[Federal Register Volume 78, Number 66 (Friday, April 5, 2013)]
[Notices]
[Pages 20632-20637]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-07977]
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ENVIRONMENTAL PROTECTION AGENCY
[EPA-HQ-OAR-2009-0927; FRL-9799-4]
Mandatory Reporting of Greenhouse Gases: Notice of Data
Availability Regarding Global Warming Potential Values for Certain
Fluorinated Greenhouse Gases and Fluorinated Heat Transfer Fluids
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of data availability and request for comment.
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SUMMARY: The EPA is announcing to the public the availability of
estimated global warming potentials, as well as data and analysis
submitted in support of them, for eight fluorinated heat transfer
fluids. We are requesting comments on the estimated global warming
potentials and the data and analysis supporting them. We are also
requesting comment on the cited global warming potentials for 35 other
fluorinated greenhouse gases and fluorinated heat transfer fluids for
which we do not currently possess supporting data and analysis. The EPA
is requesting comment on the global warming potentials of all 43
chemicals as we consider adding these global warming potentials to the
Greenhouse Gas Reporting rule.
DATES: Comments must be received on or before May 6, 2013.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2009-0927, by one of the following methods:
[[Page 20633]]
Federal eRulemaking Portal: http://www.regulations.gov:
Follow the online instructions for submitting comments.
Email: [email protected].
Fax: (202) 566-1741.
Mail: EPA Docket Center, Attention Docket EPA-HQ-OAR-2009-
0927, Mail code: 2822T, 1200 Pennsylvania Avenue NW., Washington, DC
20460.
Hand Delivery: EPA Docket Center, Public Reading Room,
Room 3334, EPA West Building, Attention Docket EPA-HQ-OAR-2009-0927,
1301 Constitution Avenue NW., Washington, DC 20004. Such deliveries are
only accepted during the Docket's normal hours of operation, and
special arrangements should be made for deliveries of boxed
information.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2009-0927. The EPA's policy is that all comments received will be
included in the public docket without change and may be made available
online at http://www.regulations.gov, including any personal
information provided, unless the comment includes information claimed
to be Confidential Business Information (CBI) or other information
whose disclosure is restricted by statute. Do not submit information
that you consider to be CBI or otherwise protected through http://www.regulations.gov. The http://www.regulations.gov Web site is an
``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an email comment directly to EPA without
going through http://www.regulations.gov your email address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, the EPA recommends that you include your
name and other contact information in the body of your comment and with
any disk or CD-ROM you submit. If the EPA cannot read your comment due
to technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses.
Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at EPA's Docket Center,
Public Reading Room, EPA West Building, Room 3334, 1301 Constitution
Avenue NW., Washington, DC 20004. This Docket Facility is open from
8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742.
FOR FURTHER INFORMATION CONTACT: Deborah Ottinger, Climate Change
Division, Office of Atmospheric Programs (6207J), Environmental
Protection Agency, 1200 Pennsylvania Avenue NW., Washington, DC 20460;
telephone number: (202) 343-9149; fax number: (202) 343-2342; email
address: [email protected].
SUPPLEMENTARY INFORMATION:
I. General Information
A. What is today's notice about?
The EPA is making available for public comment estimated
GWPs for the eight fluorinated heat transfer fluids (HTFs) listed in
Table 1 of this notice as well as data and analysis submitted in
support of those GWPs.
The EPA is also making available for public comment cited
GWPs for the 35 fluorinated GHGs and fluorinated HTFs listed in Table 2
of this notice. The EPA does not currently possess supporting data and
analysis for these GWPs.
Both sets of chemicals and their GWPs are being considered
for addition to Table A-1 to subpart A of part 98, the compendium of
GWPs used to convert tons of chemical into tons of carbon dioxide
equivalent (CO2e) under the Greenhouse Gas Reporting
Program.
B. How does this notice relate to the forthcoming proposed rule titled
``2013 Revisions to the Greenhouse Gas Reporting Rule and Proposed
Confidentiality Determinations for New or Substantially Revised Data
Elements''?
