[Federal Register Volume 64, Number 93 (Friday, May 14, 1999)]
[Rules and Regulations]
[Pages 26484-26569]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-11796]



[[Page 26483]]

_______________________________________________________________________

Part II





Environmental Protection Agency





_______________________________________________________________________



40 CFR Part 60



Test Methods: Three New Methods for Velocity and Volumetric Flow Rate 
Determination in Stacks or Ducts; Final and Proposed Rules

  Federal Register / Vol. 64, No. 93 / Friday, May 14, 1999 / Rules and 
Regulations  

[[Page 26484]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[FRL-6337-1]
RIN 2060-AH97


Test Methods: Three New Methods for Velocity and Volumetric Flow 
Rate Determination in Stacks or Ducts

AGENCY: Environmental Protection Agency (EPA).

ACTION: Direct final rule.

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SUMMARY: EPA is taking direct final action to approve three new 
optional test methods for measuring velocity and volumetric flow rate 
of flue gas from fossil fuel-fired boilers and turbines. These new 
methods allow the tester to account for velocity drop-off near the 
stack or duct wall and the yaw and pitch angles of flow. The primary 
users of the new methods will be owners and operators of utility units 
subject to the Acid Rain Program under title IV of the Clean Air Act, 
and certain large electric generating units and large non-electric 
generating units that may become subject to the nitrogen oxides 
(NOX) state implementation plan (SIP) call under Title I of 
the Clean Air Act, who must use an approved test method to periodically 
calibrate the flow rate monitors at these units. Flow rate data is used 
to determine the units' sulfur dioxide (SO2) and 
NOX mass emissions and heat inputs. The purpose of the Acid 
Rain Program and the NOX SIP call is to significantly reduce 
emissions from electric generating plants and other affected units in 
order to reduce the adverse health and environmental effects of acid 
deposition or ground level ozone resulting from these emissions.
    The sources affected by this action are primarily in the sector 
Fossil Fuel Electric Power Generation, North American Industrial 
Classification System (NAICS) code 221112, or are industrial boilers. 
The affected sources include U.S. industry establishments primarily 
engaged in operating fossil fuel powered electric power generation 
facilities. These facilities use fossil fuels, such as coal, oil, or 
gas, in boilers and combustion turbines to produce electric energy or 
steam. The electric energy produced in these establishments are 
provided to electric power transmission systems or to electric power 
distribution systems.

DATES: This rule is effective on July 13, 1999 without further notice, 
unless EPA receives adverse comment by June 14, 1999. or (if a public 
hearing is requested) by July 1, 1999. If we receive such comment, we 
will publish a timely withdrawal in the Federal Register informing the 
public that this rule will not take effect.

ADDRESSES: Any written comments must be identified with Docket No. A-
99-14, must be identified as comments on the direct final rule and 
companion proposal and must be submitted in duplicate to: EPA Air 
Docket (6102), Environmental Protection Agency, 401 M Street, SW, 
Washington, DC 20460. The docket is available for public inspection and 
copying between 8:30 a.m. and 3:30 p.m., Monday through Friday, at the 
address given above. A reasonable fee may be charged for copying. A 
detailed rationale for today's action is set forth in the Findings 
Report, which can be obtained by writing to the Air Docket at the 
address given above.

FOR FURTHER INFORMATION CONTACT: John Schakenbach, Acid Rain Division 
(6204J), U.S. Environmental Protection Agency, 401 M Street, SW, 
Washington, DC 20460, (202) 564-9158; or Elliot Lieberman, Acid Rain 
Division (6204J), U.S. Environmental Protection Agency, 401 M Street, 
SW, Washington, DC 20460, (202) 564-9136.

SUPPLEMENTARY INFORMATION: EPA is publishing this rule without prior 
proposal because we view these new test methods as noncontroversial and 
anticipate no adverse comment. We believe the rule is not controversial 
for the following reasons: (1) The rule is primarily technical in 
nature, (2) the rule is generally accepted by the scientific community, 
and (3) use of the new test methods will be optional. However, we are 
publishing a separate document that will serve as the proposal to 
approve the test methods if adverse comments are filed. This rule will 
be effective on July 13, 1999 without further notice unless we receive 
adverse comment by June 14, 1999 or (if a public hearing is requested) 
by July 1, 1999. If EPA receives timely adverse comment, we will 
publish a withdrawal in the Federal Register informing the public that 
the rule will not take effect. We will address all public comments in a 
subsequent final rule based on the proposed rule. We will not institute 
a second comment period on this action. Any parties interested in 
commenting must do so at this time.

II. Regulated Entities

    Entities potentially regulated by this action are utility and 
industrial fossil fuel-fired boilers and turbines that serve generators 
producing electricity, generate steam, or cogenerate electricity and 
steam and that are subject to EPA's monitoring regulations, 40 CFR part 
75. While part 75 primarily regulates the electric utility industry, 
today's action could potentially affect other industries, including 
those subject to the NOX SIP call. Regulated categories and 
entities include:

----------------------------------------------------------------------------------------------------------------
                Category                                      Examples of regulated entities
----------------------------------------------------------------------------------------------------------------
NAICS Code: 221112, Fossil Fuel          Electric service providers, boilers and turbines from a wide range of
 Electric Power Generation.               industries.
----------------------------------------------------------------------------------------------------------------

This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities which EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be regulated. To determine whether 
your facility, company, business, organization, etc., is regulated by 
this action, you should carefully examine the applicability criteria in 
Secs. 72.6, 72.7, 72.8, 75.70, and Appendix A of part 60 of title 40 of 
the Code of Federal Regulations. If you have questions regarding the 
applicability of this action to a particular entity, consult the person 
listed in the preceding ``For Further Information Contact'' section of 
this preamble.

II. Background

    In 1971, EPA promulgated Method 2 ``Determination of Stack Gas 
Velocity and Volumetric Flow Rate (Type S Pitot Tube)''. At the time of 
its development, Method 2 was principally used with EPA Method 5 
``Determination of Particulate Emissions from Stationary Sources'' to 
help ensure appropriate sampling rates throughout a particulate 
sampling run.
    Many EPA air quality regulations use Method 2, including part 75 of 
EPA's Acid Rain Program regulations, implementing title IV of the Clean 
Air

[[Page 26485]]

Act (the Act), and part 51 of EPA's NOx SIP call, which may result in 
states or EPA requiring certain large electric generating units and 
large non-electric generating units to comply with subpart H of part 
75. See 40 CFR parts 51 and 75; and 63 FR 57356, 57495, October 27, 
1998. Part 75 requires affected electric utility units to install and 
operate continuous emission monitoring systems that provide EPA with 
continuous hourly measurements of sulfur dioxide (SO2) 
concentration, NOX concentration, carbon dioxide 
concentration, and volumetric flow rate of flue gas in a stack or duct. 
Under the Acid Rain Program, volumetric flow rate and SO2 
concentration are used to calculate sulfur dioxide mass emissions at 
each affected unit. At the end of each year, these emissions are 
compared to the unit's sulfur dioxide allowances to determine whether 
the unit held enough allowances to cover its emissions. Volumetric flow 
rate is also used to calculate a unit's heat input. In order to ensure 
the accuracy of compliance determinations, part 75 requires owners and 
operators of a unit to conduct periodic performance testing of 
volumetric flow rate monitors by comparing flow rate data from the 
monitors with data reported using EPA's Method 2. Similarly, subpart H 
of part 75 uses Method 2 as the reference method for flow rate 
measurements used to calculate NOX mass emissions. See also 
40 CFR part 96.
    In the first three years of the Acid Rain Program, the electric 
utility industry raised concerns that under some flow conditions EPA's 
approved test method for volumetric flow rate (Method 2) could be less 
than optimal for measuring flow rate and thus for determining sulfur 
dioxide emissions and heat input. These concerns focused on situations 
where flue gas flowed at an angle (i.e., with yaw or pitch), not 
straight out of a stack or duct. Method 2 does not include procedures 
for measuring the yaw or pitch angles of flow or wall effects in 
calculating stack or duct gas velocity or volumetric flow rate.
    Volumetric flow rate is calculated by multiplying the average flue 
gas velocity by the stack or duct cross-sectional area. Yaw and pitch 
characterize the extent to which flue gas is not flowing straight out 
of a stack or duct. From the standpoint of a tester facing a vertical 
stack, a yaw angle is represented by flow movement to the left or right 
of the stack centerline. The pitch angle is represented by flow 
movement toward or away from the tester. The term ``wall effects'' 
refers to the drop-off of flue gas velocity near the inside wall of a 
stack or duct. This velocity drop-off is caused by friction from the 
stack wall.
    Some amount of yaw and pitch angle and wall effects are almost 
always present in utility stacks or ducts. Yaw and pitch angles produce 
flue gas flow that swirls and/or bounces off stack or duct walls ( 
total velocity). Only the straight-up (axial velocity) component of 
total velocity actually exits the stack. Moreover, determining axial 
velocity without accounting for the drop-off near the stack or duct 
wall can result in overstating the actual axial velocity. Thus, when 
enough yaw, pitch or wall effects are present, Method 2 can overstate 
the measured flue gas velocities (and thus volumetric flow) because it 
only allows the total velocity to be measured and does not account for 
yaw angles, pitch angles, or wall effects. If the test method 
overstates flow rate, a flow rate monitor calibrated using the test 
method may also overstate flow rate and result in overstated sulfur 
dioxide emissions and heat input.
    To address these concerns, and to provide a technical basis for 
potential new test methods, EPA initiated a flow study consisting of 
wind tunnel tests and field tests. Wind tunnel tests were performed to 
ensure accurate probe calibrations, to determine probe performance 
under different temperature conditions (Reynolds number testing), and 
to determine probe performance under different flow angle conditions 
(swirl tunnel testing). Probe calibrations were performed at three wind 
tunnel facilities: the North Carolina State University (NCSU), the 
National Institute of Standards and Technology, and the Massachusetts 
Institute of Technology (MIT). The Reynolds number testing was 
conducted at MIT. The swirl tunnel testing was performed by the Fossil 
Energy Research Corporation at a special wind tunnel installation 
developed for the Electric Power Research Institute.
    In addition, field tests were performed to evaluate new techniques 
that could improve the ability to measure flow rate under a wide range 
of conditions and to provide a technical basis for potential, new test 
methods. Field tests were performed at two natural gas-fired 750 MWe 
electric utility boilers and at a 640 MWe bituminous coal-fired utility 
boiler. These three sites were selected to provide three different flow 
swirl conditions. Four test teams were used at each site to perform 
simultaneous testing of various probes. In this manner, probes could be 
tested under essentially the same conditions. Seven different probes 
types were tested: Type S, United Sciences Testing Incorporated 
Autoprobe Type S, Prandtl (Standard Pitot), French, modified Kiel, DAT, 
and spherical. A Codel flow monitor was also tested.
    A special series of tests were also performed to investigate 
velocity drop-off near stack walls. These wall effects tests were 
performed at five sites. The sites were selected to provide different 
inside stack wall material (steel and brick and mortar) and stack gas 
flow conditions in order to test how these parameters affect stack gas 
velocity drop-off near the stack wall.
    As a result of the wind tunnel tests and field tests, a report 
describing results of the wind tunnel testing, three Site Data Reports, 
describing test activities and results at each site, and the Findings 
Report, describing overall conclusions, were written. These reports are 
included in the docket. Significant findings from the wind tunnel and 
field tests are:
     Probes that could determine the yaw and pitch angles of 
flow produced results closer to those predicted by scientific theory;
     Overall, the Type S, Autoprobe Type S, DAT, and spherical 
probes produced the best results: they tended to be less variable, did 
not consistently under-measure velocity, and were closer to 
theoretically derived results and the central tendency of the data than 
the other probes tested;
     Automated probes were less variable than manually operated 
probes;
     Several probes (modified Kiel, and the French) and the 
Codel flow monitor produced highly variable test results and should not 
be included in new test methods;
     Measuring wall effects produced a \1/2\% to 3% improvement 
in volumetric flow rate measurements.
     The amount of wall effect is lower for stacks with smooth 
interiors (steel) than for stacks with rougher interiors (brick and 
mortar);
     To produce reliable probe calibrations, wind tunnels 
should meet certain specifications related to tunnel size and flow 
conditions;
     Calibration curves for three-dimensional (3-D) probes, 
i.e., DAT and the spherical probes, are less reliable for velocities 
below 20 feet per second; and
     Contrary to expectations, scratches on the surface of 
spherical probes did not significantly effect their calibrations.

We used these data and findings to develop the three new test methods 
described in today's rulemaking.
    Review by independent experts, industry experts, and EPA experts 
was used in the three major phases of the flow study: The field test 
plan, the draft Findings Report, and the three draft test

[[Page 26486]]

methods. One significant comment by the reviewers was that we should 
keep the new test methods as effective and practical as possible, but 
still provide flexibility and a wide range of options for stack 
testers. Based on reviewer feedback on subsequent versions of the test 
methods, we believe we have accommodated all major concerns.

III. Approval of Three New Test Methods

    Today's direct final rule approves three new test methods that 
provide probes and procedures to account for yaw angles, pitch angles 
and wall effects. Method 2G allows Type S probes and 3-D probes (DAT 
and spherical) to be rotated into the flow to measure total velocity 
pressure and yaw angle. The yaw angle is used to calculate ``near-
axial'' velocity from total velocity. Method 2F allows 3-D probes to be 
used to measure total velocity, yaw angles, and pitch angle pressure. 
Pitch angle pressure is used with a calibration curve to determine 
pitch angle. Yaw and pitch angles are used to calculate axial velocity 
from total velocity. Method 2H provides a procedure for accounting for 
wall effects by using either a default wall effects adjustment factor 
or one derived from near wall measurements. The wall effects adjustment 
factor is used with the Method 2-, 2G- or 2F-calculated velocity to 
derive a wall effects adjusted velocity.
    In the Acid Rain Program, and in other programs which require 
reporting of mass emission rates (e.g., lbs NOx/hour), a 
capability to measure these parameters in the calculation of volumetric 
flow rate can improve the reporting of pollutant emissions in some 
situations (described earlier). In addition, the new test methods in 
today's rulemaking address the disparity that has sometimes been 
reported between heat rate calculated using a flow monitor and heat 
rate calculated using fuel sampling and analysis to the extent that the 
disparity results from the difficulty of measuring flue gas flow rate 
under certain flow conditions. This rule does not address the 
procedures used in fuel sampling or in the calculation of heat rate.
    EPA is voluntarily undertaking this regulatory action in response 
to requests from the regulated community. This regulatory action 
provides additional accepted scientific and analytical methods for 
measuring volumetric flow rate in stacks and ducts The additional test 
methods are the result of extensive field studies that were subjected 
to review by a panel of independent experts, utility company 
representatives, and internal EPA staff. These new test methods may be 
used instead of Method 2 in programs that use part 75 or part 96 
procedures to quantify emissions. These new test methods are discussed 
below in detail.

A. Methods 2F and 2G

    Method 2F, ``Determination of Stack Gas Velocity and Volumetric 
Flow Rate With Three-Dimensional Probes'', is a method for measuring 
the yaw and pitch angle-adjusted (or axial) velocity with 3-dimensional 
probes like the prism-shaped, five-hole probe (commonly called a DA or 
DAT probe) and the five-hole spherical probe. Method 2G, 
``Determination of Stack Gas Velocity and Volumetric Flow Rate With 
Two-Dimensional Probes'', is a variant of existing Method 2 that 
describes the use of yaw angle determination procedures with Type S or 
3-dimensional probes to determine the yaw angle-adjusted flue gas 
velocity in a stack or duct.
    The methods include step-by-step procedures specifically designed 
to provide quality assured measurements and address a number of key 
problems uncovered in the course of the wind tunnel and field testing 
of the new methods. The following summarizes the major steps for 
performing Method 2F or 2G.
(1) Qualify Wind Tunnel
    The wind tunnel tests revealed that some wind tunnels used by 
vendors or source testers to calibrate probes were inadequate, because 
they were either too small or did not have uniform flow. To avoid such 
problems, any wind tunnel used to calibrate probes for Methods 2F or 2G 
must satisfy certain design and performance specifications to ensure 
that the flow is axial (straight) and uniform in the wind tunnel 
calibration location. The wind tunnel must meet two design criteria: 
(1) The diameter must be at least 12 inches; and (2) the projected area 
of the tested probe and reference calibration pitot tube must not 
exceed 4% of the cross-sectional area of the wind tunnel. The wind 
tunnel must also meet two performance specifications: (1) A velocity 
pressure cross-check to ensure that the velocity is the same at all 
locations where the tested and reference probes will be positioned 
during calibration; and (2) an axial flow verification to ensure that 
there are no significant yaw or pitch components of flow at these 
locations. These two tests are performed before the initial use of the 
wind tunnel and are repeated after any alterations are made to the 
tunnel.
(2) Prepare To Calibrate Probe
    The wind tunnel and field tests also showed that pre-calibration 
probe inspection and procedures for placing a scribe line on a probe 
were important prerequisites for accurate yaw angle measurements. 
Therefore, the methods include the following five general activities to 
be performed prior to calibrating a probe (1) Put a straight permanent 
line (scribe line) on the probe. This activity only needs to be 
performed once, not every time a probe is calibrated. The scribe line 
must meet certain straightness and width criteria so that a yaw angle 
measuring device can be accurately placed on the probe. (2) Check that 
the probe is not bent and does not have significant sag. (3) Pressure 
devices must be zeroed and calibrated. (4) The yaw angle measurement 
device must be calibrated and aligned relative to the reference scribe 
line. (5) The probe system must be leak checked.
(3) Perform Yaw Angle Calibration
    Yaw angle errors were observed in the wind tunnel tests when the 
offset of the scribe line from the probe's zero yaw position was not 
accurately determined in the wind tunnel. The methods, therefore, 
include a yaw angle calibration procedure, which must be performed on 
the complete probe assembly in a wind tunnel to determine the 
``reference scribe line rotational offset'' angle (Rslo). 
The Rslo indicates the rotational position of a probe's 
reference scribe line relative to the probe's yaw-null position and is 
used in determining the yaw angle of flow in a stack or duct.
(4) Perform Velocity and Pitch Calibrations
    The field and wind tunnel tests showed that robust velocity and 
pitch calibration procedures were required if errors in velocity and 
volumetric flow determinations are to be avoided. For Method 2G, this 
consists of a wind tunnel procedure to determine a velocity calibration 
coefficient for the tested probe. This calibration coefficient is used 
to calculate stack gas velocity from pressure measurements taken in the 
field. The velocity calibration procedure involves taking three pairs 
of pressure measurements with the tested probe and a reference 
calibration pitot tube at two wind tunnel velocity settings. 
Calibration coefficients obtained at wind tunnel velocity settings of 
60 and 90 feet per second (fps) are usable in all field applications 
where the velocities are 30 fps or greater. Calibration coefficients 
derived at other velocity settings are usable in

