that
use high-pressure AC appliances such as those charged with HCFC-22 or
R-407C can only be serviced by a CAA section 608 certified technician.
Buses that do not use high-pressure AC systems (such as those
originally charged with CFC-12 or HFC-134a) are considered MVACs under
CAA section 609. For additional discussion of the EPA's requirements
under CAA sections 608 and 609, refer to Section VIII.B.
The requirements at 40 CFR 82.156 includes requirements for the
proper evacuation of appliances, MVACs, and MVAC-like appliances prior
to being opened.\166\ Refrigerants must be evacuated from the appliance
to the specified level using certified equipment prior to the
installation of a new service port conversion fitting and charging with
the retrofit refrigerant. These existing requirements mitigate adverse
effects to human health and the environment that would otherwise be
associated with venting or intentional releases of refrigerant.
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\166\ See 40 CFR 82.156(a), (c), and (d).
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Buses and trains are typically serviced in professional settings as
part of fleets. The EPA does not expect that significant numbers of
DIYers would retrofit bus and train MVACs. For this reason, the EPA
considered but is not proposing to require retrofits to these
refrigerants on buses and trains be performed in professional settings.
F. Modification of ``Unacceptability'' Listing Applicable to Flammable
Refrigerants in Motor Vehicle Air Conditioning
Per appendix B of 40 CFR part 82, subpart G, flammable refrigerants
in MVACs, both new and retrofit, are currently listed as unacceptable.
Unacceptability does not apply to HFO-1234yf and HFC-152a when used in
new MVAC equipment. The EPA is proposing to amend this provision so
that unacceptability also would not apply to R-444A and HFO-1234yf used
in retrofit MVACs.
The EPA had initially restricted the use of flammable refrigerants
in MVACs because of the higher risks associated with that end-use, such
as the risk of leaks due to collisions and punctures right behind the
grille, and because the risks of these refrigerants had not been
addressed by a risk assessment.\167\ As described in Section VIII.D.1.,
the EPA is proposing to determine that HFO-1234yf and R-444A may be
used safely in retrofit MVACs since flammability risk can be mitigated
by use consistent with the proposed use conditions, recommendations in
the manufacturers' SDS, and other safety precautions common in the
refrigeration and AC industry.
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\167\ See June 13, 1995, 60 FR 31092.
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G. Modifications to MVAC SNAP Requirements
The EPA is proposing a change to paragraph 2 in appendix D of 40
CFR part 82, subpart G related to labeling requirements for MVAC
retrofits. These labeling requirements are applicable to all listing of
MVAC retrofits and help to handle refrigerants safely and to avoid
unintentional mixing of refrigerants. The EPA is proposing to remove
the requirement in 2.c that the background color of the label be unique
to the refrigerant. Removing this requirement would better align the
label with industry safety standards and because the other required
labeling provisions are sufficient to alert technicians of the
refrigerant being used in the MVAC and whether that refrigerant is
flammable.
The EPA is also proposing to replace references to ``CFC-12 service
ports'' to ``original service ports'' in paragraphs 1.a. and 1.d. of
appendix D of 40 CFR part 82, subpart G. The revised language would be
as follows:
1.a. When original service ports are retrofitted, conversion
assemblies shall attach to the original fitting with a thread lock
adhesive and/or a separate mechanical latching mechanism in a manner
that permanently prevents the assembly from being removed.
[[Page 50805]]
1.d. All original service ports not retrofitted with conversion
assemblies shall be rendered permanently incompatible for use with
service equipment related to the original refrigerant by fitting with a
device attached with a thread lock adhesive and/or a separate
mechanical latching mechanism in a manner that prevents the device from
being removed.
The EPA is proposing this change because new refrigerants have
become available since these requirements were originally established,
and retrofits may be performed on vehicles that were not originally
charged with CFC-12. This update would ensure that the requirements are
applied consistently across the MVAC end-use.
The EPA is also proposing several non-substantive changes to
existing listings to reduce redundancy and improve clarity. These edits
would not change the effect of the regulatory requirements. First, the
EPA is proposing to collapse existing listings for HFO-1234yf in
appendix B of 40 CFR part 82, subpart G in new LD passenger vehicles,
new medium-duty passenger vehicles, new HD pickup trucks, new complete
vans, and new HD nonroad vehicles into a single row since the use
conditions are the same for all these end-uses. This change would
simplify and shorten the existing regulatory text. The EPA is also
proposing to reformat the existing listings for refrigerants listed in
the table titled ``Refrigerants--Unacceptable Substitutes'' in appendix
B of 40 CFR part 82, subpart G by publishing a single end-use in each
row. The EPA is lastly proposing to number each row in the tables
titled ``Refrigerants--Acceptable Subject to Use Conditions'',
``Refrigerants, Acceptable Subject to Narrowed Use Conditions'', and
``Refrigerants, Unacceptable Substitutes'', in appendix B of 40 CFR
part 82, subpart G to facilitate cross references within a table.
IX. Fire Suppression and Explosion Protection
A. What is the EPA proposing in this action?
The EPA is proposing to list the 50/50 blend of 2-BTP/
CO2 as acceptable, subject to use conditions, as a total
flooding agent in normally unoccupied spaces for use in aircraft engine
nacelles, APUs, and cargo bays. While the EPA's SNAP program has not
previously listed a blend containing both 2-BTP and CO2,
SNAP has listed 2-BTP and CO2 separately. The EPA previously
listed 2-BTP as acceptable, subject to use conditions, for use in:
Engine nacelles and APUs on aircraft in total flooding
fire suppression systems; \168\
---------------------------------------------------------------------------
\168\ See 81 FR 86778; December 1, 2016.
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Aircraft as a streaming agent; \169\
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\169\ Id.
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Normally unoccupied spaces under 500 cubic feet in total
flooding fire suppression systems; \170\ and
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\170\ See 88 FR 26382; April 28, 2023.
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Non-residential applications, other than for commercial
home office and personal watercraft, as a streaming agent.\171\
---------------------------------------------------------------------------
\171\ Id.