In the proposed rule signed March 8, 2013, titled ``2013 Revisions
to the Greenhouse Gas Reporting Rule and Proposed Confidentiality
Determinations for New or Substantially Revised Data Elements''
(hereinafter referred to as the ``2013 Technical Corrections Proposed
Rule''), the EPA is proposing to amend subpart A, General Provisions,
to propose GWPs for certain fluorinated greenhouse gases not currently
listed in Table A-1 to subpart A. This notice requests comment on GWPs
for fluorinated GHGs and fluorinated HTFs for which documented GWPs
were not available in time for inclusion in the 2013 Technical
Corrections Proposed Rule. The comments submitted in response to this
notice are intended to inform a potential future rulemaking to amend
Table A-1 to subpart A to add the GWPs of some or all of the
fluorinated GHGs and fluorinated HTFs listed in this notice.
C. Where can I get the information?
All of the information can be obtained through the Docket and at
http://www.regulations.gov (see ADDRESSES section above for docket
contact information).
D. What is the EPA taking comment on and what supporting documentation
do I need to include in my comments?
The EPA requests comment on topics including but not limited to the
following:
For the fluorinated HTFs in Table 1 of this notice, the
reliability, including the likely accuracy and precision, of the GWPs
listed in Table 1 given the data and analysis submitted in support of
them, and
The completeness, quality, and transparency of the data
and analysis submitted in support of the GWPs in Table 1 of this
notice.
For the fluorinated GHGs and HTFs in Table 2 of this
notice, the reliability, including the likely accuracy and precision,
of the GWPs listed, and
The accuracy of the chemical names and formulas listed.
For the fluorinated HTFs in Table 1 of this notice, the EPA is
specifically seeking comment on the extent to which the supporting data
and analysis includes the following:
Data and analysis related to the low-pressure gas phase
infrared absorption spectrum of the fluorinated GHG.
Data and analysis related to the estimated atmospheric
lifetime of the fluorinated GHG (reaction mechanisms and rates,
including e.g., photolysis and reaction with atmospheric components
such as OH, O3, CO, and water), including descriptions of
the measurements or modeling.
The radiative transfer analysis that integrates the
lifetime and infrared absorption spectrum data to calculate the GWP.
Any published or unpublished studies of the GWP of the
gas.
Where quantitative structure-activity relationship (QSAR) models
have been used, the EPA is seeking comment on the extent to which the
data and
[[Page 20634]]
analysis include information documenting the level of accuracy of the
QSAR-derived GWP, including:
Information on how the structure of the ``target''
fluorinated GHG is similar to the structures of the fluorinated GHGs
used to model the radiative forcing and/or reaction rate of the
``target'' fluorinated GHG.
Information on the quality (i.e., accuracy and precision)
and quantity of the measurements of the radiative forcings and/or
reaction rates of the fluorinated GHGs used to model these parameters
for the ``target'' fluorinated GHG.
Estimated uncertainties of the modeled forcings and/or
reaction rates.
Descriptions and results of any efforts to validate the
QSAR model(s).
E. What should I consider as I prepare my comments for EPA?
Explain your views as clearly as possible.
Describe any assumptions that you used.
Provide any technical information or data you used that
support your views.
Provide specific examples to illustrate your concerns.
Offer alternatives.
Make sure to submit your comments by the comment period
deadline identified.
To ensure proper receipt by EPA, identify the appropriate
docket identification number in the subject line on the first page of
your response. It would also be helpful if you provided the name, date,
and Federal Register citation related to your comments.
F. Submitting Confidential Business Information (CBI)
Do not submit information you are claiming as CBI to EPA through
http://www.regulations.gov or email. Clearly mark the part of the
information that you claim to be CBI. Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2. For CBI information in a disk or CD-ROM that you mail to EPA, mark
the outside of the disk or CD-ROM as CBI and then identify
electronically within the disk or CD-ROM the specific information that
is claimed as CBI. In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the public docket.