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field applications where the measured velocity does not fall outside 
the limits defined by those velocity settings.
    Method 2F includes wind tunnel procedures to determine both 
velocity and pitch angle calibration curves. These curves are used to 
determine both the pitch angle and velocity of flue gas flow when using 
a 3-dimensional probe. The pitch and velocity calibration procedure 
involves positioning the tested probe at a series of pitch angles 
settings relative to the flow in the wind tunnel and then taking 
pressure measurements with the tested probe and a reference probe. The 
measurements are repeated at two wind tunnel velocity settings. 
Calibration curves obtained at wind tunnel velocity settings of 60 and 
90 fps are usable in all field applications over the entire velocity 
range allowed by the method. Calibration curves derived at other 
velocity settings are usable in all field applications allowed by the 
method as long as the measured velocity does not exceed both of the 
wind tunnel velocity settings used to derive the curves.
(5) Prepare for Field Test
    The field tests showed that the inspection of probes and the set-up 
procedures described above under step 2 were not only a critical 
prerequisite for wind tunnel testing, but were equally important in 
field testing. For example, during one of the field tests, an 
inspection detected damage to the probe head which resulted in spurious 
readings from a probe. Thus, prior to beginning a field test, each 
method requires performance of all the checks described in item 2 
(``Prepare to Calibrate Probe'') above, except for putting a scribe 
line on the probe. Additionally, the tester must inspect the probe for 
damage, mark traverse point distances on the probe, and determine a 
system response time.
(6) Perform Field Test
    The field tests also showed that the quality of measurements was 
affected by procedures followed by testers when performing the field 
tests. For example, allowing sufficient response time and checking for 
probe plugging were shown to be important considerations during the 
field test. Thus, the methods give specific instructions on how to 
perform a field test. In particular, the methods instruct testers to 
perform the following steps. Insert the probe into a test port in the 
stack or duct, and move the probe to the first traverse point. After 
the system response time has elapsed, measure the yaw angle, impact 
pressure, and pitch angle pressure (Method 2F only). Take these 
measurements at each traverse point of the run. In addition, measure 
barometric pressure, flue gas molecular weight, moisture and static 
pressure. Check the probe periodically for plugging to prevent erratic 
results or sluggish responses.
(7) Perform Calculations
    To account for pitch and yaw components of flow, the methods had to 
include new calculation procedures that were not needed in Method 2. 
These procedures were employed in the field tests and shown to be 
workable. They include calculating the pitch angle (Method 2F only) and 
impact velocity at each traverse point using the pressure measurements 
taken in the field and the calibration coefficient (Method 2G) or 
curves (Method 2F) derived in the wind tunnel. Using these values and 
the yaw angles measured in the field, the axial velocity (Method 2F) or 
yaw-adjusted velocity (Method 2G) is calculated at each traverse point. 
Stack or duct average velocity is then calculated by averaging over all 
the traverse point velocities. Checks are performed to see that the 
calibration coefficients or curves are appropriate for the velocity 
encountered in the field. Finally, the volumetric flow rate is derived 
by multiplying the stack or duct cross-sectional area and the average 
velocity.

B. Method 2H

    Method 2H, ``Determination of Stack Gas Velocity Taking into 
Account Velocity Decay Near the Stack Wall'', can be used in 
conjunction with existing Method 2 or new Methods 2F or 2G to account 
for velocity drop-off near stack (or duct) walls in circular stacks (or 
ducts) no less than 3.3 feet in diameter. Method 2H is not suitable for 
use in rectangular stacks or ducts because the procedures in this 
method are not applicable to the complex and varying flow dynamics 
characteristic of such configurations.
    There are two main approaches for determining wall effects adjusted 
velocity in Method 2H. Either a default wall effects adjustment factor 
(WAF) (i.e., 0.9900 (for brick and mortar stacks), or 0.9950 (for all 
other stacks or ducts)) may be used with Method 2, 2F, or 2G without 
taking any wall effects measurements or a WAF may be calculated from 
velocity measurements taken at 16 or more Method 1 traverse points and 
at 8 or more wall effects points. EPA's Method 1, ``Sample and Velocity 
Traverses for Stationary Sources'', is the test method for determining 
the number and location of traverse points in a stack or duct. Method 1 
alone is generally not suitable for determining wall effects.
    During the course of wall effects field testing, several potential 
problems were uncovered. Procedures were incorporated into Method 2H to 
prevent these problems. These are described below.
(1) Locate Traverse Points
    The field test revealed that care needs to be exercised when 
locating wall effects traverse points; otherwise, the full wall effect 
may not be measured. Thus, Method 2H instructs testers to take 
measurements at 1-inch intervals starting at 1 inch from the wall or at 
the next closest 1-inch interval from the wall possible. Testers may 
perform either a partial or complete wall effects traverse. For a 
partial traverse, measurements are taken at two wall effects traverse 
points per test port, at a minimum. For a complete traverse, a series 
of 1-inch incremented measurements are taken beginning no further than 
4 inches from the wall and extending in 1-inch intervals as far as 12 
inches from the wall. The method presents procedures for determining 
the location of the wall effects points.
(2) Determine Sampling Order
    Field tests also showed that an incorrect WAF may be calculated if 
the wall effects sampling is decoupled from the Method 1 sampling. 
Therefore, the method includes instructions on how sampling is to be 
performed. The sampling order may be from the wall to the center or 
from the center to the wall. Although the Method 1 and wall effects 
points need not be interspersed at each port, there should be no 
interruption between sampling at the wall effects and Method 1 points. 
The intent of this sampling sequence is to keep the Method 1 and the 
wall effects measurements as close together in time as possible to 
reduce the possibility of different velocity conditions occurring 
during the Method 1 and wall effects measurements.
(3) Take and Record Measurements
    As in Methods 2F and 2G, field tests showed that the procedures 
followed by testers were critical to the quality of the measurements 
obtained. Wall effects testing not only required the procedures found 
in Method 2F and 2G, but also additional procedures for taking 
measurements close to a stack or duct wall. For example, the method had 
to include instructions for testing in situations where it may not be 
possible to obtain measurements within a certain proximity (e.g., 1 
inch) of the stack or duct wall. Method 2H instructs testers to perform 
the following steps. After inserting the probe into the gas stream,

[[Page 26488]]

wait for the pressure and temperature readings to stabilize to stack or 
duct conditions before taking measurements at the first traverse point. 
(This time period is called the ``system response time'' and is defined 
in Methods 2F and 2G.) At all other traverse points, testers must allow 
enough time to obtain representative pressure measurements. If no 
velocity is detected at the wall effects point closest to the wall, 
move to the next 1-inch incremented wall effects point. Complete the 
integrated traverse as quickly as possible, consistent with adequate 
sampling time, so that the measurements are all taken under the same 
stack or duct conditions. In addition, take other measurements required 
by Method 2, 2F, or 2G (e.g., moisture, barometric pressure). Record 
all measurements.
(4) Perform Wall Effects Calculations
    The field tests confirmed that a series of measurements near a 
stack wall could capture the impact of wall effects on flue gas flow in 
a stack or duct. To capture this effect, a new calculation procedure 
was developed which was tested in the field. This procedure was 
incorporated in Method 2H. It involves calculating the velocity at each 
wall effects traverse point and entering the resulting values in a 
table. The entered values are then used to find the wall effects-
adjusted replacement velocities for the four Method 1 traverse points 
closest to the wall. These four values and the unadjusted velocity at 
the Method 1 traverse points are used to calculate a WAF. The WAF is a 
multiplier which can then be applied to the velocity derived using 
Methods 2, 2F, and 2G to account for velocity decay near the stack or 
duct wall. The WAF may be no less than 0.9800 for a partial traverse 
and no less than 0.9700 for a complete traverse. We derived these 
limits from analysis of wall effects tests performed on a variety of 
utility stacks (different stack lining material, velocities, and stack 
dimensions). If actual field testing indicates that the WAF for a 
particular stack or duct may be less than 0.970, the tester should 
increase the number of traverse points in the Method 1 traverse (e.g., 
to 20 or 24 points if a 16-point traverse was initially performed) and 
re-calculate the WAF to capture the full extent of the wall effect.
(5) Obtain Wall Effects Adjusted Velocity and Volumetric Flow Rate
    While the field test showed the calculation procedures to be 
effective, the new test method also needed to clarify how WAFs were to 
be applied to calculate the wall effects adjusted volumetric flow rate 
for the stack or duct. Thus, the final steps in Method 2H include 
instructions on how to calculate the wall effects adjusted velocity for 
the stack or duct by multiplying the unadjusted velocity from Method 2, 
2F, or 2G by the WAF (either calculated or default). The calculated WAF 
from one run may be applied to all runs of the same relative accuracy 
test audit (RATA). If calculated WAFs are obtained for several runs, 
the tester must average the WAFs and apply the resulting value to all 
runs of the same RATA. The stack or duct volumetric flow rate is then 
obtained by multiplying the wall effects adjusted velocity by the stack 
or duct cross-sectional area.

IV. Administrative Requirements

A. Executive Order 12866

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), the 
Administrator must determine whether the regulatory action is 
``significant'' and therefore subject to Office of Management and 
Budget (OMB) review and the requirements of the Executive Order. The 
Order defines ``significant regulatory action'' as one that is likely 
to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local or tribal governments or communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    This action is not expected to have an annual effect on the economy 
of $100 million or more. Pursuant to the terms of Executive Order 
12866, it has been determined that this direct final rule is not a 
significant action. As such, the direct final rule has not been 
submitted for OMB review.
    Today's action provides options for applying scientific and 
analytical methods generally accepted by the scientific community. The 
options provided by this action are not precedential, but typical of 
the periodic improvements the Agency routinely makes to test methods 
based on advances in technology, science, and field experience. In 
keeping with past practice, we are retaining existing methods while 
offering new methods to provide the regulated community with additional 
choices and to lower the cost of compliance.
    Since use of the new methods is voluntary, we anticipate that the 
new methods will be used only if they result in overall cost savings. 
While the cost of performing the new methods may be somewhat higher 
than the existing test method (due to higher probe calibration costs, 
increased stack testing time, and additional test equipment), these 
costs should be completely offset by compliance cost savings.

B. Executive Order 12875: Enhancing Intergovernmental Partnerships

    Under Executive Order 12875, Enhancing Intergovernmental 
Partnerships, EPA may not issue a regulation that is not required by 
statute and that creates a mandate upon a State, local or tribal 
government, unless the Federal government provides the funds necessary 
to pay the direct compliance costs incurred by those governments, or 
EPA consults with those governments. If EPA complies by consulting, 
Executive Order 12875 requires EPA to provide to OMB a description of 
the extent of EPA's prior consultation with representatives of affected 
State, local and tribal governments, the nature of their concerns, 
copies of any written communications from the governments, and a 
statement supporting the need to issue the regulation. In addition, 
Executive Order 12875 requires EPA to develop an effective process 
permitting elected officials and other representatives of State, local 
and tribal governments ``to provide meaningful and timely input in the 
development of regulatory proposals containing significant unfunded 
mandates.''
    As discussed above, today's direct final rule is voluntary and does 
not create a mandate on State, local or tribal governments. The rule 
does not impose any enforceable duties on these entities, unless they 
choose to use the new optional methods. Accordingly, the requirements 
of section 1(a) of Executive Order 12875 do not apply to this rule.

C. Executive Order 13084: Consultation and Coordination With Indian 
Tribal Governments

    Under Executive Order 13084, Consultation and Coordination with 
Indian Tribal Governments, EPA may not issue a regulation that is not 
required by statute, that significantly or uniquely affects the 
communities of Indian tribal governments, and that

[[Page 26489]]

imposes substantial direct compliance costs on those communities, 
unless the Federal government provides the funds necessary to pay the 
direct compliance costs incurred by the tribal governments, or EPA 
consults with those governments. If EPA complies by consulting, 
Executive Order 13084 requires EPA to provide to OMB, in a separately 
identified section of the preamble to the rule, a description of the 
extent of EPA's prior consultation with representatives of affected 
tribal governments, a summary of the nature of their concerns, and a 
statement supporting the need to issue the regulation. In addition, 
Executive Order 13084 requires EPA to develop an effective process 
permitting elected officials and other representatives of Indian tribal 
governments ``to provide meaningful and timely input in the development 
of regulatory policies on matters that significantly or uniquely affect 
their communities.''
    Today's direct final rule does not significantly or uniquely affect 
the communities of Indian tribal governments. Today's action finalizes 
test method procedures for determining volumetric flow rate in stacks 
or ducts. Since use of the new methods is voluntary, we anticipate that 
the new methods will be used only if they result in overall cost 
savings. While the cost of performing the new methods may be somewhat 
higher than the existing test method (due to higher probe calibration 
costs, increased stack testing time, and additional test equipment), 
these costs should be completely offset either by compliance cost 
savings or increased compliance certainty. Accordingly, the 
requirements of section 3(b) of Executive Order 13084 do not apply to 
this rule.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), P.L. 
104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local, and tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective, or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows EPA to adopt an alternative other than the least 
costly, most cost-effective, or least burdensome alternative if the 
Administrator publishes with the final rule an explanation why that 
alternative was not adopted. Before EPA establishes any regulatory 
requirements that may significantly or uniquely affect small 
governments, including tribal governments, it must have developed under 
section 203 of the UMRA a small government agency plan. The plan must 
provide for notifying potentially affected small governments, enabling 
officials of affected small governments to have meaningful and timely 
input in the development of EPA regulatory proposals with significant 
Federal intergovernmental mandates, and informing, educating, and 
advising small governments on compliance with the regulatory 
requirements.
    Today's direct final rule is not expected to result in expenditures 
of more than $100 million in any one year and, as such, is not subject 
to section 202 of the UMRA. The direct final rule is not expected to 
significantly or uniquely affect small governments.

E. Paperwork Reduction Act

    Today's direct final rule will not add any additional information 
collection requirements to the current information collection 
requirements in the implementing regulations, e.g., part 75. Therefore 
an Information Collection Request was not prepared for the direct final 
rule.
    An agency may not conduct or sponsor and a person is not required 
to respond to a collection of information, unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations are listed in 40 CFR part 9 and 48 CFR chapter 15.

F. Regulatory Flexibility

    The Regulatory Flexibility Act, 5 U.S.C. 601, et seq., generally 
requires an agency to conduct a regulatory flexibility analysis of any 
rule subject to notice and comment rulemaking requirements unless the 
agency certifies that the rule will not have a significant economic 
impact on a substantial number of small entities. Small entities 
include small businesses, small not-for-profit enterprises, and 
governmental jurisdictions. EPA has determined that it is not necessary 
to prepare a regulatory flexibility analysis in connection with this 
direct final rule. EPA has also determined that this rule will not have 
a significant economic impact on a substantial number of small 
entities.
    Since use of the new test methods is voluntary, we anticipate that 
the new options will be used only if they result in overall cost 
savings. While the cost of performing the new options may be somewhat 
higher than the existing test method (due to higher probe calibration 
costs, increased stack testing time, and additional test equipment), 
these costs should be completely offset by compliance cost savings.

G. Executive Order 13045

    ``Protection of Children From Environmental Health Risks and Safety 
Risks'' (62 FR 19885, April 23, 1997) applies to any rule that: (1) Was 
initiated after April 21, 1997, or for which a Notice of Proposed 
Rulemaking was published after April 21, 1998; (2) is determined to be 
``economically significant'' as defined under E.O. 12866, and (3) 
concerns an environmental health or safety risk that EPA has reason to 
believe may have a disproportionate effect on children. If the 
regulatory action meets all three criteria, the Agency must evaluate 
the environmental health or safety effects of the planned rule on 
children and explain why the planned regulation is preferable to other 
potentially effective and reasonably feasible alternatives considered 
by the Agency.
    EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that are based on health or safety risks, such that 
the analysis required under section 5-501 of the Executive Order has 
the potential to influence the regulation. This direct final rule is 
not subject to the Executive Order because the rule does not establish 
an environmental standard intended to mitigate health or safety risks.

H. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Pub L. 104-113 15 U.S.C. 272 note, directs EPA 
to use voluntary consensus standards in its regulatory activities 
unless to do so would be inconsistent with applicable law or otherwise 
impractical. Voluntary consensus standards are technical standards 
(e.g., materials specifications, test methods, sampling procedures, 
business practices) that are developed or adopted by voluntary 
consensus standards bodies. The NTTAA requires EPA to provide Congress, 
through OMB, explanations when the Agency decides

[[Page 26490]]

not to use available and applicable voluntary consensus standards.
    EPA has not identified any voluntary consensus standards which 
might be applicable to this rulemaking.

I. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
Sec. 804(2). This rule will be effective on July 13, 1999.

List of Subjects in 40 CFR Part 60

    Air pollution control, Carbon dioxide, Continuous emission 
monitors, Electric power plants, Environmental protection, Nitrogen 
oxides, Particulate matter, Reporting and recordkeeping requirements, 
Sulfur dioxide.

    Dated: May 5, 1999.
Carol M. Browner,
Administrator.

    For the reasons set out in the preamble, title 40 chapter 1 of the 
Code of Federal Regulations is amended as follows:

PART 60--[AMENDED]

    1. The authority citation for part 60 continues to read as follows:

    Authority: 42 U.S.C. 7401, 7411, 7413, 7414, 7416, 7429, 7601 
and 7602.