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The EPA previously listed CO2 as acceptable for use as a
total flooding agent and streaming agent.\172\
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\172\ See 59 FR 13044; March 18, 1994.
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B. Background on Total Flooding Fire Suppression
In the United States, approximately 90 percent of installed total
flooding systems protect anticipated hazards from ordinary combustibles
(i.e., Class A fires), while the remaining ten percent protect against
applications involving flammable liquids and gases (i.e., Class B
fires). Approximately 75 percent of total flooding systems protect
electronics (e.g., computers, telecommunications, process control
areas), while the remaining 25 percent protect civil aviation (e.g.,
engine nacelles/APUs, cargo compartments, lavatory trash receptacles),
military weapons systems (e.g., combat vehicles, machinery spaces on
ships, aircraft engines and tanks), oil/gas and manufacturing
industries (e.g., oil/gas pumping, compressor stations), and maritime
uses (e.g., machinery spaces, cargo pump rooms).
Total flooding systems, which historically have employed halon 1301
as a fire suppression agent, are used in both normally occupied and
normally unoccupied areas. The EPA bases the terms ``occupied areas''
and ``normally unoccupied areas'' on definitions in the National Fire
Protection Association (NFPA) 2001 ``Standard on Clean Agent Fire
Extinguishing Systems.'' NFPA 2001 defines ``normally unoccupied
enclosure or space'' as ``an enclosure or space not normally occupied
but one that could be entered occasionally by one or more persons for
brief periods.'' The standard defines an ``unoccupiable enclosure or
space'' as an ``enclosure or space that has dimensional or other
physical characteristics such that it could not be entered by a
person.'' Engine nacelles and APUs are considered unoccupiable spaces,
and cargo bays are considered normally unoccupied spaces.
C. What is 2-BTP/CO2 and how does it compare to other fire suppressants
in the same end-use?
2-BTP/CO2 is the 50/50 blend of 2-BTP and CO2
which contains 50 percent 2-BTP (2-bromo-3,3,3-trifluoropropene) \173\
and 50 percent CO2.\174\
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\173\ CAS Reg. No. 1514-82-5.
\174\ CAS Reg. No. 124-38-9.
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The redacted submission and supporting documentation for 2-BTP/
CO2 is provided in the docket. The EPA performed assessments
to examine the human health and environmental risks of this substitute
during production operations and the filling of fire extinguishers as
well as in the case of an inadvertent discharge of the system during
maintenance activities on the fire extinguishing system. These
assessments are available in the docket.\175\
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\175\ ICF. Risk Screen on Substitutes in Total Flooding Systems
in Normally Unoccupied Spaces; Substitute: VERDAGENT[supreg]. 2025.
(ICF, 2025t).
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Environmental information: The specific atmospheric effects values
can be found in the risk screen for 2-BTP/CO2. Of note this
blend has an ODP of 0.0014.\176\ As reported in the 2025 Technology and
Economic Assessment Panel (TEAP) Progress Report,\177\ and as noted in
Section III of this proposed rule, under some broad definitions of PFAS
(e.g., European Chemicals Agency (ECHA) 2023 proposal), 2-BTP could be
considered a PFAS. The EPA notes that the U.S. government has not
adopted a single definition of PFAS and has not included 2-BTP in any
PFAS-related restrictions. Moreover, listing decisions consider whether
substitutes present risks that are lower than or comparable to risks
from other substitutes that are currently or potentially available in
the end-uses under consideration. The EPA does not assume any
substitute is risk free. The EPA is not proposing or seeking comment on
PFAS definitions in this rulemaking.
---------------------------------------------------------------------------
\176\ The ODP for 2-BTP/CO2 is based on the ODP of 2-
BTP that was used in previous SNAP listings (see 81 FR 86778 and 88
FR 26382).
\177\ Report of the Technology and Economic Assessment Panel,
May 2025, Volume 1: Progress report. Available online at:
ozone.unep.org/system/files/documents/TEAP-May2025-Progress-Report-vol1.pdf (TEAP, 2025).
---------------------------------------------------------------------------
2-BTP is considered a VOC and is not excluded from the EPA's
regulatory definition of VOC \178\ for the purpose of addressing the
development of SIPs to attain and maintain the NAAQS. To assess the
potential impact of this compound on local air quality, the EPA assumed
that 2.5 percent of the intended U.S. annual market for 2-BTP
[[Page 50806]]
in total flooding fire suppression applications would be released
annually.\179\ This would result in release of about one metric ton of
2-BTP into the atmosphere annually from this proposed end-use \180\
which translates to an extremely small proportion relative to total
annual anthropogenic VOC emissions in the United States.\181\ The
Agency assumes that emissions would not occur in one location at one
time, but instead much less than one metric ton would be emitted at
different locations. Further, this analysis does not account for the
fact that some releases could occur on aircraft flying at cruising
altitude (e.g., 35,000 ft), where releases would not have a significant
impact on tropospheric ozone.\182\ Given that annual 2-BTP emissions
would be many orders of magnitude lower than annual emissions of other
anthropogenic VOC emissions, and that some portion of these emissions
are likely to occur at aircraft cruising altitude, the EPA does not
consider the environmental impacts of this VOC to be a significant
concern. This aligns with the EPA's review of pure 2-BTP for use as a
total flooding agent.\183\
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\178\ 40 CFR 51.100(s).
\179\ The EPA's Vintaging Model assumes an average annual leak
rate of 2.5 percent for total flooding systems (EPA, 2022).
\180\ Based on the 2022 annual total VOC emissions for the
United States as reported in the National Emissions Inventory (ICF,
2025t).
\181\ Emissions of one metric ton of 2-BTP is approximately 7.5
x 10-8 percent of total U.S. VOC emissions.
\182\ Emission estimates calculated using CBI data.
\183\ See 88 FR at 26408-26409; April 28, 2023.