II. Background
Table A-1 to subpart A of 40 CFR part 98 (``Table A-1'') is a
compendium of GWP values of certain GHGs that are required to be
reported under one or more subparts of the Greenhouse Gas Reporting
rule (``Part 98''). These GWPs are used to convert tons of chemical
into tons of CO2-equivalent for purposes of various
calculations and reporting under the rule. As acknowledged in the
Federal Register notice for the final Part 98 (74 FR 56348, October 30,
2009), it is the EPA's intent to periodically update Table A-1 as GWPs
are evaluated or re-evaluated by the scientific community. This will
provide a more accurate and complete account of the atmospheric impacts
of GHG emissions and supplies.
Table A-1 of Part 98 currently includes 10 fluorinated HTFs of
which EPA is aware, but there are a number that it does not include. Of
the 42 fluorinated HTFs listed in this notice (none of which is on
Table A-1 of Part 98), electronics facilities reported emissions of 17
under the Greenhouse Gas Reporting Program (GHGRP). Electronics
facilities reported use of another four in a 2009 industry survey by
the International SEMATECH Manufacturing Initiative (Technology
Transfer 09065014A-TR). Other HTFs (those with vapor pressures
below 1 mm Hg at 25 degrees C) may be reported for the first time this
year because of an expanded definition of fluorinated HTF that went
into effect in 2012. Several of the fluorinated HTFs in this notice are
fully fluorinated. Fully fluorinated compounds are likely to have long
atmospheric lifetimes and high GWPs.\1\
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\1\ Fully fluorinated compounds are defined as compounds that
contain only single bonds and in which all available valence
locations are filled by fluorine atoms (e.g., saturated
perfluorocarbons; fully fluorinated linear, branched and cyclic
alkanes; fully fluorinated ethers; fully fluorinated tertiary
amines; fully fluorinated aminoethers; and perfluoropolyethers).
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There are two primary suppliers of fluorinated HTFs used in the
United States: 3M Company (3M) and Solvay. After evaluating the reports
submitted under subpart I, the EPA contacted 3M and Solvay and
requested any data and information they had regarding the GWPs of the
fluorinated HTFs that they supplied.
3M responded with estimated GWPs and supporting data and analysis
for eight fluorinated HTFs collectively composed of nine fluorinated
compounds. (One of the HTFs, FC-77, is a blend of two fluorinated
compounds.) For one of the fluorinated compounds,
C8F18, the EPA is proposing a GWP in the 2013
Technical Corrections Proposed Rule. Thus, the EPA is not requesting
comment on the GWP of C8F18 through this action.
However, the EPA is requesting comment on the GWPs and supporting data
and analysis for the other eight compounds, which are listed in Table 1
of this notice. These compounds (along with the 3M HTFs already
included on Table A-1 of Part 98) account for most of the emissions of
3M-supplied HTFs reported to EPA under subpart I to date (i.e., in
2012).
Solvay indicated that it generally did not possess data and
analysis to support estimated GWPs for the Solvay-supplied HTFs that
are not already on Table A-1 of Part 98.\2\ Table 2 of this notice
therefore includes all of the Solvay-supplied fluorinated HTFs of which
EPA is aware and which are not already included on Table A-1. It also
includes some 3M-supplied fluorinated HTFs (and one fluorinated GHG
used as a chamber cleaning gas) for whose estimated GWPs 3M did not
submit supporting data and analysis. 3M indicates that some of these
HTFs are no longer produced.
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\2\ Solvay provided a peer-reviewed paper regarding a
fluorinated compound, PFPMIE, that is already on Table A-1 and that
is sold under the trade name of Galden HT 70. (There are multiple
PFPMIEs, which have the general chemical structure
F3C(OCFCF3CF2)m(OCF2
)nOCF3. The PFPMIE that is listed on Table A-1
and is the primary component of HT 70 is the simplest version, with
m=n=1.) In addition, Solvay submitted an infrared absorption
spectrum for another fluorinated HTF that it imports into the U.S.,
Galden HT-110.
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For several of the fluorinated HTFs (and for the fluorinated GHG)
in Table 2 of this notice, approximate GWPs have been presented or
published (e.g., in presentations to the EPA or in material safety data
sheets (MSDSs)) without accompanying explanation or documentation of
how those GWPs have been developed. For a large subset of these fully
fluorinated chemicals, GWPs of 10,000 were identified in a presentation
given by 3M to EPA. For some of these chemicals, different GWPs were
identified in other sources, such as MSDSs issued by 3M or Solvay.