    2. Appendix A is amended in the introductory table of contents by 
adding in alphanumeric order Methods 2F, 2G and 2H and by adding 
Methods 2F, 2G and 2H to Appendix A to read as follows:

Appendix A to Part 60--Test Methods

* * * * *
``Method 2F--Determination of Stack Gas Velocity and Volumetric Flow 
Rate With Three-Dimensional Probes''
``Method 2G--Determination of Stack Gas Velocity and Volumetric Flow 
Rate With Two-Dimensional Probes''
``Method 2H--Determination of Stack Gas Velocity Taking Into Account 
Velocity Decay Near the Stack Wall''
* * * * *

Method 2F--Determination of Stack Gas Velocity And Volumetric Flow Rate 
With Three-Dimensional Probes

    Note: This method does not include all of the specifications 
(e.g., equipment and supplies) and procedures (e.g., sampling) 
essential to its performance. Some material has been incorporated 
from other methods in this part. Therefore, to obtain reliable 
results, those using this method should have a thorough knowledge of 
at least the following additional test methods: Methods 1, 2, 3 or 
3A, and 4.

1.0  Scope and Application

1.1  This method is applicable for the determination of yaw angle, 
pitch angle, axial velocity and the volumetric flow rate of a gas 
stream in a stack or duct using a three-dimensional (3-D) probe. 
This method may be used only when the average stack or duct gas 
velocity is greater than or equal to 20 ft/sec. When the above 
condition cannot be met, alternative procedures, approved by the 
Administrator, U.S. Environmental Protection Agency, shall be used 
to make accurate flow rate determinations.

2.0  Summary of Method

    2.1  A 3-D probe is used to determine the velocity pressure and 
the yaw and pitch angles of the flow velocity vector in a stack or 
duct. The method determines the yaw angle directly by rotating the 
probe to null the pressure across a pair of symmetrically placed 
ports on the probe head. The pitch angle is calculated using probe-
specific calibration curves. From these values and a determination 
of the stack gas density, the average axial velocity of the stack 
gas is calculated. The average gas volumetric flow rate in the stack 
or duct is then determined from the average axial velocity.

3.0  Definitions

    3.1.  Angle-measuring Device Rotational Offset 
(RADO). The rotational position of an angle-measuring 
device relative to the reference scribe line, as determined during 
the pre-test rotational position check described in section 8.3.
    3.2  Axial Velocity. The velocity vector parallel to the axis of 
the stack or duct that accounts for the yaw and pitch angle 
components of gas flow. The term ``axial'' is used herein to 
indicate that the velocity and volumetric flow rate results account 
for the measured yaw and pitch components of flow at each 
measurement point.
    3.3  Calibration Pitot Tube. The standard (Prandtl type) pitot 
tube used as a reference when calibrating a 3-D probe under this 
method.
    3.4  Field Test. A set of measurements conducted at a specific 
unit or exhaust stack/duct to satisfy the applicable regulation 
(e.g., a three-run boiler performance test, a single-or multiple-
load nine-run relative accuracy test).
    3.5  Full Scale of Pressure-measuring Device. Full scale refers 
to the upper limit of the measurement range displayed by the device. 
For bi-directional pressure gauges, full scale includes the entire 
pressure range from the lowest negative value to the highest 
positive value on the pressure scale.
    3.6  Main probe. Refers to the probe head and that section of 
probe sheath directly attached to the probe head. The main probe 
sheath is distinguished from probe extensions, which are sections of 
sheath added onto the main probe to extend its reach.
    3.7  ``May,'' ``Must,'' ``Shall,'' ``Should,'' and the 
imperative form of verbs.
    3.7.1  ``May'' is used to indicate that a provision of this 
method is optional.
    3.7.2  ``Must,'' ``Shall,'' and the imperative form of verbs 
(such as ``record'' or ``enter'') are used to indicate that a 
provision of this method is mandatory.
    3.7.3  ``Should'' is used to indicate that a provision of this 
method is not mandatory, but is highly recommended as good practice.
    3.8  Method 1. Refers to 40 CFR part 60, appendix A, ``Method 
1--Sample and velocity traverses for stationary sources.''
    3.9  Method 2. Refers to 40 CFR part 60, appendix A, ``Method 
2--Determination of stack gas velocity and volumetric flow rate 
(Type S pitot tube).''
    3.10  Method 2G. Refers to 40 CFR part 60, appendix A, ``Method 
2G--Determination of stack gas velocity and volumetric flow rate 
with two-dimensional probes.''
    3.11  Nominal Velocity. Refers to a wind tunnel velocity setting 
that approximates the actual wind tunnel velocity to within 
1.5 m/sec (5 ft/sec).
    3.12  Pitch Angle. The angle between the axis of the stack or 
duct and the pitch component of flow, i.e., the component of the 
total velocity vector in a plane defined by the traverse line and 
the axis of the stack or duct. (Figure 2F-1 illustrates the ``pitch 
plane.'') From the standpoint of a tester facing a test port in a 
vertical stack, the pitch component of flow is the vector of flow 
moving from the center of the stack toward or away from that test 
port. The pitch angle is the angle described by this pitch component 
of flow and the vertical axis of the stack.
    3.13  Readability. For the purposes of this method, readability 
for an analog measurement device is one half of the smallest scale 
division. For a digital measurement device, it is the number of 
decimals displayed by the device.
    3.14  Reference Scribe Line. A line permanently inscribed on the 
main probe sheath (in accordance with section 6.1.6.1) to serve as a 
reference mark for determining yaw angles.
    3.15  Reference Scribe Line Rotational Offset (RSLO). 
The rotational position of a probe's reference scribe line relative 
to the probe's yaw-null position, as determined during the yaw angle 
calibration described in section 10.5.
    3.16  Response Time. The time required for the measurement 
system to fully respond to a change from zero differential pressure 
and ambient temperature to the stable stack or duct pressure and 
temperature readings at a traverse point.
    3.17  Tested Probe. A 3-D probe that is being calibrated.
    3.18  Three-dimensional (3-D) Probe. A directional probe used to 
determine the velocity pressure and yaw and pitch angles in a 
flowing gas stream.
    3.19  Traverse Line. A diameter or axis extending across a stack 
or duct on which

[[Page 26491]]

measurements of differential pressure and flow angles are made.
    3.20  Wind Tunnel Calibration Location. A point, line, area, or 
volume within the wind tunnel test section at, along, or within 
which probes are calibrated. At a particular wind tunnel velocity 
setting, the average velocity pressures at specified points at, 
along, or within the calibration location shall vary by no more than 
2 percent or 0.3 mm H2O (0.01 in. H2O), 
whichever is less restrictive, from the average velocity pressure at 
the calibration pitot tube location. Air flow at this location shall 
be axial, i.e., yaw and pitch angles within  deg. of 
0 deg.. Compliance with these flow criteria shall be demonstrated by 
performing the procedures prescribed in sections 10.1.1 and 10.1.2. 
For circular tunnels, no part of the calibration location may be 
closer to the tunnel wall than 10.2 cm (4 in.) or 25 percent of the 
tunnel diameter, whichever is farther from the wall. For elliptical 
or rectangular tunnels, no part of the calibration location may be 
closer to the tunnel wall than 10.2 cm (4 in.) or 25 percent of the 
applicable cross-sectional axis, whichever is farther from the wall.
    3.21  Wind Tunnel with Documented Axial Flow. A wind tunnel 
facility documented as meeting the provisions of sections 10.1.1 
(velocity pressure cross-check) and 10.1.2 (axial flow verification) 
using the procedures described in these sections or alternative 
procedures determined to be technically equivalent.
    3.22  Yaw Angle. The angle between the axis of the stack or duct 
and the yaw component of flow, i.e., the component of the total 
velocity vector in a plane perpendicular to the traverse line at a 
particular traverse point. (Figure 2F-1 illustrates the ``yaw 
plane.'') From the standpoint of a tester facing a test port in a 
vertical stack, the yaw component of flow is the vector of flow 
moving to the left or right from the center of the stack as viewed 
by the tester. (This is sometimes referred to as ``vortex flow,'' 
i.e., flow around the centerline of a stack or duct.) The yaw angle 
is the angle described by this yaw component of flow and the 
vertical axis of the stack. The algebraic sign convention is 
illustrated in Figure 2F-2.
    3.23  Yaw Nulling. A procedure in which a probe is rotated about 
its axis in a stack or duct until a zero differential pressure 
reading (``yaw null'') is obtained. When a 3-D probe is yaw-nulled, 
its impact pressure port (P1) faces directly into the 
direction of flow in the stack or duct and the differential pressure 
between pressure ports P2 and P3 is zero.
    4.0  Interferences. [Reserved]
    5.0  Safety.
    5.1  This test method may involve hazardous operations and the 
use of hazardous materials or equipment. This method does not 
purport to address all of the safety problems associated with its 
use. It is the responsibility of the user to establish and implement 
appropriate safety and health practices and to determine the 
applicability of regulatory limitations before using this test 
method.

6.0 Equipment and Supplies

    6.1   Three-dimensional Probes. The 3-D probes as specified in 
subsections 6.1.1 through 6.1.3 below qualify for use based on 
comprehensive wind tunnel and field studies involving both inter-and 
intra-probe comparisons by multiple test teams. Other types of 
probes shall not be used unless approved by the Administrator. Each 
3-D probe shall have a unique identification number or code 
permanently marked on the main probe sheath. The minimum recommended 
diameter of the sensing head of any probe used under this method is 
2.5 cm (1 in.). Each probe shall be calibrated prior to use 
according to the procedures in section 10. Manufacturer-supplied 
calibration data shall be used as example information only, except 
when the manufacturer calibrates the 3-D probe as specified in 
section 10 and provides complete documentation.
    6.1.1   Five-hole prism-shaped probe. This type of probe 
consists of five pressure taps in the flat facets of a prism-shaped 
sensing head. The pressure taps are numbered 1 through 5, with the 
pressures measured at each hole referred to as P1, 
P2, P3, P4, and P5, 
respectively. Figure 2F-3 is an illustration of the placement of 
pressure taps on a commonly available five-hole prism-shaped probe, 
the 2.5-cm (1-in.) DAT probe. (Note: Mention of trade names or 
specific products does not constitute endorsement by the U.S. 
Environmental Protection Agency.) The numbering arrangement for the 
prism-shaped sensing head presented in Figure 2F-3 shall be followed 
for correct operation of the probe. A brief description of the probe 
measurements involved is as follows: the differential pressure 
P2-P3 is used to yaw null the probe and 
determine the yaw angle; the differential pressure P4-
P5 is a function of pitch angle; and the differential 
pressure P1-P2 is a function of total 
velocity.
    6.1.2   Five-hole spherical probe. This type of probe consists 
of five pressure taps in a spherical sensing head. As with the 
prism-shaped probe, the pressure taps are numbered 1 through 5, with 
the pressures measured at each hole referred to as P1, 
P2, P3, P4, and P5, 
respectively. However, the P4 and P5 pressure 
taps are in the reverse location from their respective positions on 
the prism-shaped probe head. The differential pressure 
P2-P3 is used to yaw null the probe and 
determine the yaw angle; the differential pressure P4-
P5 is a function of pitch angle; and the differential 
pressure P1-P2 is a function of total 
velocity. A diagram of a typical spherical probe sensing head is 
presented in Figure 2F-4. Typical probe dimensions are indicated in 
the illustration.
    6.1.3   A manual 3-D probe refers to a five-hole prism-shaped or 
spherical probe that is positioned at individual traverse points and 
yaw nulled manually by an operator. An automated 3-D probe refers to 
a system that uses a computer-controlled motorized mechanism to 
position the five-hole prism-shaped or spherical head at individual 
traverse points and perform yaw angle determinations.
    6.1.4   Other three-dimensional probes. [Reserved]
    6.1.5   Probe sheath. The probe shaft shall include an outer 
sheath to: (1) provide a surface for inscribing a permanent 
reference scribe line, (2) accommodate attachment of an angle-
measuring device to the probe shaft, and (3) facilitate precise 
rotational movement of the probe for determining yaw angles. The 
sheath shall be rigidly attached to the probe assembly and shall 
enclose all pressure lines from the probe head to the farthest 
position away from the probe head where an angle-measuring device 
may be attached during use in the field. The sheath of the fully 
assembled probe shall be sufficiently rigid and straight at all 
rotational positions such that, when one end of the probe shaft is 
held in a horizontal position, the fully extended probe meets the 
horizontal straightness specifications indicated in section 8.2 
below.
    6.1.6   Scribe lines.
    6.1.6.1   Reference scribe line. A permanent line, no greater 
than 1.6 mm (1/16 in.) in width, shall be inscribed on each manual 
probe that will be used to determine yaw angles of flow. This line 
shall be placed on the main probe sheath in accordance with the 
procedures described in section 10.4 and is used as a reference 
position for installation of the yaw angle-measuring device on the 
probe. At the discretion of the tester, the scribe line may be a 
single line segment placed at a particular position on the probe 
sheath (e.g., near the probe head), multiple line segments placed at 
various locations along the length of the probe sheath (e.g., at 
every position where a yaw angle-measuring device may be mounted), 
or a single continuous line extending along the full length of the 
probe sheath.
    6.1.6.2   Scribe line on probe extensions. A permanent line may 
also be inscribed on any probe extension that will be attached to 
the main probe in performing field testing. This allows a yaw angle-
measuring device mounted on the extension to be readily aligned with 
the reference scribe line on the main probe sheath.
    6.1.6.3   Alignment specifications. This specification shall be 
met separately, using the procedures in section 10.4.1, on the main 
probe and on each probe extension. The rotational position of the 
scribe line or scribe line segments on the main probe or any probe 
extension must not vary by more than 2 deg.. That is, the difference 
between the minimum and maximum of all of the rotational angles that 
are measured along the full length of the main probe or the probe 
extension must not exceed 2 deg..
    6.1.7   Probe and system characteristics to ensure horizontal 
stability.
    6.1.7.1  For manual probes, it is recommended that the effective 
length of the probe (coupled with a probe extension, if necessary) 
be at least 0.9 m (3 ft.) longer than the farthest traverse point 
mark on the probe shaft away from the probe head. The operator 
should maintain the probe's horizontal stability when it is fully 
inserted into the stack or duct. If a shorter probe is used, the 
probe should be inserted through a bushing sleeve, similar to the 
one shown in Figure 2F-5, that is installed on the test port; such a 
bushing shall fit snugly around the probe and be secured to the 
stack or duct entry port in such a manner as to maintain the probe's 
horizontal stability when fully inserted into the stack or duct.
    6.1.7.2  An automated system that includes an external probe 
casing with a

[[Page 26492]]