---------------------------------------------------------------------------
CO2 is excluded from the EPA's regulatory definition of
VOC \184\ for the purpose of addressing the development of SIPs to
attain and maintain the NAAQS.
---------------------------------------------------------------------------
\184\ 40 CFR 51.100(s).
---------------------------------------------------------------------------
Flammability information: 2-BTP/CO2 is nonflammable. The
individual components, 2-BTP and CO2, are also nonflammable.
Toxicity and exposure data: The EPA assessed potential health risks
from exposure to the proposed substitute as a total flooding agent in
normally unoccupied spaces. To assess potential health risks from
exposure to the proposed substitute for personnel during manufacturing,
EPA developed a New Chemical Exposure Limit (NCEL) of 1 ppm for 2-BTP
based on review of available toxicity studies.\185\ CO2 has
an OSHA PEL of 5,000 ppm.\186\ These exposure limits represent the
maximum eight-hour TWA exposure at which personnel in an occupational
environment can be exposed regularly without adverse effects.
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\185\ See 40 CFR 721.10966.
\186\ Available at: http://www.cdc.gov/Niosh/npg/npgd0103.html.
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2-BTP is subject to a SNUR under 40 CFR 721.10966. Significant new
uses under this requirement include any use other than as either a
total flooding agent in unoccupied spaces, specifically engine nacelles
and APUs in aircraft; or as a streaming fire extinguishing agent for
use only in handheld extinguishers in aircraft. This SNUR also contains
requirements for workplace protections and for hazard communication.
According to the SDS, exposure to this blend following a discharge
may be hazardous if inhalation, skin contact, or eye contact with the
proposed substitute occurs at sufficiently high levels. The most likely
pathway of exposure is through inhalation. Overexposure via inhalation
to the proposed substitute may cause central nervous system effects,
such as dizziness, confusion, physical incoordination, drowsiness,
anesthesia, or unconsciousness. At concentrations of 1.0 percent, or
10,000 ppm, or higher, the proposed substitute may cause increased
sensitivity of the heart to adrenaline which might cause irregular
heartbeats and possibly ventricular fibrillation or death. In the case
that the proposed substitute is inhaled, person(s) should be
immediately removed and exposed to fresh air. The SDS recommends that
if breathing is difficult, person(s) should seek medical attention.
Short ocular, dermal, or ingestion exposures are not expected to
pose a hazard. However, in case of ocular exposure, the SDS for the
proposed substitute recommends that person(s) immediately flush the
eyes, including under the eyelids, with water and move to a non-
contaminated area. Medical attention should be sought if irritation
develops or persists. In the case of dermal exposure, the SDS
recommends that person(s) immediately wash the affected area with large
amounts of water and remove all contaminated clothing and footwear to
avoid irritation. If water is not available, cover the affected area
with a clean, soft cloth. Medical attention should be sought if
irritation develops or persists. The proposed substitute is not likely
to be hazardous by ingestion; however, in case of ingestion, the SDS
recommends the person(s) consult a physician immediately. Do not induce
vomiting without medical advice.
Vapors from 2-BTP/CO2 can cause suffocation by reducing
oxygen available for breathing, causing asphyxiation in high
concentrations. Such vapors pose a potential hazard if large volumes
are trapped in enclosed or low places. If person(s) are exposed to high
concentrations, the person(s) will likely not realize that he/she is
suffocating, but may experience central nervous system effects, such as
drowsiness and dizziness.
The risks and procedures after exposure to the proposed substitute
are similar for other common fire suppressants. The potential health
effects of exposure to this substitute can be minimized by following
the exposure guidelines, ventilation, and PPE recommendations in the
installation and use manual for this proposed substitute. In addition,
industry safety standards such as the NFPA 2001 standard for clean
agent fire extinguishing systems and the NFPA 12 standard for
CO2 extinguishing systems provide guidelines for safe use of
the components of this fire suppressant blend.
The EPA also evaluated the risks associated with potential
exposures to the blend during manufacture (e.g., filling total flooding
systems), in the case of an inadvertent discharge of the system during
installation and maintenance activities, and during clean up after
system discharge.
The risks to workers are expected to be sufficiently mitigated when
the engineering controls and PPE recommendations referenced in the SDS
for this proposed substitute are followed. For operations requiring
handling of the substitute, engineering controls should include
adequate ventilation systems and enclosed or confined operations to
ensure exposure levels are below the NCEL. Appropriate protective
measures should be taken, and proper training administered for the
manufacture, clean up, and disposal of this product.
In general, use of appropriate PPE is recommended, specifically
respirators, during activities in which exposure to 2-BTP/
CO2 cannot be controlled through other means. If handled in
enclosed spaces where exposure limits might be exceeded, a self-
contained breathing apparatus (SCBA) should be used. When handling a
leak in a storage container, protective clothing is recommended as well
as vapor-in air detection systems. If detected in the workplace
atmosphere, there may be a need to purge the gas from the confined
space (e.g., with air, or an inert gas followed by air), followed by
additional testing of the space to ensure it has been removed
completely from the atmosphere. Furthermore, gloves (e.g., neoprene,
polyvinyl chloride, or polyvinyl alcohol) should be worn when handling
equipment containing the proposed substitute for prolonged periods. The
combination of appropriate
[[Page 50807]]
engineering controls and the use of PPE would ensure exposure levels
are below the NCEL.
When used as intended by the submitter and in accordance with the
proper safety and disposal precautions as listed in the risk screen and
in the NFPA 2001 and NFPA 12 standards,\187\ releases of this proposed
substitute are not expected to cause a significant risk to the
environment and human health in the general population when
manufactured or used in normally unoccupied and unoccupiable spaces.
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\187\ ICF, 2025t. Risk Screen on Substitutes in Total Flooding
Systems in Normally Unoccupied Spaces; Substitute:
VERDAGENT[supreg].
---------------------------------------------------------------------------
Comparison to other fire suppressants: The atmospheric effects of
2-BTP/CO2 are comparable to or lower than other listed
substitutes in this end-use including substitutes with ODPs such as
phosphorus tribromide and trifluoromethyl iodide (CF3I).