These are the GWPs that are included in Table 2. The EPA does not
intend to add the cited GWPs for these compounds to Table A-1 of Part
98 without supporting data and analysis. We are therefore continuing to
assemble and evaluate information regarding the GWPs for the compounds
in Table 2 of this notice. We request comment on these GWPs and on the
accuracy of the listed chemical names and formulas for the compounds.
III. GWP Values on Which EPA is Seeking Comment
[[Page 20635]]
Table 1--F-HTFs With Documented GWPs
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Chemical name and Source of submitted
Trade name(s) CAS No. formula Submitted GWP GWP
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Fluorinert FC-77 (component); 335-36-4........ Perfluoro-2- 9,600........... GWP and calculation
Fluorinert FC-75. butyltetrahydro- methodology provided
furan. by manufacturer
C8F16O...............
Fluorinert FC-3283............ 338-83-0........ Perfluoro- 8,690........... GWP and calculation
tripropylamine methodology provided
(PTPA). by manufacturer
(C3F7)3N.............
Fluorinert FC-40.............. 1064698-37-8.... Perfluoro- 9,020........... GWP and calculation
tributylamine (PTBA). methodology provided
(C4F9)3N............. by manufacturer
Fluorinert FC-3284, PF-5052... 382-28-5........ Perfluoromethyl 9,500........... GWP and calculation
morpholine (PMM). methodology provided
C5F11NO.............. by manufacturer
Fluorinert FC-770............. 1093615-61-2.... Perfluoro-isopropyl 11,000.......... GWP and calculation
morpholine (PIPM). methodology provided
C7F15NO.............. by manufacturer
Novec 7300, HFE-7300.......... 132182-92-4..... 1,1,1,2,2,3,4,5,5,5- 310............. GWP and calculation
decafluoro-3-methoxy- methodology provided
4-trifluoromethyl- by manufacturer
pentane.
CF3CF2CF(OCH3)CF(CF3)
2.
Novec 7500, HFE-7500.......... 297730-93-9..... 3-ethoxy- 100............. GWP and calculation
1,1,1,2,3,4,4,5,5,6, methodology provided
6,6-dodecafluoro-2- by manufacturer
trifluoromethyl-
hexane.
CF3CF2CF2CF(OC2H5)CF(
CF3)2.
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F-HTFs with Vapor Pressure Less than 1 mm Hg
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Fluorinert FC-70.............. 338-84-1........ Perfluoro- 8,900........... GWP and calculation
triamylamine (PTAA). methodology provided
(C5F11)3N............ by manufacturer
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Table 2--F-GHGs and F-HTFs for whose GWPs Documentation is Not Available
----------------------------------------------------------------------------------------------------------------
Chemical name and
Trade name(s) CAS No. formula Cited GWP Source of cited GWP
----------------------------------------------------------------------------------------------------------------
Heptafluorobutanoyl fluoride.. 773-14-8........ C4F8O................ 8,700........... Identified in Pruette
et al. (2000) \a\
Fluorinert FC-3255, FC-104.... 335-36-4........ Predominantly C5-C18. 10,000.......... Identified in
presentation to EPA
\b\
Fluorinert FC-5311, 306-91-2........ Perfluoroperhydrophen 10,000.......... Identified in
Phenanthrene. anthrene. presentation to EPA
C14F24............... \b\
Fluorinert FC-5320............ 86508-42-1...... Perfluoro-compounds >5,000.......... Identified in
C5-C18. manufacturer's
literature \c\
Fluorinert FC-8270............ 338-83-0........ Perfluoro compounds 10,000.......... Identified in
(primarily compounds presentation to EPA
with 9 carbons). \b\
Novec 7600, HFE-7600.......... 870778-34-0..... 1,1,1,2,3,3- 700............. Identified in
Hexafluoro-4- manufacturer's
(1,1,2,3,3,3- literature \d\
hexafluoroprop-oxy)-
pentane.