transport system shall have a mechanism for maintaining horizontal 
stability comparable to that obtained by manual probes following the 
provisions of this method. The automated probe assembly shall also 
be constructed to maintain the alignment and position of the 
pressure ports during sampling at each traverse point. The design of 
the probe casing and transport system shall allow the probe to be 
removed from the stack or duct and checked through direct physical 
measurement for angular position and insertion depth.
    6.1.8  The tubing that is used to connect the probe and the 
pressure-measuring device should have an inside diameter of at least 
3.2 mm (1/8 in.), to reduce the time required for pressure 
equilibration, and should be as short as practicable.
    6.2  Yaw Angle-measuring Device. One of the following devices 
shall be used for measurement of the yaw angle of flow.
    6.2.1  Digital inclinometer. This refers to a digital device 
capable of measuring and displaying the rotational position of the 
probe to within 1 deg.. The device shall be able to be 
locked into position on the probe sheath or probe extension, so that 
it indicates the probe's rotational position throughout the test. A 
rotational position collar block that can be attached to the probe 
sheath (similar to the collar shown in Figure 2F-6) may be required 
to lock the digital inclinometer into position on the probe sheath.
    6.2.2  Protractor wheel and pointer assembly. This apparatus, 
similar to that shown in Figure 2F-7, consists of the following 
components.
    6.2.2.1  A protractor wheel that can be attached to a port 
opening and set in a fixed rotational position to indicate the yaw 
angle position of the probe's scribe line relative to the 
longitudinal axis of the stack or duct. The protractor wheel must 
have a measurement ring on its face that is no less than 17.8 cm (7 
in.) in diameter, shall be able to be rotated to any angle and then 
locked into position on the stack or duct port, and shall indicate 
angles to a resolution of 1 deg..
    6.2.2.2  A pointer assembly that includes an indicator needle 
mounted on a collar that can slide over the probe sheath and be 
locked into a fixed rotational position on the probe sheath. The 
pointer needle shall be of sufficient length, rigidity, and 
sharpness to allow the tester to determine the probe's angular 
position to within 1 deg. from the markings on the protractor wheel. 
Corresponding to the position of the pointer, the collar must have a 
scribe line to be used in aligning the pointer with the scribe line 
on the probe sheath.
    6.2.3  Other yaw angle-measuring devices. Other angle-measuring 
devices with a manufacturer's specified precision of 1 deg. or 
better may be used, if approved by the Administrator.
    6.3  Probe Supports and Stabilization Devices. When probes are 
used for determining flow angles, the probe head should be kept in a 
stable horizontal position. For probes longer than 3.0 m (10 ft.), 
the section of the probe that extends outside the test port shall be 
secured. Three alternative devices are suggested for maintaining the 
horizontal position and stability of the probe shaft during flow 
angle determinations and velocity pressure measurements: (1) 
Monorails installed above each port, (2) probe stands on which the 
probe shaft may be rested, or (3) bushing sleeves of sufficient 
length secured to the test ports to maintain probes in a horizontal 
position. Comparable provisions shall be made to ensure that 
automated systems maintain the horizontal position of the probe in 
the stack or duct. The physical characteristics of each test 
platform may dictate the most suitable type of stabilization device. 
Thus, the choice of a specific stabilization device is left to the 
judgment of the testers.
    6.4  Differential Pressure Gauges. The pressure (P) 
measuring devices used during wind tunnel calibrations and field 
testing shall be either electronic manometers (e.g., pressure 
transducers), fluid manometers, or mechanical pressure gauges (e.g., 
Magnehelic gauges). Use of electronic manometers is 
recommended. Under low velocity conditions, use of electronic 
manometers may be necessary to obtain acceptable measurements.
    6.4.1  Differential pressure-measuring device. This refers to a 
device capable of measuring pressure differentials and having a 
readability of 1 percent of full scale. The device shall 
be capable of accurately measuring the maximum expected pressure 
differential. Such devices are used to determine the following 
pressure measurements: velocity pressure, static pressure, yaw-null 
pressure, and pitch-angle pressure. For an inclined-vertical 
manometer, the readability specification of 1 percent 
shall be met separately using the respective full-scale upper limits 
of the inclined and vertical portions of the scales. To the extent 
practicable, the device shall be selected such that most of the 
pressure readings are between 10 and 90 percent of the device's 
full-scale measurement range (as defined in section 3.5). Typical 
velocity pressure (P1-P2 ranges for both the 
prism-shaped probe and the spherical probe are 0 to 1.3 cm 
H2O (0 to 0.5 in. H2O), 0 to 5.1 cm 
H2O (0 to 2 in. H2O), and 0 to 12.7 cm 
H2O (0 to 5 in. H2O). The pitch angle 
(P4-P5) pressure range is typically -6.4 to 
+6.4 mm H2O (-0.25 to +0.25 in. H2O) or -12.7 
to +12.7 mm H2O (-0.5 to +0.5 in. H2O) for the 
prism-shaped probe, and -12.7 to +12.7 mm H2O (-0.5 to 
+0.5 in. H2O) or -5.1 to +5.1 cm H2O (-2 to +2 
in. H2O) for the spherical probe. The pressure range for 
the yaw null (P2-P3) readings is typically 
-12.7 to +12.7 mm H2O (-0.5 to +0.5 in. H2O) 
for both probe types. In addition, pressure-measuring devices should 
be selected such that the zero does not drift by more than 5 percent 
of the average expected pressure readings to be encountered during 
the field test. This is particularly important under low pressure 
conditions.
    6.4.2  Gauge used for yaw nulling. The differential pressure-
measuring device chosen for yaw nulling the probe during the wind 
tunnel calibrations and field testing shall be bi-directional, i.e., 
capable of reading both positive and negative differential 
pressures. If a mechanical, bi-directional pressure gauge is chosen, 
it shall have a full-scale range no greater than 2.6 cm 
H2O (1 in. H2O) [i.e., -1.3 to +1.3 cm 
H2O (-0.5 in. to +0.5 in.)].
    6.4.3  Devices for calibrating differential pressure-measuring 
devices. A precision manometer (e.g., a U-tube, inclined, or 
inclined-vertical manometer, or micromanometer) or NIST (National 
Institute of Standards and Technology) traceable pressure source 
shall be used for calibrating differential pressure-measuring 
devices. The device shall be maintained under laboratory conditions 
or in a similar protected environment (e.g., a climate-controlled 
trailer). It shall not be used in field tests. The precision 
manometer shall have a scale gradation of 0.3 mm H2O 
(0.01 in. H2O), or less, in the range of 0 to 5.1 cm 
H2O (0 to 2 in. H2O) and 2.5 mm H2O 
(0.1 in. H2O), or less, in the range of 5.1 to 25.4 cm 
H2O (2 to 10 in. H2O). The manometer shall 
have manufacturer's documentation that it meets an accuracy 
specification of at least 0.5 percent of full scale. The NIST-
traceable pressure source shall be recertified annually.
    6.4.4  Devices used for post-test calibration check. A precision 
manometer meeting the specifications in section 6.4.3, a pressure-
measuring device or pressure source with a documented calibration 
traceable to NIST, or an equivalent device approved by the 
Administrator shall be used for the post-test calibration check. The 
pressure-measuring device shall have a readability equivalent to or 
greater than the tested device. The pressure source shall be capable 
of generating pressures between 50 and 90 percent of the range of 
the tested device and known to within 1 percent of the 
full scale of the tested device. The pressure source shall be 
recertified annually.
    6.5  Data Display and Capture Devices. Electronic manometers (if 
used) shall be coupled with a data display device (such as a digital 
panel meter, personal computer display, or strip chart) that allows 
the tester to observe and validate the pressure measurements taken 
during testing. They shall also be connected to a data recorder 
(such as a data logger or a personal computer with data capture 
software) that has the ability to compute and retain the appropriate 
average value at each traverse point, identified by collection time 
and traverse point.
    6.6  Temperature Gauges. For field tests, a thermocouple or 
resistance temperature detector (RTD) capable of measuring 
temperature to within 3 deg.C (5 deg.F) of 
the stack or duct temperature shall be used. The thermocouple shall 
be attached to the probe such that the sensor tip does not touch any 
metal and is located on the opposite side of the probe head from the 
pressure ports so as not to interfere with the gas flow around the 
probe head. The position of the thermocouple relative to the 
pressure port face openings shall be in the same configuration as 
used for the probe calibrations in the wind tunnel. Temperature 
gauges used for wind tunnel calibrations shall be capable of 
measuring temperature to within 0.6 deg.C 
(1 deg.F) of the temperature of the flowing gas stream 
in the wind tunnel.
    6.7  Stack or Duct Static Pressure Measurement. The pressure-
measuring

[[Page 26493]]

device used with the probe shall be as specified in section 6.4 of 
this method. The static tap of a standard (Prandtl type) pitot tube 
or one leg of a Type S pitot tube with the face opening planes 
positioned parallel to the gas flow may be used for this 
measurement. Also acceptable is the pressure differential reading of 
P1-Pbar from a five-hole prism-shaped probe 
(e.g., Type DA or DAT probe) with the P1 pressure port 
face opening positioned parallel to the gas flow in the same manner 
as the Type S probe. However, the spherical probe, as specified in 
section 6.1.2, is unable to provide this measurement and shall not 
be used to take static pressure measurements. Static pressure 
measurement is further described in section 8.11.
    6.8  Barometer. Same as Method 2, section 2.5.
    6.9  Gas Density Determination Equipment. Method 3 or 3A shall 
be used to determine the dry molecular weight of the stack gas. 
Method 4 shall be used for moisture content determination and 
computation of stack gas wet molecular weight. Other methods may be 
used, if approved by the Administrator.
    6.10  Calibration Pitot Tube. Same as Method 2, section 2.7.
    6.11  Wind Tunnel for Probe Calibration. Wind tunnels used to 
calibrate velocity probes must meet the following design 
specifications.
    6.11.1  Test section cross-sectional area. The flowing gas 
stream shall be confined within a circular, rectangular, or 
elliptical duct. The cross-sectional area of the tunnel must be 
large enough to ensure fully developed flow in the presence of both 
the calibration pitot tube and the tested probe. The calibration 
site, or ``test section,'' of the wind tunnel shall have a minimum 
diameter of 30.5 cm (12 in.) for circular or elliptical duct cross-
sections or a minimum width of 30.5 cm (12 in.) on the shorter side 
for rectangular cross-sections. Wind tunnels shall meet the probe 
blockage provisions of this section and the qualification 
requirements prescribed in section 10.1. The projected area of the 
portion of the probe head, shaft, and attached devices inside the 
wind tunnel during calibration shall represent no more than 4 
percent of the cross-sectional area of the tunnel. The projected 
area shall include the combined area of the calibration pitot tube 
and the tested probe if both probes are placed simultaneously in the 
same cross-sectional plane in the wind tunnel, or the larger 
projected area of the two probes if they are placed alternately in 
the wind tunnel.
    6.11.2  Velocity range and stability. The wind tunnel should be 
capable of maintaining velocities between 6.1 m/sec and 30.5 m/sec 
(20 ft/sec and 100 ft/sec). The wind tunnel shall produce fully 
developed flow patterns that are stable and parallel to the axis of 
the duct in the test section.
    6.11.3  Flow profile at the calibration location. The wind 
tunnel shall provide axial flow within the test section calibration 
location (as defined in section 3.20). Yaw and pitch angles in the 
calibration location shall be within 3 deg. of 0 deg.. 
The procedure for determining that this requirement has been met is 
described in section 10.1.2.
    6.11.4  Entry ports in the wind tunnel test section.
    6.11.4.1  Port for tested probe. A port shall be constructed for 
the tested probe. The port should have an elongated slot parallel to 
the axis of the duct at the test section. The elongated slot should 
be of sufficient length to allow attaining all the pitch angles at 
which the probe will be calibrated for use in the field. To 
facilitate alignment of the probe during calibration, the test 
section should include a window constructed of a transparent 
material to allow the tested probe to be viewed. This port shall be 
located to allow the head of the tested probe to be positioned 
within the calibration location (as defined in section 3.20) at all 
pitch angle settings.
    6.11.4.2  Port for verification of axial flow. Depending on the 
equipment selected to conduct the axial flow verification prescribed 
in section 10.1.2, a second port, located 90 deg. from the entry 
port for the tested probe, may be needed to allow verification that 
the gas flow is parallel to the central axis of the test section. 
This port should be located and constructed so as to allow one of 
the probes described in section 10.1.2.2 to access the same test 
point(s) that are accessible from the port described in section 
6.11.4.1.
    6.11.4.3  Port for calibration pitot tube. The calibration pitot 
tube shall be used in the port for the tested probe or a separate 
entry port. In either case, all measurements with the calibration 
pitot tube shall be made at the same point within the wind tunnel 
over the course of a probe calibration. The measurement point for 
the calibration pitot tube shall meet the same specifications for 
distance from the wall and for axial flow as described in section 
3.20 for the wind tunnel calibration location.
    6.11.5  Pitch angle protractor plate. A protractor plate shall 
be attached directly under the port used with the tested probe and 
set in a fixed position to indicate the pitch angle position of the 
probe relative to the longitudinal axis of the wind tunnel duct 
(similar to Figure 2F-8). The protractor plate shall indicate angles 
in 5 deg. increments with a minimum resolution of 
2 deg.. The tested probe shall be able to be locked into 
position at the desired pitch angle delineated on the protractor. 
The probe head position shall be maintained within the calibration 
location (as defined in section 3.20) in the test section of the 
wind tunnel during all tests across the range of pitch angles.

7.0  Reagents and Standards. [Reserved]

8.0 Sample Collection and Analysis

8.1  Equipment Inspection and Set-Up

    8.1.1 All probes, differential pressure-measuring devices, yaw 
angle-measuring devices, thermocouples, and barometers shall have a 
current, valid calibration before being used in a field test. (See 
sections 10.3.3, 10.3.4, and 10.5 through10.10 for the applicable 
calibration requirements.)
    8.1.2 Before each field use of a 3-D probe, perform a visual 
inspection to verify the physical condition of the probe head 
according to the procedures in section 10.2. Record the inspection 
results on a form similar to Table 2F-1. If there is visible damage 
to the 3-D probe, the probe shall not be used until it is 
recalibrated.
    8.1.3 After verifying that the physical condition of the probe 
head is acceptable, set up the apparatus using lengths of flexible 
tubing that are as short as practicable. Surge tanks installed 
between the probe and pressure-measuring device may be used to 
dampen pressure fluctuations provided that an adequate measurement 
response time (see section 8.8) is maintained.
    8.2 Horizontal Straightness Check. A horizontal straightness 
check shall be performed before the start of each field test, except 
as otherwise specified in this section. Secure the fully assembled 
probe (including the probe head and all probe shaft extensions) in a 
horizontal position using a stationary support at a point along the 
probe shaft approximating the location of the stack or duct entry 
port when the probe is sampling at the farthest traverse point from 
the stack or duct wall. The probe shall be rotated to detect bends. 
Use an angle-measuring device or trigonometry to determine the bend 
or sag between the probe head and the secured end. (See Figure 2F-
9.) Probes that are bent or sag by more than 5 deg. shall not be 
used. Although this check does not apply when the probe is used for 
a vertical traverse, care should be taken to avoid the use of bent 
probes when conducting vertical traverses. If the probe is 
constructed of a rigid steel material and consists of a main probe 
without probe extensions, this check need only be performed before 
the initial field use of the probe, when the probe is recalibrated, 
when a change is made to the the design or material of the probe 
assembly, and when the probe becomes bent. With such probes, a 
visual inspection shall be made of the fully assembled probe before 
each field test to determine if a bend is visible. The probe shall 
be rotated to detect bends. The inspection results shall be 
documented in the field test report. If a bend in the probe is 
visible, the horizontal straightness check shall be performed before 
the probe is used.
    8.3 Rotational Position Check. Before each field test, and each 
time an extension is added to the probe during a field test, a 
rotational position check shall be performed on all manually 
operated probes (except as noted in section 8.3.5, below) to ensure 
that, throughout testing, the angle-measuring device is either: 
aligned to within 1 deg. of the rotational position of 
the reference scribe line; or is affixed to the probe such that the 
rotational offset of the device from the reference scribe line is 
known to within 1 deg.. This check shall consist of 
direct measurements of the rotational positions of the reference 
scribe line and angle-measuring device sufficient to verify that 
these specifications are met. Annex A in section 18 of this method 
gives recommended procedures for performing the rotational position 
check, and Table 2F-2 gives an example data form. Procedures other 
than those recommended in Annex A in section 18 may be used, 
provided they demonstrate whether the alignment specification is met 
and are explained in detail in the field test report.
    8.3.1 Angle-measuring device rotational offset. The tester shall 
maintain a record of

[[Page 26494]]

the angle-measuring device rotational offset, RADO, as 
defined in section 3.1. Note that RADO is assigned a 
value of 0 deg. when the angle-measuring device is aligned to within 
1 deg. of the rotational position of the reference 
scribe line. The RADO shall be used to determine the yaw 
angle of flow in accordance with section 8.9.4.
    8.3.2 Sign of angle-measuring device rotational offset. The sign 
of RADO is positive when the angle-measuring device (as 
viewed from the ``tail'' end of the probe) is positioned in a 
clockwise direction from the reference scribe line and negative when 
the device is positioned in a counterclockwise direction from the 
reference scribe line.
    8.3.3 Angle-measuring devices that can be independently adjusted 
(e.g., by means of a set screw), after being locked into position on 
the probe sheath, may be used. However, the RADO must 
also take into account this adjustment.
    8.3.4 Post-test check. If probe extensions remain attached to 
the main probe throughout the field test, the rotational position 
check shall be repeated, at a minimum, at the completion of the 
field test to ensure that the angle-measuring device has remained 
within 2 deg. of its rotational position established 
prior to testing. At the discretion of the tester, additional checks 
may be conducted after completion of testing at any sample port or 
after any test run. If the 2 deg. specification is not 
met, all measurements made since the last successful rotational 
position check must be repeated. Section 18.1.1.3 of Annex A 
provides an example procedure for performing the post-test check.
    8.3.5 Exceptions.
    8.3.5.1 A rotational position check need not be performed if, 
for measurements taken at all velocity traverse points, the yaw 
angle-measuring device is mounted and aligned directly on the 
reference scribe line specified in sections 6.1.6.1 and 6.1.6.3 and 
no independent adjustments, as described in section 8.3.3, are made 
to the device's rotational position.
    8.3.5.2 If extensions are detached and re-attached to the probe 
during a field test, a rotational position check need only be 
performed the first time an extension is added to the probe, rather 
than each time the extension is re-attached, if the probe extension 
is designed to be locked into a mechanically fixed rotational 
position (e.g., through use of interlocking grooves) that can re-
establish the initial rotational position to within 
1 deg..
    8.4  Leak Checks. A pre-test leak check shall be conducted 
before each field test. A post-test check shall be performed at the 
end of the field test, but additional leak checks may be conducted 
after any test run or group of test runs. The post-test check may 
also serve as the pre-test check for the next group of test runs. If 
any leak check is failed, all runs since the last passed leak check 
are invalid. While performing the leak check procedures, also check 
each pressure device's responsiveness to the changes in pressure.
    8.4.1  To perform the leak check, pressurize the probe's 
P1 pressure port until at least 7.6 cm H2O (3 
in. H2O) pressure, or a pressure corresponding to 
approximately 75 percent of the pressure-measuring device's 
measurement scale, whichever is less, registers on the device; then, 
close off the pressure port. The pressure shall remain stable 
[2.5 mm H2O (0.10 in. 
H2O)] for at least 15 seconds. Check the P2, 
P3, P4, and P5 pressure ports in 
the same fashion. Other leak-check procedures may be used, if 
approved by the Administrator.
    8.5  Zeroing the Differential Pressure-measuring Device. Zero 
each differential pressure-measuring device, including the device 
used for yaw nulling, before each field test. At a minimum, check 
the zero after each field test. A zero check may also be performed 
after any test run or group of test runs. For fluid manometers and 
mechanical pressure gauges (e.g., Magnehelic gauges), 
the zero reading shall not deviate from zero by more than 
0.8 mm H2O (0.03 in. 
H2O) or one minor scale division, whichever is greater, 
between checks. For electronic manometers, the zero reading shall 
not deviate from zero between checks by more than: 0.3 
mm H2O (0.01 in. H2O), for full 
scales less than or equal to 5.1 cm H2O (2.0 in. 
H2O); or 0.8 mm H2O 
(0.03 in. H2O), for full scales greater than 
5.1 cm H2O (2.0 in. H2O). (Note: If negative 
zero drift is not directly readable, estimate the reading based on 
the position of the gauge oil in the manometer or of the needle on 
the pressure gauge.) In addition, for all pressure-measuring devices 
except those used exclusively for yaw nulling, the zero reading 
shall not deviate from zero by more than 5 percent of the average 
measured differential pressure at any distinct process condition or 
load level. If any zero check is failed at a specific process 
condition or load level, all runs conducted at that process 
condition or load level since the last passed zero check are 
invalid.
    8.6  Traverse Point Verification. The number and location of the 
traverse points shall be selected based on Method 1 guidelines. The 
stack or duct diameter and port nipple lengths, including any 
extension of the port nipples into stack or duct, shall be verified 
the first time the test is performed; retain and use this 
information for subsequent field tests, updating it as required. 
Physically measure the stack or duct dimensions or use a calibrated 
laser device; do not use engineering drawings of the stack or duct. 
The probe length necessary to reach each traverse point shall be 
recorded to within 6.4 mm (1/4 in.) and, for 
manual probes, marked on the probe sheath. In determining these 
lengths, the tester shall take into account both the distance that 
the port flange projects outside of the stack and the depth that any 
port nipple extends into the gas stream. The resulting point 
positions shall reflect the true distances from the inside wall of 
the stack or duct, so that when the tester aligns any of the 
markings with the outside face of the stack port, the probe's impact 
port shall be located at the appropriate distance from the inside 
wall for the respective Method 1 traverse point. Before beginning 
testing at a particular location, an out-of-stack or duct 
verification shall be performed on each probe that will be used to 
ensure that these position markings are correct. The distances 
measured during the verification must agree with the previously 
calculated distances to within 1/4 in. For manual 
probes, the traverse point positions shall be verified by measuring 
the distance of each mark from the probe's P1 pressure 
port. A comparable out-of-stack test shall be performed on automated 
probe systems. The probe shall be extended to each of the prescribed 
traverse point positions. Then, the accuracy of the positioning for 
each traverse point shall be verified by measuring the distance 
between the port flange and the probe's P1 pressure port.
    8.7  Probe Installation. Insert the probe into the test port. A 
solid material shall be used to seal the port.
    8.8  System Response Time. Determine the response time of the 
probe measurement system. Insert and position the ``cold'' probe (at 
ambient temperature and pressure) at any Method 1 traverse point. 
Read and record the probe's P1-P2 differential 
pressure, temperature, and elapsed time at 15-second intervals until 
stable readings for both pressure and temperature are achieved. The 
response time is the longer of these two elapsed times. Record the 
response time.
    8.9  Sampling.
    8.9.1  Yaw angle measurement protocol. With manual probes, yaw 
angle measurements may be obtained in two alternative ways during 
the field test, either by using a yaw angle-measuring device (e.g., 
digital inclinometer) affixed to the probe, or using a protractor 
wheel and pointer assembly. For horizontal traversing, either 
approach may be used. For vertical traversing, i.e., when measuring 
from on top or into the bottom of a horizontal duct, only the 
protractor wheel and pointer assembly may be used. With automated 
probes, curve-fitting protocols may be used to obtain yaw-angle 
measurements.
    8.9.1.1  If a yaw angle-measuring device affixed to the probe is 
to be used, lock the device on the probe sheath, aligning it either 
on the reference scribe line or in the rotational offset position 
established under section 8.3.1.
    8.9.1.2  If a protractor wheel and pointer assembly is to be 
used, follow the procedures in Annex B of this method.
    8.9.1.3  Other yaw angle-determination procedures. If approved 
by the Administrator, other procedures for determining yaw angle may 
be used, provided that they are verified in a wind tunnel to be able 
to perform the yaw angle calibration procedure as described in 
section 10.5.
    8.9.2  Sampling strategy. At each traverse point, first yaw-null 
the probe, as described in section 8.9.3, below. Then, with the 
probe oriented into the direction of flow, measure and record the 
yaw angle, the differential pressures and the temperature at the 
traverse point, after stable readings are achieved, in accordance 
with sections 8.9.4 and 8.9.5. At the start of testing in each port 
(i.e., after a probe has been inserted into the flue gas stream), 
allow at least the response time to elapse before beginning to take 
measurements at the first traverse point accessed from that port. 
Provided that the probe is not removed from the flue gas stream, 
measurements may be taken at subsequent traverse points accessed 
from the