Other alternatives with comparable or better overall atmospheric effect
profiles have not proven viable for certain aviation applications such
as cargo bays. 2-BTP is considered a VOC and is not excluded from the
EPA's regulatory definition of VOC \188\ for the purpose of addressing
the development of SIPs to attain and maintain the NAAQS. Other
acceptable fire suppression agents currently in use in this end-use are
also VOC (e.g., pure 2-BTP, C6-perfluoroketone). 2-BTP/CO2
is anticipated to pose no greater risk as a VOC than other alternatives
listed as acceptable in this end-use (e.g., C6-perfluoroketone) and
would present half the risk from VOC impacts of pure 2-BTP. 2-BTP/
CO2 is nonflammable, as are all other available total
flooding agents. The extinguishing cylinders for 2-BTP/CO2
can weigh less and/or take up less space than cylinders such as those
that contain CO2 alone, since CO2 typically
requires a larger amount of substance to extinguish fires. This is
particularly important for fire suppression aboard aircraft where
transition from the class I ODS fire suppression agents (e.g., halon
1301 and halon 1211) has been particularly challenging. The EPA is
aware that other listed alternatives may not be viable especially for
aircraft cargo bays. The EPA is proposing to find 2-BTP/CO2
as acceptable, subject to use conditions, as a total flooding agent for
use in normally unoccupied spaces in aircraft engine nacelles, APUs,
and cargo bays because the overall human health and environmental risk
posed by the substitute is lower than or comparable to the overall risk
posed by other alternatives listed as acceptable in the same end-use.
---------------------------------------------------------------------------
\188\ 40 CFR 51.100(s).
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D. What use conditions is the EPA proposing?
The EPA is proposing to list 2-BTP/CO2 as acceptable,
subject to use conditions, as a total flooding agent. The use condition
is that this substitute be used only in normally unoccupied spaces,
specifically only in aircraft engine nacelles, APUs, or cargo bays. The
Agency notes that engine nacelles and APUs are unoccupiable spaces.
Cargo bays are normally unoccupied, but people could enter cargo bays
(e.g., when loading or unloading cargo) and live animals may be
transported in cargo bays.
This proposal includes the EPA's recommendation that this
substitute be used as intended by the submitter and in accordance with
the proper safety and disposal precautions as listed in the risk
screen.\189\ While this recommendation would not be legally binding
under the SNAP program, the EPA would encourage users of this
substitute to apply these recommendations, and others listed in the
risk screen, in their use of this substitute as best practices for
safer use.
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\189\ ICF, 2025t. Risk Screen on Substitutes in Total Flooding
Systems in Normally Unoccupied Spaces; Substitute:
VERDAGENT[supreg].
---------------------------------------------------------------------------
E. Why is the EPA proposing these specific use conditions?
The EPA is proposing to list 2-BTP/CO2 as acceptable as
a total flooding agent with the use condition that it is only
acceptable for use onboard aircraft in engine nacelles, APUs, and cargo
bays which are considered normally unoccupied spaces. These
applications are consistent with the information submitted to the EPA
supporting use in normally unoccupied spaces and as requested by the
submitter.
F. What additional information is the EPA including in this proposed
listing?
Emissions of 2-BTP/CO2 should be controlled by adhering
to standard industry practices. Toxicity risks can be minimized by use
consistent with the NFPA 2001 and 12 standards,\190\ recommendations in
the SDS, and other safety precautions common in the fire suppression
industry.
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\190\ NFPA 2001, ``Standard on Clean Agent Fire Extinguishing
Systems.''
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X. On which topics is the EPA specifically requesting comment?
A. Residential and Light Commercial AC and Heat Pumps, Household
Refrigerators and Freezers, and Water Coolers
1. The EPA is requesting comment on requiring labeling, the height
of the lettering, and the likelihood of labels remaining on a product
throughout the lifecycle of the product, including its disposal. This
request is applicable to all proposed listings in Sections IV. through
VI.
2. The EPA is requesting comment on whether specifying a particular
shade of red for the color-coded hoses and piping is necessary to
mitigate risks associated with using flammable refrigerants, or if a
requirement for red markings, without specifying a particular shade,
would be sufficiently protective. This request is applicable to all
proposed listings in Sections IV. through VI.
3. The EPA is requesting comment on the two co-proposed options for
use conditions related to equipment certification or industry safety
standard requirements, described in Sections IV.F.4., V.E.4., and
VI.E.4. This request is applicable to all proposed listings in Sections
IV. through VI.
4. With respect to the proposed listing for household refrigerators
and freezers under the incorporate by reference option described in
Section V.E.4.a., the EPA is requesting comment on the risk mitigation
offered by compliance with the current version of the standard proposed
as use conditions, i.e., 3rd edition of UL 60335-2-24, the nature of
any updates proposed for this standard, and the expected timeline for
those updates.
5. With respect to the proposed listing for water coolers under the
incorporate by reference option described in Section VI.E.4.a., the EPA
is requesting comment on whether the proposed listing of R-290 in water
coolers should be updated to use conditions consistent with UL 399, 8th
edition or should remain as currently listed, consistent with the
requirements of UL 399, 7th edition.
6. Regarding the third-party certification option discussed in
Sections IV.F.4.b., V.E.4.b., and VI.E.4.b., the EPA is requesting
comment on the proposed use condition that would require equipment in
these three end-uses to be certified by an OSHA-recognized NRTL. The
EPA is requesting comment on the applicability of OSHA's NRTL Program
to all applications within these three end-uses. Specifically, the EPA
requests comments about whether there are
[[Page 50808]]
situations under these end-uses where certification by an NRTL would
not occur. The EPA is requesting comment on any safety or environmental
concerns that would not be addressed through this proposed use
condition option when compared to the use conditions that the EPA
previously listed for these end-uses or when compared to the
incorporation by reference option.