C8H6F12O.............
H-Galden ZT-130............... 188690-77-9..... HCF2OCF2OCF2CF2OCF2H. 3000-5000....... Identified in
presentation to EPA
\b\
H-Galden ZT-150............... 188690-77-9..... HCF2OCF2OCF2CF2OCF2H. 3000-5000....... Identified in
presentation to EPA
\b\
H-Galden ZT-180............... 188690-77-9..... HCF2OCF2OCF2CF2OCF2H. 3000-5000....... Identified in
presentation to EPA
\b\
H-Galden ZV60................. Not Available... HCF2O-(CF2O)p- 3,000-5,000..... Identified in
(CF2CF2O)q-CF2H. presentation to EPA
(ratio of p/q is 2/3) \b\
H-Galden ZV85, ZT-85.......... Not Available... Not Available........ 3,000-5,000..... Identified in
presentation to EPA
\b\
H-Galden ZV100................ Not Available... Not Available........ 3,000-5,000..... Identified in
presentation to EPA
\b\
H-Galden ZV135................ Not Available... Not Available........ 3,000-5,000..... Identified in
presentation to EPA
\b\
Galden DET.................... Not Available... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
\b\
Galden E85.................... Not Available... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
\b\
Galden HT-55.................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 2.03 to 9.26 \h\. \b\
m = 0.04 to 0.19.....
[[Page 20636]]
Galden HT-90.................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 2.03 to 9.26 \h\) \b\
m = 0.04 to 0.19.....
Galden HT-110................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 2.03 to 9.26 \h\. b,e
m = 0.04 to 0.19.....
Galden HT-135................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 2.03 to 9.26 \h\. \b\
m = 0.04 to 0.19.....
Galden HT-170................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 2.03 to 9.26 \h\. \b\
m = 0.04 to 0.19.....
Galden D02--TS................ 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
\b\
Galden D02--TSX............... 69991-67-9...... CF3(OCFCF3CF2)n- None provided... No GWP found
(OCF2)m-OCF3.
Galden PFS 2.................. 69991-67-9 and CF3(OCFCF3CF2)n- None provided... HTF identified in
9002-84-0. (OCF2)m-OCF3. distributor's
literature \f\
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F-HTFs with Vapor Pressure Less than 1 mm Hg
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Fluorinert FC-43.............. 311-89-7........ N(CF2CF2CF2CF3)3..... 10,000.......... Identified in
presentation to EPA
\b\
Fluorinert FC-5312............ 338-84-1........ Perfluoro compounds 10,000.......... Identified in
(primarily with 15 presentation to EPA
carbons). \b\
Galden D02.................... 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
\b\
Galden D03.................... 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
\b\
Galden D05.................... 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
\b\
Galden HS-240................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 6.4 to 7.3 \h\... \b\
m = 0.1 to 0.15......
Galden HS-260................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 6.4 to 7.3 \h\... \b\
m = 0.1 to 0.15......
Galden HT-200................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 2.03 to 9.26 \h\. \b\
m = 0.04 to 0.19.....
Galden HT-230................. 69991-67-9...... CF3(OCFCF3CF2)n- None provided... HTF identified in
(OCF2)m-OCF3. distributor's
n = 2.03 to 9.26 \h\. literature \g\
m = 0.04 to 0.19.....
Galden LS-200................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 5.2 to 6.1 \h\... \b\
m = 0.1 to 0.12......
Galden LS-215................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 5.2 to 6.1 \h\... \b\
m = 0.1 to 0.12......
Galden LS-230................. 69991-67-9...... CF3(OCFCF3CF2)n- 10,000.......... Identified in
(OCF2)m-OCF3. presentation to EPA
n = 5.2 to 6.1 \h\... \b\
m = 0.1 to 0.12......
----------------------------------------------------------------------------------------------------------------
\a\ Pruette, L., S. Karecki, R. Reif, L. Tousignant, W. Reagan, S. Kesari, and L. Zazzera. ``Evaulation of C4F8O
as an Alternative Plasma-Enhanced Chemical Vapor Deposition Chamber Clean Chemistry.'' Journal of the
Electrochemical Society, 147 (3): 1149-1153, 2000.