[[Page 26495]]

same test port without waiting again for the response time to 
elapse.
    8.9.3  Yaw-nulling procedure. In preparation for yaw angle 
determination, the probe must first be yaw nulled. After positioning 
the probe at the appropriate traverse point, perform the following 
procedures.
    8.9.3.1  Rotate the probe until a null differential pressure 
reading (the difference in pressures across the P2 and 
P3 pressure ports is zero, i.e., P2 = 
P3) is indicated by the yaw angle pressure gauge. Read 
and record the angle displayed by the angle-measuring device.
    8.9.3.2  Sign of the measured angle. The angle displayed on the 
angle-measuring device is considered positive when the probe's 
impact pressure port (as viewed from the ``tail'' end of the probe) 
is oriented in a clockwise rotational position relative to the stack 
or duct axis and is considered negative when the probe's impact 
pressure port is oriented in a counterclockwise rotational position 
(see Figure 2F-10).
    8.9.4  Yaw angle determination. After performing the yaw-nulling 
procedure in section 8.9.3, determine the yaw angle of flow 
according to one of the following procedures. Special care must be 
observed to take into account the signs of the recorded angle and 
all offsets.
    8.9.4.1  Direct-reading. If all rotational offsets are zero or 
if the angle-measuring device rotational offset (RADO) 
determined in section 8.3 exactly compensates for the scribe line 
rotational offset (RSLO) determined in section 10.5, then 
the magnitude of the yaw angle is equal to the displayed angle-
measuring device reading from section 8.9.3.1. The algebraic sign of 
the yaw angle is determined in accordance with section 8.9.3.2.

    Note: Under certain circumstances (e.g., testing of horizontal 
ducts), a 90 deg. adjustment to the angle-measuring device readings 
may be necessary to obtain the correct yaw angles.

    8.9.4.2  Compensation for rotational offsets during data 
reduction. When the angle-measuring device rotational offset does 
not compensate for reference scribe line rotational offset, the 
following procedure shall be used to determine the yaw angle:
    (a) Enter the reading indicated by the angle-measuring device 
from section 8.9.3.1.
    (b) Associate the proper algebraic sign from section 8.9.3.2 
with the reading in step (a).
    (c) Subtract the reference scribe line rotational offset, 
RSLO, from the reading in step (b).
    (d) Subtract the angle-measuring device rotational offset, 
RADO, if any, from the result obtained in step (c).
    (e) The final result obtained in step (d) is the yaw angle of 
flow.

    Note: It may be necessary to first apply a 90 deg. adjustment to 
the reading in step (a), in order to obtain the correct yaw angle.

    8.9.4.3  Record the yaw angle measurements on a form similar to 
Table 2F-3.
    8.9.5  Velocity determination. Maintain the probe rotational 
position established during the yaw angle determination. Then, begin 
recording the pressure-measuring device readings for the impact 
pressure (P1-P2) and pitch angle pressure 
(P4-P5). These pressure measurements shall be 
taken over a sampling period of sufficiently long duration to ensure 
representative readings at each traverse point. If the pressure 
measurements are determined from visual readings of the pressure 
device or display, allow sufficient time to observe the pulsation in 
the readings to obtain a sight-weighted average, which is then 
recorded manually. If an automated data acquisition system (e.g., 
data logger, computer-based data recorder, strip chart recorder) is 
used to record the pressure measurements, obtain an integrated 
average of all pressure readings at the traverse point. Stack or 
duct gas temperature measurements shall be recorded, at a minimum, 
once at each traverse point. Record all necessary data as shown in 
the example field data form (Table 2F-3).
    8.9.6  Alignment check. For manually operated probes, after the 
required yaw angle and differential pressure and temperature 
measurements have been made at each traverse point, verify (e.g., by 
visual inspection) that the yaw angle-measuring device has remained 
in proper alignment with the reference scribe line or with the 
rotational offset position established in section 8.3. If, for a 
particular traverse point, the angle-measuring device is found to be 
in proper alignment, proceed to the next traverse point; otherwise, 
re-align the device and repeat the angle and differential pressure 
measurements at the traverse point. In the course of a traverse, if 
a mark used to properly align the angle-measuring device (e.g., as 
described in section 18.1.1.1) cannot be located, re-establish the 
alignment mark before proceeding with the traverse.
    8.10  Probe Plugging. Periodically check for plugging of the 
pressure ports by observing the responses on pressure differential 
readouts. Plugging causes erratic results or sluggish responses. 
Rotate the probe to determine whether the readouts respond in the 
expected direction. If plugging is detected, correct the problem and 
repeat the affected measurements.
    8.11  Static Pressure. Measure the static pressure in the stack 
or duct using the equipment described in section 6.7.
    8.11.1  If a Type DA or DAT probe is used for this measurement, 
position the probe at or between any traverse point(s) and rotate 
the probe until a null differential pressure reading is obtained at 
P2-P3. Rotate the probe 90 deg.. Disconnect 
the P2 pressure side of the probe and read the pressure 
P1-Pbar and record as the static pressure. 
(Note: The spherical probe, specified in section 6.1.2, is unable to 
provide this measurement and shall not be used to take static 
pressure measurements.)
    8.11.2  If a Type S probe is used for this measurement, position 
the probe at or between any traverse point(s) and rotate the probe 
until a null differential pressure reading is obtained. Disconnect 
the tubing from one of the pressure ports; read and record the 
P. For pressure devices with one-directional scales, if a 
deflection in the positive direction is noted with the negative side 
disconnected, then the static pressure is positive. Likewise, if a 
deflection in the positive direction is noted with the positive side 
disconnected, then the static pressure is negative.
    8.12  Atmospheric Pressure. Determine the atmospheric pressure 
at the sampling elevation during each test run following the 
procedure described in section 2.5 of Method 2.
    8.13  Molecular Weight. Determine the stack gas dry molecular 
weight. For combustion processes or processes that emit essentially 
CO2, O2, CO, and N2, use Method 3 
or 3A. For processes emitting essentially air, an analysis need not 
be conducted; use a dry molecular weight of 29.0. Other methods may 
be used, if approved by the Administrator.
    8.14  Moisture. Determine the moisture content of the stack gas 
using Method 4 or equivalent.
    8.15  Data Recording and Calculations. Record all required data 
on a form similar to Table 2F-3.
    8.15.1  Selection of appropriate calibration curves. Choose the 
appropriate pair of F1 and F2 versus pitch 
angle calibration curves, created as described in section 10.6.
    8.15.2  Pitch angle derivation. Use the appropriate calculation 
procedures in section 12.2 to find the pitch angle ratios that are 
applicable at each traverse point. Then, find the pitch angles 
corresponding to these pitch angle ratios on the ``F1 
versus pitch angle'' curve for the probe.
    8.15.3  Velocity calibration coefficient derivation. Use the 
pitch angle obtained following the procedures described in section 
8.15.2 to find the corresponding velocity calibration coefficients 
from the ``F2 versus pitch angle'' calibration curve for 
the probe.
    8.15.4  Calculations. Calculate the axial velocity at each 
traverse point using the equations presented in section 12.2 to 
account for the yaw and pitch angles of flow. Calculate the test run 
average stack gas velocity by finding the arithmetic average of the 
point velocity results in accordance with sections 12.3 and 12.4, 
and calculate the stack gas volumetric flow rate in accordance with 
section 12.5 or 12.6, as applicable.

9.0  Quality Control

    9.1  Quality Control Activities. In conjunction with the yaw 
angle determination and the pressure and temperature measurements 
specified in section 8.9, the following quality control checks 
should be performed.
    9.1.1  Range of the differential pressure gauge. In accordance 
with the specifications in section 6.4, ensure that the proper 
differential pressure gauge is being used for the range of 
P values encountered. If it is necessary to change to a 
more sensitive gauge, replace the gauge with a gauge calibrated 
according to section 10.3.3, perform the leak check described in 
section 8.4 and the zero check described in section 8.5, and repeat 
the differential pressure and temperature readings at each traverse 
point.
    9.1.2  Horizontal stability check. For horizontal traverses of a 
stack or duct, visually check that the probe shaft is maintained in 
a horizontal position prior to taking a pressure reading. 
Periodically,

[[Page 26496]]

during a test run, the probe's horizontal stability should be 
verified by placing a carpenter's level, a digital inclinometer, or 
other angle-measuring device on the portion of the probe sheath that 
extends outside of the test port. A comparable check should be 
performed by automated systems.

10.0  Calibration

    10.1  Wind Tunnel Qualification Checks. To qualify for use in 
calibrating probes, a wind tunnel shall have the design features 
specified in section 6.11 and satisfy the following qualification 
criteria. The velocity pressure cross-check in section 10.1.1 and 
axial flow verification in section 10.1.2 shall be performed before 
the initial use of the wind tunnel and repeated immediately after 
any alteration occurs in the wind tunnel's configuration, fans, 
interior surfaces, straightening vanes, controls, or other 
properties that could reasonably be expected to alter the flow 
pattern or velocity stability in the tunnel. The owner or operator 
of a wind tunnel used to calibrate probes according to this method 
shall maintain records documenting that the wind tunnel meets the 
requirements of sections 10.1.1 and 10.1.2 and shall provide these 
records to the Administrator upon request.
    10.1.1  Velocity pressure cross-check. To verify that the wind 
tunnel produces the same velocity at the tested probe head as at the 
calibration pitot tube impact port, perform the following cross-
check. Take three differential pressure measurements at the fixed 
calibration pitot tube location, using the calibration pitot tube 
specified in section 6.10, and take three measurements with the 
calibration pitot tube at the wind tunnel calibration location, as 
defined in section 3.20. Alternate the measurements between the two 
positions. Perform this procedure at the lowest and highest velocity 
settings at which the probes will be calibrated. Record the values 
on a form similar to Table 2F-4. At each velocity setting, the 
average velocity pressure obtained at the wind tunnel calibration 
location shall be within 2 percent or 2.5 mm 
H2O (0.01 in. H2O), whichever is less 
restrictive, of the average velocity pressure obtained at the fixed 
calibration pitot tube location. This comparative check shall be 
performed at 2.5-cm (1-in.), or smaller, intervals across the full 
length, width, and depth (if applicable) of the wind tunnel 
calibration location. If the criteria are not met at every tested 
point, the wind tunnel calibration location must be redefined, so 
that acceptable results are obtained at every point. Include the 
results of the velocity pressure cross-check in the calibration data 
section of the field test report. (See section 16.1.4.)
    10.1.2  Axial flow verification. The following procedures shall 
be performed to demonstrate that there is fully developed axial flow 
within the calibration location and at the calibration pitot tube 
location. Two testing options are available to conduct this check.
    10.1.2.1  Using a calibrated 3-D probe. A 3-D probe that has 
been previously calibrated in a wind tunnel with documented axial 
flow (as defined in section 3.21) may be used to conduct this check. 
Insert the calibrated 3-D probe into the wind tunnel test section 
using the tested probe port. Following the procedures in sections 
8.9 and 12.2 of this method, determine the yaw and pitch angles at 
all the point(s) in the test section where the velocity pressure 
cross-check, as specified in section 10.1.1, is performed. This 
includes all the points in the calibration location and the point 
where the calibration pitot tube will be located. Determine the yaw 
and pitch angles at each point. Repeat these measurements at the 
highest and lowest velocities at which the probes will be 
calibrated. Record the values on a form similar to Table 2F-5. Each 
measured yaw and pitch angle shall be within 3 deg. of 
0 deg.. Exceeding the limits indicates unacceptable flow in the test 
section. Until the problem is corrected and acceptable flow is 
verified by repetition of this procedure, the wind tunnel shall not 
be used for calibration of probes. Include the results of the axial 
flow verification in the calibration data section of the field test 
report. (See section 16.1.4.)
    10.1.2.2  Using alternative probes. Axial flow verification may 
be performed using an uncalibrated prism-shaped 3-D probe (e.g., DA 
or DAT probe) or an uncalibrated wedge probe. (Figure 2F-11 
illustrates a typical wedge probe.) This approach requires use of 
two ports: the tested probe port and a second port located 90 deg. 
from the tested probe port. Each port shall provide access to all 
the points within the wind tunnel test section where the velocity 
pressure cross-check, as specified in section 10.1.1, is conducted. 
The probe setup shall include establishing a reference yaw-null 
position on the probe sheath to serve as the location for installing 
the angle-measuring device. Physical design features of the DA, DAT, 
and wedge probes are relied on to determine the reference position. 
For the DA or DAT probe, this reference position can be determined 
by setting a digital inclinometer on the flat facet where the 
P1 pressure port is located and then identifying the 
rotational position on the probe sheath where a second angle-
measuring device would give the same angle reading. The reference 
position on a wedge probe shaft can be determined either 
geometrically or by placing a digital inclinometer on each side of 
the wedge and rotating the probe until equivalent readings are 
obtained. With the latter approach, the reference position is the 
rotational position on the probe sheath where an angle-measuring 
device would give a reading of 0 deg.. After installing the angle-
measuring device in the reference yaw-null position on the probe 
sheath, determine the yaw angle from the tested port. Repeat this 
measurement using the 90 deg. offset port, which provides the pitch 
angle of flow. Determine the yaw and pitch angles at all the 
point(s) in the test section where the velocity pressure cross-
check, as specified in section 10.1.1, is performed. This includes 
all the points in the wind tunnel calibration location and the point 
where the calibration pitot tube will be located. Perform this check 
at the highest and lowest velocities at which the probes will be 
calibrated. Record the values on a form similar to Table 2F-5. Each 
measured yaw and pitch angle shall be within 3 deg. of 
0 deg.. Exceeding the limits indicates unacceptable flow in the test 
section. Until the problem is corrected and acceptable flow is 
verified by repetition of this procedure, the wind tunnel shall not 
be used for calibration of probes. Include the results in the probe 
calibration report.
    10.1.3  Wind tunnel audits.
    10.1.3.1  Procedure. Upon the request of the Administrator, the 
owner or operator of a wind tunnel shall calibrate a 3-D audit probe 
in accordance with the procedures described in sections 10.3 through 
10.6. The calibration shall be performed at two velocities and over 
a pitch angle range that encompasses the velocities and pitch angles 
typically used for this method at the facility. The resulting 
calibration data and curves shall be submitted to the Agency in an 
audit test report. These results shall be compared by the Agency to 
reference calibrations of the audit probe at the same velocity and 
pitch angle settings obtained at two different wind tunnels.
    10.1.3.2  Acceptance criteria. The audited tunnel's calibration 
is acceptable if all of the following conditions are satisfied at 
each velocity and pitch setting for the reference calibration 
obtained from at least one of the wind tunnels. For pitch angle 
settings between -15 deg. and +15 deg., no velocity calibration 
coefficient (i.e., F2) may differ from the corresponding 
reference value by more than 3 percent. For pitch angle settings 
outside of this range (i.e., less than -15 deg. and greater than 
+15 deg.), no velocity calibration coefficient may differ by more 
than 5 percent from the corresponding reference value. If the 
acceptance criteria are not met, the audited wind tunnel shall not 
be used to calibrate probes for use under this method until the 
problems are resolved and acceptable results are obtained upon 
completion of a subsequent audit.
    10.2  Probe Inspection. Before each calibration of a 3-D probe, 
carefully examine the physical condition of the probe head. 
Particular attention shall be paid to the edges of the pressure 
ports and the surfaces surrounding these ports. Any dents, 
scratches, or asymmetries on the edges of the pressure ports and any 
scratches or indentations on the surfaces surrounding the pressure 
ports shall be noted because of the potential effect on the probe's 
pressure readings. If the probe has been previously calibrated, 
compare the current condition of the probe's pressure ports and 
surfaces to the results of the inspection performed during the 
probe's most recent wind tunnel calibration. Record the results of 
this inspection on a form and in diagrams similar to Table 2F-1. The 
information in Table 2F-1 will be used as the basis for comparison 
during the probe head inspections performed before each subsequent 
field use.
    10.3  Pre-Calibration Procedures. Prior to calibration, a scribe 
line shall have been placed on the probe in accordance with section 
10.4. The yaw angle and velocity calibration procedures shall not 
begin until the pre-test requirements in sections 10.3.1 through 
10.3.4 have been met.
    10.3.1  Perform the horizontal straightness check described in 
section 8.2 on the probe