7. Regarding the proposed timing for when the updated use
conditions would take effect for proposed updates to refrigerant
listings in the residential and light commercial AC and heat pumps and
water coolers end-uses, the EPA is requesting comment on the proposal
that users (e.g., manufacturers) be able to follow either the existing
use conditions or the proposed updated use conditions from the
effective date of the final rule until two years after that effective
date to allow adequate time to transition from the existing to the new
use conditions. The Agency also requests comment on the proposed timing
for when the use conditions would be required for use of HCR 4141 in
household refrigerators and freezers, i.e., on and after the effective
date of the final rule.
B. Chillers
1. The EPA is requesting comment on the proposed use conditions for
use of R-516A, including the proposed requirements to comply with both
the 4th edition of UL 60335-2-40 and ASHRAE 15-2024 including published
addenda. The EPA is requesting comment on the risk mitigation offered
by compliance with the current version of these standards proposed as
use conditions, the nature of any updates to these standards that are
expected to be adopted, and the expected timeline for those updates.
2. The EPA is requesting comment on the applicability of UL 60335-
2-40, 4th edition to chillers, including which chillers and under which
applications the standard applies, as well as on the applicability of
ASHRAE 15-2024 with the addenda published to date.
C. Motor Vehicle Air Conditioning
1. The EPA is requesting comment on the proposal to consider BTMS
in nonroad and HD vehicles as MVACs under SNAP. The EPA is requesting
comment on whether existing use conditions for MVACs in these vehicle
types would be suitable for BTMS. The Agency also requests comment on
whether stand-alone BTMS exist in other vehicle types (such as LMDVs)
and whether the EPA should expand this interpretation to include stand-
alone BTMS in other vehicle types.
2. The EPA is requesting comment on the proposed use conditions
intended to mitigate potential flammability risk from the refrigerants
with an ASHRAE flammability rating of 2L, namely HFO-1234yf for use in
new HDOH MVACs and the flammability risk of retrofits using HFO-1234yf
and R-444A in LMDV. Specifically, retrofitting MVACs designed for a
nonflammable refrigerant such as HFC-134a to use a flammable
refrigerant may present new risks. The EPA seeks comment on whether
additional strategies to mitigate the flammability risk of A2L
refrigerants are necessary and suggestions of what those strategies may
be.
3. The EPA is requesting comment on the unique service fittings
proposed for use with R-444A and R-456A. The unique fittings proposed
to be used were originally assigned to other refrigerants that are now
listed as unacceptable and should no longer be in use. The EPA requests
data on whether Freeze-12 and R-416A may still be in use in MVACs and
whether that could raise concerns the proposal to reassign these unique
fittings to other refrigerants.
4. The EPA is requesting comment on the environmental impacts of
the use of R-444A in retrofit LMDVs. The EPA seeks comment on our
evaluation that the overall environmental impact is comparable between
R-444A and HFO-1234yf.
5. The EPA is requesting comment on whether to require as a use
condition that new HDOH vehicles and new buses charged with HFO-1234yf
follow the requirements of SAE J639. As discussed in Sections VIII.E.2.
and VIII.E.3., the EPA is not proposing a use condition that new MVACs
in buses comply with all requirements of SAE J639. The EPA is proposing
that use conditions mirror the safety requirements associated with HFO-
1234yf in SAE J639.
D. Fire Suppression and Explosion Protection
People are not normally present in cargo bays of civilian aircraft,
although workers could be exposed in an accidental discharge of the
fire suppression system (e.g., during servicing of the system). In
addition, there is the occasional presence of living animals in cargo
bays for the duration of a flight who could be exposed to the fire
suppression agent in the event of a system discharge (e.g., cargo fire)
until the aircraft can safely land. The EPA is requesting comments on
exposure of personnel and animals to 2-BTP/CO2 in aircraft
cargo bays.
XI. Statutory and Executive Order Reviews
Additional information about these statutes and Executive Orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
This action is expected to be an Executive Order 14192 deregulatory
action. This proposed rule is expected to provide burden reduction by
proposing to list more alternatives that would be available for use by
industry, and in certain end-uses, better align EPA requirements with
updated industry standards.
C. Paperwork Reduction Act (PRA)
This action does not impose any new information collection burden
under the PRA. OMB has previously approved the information collection
activities contained in the existing regulations and has assigned OMB
control number 2060-0226. This rule contains no new requirements for
reporting or recordkeeping.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, the EPA concludes that the impact of concern
for this rule is any significant adverse economic impact on small
entities and that the agency is certifying that this rule will not have
a significant economic impact on a substantial number of small entities
because the rule has no net burden on the small entities subject to the
rule. This action proposes to add the additional options under SNAP of
using 2-BTP/CO2, HCR 4141, HFO-1234yf, HFO-1234ze(E), R-
444A, R-453A, R-456A, R-480A and R-516A in the specified end-uses but
does not mandate such use. Because equipment for HCR 4141 using
residential and light commercial AC and heat pumps--self-contained room
air conditioners and HFO-1234ze(E) using residential and light
commercial AC and heat pumps, and R-516A using residential and light
commercial AC and heat pumps is not manufactured yet in the United
States, no change in business practice is
[[Page 50809]]
required to meet the use conditions, resulting in no adverse impact
compared with the absence of this rule. The revised use conditions for
R-290 in water coolers and for HFC-32, R-290, R-441A, R-454A, R-454B,
R-454C, and R-457A in residential and light commercial AC and heat
pumps were requested by industry and allow for consistency with the
latest, updated standards; these would allow for greater consistency in
business practices for different types of equipment using the same
refrigerants, as well as provide greater flexibility in designing and
manufacturing equipment. Equipment using the proposed refrigerants
already manufactured prior to the effective date of the final rule
would not be required to be changed. Water coolers using R-290 and
residential and light commercial AC and heat pumps using HFC-32, R-290,
R-441A, R-454A, R-454B, R-454C, or R-457A have been subject to similar
use conditions and would allow for use consistent with industry safety
standards, and thus the updated requirements would result in no adverse
impact compared with the absence of this rule. Thus, if the rule were
finalized as proposed, it would not impose new costs on small entities.