\b\ 3M Company. ``Greenhouse Gas Reporting of Heat Transfer Fluids.'' Presentation by Kurt Werner of 3M
Electronics Markets Materials Division. Presented to the EPA, January 2011. Available in Docket No. EPA-HQ-OAR-
2011-0512.
\c\ 3M Company. ``Material Safety Data Sheet: 3MTM FluorinertTM FC-5320 Electronic Liquid.'' 2012. Available
online at: http://multimedia.3m.com/mws/mediawebserver?SSSSSuUn_zu8l00x4xtZm8m94v70k17zHvu9lxtD7SSSSSS--
\d\ 3M Company. ``Material Safety Data Sheet: 3MTM NovecTM 7600 Engineered Fluid.'' 2011. Available online at:
http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSuUn_zu8l00xMxmGmxtx4v70k17zHvu9lxtD7SSSSSS--.
\e\ Solvay provided an infrared (IR) spectrum for this compound, but not an estimated atmospheric lifetime or
GWP.
[[Page 20637]]
\f\ http://www.sigmaaldrich.com/catalog/product/aldrich/374431?lang=en®ion=US.
\g\ https://www.lesker.com/newweb/fluids/msds/Galden_HT230.pdf.
\h\ In the chemical formulas for the Galden series, ``n'' and ``m'' indicate the number of times each group (in
parentheses) is repeated in the compound. While ``n'' and ``m'' are integers in any single molecule, the
Galden HTFs are typically made up of mixtures of different molecules. The values for ``n'' and ``m'' for any
single Galden HTF represent averages for that HTF. Table 2 provides the ranges of the average values of ``n''
and ``m'' for the Solvay HTFs in each Galden series (Galden HT, LS, etc.).
IV. Summary of EPA Assessment of Submitted GWPs and the Data and
Analysis Supporting Them
The EPA completed a review of the GWPs listed in Table 1 of this
notice and the data and analysis submitted in support of them. That
assessment is available in the docket, together with the submitted data
and analyses. In general, we found that the data and methods used to
estimate the GWPs were reasonable and that the GWPs were consistent
with what would be expected for compounds of the types analyzed.
However, there were some limitations to the data and analysis. First,
in some cases the transparency of the data and analysis were limited
because some of the reports containing the detailed background
information were not available for review in time for this notice.
Second, some of the data were of uncertain quality because they were
based on an unpublished master's thesis. Third, because some of the
analyses were performed in the early 1990s, some of the models used to
estimate lifetimes or radiative efficiencies were out of date. Fourth,
in one case (PTAA), radiative efficiency estimates were based on a
quantitative structural activity relationship (QSAR) of uncertain
predictive ability. Fifth, the atmospheric lifetime for one of the
short-lived compounds (HFE-7300) was estimated based on an atmospheric
lifetime for methane that is lower than the currently accepted
lifetime, resulting in an underestimated lifetimes for that compound.
Finally, for the six long-lived compounds, experimental limitations
prevented 3M or its researchers from establishing more than minimum
atmospheric lifetimes, and the GWPs based on these lifetimes are
therefore also minimums.
Overall, we do not expect that these limitations resulted in large
errors in the resulting GWPs; and with the exception of the errors
attributable to the last two issues (related to atmospheric lifetimes),
we expect that these are random rather than systematic errors. To
address the last two issues, we examined the sensitivity of the GWPs of
the compounds to atmospheric lifetime. In general, 100-year GWPs for
very long-lived compounds are relatively insensitive to increases in
assumed atmospheric lifetime, and our analysis confirmed this. However,
the 100-year GWPs for the short-lived compounds are sensitive to
increases in the assumed atmospheric lifetime. For example, updating
the atmospheric lifetime for HFE-7300 based on the currently accepted
atmospheric lifetime of methane increases the estimated GWP of HFE-7300
by 10 percent.
Dated: April 1, 2013.
Sarah Dunham,
Director, Office of Atmospheric Programs.
[FR Doc. 2013-07977 Filed 4-4-13; 8:45 am]
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