[[Page 26497]]

assembly that will be calibrated in the wind tunnel.
    10.3.2  Perform a leak check in accordance with section 8.4.
    10.3.3  Except as noted in section 10.3.3.3, calibrate all 
differential pressure-measuring devices to be used in the probe 
calibrations, using the following procedures. At a minimum, 
calibrate these devices on each day that probe calibrations are 
performed.
    10.3.3.1  Procedure. Before each wind tunnel use, all 
differential pressure-measuring devices shall be calibrated against 
the reference device specified in section 6.4.3 using a common 
pressure source. Perform the calibration at three reference 
pressures representing 30, 60, and 90 percent of the full-scale 
range of the pressure-measuring device being calibrated. For an 
inclined-vertical manometer, perform separate calibrations on the 
inclined and vertical portions of the measurement scale, considering 
each portion of the scale to be a separate full-scale range. [For 
example, for a manometer with a 0- to 2.5-cm H2O (0- to 
1-in. H2O) inclined scale and a 2.5- to 12.7-cm 
H2O (1- to 5-in. H2O) vertical scale, 
calibrate the inclined portion at 7.6, 15.2, and 22.9 mm 
H2O (0.3, 0.6, and 0.9 in. H2O), and calibrate 
the vertical portion at 3.8, 7.6, and 11.4 cm H2O (1.5, 
3.0, and 4.5 in. H2O).] Alternatively, for the vertical 
portion of the scale, use three evenly spaced reference pressures, 
one of which is equal to or higher than the highest differential 
pressure expected in field applications.
    10.3.3.2  Acceptance criteria. At each pressure setting, the two 
pressure readings made using the reference device and the pressure-
measuring device being calibrated shall agree to within 
2 percent of full scale of the device being calibrated 
or 0.5 mm H2O (0.02 in. H2O), whichever is 
less restrictive. For an inclined-vertical manometer, these 
requirements shall be met separately using the respective full-scale 
upper limits of the inclined and vertical portions of the scale. 
Differential pressure-measuring devices not meeting the 
2 percent of full scale or 0.5 mm H2O (0.02 
in. H2O) calibration requirement shall not be used.
    10.3.3.3  Exceptions. Any precision manometer that meets the 
specifications for a reference device in section 6.4.3 and that is 
not used for field testing does not require calibration, but must be 
leveled and zeroed before each wind tunnel use. Any pressure device 
used exclusively for yaw nulling does not require calibration, but 
shall be checked for responsiveness to rotation of the probe prior 
to each wind tunnel use.
    10.3.4  Calibrate digital inclinometers on each day of wind 
tunnel or field testing (prior to beginning testing) using the 
following procedures. Calibrate the inclinometer according to the 
manufacturer's calibration procedures. In addition, use a triangular 
block (illustrated in Figure 2F-12) with a known angle, 0, 
independently determined using a protractor or equivalent device, 
between two adjacent sides to verify the inclinometer readings.

    Note: If other angle-measuring devices meeting the provisions of 
section 6.2.3 are used in place of a digital inclinometer, 
comparable calibration procedures shall be performed on such 
devices.)

Secure the triangular block in a fixed position. Place the 
inclinometer on one side of the block (side A) to measure the angle 
of inclination (R1). Repeat this measurement on the 
adjacent side of the block (side B) using the inclinometer to obtain 
a second angle reading (R2). The difference of the sum of 
the two readings from 180 deg. (i.e., 180 deg. -R1 
-R2) shall be within 2 deg. of the known 
angle, 
    10.4  Placement of Reference Scribe Line. Prior to the first 
calibration of a probe, a line shall be permanently inscribed on the 
main probe sheath to serve as a reference mark for determining yaw 
angles. Annex C in section 18 of this method gives a guideline for 
placement of the reference scribe line.
    10.4.1  This reference scribe line shall meet the specifications 
in sections 6.1.6.1 and 6.1.6.3 of this method. To verify that the 
alignment specification in section 6.1.6.3 is met, secure the probe 
in a horizontal position and measure the rotational angle of each 
scribe line and scribe line segment using an angle-measuring device 
that meets the specifications in section 6.2.1 or 6.2.3. For any 
scribe line that is longer than 30.5 cm (12 in.), check the line's 
rotational position at 30.5-cm (12-in.) intervals. For each line 
segment that is 30.5 cm (12 in.) or less in length, check the 
rotational position at the two endpoints of the segment. To meet the 
alignment specification in section 6.1.6.3, the minimum and maximum 
of all of the rotational angles that are measured along the full 
length of the main probe must not differ by more than 2 deg..

    Note: A short reference scribe line segment [e.g., 15.2 cm (6 
in.) or less in length] meeting the alignment specifications in 
section 6.1.6.3 is fully acceptable under this method. See section 
18.1.1.1 of Annex A for an example of a probe marking procedure, 
suitable for use with a short reference scribe line.

    10.4.2  The scribe line should be placed on the probe first and 
then its offset from the yaw-null position established (as specified 
in section 10.5). The rotational position of the reference scribe 
line relative to the yaw-null position of the probe, as determined 
by the yaw angle calibration procedure in section 10.5, is defined 
as the reference scribe line rotational offset, RSLO. The 
reference scribe line rotational offset shall be recorded and 
retained as part of the probe's calibration record.
    10.4.3  Scribe line for automated probes. A scribe line may not 
be necessary for an automated probe system if a reference rotational 
position of the probe is built into the probe system design. For 
such systems, a ``flat'' (or comparable, clearly identifiable 
physical characteristic) should be provided on the probe casing or 
flange plate to ensure that the reference position of the probe 
assembly remains in a vertical or horizontal position. The 
rotational offset of the flat (or comparable, clearly identifiable 
physical characteristic) needed to orient the reference position of 
the probe assembly shall be recorded and maintained as part of the 
automated probe system's specifications.
    10.5  Yaw Angle Calibration Procedure. For each probe used to 
measure yaw angles with this method, a calibration procedure shall 
be performed in a wind tunnel meeting the specifications in section 
10.1 to determine the rotational position of the reference scribe 
line relative to the probe's yaw-null position. This procedure shall 
be performed on the main probe with all devices that will be 
attached to the main probe in the field [such as thermocouples or 
resistance temperature detectors (RTDs)] that may affect the flow 
around the probe head. Probe shaft extensions that do not affect 
flow around the probe head need not be attached during calibration. 
At a minimum, this procedure shall include the following steps.
    10.5.1  Align and lock the angle-measuring device on the 
reference scribe line. If a marking procedure (such as that 
described in section 18.1.1.1) is used, align the angle-measuring 
device on a mark within 1 deg. of the rotational 
position of the reference scribe line. Lock the angle-measuring 
device onto the probe sheath at this position.
    10.5.2  Zero the pressure-measuring device used for yaw nulling.
    10.5.3  Insert the probe assembly into the wind tunnel through 
the entry port, positioning the probe's impact port at the 
calibration location. Check the responsiveness of the pressure-
measurement device to probe rotation, taking corrective action if 
the response is unacceptable.
    10.5.4  Ensure that the probe is in a horizontal position, using 
a carpenter's level.
    10.5.5  Rotate the probe either clockwise or counterclockwise 
until a yaw null (P2 = P3) is obtained.
    10.5.6  Use the reading displayed by the angle-measuring device 
at the yaw-null position to determine the magnitude of the reference 
scribe line rotational offset, RSLO, as defined in 
section 3.15. Annex D in section 18 of this method provides a 
recommended procedure for determining the magnitude of 
RSLO with a digital inclinometer and a second procedure 
for determining the magnitude of RSLO with a protractor 
wheel and pointer device. Table 2F-6 presents an example data form 
and Table 2F-7 is a look-up table with the recommended procedure. 
Procedures other than those recommended in Annex D in section 18 may 
be used, if they can determine RSLO to within 
1 deg. and are explained in detail in the field test 
report. The algebraic sign of RSLO will either be 
positive, if the rotational position of the reference scribe line 
(as viewed from the ``tail'' end of the probe) is clockwise, or 
negative, if counterclockwise with respect to the probe's yaw-null 
position. (This is illustrated in Figure 2F-13.)
    10.5.7  The steps in sections 10.5.3 through 10.5.6 shall be 
performed twice at each of the velocities at which the probe will be 
calibrated (in accordance with section 10.6). Record the values of 
RSLO.
    10.5.8  The average of all of the RSLO values shall 
be documented as the reference scribe line rotational offset for the 
probe.
    10.5.9  Use of reference scribe line offset. The reference 
scribe line rotational offset shall be used to determine the yaw 
angle of flow in accordance with section 8.9.4.
    10.6  Pitch Angle and Velocity Pressure Calibrations. Use the 
procedures in sections 10.6.1 through 10.6.16 to generate an 
appropriate set (or sets) of pitch angle and velocity pressure 
calibration curves for each

[[Page 26498]]

probe. The calibration procedure shall be performed on the main 
probe and all devices that will be attached to the main probe in the 
field (e.g., thermocouple or RTDs) that may affect the flow around 
the probe head. Probe shaft extensions that do not affect flow 
around the probe head need not be attached during calibration. 
(Note: If a sampling nozzle is part of the assembly, a wind tunnel 
demonstration shall be performed that shows the probe's ability to 
measure velocity and yaw null is not impaired when the nozzle is 
drawing a sample.) The calibration procedure involves generating two 
calibration curves, F1 versus pitch angle and 
F2 versus pitch angle. To generate these two curves, 
F1 and F2 shall be derived using Equations 2F-
1 and 2F-2, below. Table 2F-8 provides an example wind tunnel 
calibration data sheet, used to log the measurements needed to 
derive these two calibration curves.
    10.6.1  Calibration velocities. The tester may calibrate the 
probe at two nominal wind tunnel velocity settings of 18.3 m/sec and 
27.4 m/sec (60 ft/sec and 90 ft/sec) and average the results of 
these calibrations, as described in section 10.6.16.1, in order to 
generate a set of calibration curves. If this option is selected, 
this single set of calibration curves may be used for all field 
applications over the entire velocity range allowed by the method. 
Alternatively, the tester may customize the probe calibration for a 
particular field test application (or for a series of applications), 
based on the expected average velocity(ies) at the test site(s). If 
this option is selected, generate each set of calibration curves by 
calibrating the probe at two nominal wind tunnel velocity settings, 
at least one of which is greater than or equal to the expected 
average velocity(ies) for the field application(s), and average the 
results as described in section 10.6.16.1. Whichever calibration 
option is selected, the probe calibration coefficients 
(F2 values) obtained at the two nominal calibration 
velocities shall, for the same pitch angle setting, meet the 
conditions specified in section 10.6.16.
    10.6.2  Pitch angle calibration curve (F-1) versus pitch angle). 
The pitch angle calibration involves generating a calibration curve 
of calculated F1 values versus tested pitch angles, where 
F1 is the ratio of the pitch pressure to the velocity 
pressure, i.e.,
[GRAPHIC] [TIFF OMITTED] TR14MY99.049

See Figure 2F-14 for an example F1 versus pitch angle 
calibration curve.
    10.6.3  Velocity calibration curve (F2 versus pitch 
angle). The velocity calibration involves generating a calibration 
curve of the 3-D probe's F2 coefficient against the 
tested pitch angles, where
[GRAPHIC] [TIFF OMITTED] TR14MY99.050

and

Cp = calibration pitot tube coefficient, and
Pstd = velocity pressure from the calibration 
pitot tube.

See Figure 2F-15 for an example F2 versus pitch angle 
calibration curve.
    10.6.4  Connect the tested probe and calibration pitot probe to 
their respective pressure-measuring devices. Zero the pressure-
measuring devices. Inspect and leak-check all pitot lines; repair or 
replace, if necessary. Turn on the fan, and allow the wind tunnel 
air flow to stabilize at the first of the two selected nominal 
velocity settings.
    10.6.5  Position the calibration pitot tube at its measurement 
location (determined as outlined in section 6.11.4.3), and align the 
tube so that its tip is pointed directly into the flow. Ensure that 
the entry port surrounding the tube is properly sealed. The 
calibration pitot tube may either remain in the wind tunnel 
throughout the calibration, or be removed from the wind tunnel while 
measurements are taken with the probe being calibrated.
    10.6.6  Set up the pitch protractor plate on the tested probe's 
entry port to establish the pitch angle positions of the probe to 
within 2 deg..
    10.6.7  Check the zero setting of each pressure-measuring 
device.
    10.6.8  Insert the tested probe into the wind tunnel and align 
it so that its P1 pressure port is pointed directly into 
the flow and is positioned within the calibration location (as 
defined in section 3.20). Secure the probe at the 0 deg. pitch angle 
position. Ensure that the entry port surrounding the probe is 
properly sealed.
    10.6.9  Read the differential pressure from the calibration 
pitot tube (Pstd), and record its value. Read 
the barometric pressure to within 2.5 mm Hg 
(0.1 in. Hg) and the temperature in the wind tunnel to 
within 0.6 deg.C (1 deg.F). Record these values on a data form 
similar to Table 2F-8.
    10.6.10  After the tested probe's differential pressure gauges 
have had sufficient time to stabilize, yaw null the probe, then 
obtain differential pressure readings for (P1-
P2) and (P4-P5). Record the yaw 
angle and differential pressure readings. After taking these 
readings, ensure that the tested probe has remained at the yaw-null 
position.
    10.6.11  Either take paired differential pressure measurements 
with both the calibration pitot tube and tested probe (according to 
sections 10.6.9 and 10.6.10) or take readings only with the tested 
probe (according to section 10.6.10) in 5 deg. increments over the 
pitch-angle range for which the probe is to be calibrated. The 
calibration pitch-angle range shall be symmetric around 0 deg. and 
shall exceed the largest pitch angle expected in the field by 
5 deg.. At a minimum, probes shall be calibrated over the range of 
-15 deg. to +15 deg.. If paired calibration pitot tube and tested 
probe measurements are not taken at each pitch angle setting, the 
differential pressure from the calibration pitot tube shall be read, 
at a minimum, before taking the tested probe's differential pressure 
reading at the first pitch angle setting and after taking the tested 
probe's differential pressure readings at the last pitch angle 
setting in each replicate.
    10.6.12  Perform a second replicate of the procedures in 
sections 10.6.5 through 10.6.11 at the same nominal velocity 
setting.
    10.6.13  For each replicate, calculate the F1 and 
F2 values at each pitch angle. At each pitch angle, 
calculate the percent difference between the two F2 
values using Equation 2F-3.
[GRAPHIC] [TIFF OMITTED] TR14MY99.051

Eq. 2F-3

If the percent difference is less than or equal to 2 percent, 
calculate an average F1 value and an average 
F2 value at that pitch angle. If the percent difference 
is greater than 2 percent and less than or equal to 5 percent, 
perform a third repetition at that angle and calculate an average 
F1 value and an average F2 value using all 
three repetitions. If the percent difference is greater than 5 
percent, perform four additional repetitions at that angle and 
calculate an average F1 value and an average 
F2 value using all six repetitions. When additional 
repetitions are required at any pitch angle, move the probe by at 
least 5 deg. and then return to the specified pitch angle before 
taking the next measurement. Record the average values on a form 
similar to Table 2F-9.
    10.6.14  Repeat the calibration procedures in sections 10.6.5 
through 10.6.13 at the second selected nominal wind tunnel velocity 
setting.
    10.6.15  Velocity drift check. The following check shall be 
performed, except when paired calibration pitot tube and tested 
probe pressure measurements are taken at each pitch angle setting. 
At each velocity setting, calculate the percent difference between 
consecutive differential pressure measurements made with the 
calibration pitot tube. If a measurement differs from the previous 
measurement by more than 2 percent or 0.25 mm H2O (0.01 
in. H2O), whichever is less restrictive, the calibration 
data collected between these calibration pitot tube measurements may 
not be used, and the measurements shall be repeated.
    10.6.16  Compare the averaged F2 coefficients 
obtained from the calibrations at the two selected nominal 
velocities, as follows. At each pitch angle setting, use Equation 
2F-3 to calculate the difference between the corresponding average 
F2 values at the two calibration velocities. At each 
pitch angle in the -15 deg. to +15 deg. range, the percent 
difference between the average F2 values shall not exceed 
3.0 percent. For pitch angles outside this range (i.e., less than 
-15 deg.0 and greater than +15 deg.), the percent difference shall 
not exceed 5.0 percent.
    10.6.16.1  If the applicable specification in section 10.6.16 is 
met at each pitch angle setting, average the results obtained at the 
two nominal calibration velocities to produce a calibration record 
of F1 and F2 at each pitch angle tested. 
Record these values on a form similar to Table 2F-9. From these 
values, generate one calibration curve representing F1 
versus pitch angle and a second curve representing F2 
versus pitch angle. Computer spreadsheet programs may be used to 
graph the calibration data and to develop polynomial equations that 
can be used to calculate pitch angles and axial velocities.