We have therefore concluded that this action will have no net
regulatory burden for all directly regulated small entities.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain an unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local or Tribal governments or the private sector.
F. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.
G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have Tribal implications as specified in
Executive Order 13175. It will not have substantial direct effects on
Tribal governments, on the relationship between the Federal government
and Indian Tribes, or on the distribution of power and responsibilities
between the Federal government and Indian Tribes, as specified in
Executive Order 13175. Thus, Executive Order 13175 does not apply to
this action.
H. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks
Executive Order 13045 directs federal agencies to include an
evaluation of the health and safety effects of the planned regulation
on children in federal health and safety standards and explain why the
regulation is preferable to potentially effective and reasonably
feasible alternatives. This action is not subject to Executive Order
13045 because it is not a significant regulatory action under section
3(f)(1) of Executive Order 12866, and because the EPA does not believe
the environmental health or safety risks addressed by this action
present a disproportionate risk to children. While the EPA has not
conducted a separate analysis of risks to infants and children
associated with this rule, the rule does contain use conditions that
would reduce exposure risks to the general population, with the
reduction of exposure being most important to the most sensitive
individuals. This action's health and risk assessments are contained in
the comparisons of toxicity for the various substitutes, as well as in
the risk screens for the substitutes that are listed in this proposed
rule. The risk screens are in the docket. However, the EPA's Policy on
Children's Health applies to this action.
I. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
J. National Technology Transfer and Advancement Act
This action involves technical standards. The EPA proposes to
incorporate by reference the 4th edition (2022) of UL 60335-2-40, which
establishes requirements for the evaluation of AC and heat pump
equipment and safe use of flammable refrigerants, among other things.
This standard is discussed in greater detail in Section IV.F.4. The EPA
also proposes to incorporate by reference the 3rd edition (2023) of UL
60335-2-24, which establishes requirements for the evaluation of
household refrigerators and freezers and related small, household
refrigerated appliances and safe use of flammable refrigerants, among
other things. This standard is discussed in greater detail in Section
V.E.4. The EPA also proposes to incorporate by reference Supplement SB
of the 8th edition of UL 399, which establishes requirements for the
evaluation of water coolers and safe use of flammable refrigerants,
among other things. This standard is discussed in greater detail in
Section VI.E.4.
The 4th edition of UL 60335-2-40, ``Household and Similar
Electrical Appliances--Safety--Part 2-40: Particular Requirements for
Electrical Heat Pumps, Air-Conditioners and Dehumidifiers'', dated
December 15, 2022, is available at: https://www.shopulstandards.com/ProductDetail.aspx?productId=UL60335-2-40. The 3rd edition of UL 60335-
2-24, ``Household and Similar Electrical Appliances--Safety--Part 2-24:
Particular Requirements for Refrigerating Appliances, Ice-Cream
Appliances and Ice-Makers,'' dated July 29, 2022, and revisions through
February 20, 2024, is available at: https://www.shopulstandards.com/ProductDetail.aspx?UniqueKey=43189. The 8th edition of UL 399,
``Drinking Water Coolers,'' dated March 30, 2017, and revisions through
February 28, 2024, is available at https://www.shopulstandards.com/ProductDetail.aspx?productId=UL399_8_S_20170330. All three UL standards
may be purchased by mail at: COMM 2000, 151 Eastern Avenue,
Bensenville, IL 60106; Email: [email protected]; Telephone: 1-
888-853-3503 in the United States or Canada (other countries dial 1-
415-352-2178); internet address: https://ulstandards.ul.com or https://www.shopulstandards.com. The cost of the 4th edition (2022) of UL
60335-2-40 is $521 for an electronic copy and $652 for a hard copy. The
cost of the 3rd edition (2022) of UL 60335-2-24, is $555 for an
electronic copy and $694 for a hard copy. The cost of the February 2024
revision to the 8th edition of UL 399 is $798 for an electronic copy
and $998 for a hard copy. UL also offers a subscription service to the
Standards Certification Customer Library that allows unlimited access
to their standards and related documents. The cost of obtaining this
standard is not a significant financial burden for equipment
manufacturers and purchase is not necessary for those selling,
installing, and servicing the equipment. Therefore, the EPA concludes
that the UL standards the EPA is proposing to incorporate by reference
are reasonably available.
The EPA is also proposing to incorporate by reference ASHRAE 15-
2024, which specifies requirements for the safe design, construction,
[[Page 50810]]
installation, and operation of refrigeration systems, among other
things. This standard is discussed in greater detail in Section VII.E.
ANSI/ASHRAE Standard 15-2024, ``Safety Standard for Refrigeration
Systems,'' is available at https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources, and may be purchased by mail
at: 180 Technology Parkway NW, Peachtree Corners, Georgia 30092; by
email at [email protected]; by telephone: 1-800-527-4723 in the
United States or Canada; or at internet address: https://store.accuristech.com/ashrae/standards/ashrae-15-2024-packaged-w-standard-34-2024?product_id=2922394. ASHRAE 15-2024 and ASHRAE 34-2024
are available as a bundle costing $178.00 for an electronic copy or
hard copy. The cost of obtaining these standards is not a significant
financial burden for equipment manufacturers or for those selling,
installing and servicing the equipment. Therefore, the EPA concludes
that the ASHRAE standard the EPA is proposing to incorporate by
reference is reasonably available.
The EPA is proposing to incorporate by reference several industry
safety standards from SAE in the use conditions for use of HFO-1234yf
in MVACs in several types of equipment: SAE J639 (revised November
2020), ``Safety and Design Standards for Motor Vehicle Refrigerant
Vapor Compression Systems;'' SAE J1739 (revised January 2021),
``Potential Failure Mode and Effects Analysis (FMEA) Including Design
FMEA, Supplemental FMEA-MSR, and Process FMEA;'' and SAE J2844 (revised
January 2013), ``R-1234yf (HFO-1234yf) New Refrigerant Purity and
Container Requirements for Use in Mobile Air-Conditioning Systems.''