[[Page 26499]]

    10.6.16.2  If the applicable specification in section 10.6.16 is 
exceeded at any pitch angle setting, the probe shall not be used 
unless: (1) the calibration is repeated at that pitch angle and 
acceptable results are obtained or (2) values of F1 and 
F2 are obtained at two nominal velocities for which the 
specifications in section 10.6.16 are met across the entire pitch 
angle range.
    10.7  Recalibration. Recalibrate the probe using the procedures 
in section 10 either within 12 months of its first field use after 
its most recent calibration or after 10 field tests (as defined in 
section 3.4), whichever occurs later. In addition, whenever there is 
visible damage to the 3-D head, the probe shall be recalibrated 
before it is used again.
    10.8  Calibration of pressure-measuring devices used in field 
tests. Before its initial use in a field test, calibrate each 
pressure-measuring device (except those used exclusively for yaw 
nulling) using the three-point calibration procedure described in 
section 10.3.3. The device shall be recalibrated according to the 
procedure in section 10.3.3 no later than 90 days after its first 
field use following its most recent calibration. At the discretion 
of the tester, more frequent calibrations (e.g., after a field test) 
may be performed. No adjustments, other than adjustments to the zero 
setting, shall be made to the device between calibrations.
    10.8.1  Post-test calibration check. A single-point calibration 
check shall be performed on each pressure-measuring device after 
completion of each field test. At the discretion of the tester, more 
frequent single-point calibration checks (e.g., after one or more 
field test runs) may be performed. It is recommended that the post-
test check be performed before leaving the field test site. The 
check shall be performed at a pressure between 50 and 90 percent of 
full scale by taking a common pressure reading with the tested 
device and a reference pressure-measuring device (as described in 
section 6.4.4) or by challenging the tested device with a reference 
pressure source (as described in section 6.4.4) or by performing an 
equivalent check using a reference device approved by the 
Administrator.
    10.8.2  Acceptance criterion. At the selected pressure setting, 
the pressure readings made using the reference device and the tested 
device shall agree to within 3 percent of full scale of the tested 
device or 0.8 mm H2O (0.03 in. H2O), whichever 
is less restrictive. If this specification is met, the test data 
collected during the field test are valid. If the specification is 
not met, all test data collected since the last successful 
calibration or calibration check are invalid and shall be repeated 
using a pressure-measuring device with a current, valid calibration. 
Any device that fails the calibration check shall not be used in a 
field test until a successful recalibration is performed according 
to the procedures in section 10.3.3.
    10.9  Temperature Gauges. Same as Method 2, section 4.3. The 
alternative thermocouple calibration procedures outlined in Emission 
Measurement Center (EMC) Approved Alternative Method (ALT-011) 
``Alternative Method 2 Thermocouple Calibration Procedure'' may be 
performed. Temperature gauges shall be calibrated no more than 30 
days prior to the start of a field test or series of field tests and 
recalibrated no more than 30 days after completion of a field test 
or series of field tests.
    10.10  Barometer. Same as Method 2, section 4.4. The barometer 
shall be calibrated no more than 30 days prior to the start of a 
field test or series of field tests.

11.0  Analytical Procedure

    Sample collection and analysis are concurrent for this method 
(see section 8.0).

12.0  Data Analysis and Calculations

    These calculations use the measured yaw angle, derived pitch 
angle, and the differential pressure and temperature measurements at 
individual traverse points to derive the axial flue gas velocity 
(va(i)) at each of those points. The axial velocity 
values at all traverse points that comprise a full stack or duct 
traverse are then averaged to obtain the average axial flue gas 
velocity (va (avg)). Round off figures only in the final 
calculation of reported values.

12.1  Nomenclature

A = Cross-sectional area of stack or duct, m \2\ (ft \2\).
Bws = Water vapor in the gas stream (from Method 4 or 
alternative), proportion by volume.
Kp = Conversion factor (a constant),
[GRAPHIC] [TIFF OMITTED] TR14MY99.052

for the metric system, and
[GRAPHIC] [TIFF OMITTED] TR14MY99.053

for the English system.

Md = Molecular weight of stack or duct gas, dry basis 
(see section 8.13), g/g-mole (lb/lb-mole).
Ms = Molecular weight of stack or duct gas, wet basis, g/
g-mole (lb/lb-mole).
[GRAPHIC] [TIFF OMITTED] TR14MY99.054

Pbar = Barometric pressure at measurement site, mm Hg 
(in. Hg).
Pg = Stack or duct static pressure, mm H2O 
(in. H2O).
Ps = Absolute stack or duct pressure, mm Hg (in. Hg),
[GRAPHIC] [TIFF OMITTED] TR14MY99.055

Pstd = Standard absolute pressure, 760 mm Hg (29.92 in. 
Hg).
13.6 = Conversion from mm H2O (in. H2O) to mm 
Hg (in. Hg).
Qsd = Average dry-basis volumetric stack or duct gas flow 
rate corrected to standard conditions, dscm/hr (dscf/hr).
Qsw = Average wet-basis volumetric stack or duct gas flow 
rate corrected to standard conditions, wscm/hr (wscf/hr).
Ts(avg) = Average absolute stack or duct gas temperature 
across all traverse points.
ts(i) = Stack or duct gas temperature, C (F), at traverse 
point i.
Ts(i) = Absolute stack or duct gas temperature, K (R), at 
traverse point i,
[GRAPHIC] [TIFF OMITTED] TR14MY99.056

for the metric system, and
[GRAPHIC] [TIFF OMITTED] TR14MY99.057

for the English system.
Tstd = Standard absolute temperature, 293 deg.K 
(528 deg.R).
F1(i) = Pitch angle ratio, applicable at traverse point 
i, dimensionless.
F2(i) = 3-D probe velocity calibration coefficient, 
applicable at traverse point i, dimensionless.
(P4-P5)i = Pitch differential 
pressure of stack or duct gas flow, mm H2O (in. 
H2O), at traverse point i.
(P1-P2)i = Velocity head 
(differential pressure) of stack or duct gas flow, mm H2O 
(in. H2O), at traverse point i.
va(i) = Reported stack or duct gas axial velocity, m/sec 
(ft/sec), at traverse point i.
va(avg) = Average stack or duct gas axial velocity, m/sec 
(ft/sec), across all traverse points.
3,600 = Conversion factor, sec/hr.
18.0 = Molecular weight of water, g/g-mole (lb/lb-mole).
y(i) = Yaw angle, degrees, at traverse point i.
p(i) = Pitch angle, degrees, at traverse point 
i.
n = Number of traverse points.

    12.2  Traverse Point Velocity Calculations. Perform the 
following calculations from the measurements obtained at each 
traverse point.
    12.2.1  Selection of calibration curves. Select calibration 
curves as described in section 10.6.1.
    12.2.2  Traverse point pitch angle ratio. Use Equation 2F-1, as 
described in section 10.6.2, to calculate the pitch angle ratio, 
F1(i), at each traverse point.
    12.2.3  Pitch angle. Use the pitch angle ratio, 
F1(i), to derive the pitch angle, 
p(i), at traverse point i from the 
F1 versus pitch angle calibration curve generated under 
section 10.6.16.1.
    12.2.4  Velocity calibration coefficient. Use the pitch angle, 
p(i), to obtain the probe velocity calibration 
coefficient, F2(i), at traverse point i from the 
``velocity pressure calibration curve,'' i.e., the F2 
versus pitch angle calibration curve generated under section 
10.6.16.1.
    12.2.5  Axial velocity. Use the following equation to calculate 
the axial velocity, va(i), from the differential pressure 
(P1-P2)i and yaw angle, 
y(i), measured at traverse point i and the 
previously calculated values for the velocity calibration 
coefficient, F2(i), absolute stack or duct standard 
temperature, Ts(i), absolute stack or duct pressure, 
Ps, molecular weight, Ms, and pitch angle, 
``p(i).

[[Page 26500]]

[GRAPHIC] [TIFF OMITTED] TR14MY99.058


    12.2.6  Handling multiple measurements at a traverse point. For 
pressure or temperature devices that take multiple measurements at a 
traverse point, the multiple measurements (or where applicable, 
their square roots) may first be averaged and the resulting average 
values used in the equations above. Alternatively, the individual 
measurements may be used in the equations above and the resulting 
multiple calculated values may then be averaged to obtain a single 
traverse point value. With either approach, all of the individual 
measurements recorded at a traverse point must be used in 
calculating the applicable traverse point value.
    12.3  Average Axial Velocity in Stack or Duct. Use the reported 
traverse point axial velocity in the following equation.
[GRAPHIC] [TIFF OMITTED] TR14MY99.059

    12.4  Acceptability of Results. The test results are acceptable 
and the calculated value of va(avg) may be reported as 
the average axial velocity for the test run if the conditions in 
either section 12.4.1 or 12.4.2 are met.
    12.4.1  The calibration curves were generated at nominal 
velocities of 18.3 m/sec and 27.4 m/sec (60 ft/sec and 90 ft/sec).
    12.4.2  The calibration curves were generated at nominal 
velocities other than 18.3 m/sec and 27.4 m/sec (60 ft/sec and 90 
ft/sec), and the value of va(avg) obtained using Equation 
2F-9 is less than or equal to at least one of the nominal velocities 
used to derive the F1 and F2 calibration 
curves.
    12.4.3  If the conditions in neither section 12.4.1 nor section 
12.4.2 are met, the test results obtained in Equation 2F-9 are not 
acceptable, and the steps in sections 12.2 and 12.3 must be repeated 
using a set of F1 and F2 calibration curves 
that satisfies the conditions specified in section 12.4.1 or 12.4.2.
    12.5  Average Gas Wet Volumetric Flow Rate in Stack or Duct. Use 
the following equation to compute the average volumetric flow rate 
on a wet basis.
[GRAPHIC] [TIFF OMITTED] TR14MY99.060

    12.6  Average Gas Dry Volumetric Flow Rate in Stack or Duct. Use 
the following equation to compute the average volumetric flow rate 
on a dry basis.
[GRAPHIC] [TIFF OMITTED] TR14MY99.061

13.0  Method Performance. [Reserved]

14.0  Pollution Prevention. [Reserved]

15.0  Waste Management. [Reserved]

16.0  Reporting

    16.1  Field Test Reports. Field test reports shall be submitted 
to the Agency according to applicable regulatory requirements. Field 
test reports should, at a minimum, include the following elements.
    16.1.1  Description of the source. This should include the name 
and location of the test site, descriptions of the process tested, a 
description of the combustion source, an accurate diagram of stack 
or duct cross-sectional area at the test site showing the dimensions 
of the stack or duct, the location of the test ports, and traverse 
point locations and identification numbers or codes. It should also 
include a description and diagram of the stack or duct layout, 
showing the distance of the test location from the nearest upstream 
and downstream disturbances and all structural elements (including 
breachings, baffles, fans, straighteners, etc.) affecting the flow 
pattern. If the source and test location descriptions have been 
previously submitted to the Agency in a document (e.g., a monitoring 
plan or test plan), referencing the document in lieu of including 
this information in the field test report is acceptable.
    16.1.2  Field test procedures. These should include a 
description of test equipment and test procedures. Testing 
conventions, such as traverse point numbering and measurement 
sequence (e.g., sampling from center to wall, or wall to center), 
should be clearly stated. Test port identification and directional 
reference for each test port should be included on the appropriate 
field test data sheets.
    16.1.3  Field test data.
    16.1.3.1  Summary of results. This summary should include the 
dates and times of testing and the average axial gas velocity and 
the average flue gas volumetric flow results for each run and tested 
condition.
    16.1.3.2  Test data. The following values for each traverse 
point should be recorded and reported:

(a) P1-P2 and P4-P5 
differential pressures
(b) Stack or duct gas temperature at traverse point i 
(ts(i))
(c) Absolute stack or duct gas temperature at traverse point i 
(Ts(i))
(d) Yaw angle at each traverse point i (y(i))
(e) Pitch angle at each traverse point i (p(i))
(f) Stack or duct gas axial velocity at traverse point i 
(va(i))

    16.1.3.3  The following values should be reported once per run:

(a) Water vapor in the gas stream (from Method 4 or alternative), 
proportion by volume (Bws), measured at the frequency 
specified in the applicable regulation
(b) Molecular weight of stack or duct gas, dry basis (Md)
(c) Molecular weight of stack or duct gas, wet basis (Ms)
(d) Stack or duct static pressure (Pg)
(e) Absolute stack or duct pressure (Ps)
(f) Carbon dioxide concentration in the flue gas, dry basis (\0/
0\d CO2)
(g) Oxygen concentration in the flue gas, dry basis (\0/
0\d O2)
(h) Average axial stack or duct gas velocity (va(avg)) 
across all traverse points
(i) Gas volumetric flow rate corrected to standard conditions, dry 
or wet basis as required by the applicable regulation 
(Qsd or Qsw)

16.1.3.4  The following should be reported once per complete set of 
test runs:

(a) Cross-sectional area of stack or duct at the test location (A)
(b) Measurement system response time (sec)
(c) Barometric pressure at measurement site (Pbar)

16.1.4  Calibration data. The field test report should include 
calibration data for all probes and test equipment used in the field 
test. At a minimum, the probe calibration data reported to the 
Agency should include the following:

(a) Date of calibration
(b) Probe type
(c) Probe identification number(s) or code(s)
(d) Probe inspection sheets

[[Page 26501]]

(e) Pressure measurements and intermediate calculations of 
F1 and F2 at each pitch angle used to obtain 
calibration curves in accordance with section 10.6 of this method
(f) Calibration curves (in graphic or equation format) obtained in 
accordance with sections 10.6.11 of this method
(g) Description and diagram of wind tunnel used for the calibration, 
including dimensions of cross-sectional area and position and size 
of the test section
(h) Documentation of wind tunnel qualification tests performed in 
accordance with section 10.1 of this method

    16.1.5  Quality Assurance. Specific quality assurance and 
quality control procedures used during the test should be described.

17.0  Bibliography

(1) 40 CFR Part 60, Appendix A, Method 1--Sample and velocity 
traverses for stationary sources.
(2) 40 CFR Part 60, Appendix A, Method 2H--Determination of stack 
gas velocity taking into account velocity decay near the stack wall.
(3) 40 CFR Part 60, Appendix A, Method 2--Determination of stack gas 
velocity and volumetric flow rate (Type S pitot tube).
(4) 40 CFR Part 60, Appendix A, Method 3--Gas analysis for carbon 
dioxide, oxygen, excess air, and dry molecular weight.
(5) 40 CFR Part 60, Appendix A, Method 3A--Determination of oxygen 
and carbon dioxide concentrations in emissions from stationary 
sources (instrumental analyzer procedure).
(6) 40 CFR Part 60, Appendix A, Method 4--Determination of moisture 
content in stack gases.
(7) Emission Measurement Center (EMC) Approved Alternative Method 
(ALT-011) ``Alternative Method 2 Thermocouple Calibration 
Procedure.''
(8) Electric Power Research Institute, Interim Report EPRI TR-
106698, ``Flue Gas Flow Rate Measurement Errors,'' June 1996.
(9) Electric Power Research Institute, Final Report EPRI TR-108110, 
``Evaluation of Heat Rate Discrepancy from Continuous Emission 
Monitoring Systems,'' August 1997.
(10) Fossil Energy Research Corporation, Final Report, ``Velocity 
Probe Tests in Non-axial Flow Fields,'' November 1998, Prepared for 
the U.S. Environmental Protection Agency.
(11) Fossil Energy Research Corporation, ``Additional Swirl Tunnel 
Tests: E-DAT and T-DAT Probes,'' February 24, 1999, Technical 
Memorandum Prepared for U.S. Environmental Protection Agency, P.O. 
No. 7W-1193-NALX.
(12) Massachusetts Institute of Technology, Report WBWT-TR-1317, 
``Calibration of Eight Wind Speed Probes Over a Reynolds Number 
Range of 46,000 to 725,000 Per Foot, Text and Summary Plots,'' Plus 
appendices, October 15, 1998, Prepared for The Cadmus Group, Inc.
(13) National Institute of Standards and Technology, Special 
Publication 250, ``NIST Calibration Services Users Guide 1991,'' 
Revised October 1991, U.S. Department of Commerce, p. 2.
(14) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four Prandtl Probes, 
Four S-Type Probes, Four French Probes, Four Modified Kiel Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
#DW13938432-01-0.
(15) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Five Autoprobes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
#DW13938432-01-0.
(16) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Eight Spherical 
Probes,'' Prepared for the U.S. Environmental Protection Agency 
under IAG #DW13938432-01-0.
(17) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four DAT Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
#DW13938432-01-0.
(18) Norfleet, S.K., ``An Evaluation of Wall Effects on Stack Flow 
Velocities and Related Overestimation Bias in EPA's Stack Flow 
Reference Methods,'' EPRI CEMS User's Group Meeting, New Orleans, 
Louisiana, May 13-15, 1998.
(19) Page, J.J., E.A. Potts, and R.T. Shigehara, ``3-D Pitot Tube 
Calibration Study,'' EPA Contract No. 68-D1-0009, Work Assignment 
No. I-121, March 11, 1993.
(20) Shigehara, R.T., W.F. Todd, and W.S. Smith, ``Significance of 
Errors in Stack Sampling Measurements,'' Presented at the Annual 
Meeting of the Air Pollution Control Association, St. Louis, 
Missouri, June 14-19, 1970.
(21) The Cadmus Group, Inc., May 1999, ``EPA Flow Reference Method 
Testing and Analysis: Findings Report,'' EPA/430-R-99-009.
(22) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, DeCordova Steam 
Electric Station, Volume I: Test Description and Appendix A (Data 
Distribution Package),'' EPA/430-R-98-015a.
(23) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, Lake Hubbard 
Steam Electric Station, Volume I: Test Description and Appendix A 
(Data Distribution Package),'' EPA/430-R-98-017a.
(24) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Pennsylvania Electric Co., G.P.U. 
Genco Homer City Station: Unit 1, Volume I: Test Description and 
Appendix A (Data Distribution Package),'' EPA/430-R-98-018a.
(25) The Cadmus Group, Inc., 1997, ``EPA Flow Reference Method 
Testing and Analysis: Wind Tunnel Experimental Results,'' EPA/430-R-
97-013.