These standards may be purchased by mail at: SAE Customer Service, 400
Commonwealth Drive, Warrendale, PA 15096-0001; by telephone: 1-877-606-
7323 in the United States or 724-776-4970 outside the United States or
in Canada. The cost of SAE J639, SAE J1739, and SAE J2844 is $85 each
for an electronic or hardcopy. The cost of obtaining these standards is
not a significant financial burden for manufacturers of MVACs and
purchase is not required for those selling, installing, and servicing
the systems. Therefore, the EPA proposes to conclude that the use of
SAE J639, SAE J1739, and SAE J2844 are reasonably available.
XII. References
Unless specified otherwise, all documents are available
electronically at https://regulations.gov, docket number EPA-HQ-OAR-
2024-0503.
Annex F of the Montreal Protocol. Controlled substances. Available
at: https://ozone.unep.org/treaties/montreal-protocol/articles/annex-f-controlled-substances.
ASHRAE, 2024a. ANSI/ASHRAE Standard 15-2024: Safety Standard for
Refrigeration Systems. 2024.
ASHRAE, 2024b. ANSI/ASHRAE Standard 34-2024: Designation and Safety
Classification of Refrigerants. 2024.
Carter, 2010. ``Development of the SAPRC-07 Chemical Mechanism and
Updated Ozone Reactivity Scales,'' Report to the California Air
Resources Board by William P.L. Carter. Revised January 27, 2010.
EEAP, 2023. Environmental Effects of Stratospheric Ozone Depletion,
UV Radiation, and Interactions with Climate Change. 2022 Assessment
Report. UNEP, Environmental Effects Assessment Panel. March, 2023.
Available at: https://ozone.unep.org/system/files/documents/EEAP-2022-Assessment-Report-May2023.pdf. (EEAP, 2023).
Gradient Corporation, 2008. Risk Assessment For Alternative
Refrigerant HFO-1234yf. (Phase I) Prepared for the Society of
Automotive Engineers (SAE) Cooperative Research Project 150.
February 2008.
Gradient Corporation, 2009. Risk Assessment for Alternative
Refrigerants HFO-1234yf and R-744 (CO2). Confidential
report prepared for SAE International Cooperative Research Program
1234. December 17, 2009.
Gradient Corporation, 2013a. Additional Risk Assessment of
Alternative Refrigerant R-1234yf. Confidential report prepared for
SAE International Cooperative Research Program 1234-4. July 24,
2013.
Gradient Corporation, 2013b. Risk Assessment for Alternative
Refrigerants R-445A and R-1234yf. Phase III. Prepared for SAE
International MRB CRP. December 30, 2013.
Gradient Corporation, 2023a. Retrofit Analysis Letter. Prepared for
Honeywell International. September 26, 2023.
Gradient Corporation, 2023b. Gradient Risk Analysis for Heavy-Duty
On-Highway Vehicles. 2023.
ICF, 2009. Risk Screen on Substitutes for CFC-12 in Motor Vehicle
Air Conditioning: Substitute: HFO-1234yf.
ICF, 2014. Assessment of the Potential Impact of Hydrocarbon
Refrigerants on Ground Level Ozone Concentrations. February 2014.
ICF, 2016. Additional Follow-on Assessment of the Potential Impact
of Hydrocarbon Refrigerants on Ground Level Ozone Concentrations.
September 2016.
ICF, 2022. Additional Assessment of the Potential Impact of
Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. May
2022.
ICF, 2025a. Risk Screen on Substitutes in Residential and Light
Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: HCR 4141.
ICF, 2025b. Risk Screen on Substitutes in Residential and Light
Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: HFO-1234ze(E) (Solstice[supreg] ze, Solstice[supreg]
1234ze).
ICF, 2025c. Risk Screen on Substitutes in Residential and Light
Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-516A (Forane[supreg] 516A).
ICF, 2025e. Risk Screen on Substitutes in Residential and Light
Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-441A.
ICF, 2025f. Risk Screen on Substitutes in Residential and Light
Commercial Air Conditioning and Heat Pumps (New Equipment);
Substitute: R-454C (OpteonTM XL20).
ICF, 2025g. Risk Screen on Substitutes in Residential and Light
Commercial Air Conditioning and Heat Pumps Commercial Ice Machines
(New Equipment); Substitute: R-457A (Forane[supreg] 457A).
ICF, 2025h. Risk Screen on Substitutes in Household Refrigerators
and Freezers (New Equipment); Substitute: HCR 4141.
ICF, 2025i. Risk Screen on Substitutes in Water Coolers (New
Equipment); Substitute: Propane (R-290).
ICF, 2025j. Risk Screen on Substitutes in Chillers (New Equipment);
Substitute: R-516A (Forane[supreg] 516A).
ICF, 2025k. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty and Medium-Duty Vehicles) (Retrofit
Equipment); Substitute: HFO-1234yf (Solstice[supreg] yf or
Solstice[supreg] 1234yf).
ICF, 2025l. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty Vehicles, Medium-Duty Vehicles, and Heavy-
Duty Vehicles) (Retrofit Equipment); Substitute: R-444A
(Klea[supreg] 444A).
ICF, 2025m. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty Vehicles, Medium-Duty Vehicles, and Heavy-
Duty Vehicles) (Retrofit Equipment); Substitute: R-456A
(Klea[supreg] 456A).
ICF, 2025n. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Light-Duty Vehicles, Medium-Duty Vehicles, and Heavy-
Duty Vehicles) (Retrofit Equipment); Substitute: R-480A (RS-20).
ICF, 2025o. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Heavy-Duty On-Highway (HDOH) Vehicles) (New
Equipment); Substitute: HFO-1234yf (Solstice[supreg] yf or
Solstice[supreg] 1234yf).
ICF, 2025p. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Buses) (New Equipment); Substitute: HFO-1234yf
(Solstice[supreg] yf or Solstice[supreg] 1234yf).
ICF, 2025q. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Buses and Passenger Rail) (Retrofit Equipment);
Substitute: R-453A (RS-70).
ICF, 2025r. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Buses and Passenger Rail) (Retrofit Equipment);
Substitute: R-456A (Klea[supreg] 456A).
ICF, 2025s. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning--Buses and Passenger Rail (Retrofit Equipment);
Substitute: R-480A (RS-20).
ICF, 2025t. Risk Screen on Substitutes in Total Flooding Systems in
Normally
[[Page 50811]]
Unoccupied Spaces; Substitute: VERDAGENT[supreg].
IPCC, 2007. Climate Change 2007: The Physical Science Basis.
Contribution of Working Group I to the Fourth Assessment Report of
the Intergovernmental Panel on Climate Change. Solomon, S., Qin, D.,
Manning, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M., and
Miller, H.L. (eds.). Cambridge University Press. Cambridge, United
Kingdom and New York, NY, USA. Available at: https://www.ipcc.ch/report/ar4/wg1.
Metghalchi and Keck, 1980. M. Metghalchi and J.C. Keck. Laminar
Burning Velocity of Propane-Air Mixtures at High Temperature and
Pressure. Combustion And Flame 38: 143-154 (1980). Available online
at: https://james-keck-memorial-collection.unibs.it/JCKeck-papers/MetghalchiKeck-CombustionFlame-38-143-1980.pdf.
Minor et al., 2009. B. Minor, D. Herrmann, and B. Gravell. (111g)
Flammability Characteristics of Low GWP Refrigerant HFO-1234yf.
AIChE 2009 Spring Meeting & 5th Global Congress on Process Safety.
Available online at: https://proceedings.aiche.org/conferences/aiche-spring-meeting-and-global-congress-on-process-safety/2009/proceeding/paper/111g-flammability-characteristics-low-gwp-refrigerant-hfo-1234yf.
SAE J639, ``Safety and Design Standards for Motor Vehicle
Refrigerant Vapor Compression Systems.'' Dated November 2020.
SAE J1660, ``Fittings and Labels for Retrofit of CFC-12 (R-12)
Mobile Air-Conditioning Systems to HFC-134a (R-134a).'' Dated April
2011.
SAE J1739, ``Potential Failure Mode and Effects Analysis (FMEA)
Including Design FMEA, Supplemental FMEA-MSR, and Process FMEA.
Dated January 2021.
SAE J2064, ``Coupled Automotive Refrigerant Air-Conditioning Hose
Assemblies.'' Dated April 2021.
SAE J2099, ``Standard of Purity for Recycled R-134a (HFC-134a) and
R-1234yf (HFO-1234yf) for Use in Mobile Air-conditioning Systems.''
Dated February 2011.
SAE J2843, ``R-1234yf (HFO-1234yf) Recovery/Recycling/Recharging
Equipment for Flammable Refrigerants for Mobile Air-Conditioning
Systems.'' Dated July 2019.
SAE J2844, ``R-1234yf (HFO-1234yf) New Refrigerant Purity and
Container Requirements for Use in Mobile Air-Conditioning Systems.''
Dated January 2013.
SAE J2851, ``Recovery Equipment for Contaminated R-134a or R-1234yf
Refrigerant from Mobile Automotive Air Conditioning Systems.'' Dated
September 2022.
Takizawa et al., 2005. Kenji Takizawa, Akifumi Takahashi, Kazuaki
Tokuhashi, Shigeo Kondo, and Akira Sekiya. Burning velocity
measurement of fluorinated compounds by the spherical-vessel method,
Combustion and Flame, Volume 141, Issue 3, Pages 298-307, 2005.
Available online at https://doi.org/10.1016/j.combustflame.2005.01.009.
TEAP, 2025. Report of the Technology and Economic Assessment Panel,
May 2025, Volume 1: Progress report. Available online at:
ozone.unep.org/system/files/documents/TEAP-May2025-Progress-Report-vol1.pdf.
UL 399, 2017. Standard for Safety: Drinking Water Coolers. 7th
edition. Dated July 29, 2022.
UL 399, 2024. Standard for Safety: Drinking Water Coolers. 8th
edition. Dated March 30, 2017, with revisions through February 28,
2024.
UL 484, 2012. Room Air Conditioners. Supplement SA and Appendices B
through F to the 8th edition. Dated August 2, 2012.
UL 60335-2-24, 2017. Safety Requirements for Household and Similar
Electrical Appliances, Part 2: Particular Requirements for
Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers (2nd
Edition, dated April 28, 2017).
UL 60335-2-24, 2024. Safety Requirements for Household and Similar
Electrical Appliances, Part 2: Particular Requirements for
Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers (3rd
Edition, dated July 29, 2022, with revisions through February 29,
2024).
UL 60335-2-40, 2019. Standard for Safety: Household And Similar
Electrical Appliances--Safety--Part 2-40: Particular Requirements
for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers, 3rd
Edition, Dated November 1, 2019.
UL 60335-2-40, 2022. Standard for Safety: Household And Similar
Electrical Appliances--Safety--Part 2-40: Particular Requirements
for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers, 4th
Edition, Dated December 15, 2022.
U.S. EPA, 2020. 2017 National Emissions Inventory Report. U.S.
Environmental Protection Agency. Available at: https://gispub.epa.gov/neireport/2017.
U.S. EPA, 2024. EPA Automotive Trends Report: Greenhouse Gas
Emissions, Fuel Economy, and Technology since 1975. U.S. EPA.
November, 2024.
WMO, Scientific Assessment of Ozone Depletion: 2022, GAW Report No.
278, 509 pp.; WMO: Geneva, 2022. Available at: https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022.pdf. (WMO, 2022).
List of Subjects in 40 CFR Part 82
Environmental protection, Administrative practice and procedure,
Air pollution control, Chemicals.
Lee Zeldin,
Administrator.
[FR Doc. 2025-19812 Filed 11-7-25; 8:45 am]
BILLING CODE 6560-50-P