18.0  Annexes

    Annex A, C, and D describe recommended procedures for meeting 
certain provisions in sections 8.3, 10.4, and 10.5 of this method. 
Annex B describes procedures to be followed when using the 
protractor wheel and pointer assembly to measure yaw angles, as 
provided under section 8.9.1.
    18.1 Annex A--Rotational Position Check. The following are 
recommended procedures that may be used to satisfy the rotational 
position check requirements of section 8.3 of this method and to 
determine the angle-measuring device rotational offset (RADO).
    18.1.1 Rotational position check with probe outside stack. Where 
physical constraints at the sampling location allow full assembly of 
the probe outside the stack and insertion into the test port, the 
following procedures should be performed before the start of 
testing. Two angle-measuring devices that meet the specifications in 
section 6.2.1 or 6.2.3 are required for the rotational position 
check. An angle measuring device whose position can be independently 
adjusted (e.g., by means of a set screw) after being locked into 
position on the probe sheath shall not be used for this check unless 
the independent adjustment is set so that the device performs 
exactly like a device without the capability for independent 
adjustment. That is, when aligned on the probe such a device must 
give the same reading as a device that does not have the capability 
of being independently adjusted. With the fully assembled probe 
(including probe shaft extensions, if any) secured in a horizontal 
position, affix one yaw angle-measuring device to the probe sheath 
and lock it into position on the reference scribe line specified in 
section 6.1.6.1. Position the second angle-measuring device using 
the procedure in section 18.1.1.1 or 18.1.1.2.
    18.1.1.1  Marking procedure. The procedures in this section 
should be performed at each location on the fully assembled probe 
where the yaw angle-measuring device will be mounted during the 
velocity traverse. Place the second yaw angle-measuring device on 
the main probe sheath (or extension) at the position where a yaw 
angle will be measured during the velocity traverse. Adjust the 
position of the second angle-measuring device until it indicates the 
same angle (1 deg.) as the reference device, and affix 
the second device to the probe sheath (or extension). Record the 
angles indicated by the two angle-measuring devices on a form 
similar to Table 2F-2. In this position, the second angle-measuring 
device is considered to be properly positioned for yaw angle 
measurement. Make a mark, no wider than 1.6 mm (1/16 in.), on the 
probe sheath (or extension), such that the yaw angle-measuring 
device can be re-affixed at this same properly aligned position 
during the velocity traverse.
    18.1.1.2  Procedure for probe extensions with scribe lines. If, 
during a velocity traverse the angle-measuring device will be 
affixed to a probe extension having a scribe line as specified in 
section 6.1.6.2, the following procedure may be used to align the 
extension's scribe line with the reference scribe line instead of 
marking the extension as described in section 18.1.1.1. Attach the 
probe extension to the main probe. Align and lock the second angle-
measuring device on the probe extension's scribe line. Then, rotate 
the extension until both measuring devices

[[Page 26502]]

indicate the same angle (1 deg.). Lock the extension at 
this rotational position. Record the angles indicated by the two 
angle-measuring devices on a form similar to Table 2F-2. An angle-
measuring device may be aligned at any position on this scribe line 
during the velocity traverse, if the scribe line meets the alignment 
specification in section 6.1.6.3.
    18.1.1.3  Post-test rotational position check. If the fully 
assembled probe includes one or more extensions, the following check 
should be performed immediately after the completion of a velocity 
traverse. At the discretion of the tester, additional checks may be 
conducted after completion of testing at any sample port. Without 
altering the alignment of any of the components of the probe 
assembly used in the velocity traverse, secure the fully assembled 
probe in a horizontal position. Affix an angle-measuring device at 
the reference scribe line specified in section 6.1.6.1. Use the 
other angle-measuring device to check the angle at each location 
where the device was checked prior to testing. Record the readings 
from the two angle-measuring devices.
    18.1.2  Rotational position check with probe in stack. This 
section applies only to probes that, due to physical constraints, 
cannot be inserted into the test port as fully assembled with all 
necessary extensions needed to reach the inner-most traverse 
point(s).
    18.1.2.1  Perform the out-of-stack procedure in section 18.1.1 
on the main probe and any attached extensions that will be initially 
inserted into the test port.
    18.1.2.2  Use the following procedures to perform additional 
rotational position check(s) with the probe in the stack, each time 
a probe extension is added. Two angle-measuring devices are 
required. The first of these is the device that was used to measure 
yaw angles at the preceding traverse point, left in its properly 
aligned measurement position. The second angle-measuring device is 
positioned on the added probe extension. Use the applicable 
procedures in section 18.1.1.1 or 18.1.1.2 to align, adjust, lock, 
and mark (if necessary) the position of the second angle-measuring 
device to within 1 deg. of the first device. Record the 
readings of the two devices on a form similar to Table 2F-2.
    18.1.2.3  The procedure in section 18.1.2.2 should be performed 
at the first port where measurements are taken. The procedure should 
be repeated each time a probe extension is re-attached at a 
subsequent port, unless the probe extensions are designed to be 
locked into a mechanically fixed rotational position (e.g., through 
use of interlocking grooves), which can be reproduced from port to 
port as specified in section 8.3.5.2.
    18.2  Annex B--Angle Measurement Protocol for Protractor Wheel 
and Pointer Device. The following procedure shall be used when a 
protractor wheel and pointer assembly, such as the one described in 
section 6.2.2 and illustrated in Figure 2F-7 is used to measure the 
yaw angle of flow. With each move to a new traverse point, unlock, 
re-align, and re-lock the probe, angle-pointer collar, and 
protractor wheel to each other. At each such move, particular 
attention is required to ensure that the scribe line on the angle 
pointer collar is either aligned with the reference scribe line on 
the main probe sheath or is at the rotational offset position 
established under section 8.3.1. The procedure consists of the 
following steps:
    18.2.1  Affix a protractor wheel to the entry port for the test 
probe in the stack or duct.
    18.2.2  Orient the protractor wheel so that the 0 deg. mark 
corresponds to the longitudinal axis of the stack or duct. For 
stacks, vertical ducts, or ports on the side of horizontal ducts, 
use a digital inclinometer meeting the specifications in section 
6.2.1 to locate the 0 deg. orientation. For ports on the top or 
bottom of horizontal ducts, identify the longitudinal axis at each 
test port and permanently mark the duct to indicate the 0 deg. 
orientation. Once the protractor wheel is properly aligned, lock it 
into position on the test port.
    18.2.3  Move the pointer assembly along the probe sheath to the 
position needed to take measurements at the first traverse point. 
Align the scribe line on the pointer collar with the reference 
scribe line or at the rotational offset position established under 
section 8.3.1. Maintaining this rotational alignment, lock the 
pointer device onto the probe sheath. Insert the probe into the 
entry port to the depth needed to take measurements at the first 
traverse point.
    18.2.4  Perform the yaw angle determination as specified in 
sections 8.9.3 and 8.9.4 and record the angle as shown by the 
pointer on the protractor wheel. Then, take velocity pressure and 
temperature measurements in accordance with the procedure in section 
8.9.5. Perform the alignment check described in section 8.9.6.
    18.2.5  After taking velocity pressure measurements at that 
traverse point, unlock the probe from the collar and slide the probe 
through the collar to the depth needed to reach the next traverse 
point.
    18.2.6  Align the scribe line on the pointer collar with the 
reference scribe line on the main probe or at the rotational offset 
position established under section 8.3.1. Lock the collar onto the 
probe.
    18.2.7  Repeat the steps in sections 18.2.4 through 18.2.6 at 
the remaining traverse points accessed from the current stack or 
duct entry port.
    18.2.8  After completing the measurement at the last traverse 
point accessed from a port, verify that the orientation of the 
protractor wheel on the test port has not changed over the course of 
the traverse at that port. For stacks, vertical ducts, or ports on 
the side of horizontal ducts, use a digital inclinometer meeting the 
specifications in section 6.2.1 to check the rotational position of 
the 0 deg. mark on the protractor wheel. For ports on the top or 
bottom of horizontal ducts, observe the alignment of the angle wheel 
0 deg. mark relative to the permanent 0 deg. mark on the duct at 
that test port. If these observed comparisons exceed 
2 deg. of 0 deg., all angle and pressure measurements 
taken at that port since the protractor wheel was last locked into 
position on the port shall be repeated.
    18.2.9  Move to the next stack or duct entry port and repeat the 
steps in sections 18.2.1 through 18.2.8.
    18.3  Annex C--Guideline for Reference Scribe Line Placement. 
Use of the following guideline is recommended to satisfy the 
requirements of section 10.4 of this method. The rotational position 
of the reference scribe line should be either 90 deg. or 180 deg. 
from the probe's impact pressure port.
    18.4  Annex D--Determination of Reference Scribe Line Rotational 
Offset. The following procedures are recommended for determining the 
magnitude and sign of a probe's reference scribe line rotational 
offset, RSLO. Separate procedures are provided for two 
types of angle-measuring devices: digital inclinometers and 
protractor wheel and pointer assemblies.
    18.4.1  Perform the following procedures on the main probe with 
all devices that will be attached to the main probe in the field 
[such as thermocouples or resistance temperature detectors (RTDs)] 
that may affect the flow around the probe head. Probe shaft 
extensions that do not affect flow around the probe head need not be 
attached during calibration.
    18.4.2  The procedures below assume that the wind tunnel duct 
used for probe calibration is horizontal and that the flow in the 
calibration wind tunnel is axial as determined by the axial flow 
verification check described in section 10.1.2. Angle-measuring 
devices are assumed to display angles in alternating 0 deg. to 
90 deg. and 90 deg. to 0 deg. intervals. If angle-measuring devices 
with other readout conventions are used or if other calibration wind 
tunnel duct configurations are used, make the appropriate 
calculational corrections.
    18.4.2.1  Position the angle-measuring device in accordance with 
one of the following procedures.
    18.4.2.1.1  If using a digital inclinometer, affix the 
calibrated digital inclinometer to the probe. If the digital 
inclinometer can be independently adjusted after being locked into 
position on the probe sheath (e.g., by means of a set screw), the 
independent adjustment must be set so that the device performs 
exactly like a device without the capability for independent 
adjustment. That is, when aligned on the probe the device must give 
the same readings as a device that does not have the capability of 
being independently adjusted. Either align it directly on the 
reference scribe line or on a mark aligned with the scribe line 
determined according to the procedures in section 18.1.1.1. 
Maintaining this rotational alignment, lock the digital inclinometer 
onto the probe sheath.
    18.4.2.1.2  If using a protractor wheel and pointer device, 
orient the protractor wheel on the test port so that the 0 deg. mark 
is aligned with the longitudinal axis of the wind tunnel duct. 
Maintaining this alignment, lock the wheel into place on the wind 
tunnel test port. Align the scribe line on the pointer collar with 
the reference scribe line or with a mark aligned with the reference 
scribe line, as determined under section 18.1.1.1. Maintaining this 
rotational alignment, lock the pointer device onto the probe sheath.
    18.4.2.2  Zero the pressure-measuring device used for yaw 
nulling.
    18.4.2.3  Insert the probe assembly into the wind tunnel through 
the entry port,

[[Page 26503]]

positioning the probe's impact port at the calibration location. 
Check the responsiveness of the pressure-measuring device to probe 
rotation, taking corrective action if the response is unacceptable.
    18.4.2.4  Ensure that the probe is in a horizontal position 
using a carpenter's level.
    18.4.2.5  Rotate the probe either clockwise or counterclockwise 
until a yaw null (P2=P3) is obtained.
    18.4.2.6  Read and record the value of null, 
the angle indicated by the angle-measuring device at the yaw-null 
position. Record the angle reading on a form similar to Table 2F-6. 
Do not associate an algebraic sign with this reading.
    18.4.2.7  Determine the magnitude and algebraic sign of the 
reference scribe line rotational offset, RSLO. The 
magnitude of RSLO will be equal to either 
null or (90 deg.-null), 
depending on the angle-measuring device used. (See Table 2F-7 for a 
summary.) The algebraic sign of RSLO will either be 
positive, if the rotational position of the reference scribe line is 
clockwise, or negative, if counterclockwise with respect to the 
probe's yaw-null position. Figure 2F-13 illustrates how the 
magnitude and sign of RSLO are determined.
    18.4.2.8  Perform the steps in sections 18.4.2.3 through 
18.4.2.7 twice at each of the two calibration velocities selected 
for the probe under section 10.6. Record the values of 
RSLO in a form similar to Table 2F-6.
    18.4.2.9  The average of all RSLO values is the 
reference scribe line rotational offset for the probe.

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Method 2G--Determination of Stack Gas Velocity and Volumetric Flow Rate 
With Two-Dimensional Probes

    Note: This method does not include all of the specifications 
(e.g., equipment and supplies) and procedures (e.g., sampling) 
essential to its performance. Some material has been incorporated 
from other methods in this part. Therefore, to obtain reliable 
results, those using this method should have a thorough knowledge of 
at least the following additional test methods: Methods 1, 2, 3 or 
3A, and 4.

1.0  Scope and Application

    1.1  This method is applicable for the determination of yaw 
angle, near-axial velocity, and the volumetric flow rate of a gas 
stream in a stack or duct using a two-dimensional (2-D) probe.

2.0  Summary of Method

2.1  A 2-D probe is used to measure the velocity pressure and the 
yaw angle of the flow velocity vector in a stack or duct. 
Alternatively, these measurements may be made by operating one of 
the three-dimensional (3-D) probes described in Method 2F, in yaw 
determination mode only. From these measurements and a determination 
of the stack gas density, the average near-axial velocity of the 
stack gas is calculated. The near-axial velocity accounts for the 
yaw, but not the pitch, component of flow. The average gas 
volumetric flow rate in the stack or duct is then determined from 
the average near-axial velocity.

3.0  Definitions

    3.1.  Angle-measuring Device Rotational Offset 
(RADO). The rotational position of an angle-measuring 
device relative to the reference scribe line, as determined during 
the pre-test rotational position check described in section 8.3.
    3.2  Calibration Pitot Tube. The standard (Prandtl type) pitot 
tube used as a reference when calibrating a probe under this method.
    3.3  Field Test. A set of measurements conducted at a specific 
unit or exhaust stack/duct to satisfy the applicable regulation 
(e.g., a three-run boiler performance test, a single-or multiple-
load nine-run relative accuracy test).
    3.4  Full Scale of Pressure-measuring Device. Full scale refers 
to the upper limit of the measurement range displayed by the device. 
For bi-directional pressure gauges, full scale includes the entire 
pressure range from the lowest negative value to the highest 
positive value on the pressure scale.
    3.5  Main probe. Refers to the probe head and that section of 
probe sheath directly attached to the probe head. The main probe 
sheath is distinguished from probe extensions, which are sections of 
sheath added onto the main probe to extend its reach.
    3.6 ``May,'' ``Must,'' ``Shall,'' ``Should,'' and the imperative 
form of verbs.
    3.6.1 ``May'' is used to indicate that a provision of this 
method is optional.
    3.6.2 ``Must,'' ``Shall,'' and the imperative form of verbs 
(such as ``record'' or ``enter'') are used to indicate that a 
provision of this method is mandatory.
    3.6.3 ``Should'' is used to indicate that a provision of this 
method is not mandatory, but is highly recommended as good practice.
    3.7 Method 1. Refers to 40 CFR part 60, appendix A, ``Method 1--
Sample and velocity traverses for stationary sources.''
    3.8 Method 2. Refers to 40 CFR part 60, appendix A, ``Method 2--
Determination of stack gas velocity and volumetric flow rate (Type S 
pitot tube).''
    3.9 Method 2F. Refers to 40 CFR part 60, appendix A, ``Method 
2F--Determination of stack gas velocity and volumetric flow rate 
with three-dimensional probes.''
    3.10 Near-axial Velocity. The velocity vector parallel to the 
axis of the stack or duct that accounts for the yaw angle component 
of gas flow. The term ``near-axial'' is used herein to indicate that 
the velocity and volumetric flow rate results account for the 
measured yaw angle component of flow at each measurement point.
    3.11 Nominal Velocity. Refers to a wind tunnel velocity setting 
that approximates the actual wind tunnel velocity to within 
1.5 m/sec (5 ft/sec).
    3.12 Pitch Angle. The angle between the axis of the stack or 
duct and the pitch component of flow, i.e., the component of the 
total velocity vector in a plane defined by the traverse line and 
the axis of the stack or duct. (Figure 2G-1 illustrates the ``pitch 
plane.'') From the standpoint of a tester facing a test port in a 
vertical stack, the pitch component of flow is the vector of flow 
moving from the center of the stack toward or away from that test 
port. The pitch angle is the angle described by this pitch component 
of flow and the vertical axis of the stack.
    3.13  Readability. For the purposes of this method, readability 
for an analog measurement device is one half of the smallest scale 
division. For a digital measurement device, it is the number of 
decimals displayed by the device.
    3.14  Reference Scribe Line. A line permanently inscribed on the 
main probe sheath (in accordance with section 6.1.5.1) to serve as a 
reference mark for determining yaw angles.
    3.15  Reference Scribe Line Rotational Offset (RSLO). 
The rotational position of a probe's reference scribe line relative 
to the probe's yaw-null position, as determined during the yaw angle 
calibration described in section 10.5.
    3.16  Response Time. The time required for the measurement 
system to fully respond to a change from zero differential pressure 
and ambient temperature to the stable stack or duct pressure and 
temperature readings at a traverse point.
    3.17  Tested Probe. A probe that is being calibrated.
    3.18  Three-dimensional (3-D) Probe. A directional probe used to 
determine the velocity pressure and the yaw and pitch angles in a 
flowing gas stream.
    3.19  Two-dimensional (2-D) Probe. A directional probe used to 
measure velocity pressure and yaw angle in a flowing gas stream.
    3.20  Traverse Line. A diameter or axis extending across a stack 
or duct on which measurements of velocity pressure and flow angles 
are made.
    3.21  Wind Tunnel Calibration Location. A point, line, area, or 
volume within the wind tunnel test section at, along, or within 
which probes are calibrated. At a particular wind tunnel velocity 
setting, the average velocity pressures at specified points at, 
along, or within the calibration location shall vary by no more than 
2 percent or 0.3 mm H20 (0.01 in. H2O), 
whichever is less restrictive, from the average velocity pressure at 
the calibration pitot tube location. Air flow at this location shall 
be axial, i.e., yaw and pitch angles within 3 of 0. 
Compliance with these flow criteria shall be demonstrated by 
performing the procedures prescribed in sections 10.1.1 and 10.1.2. 
For circular tunnels, no part of the calibration location may be 
closer to the tunnel wall than 10.2 cm (4 in.) or 25 percent of the 
tunnel diameter, whichever is farther from the wall. For elliptical 
or rectangular tunnels, no part of the calibration location may be 
closer to the tunnel wall than 10.2 cm (4 in.) or 25 percent of the 
applicable cross-sectional axis, whichever is farther from the wall.
    3.22  Wind Tunnel with Documented Axial Flow. A wind tunnel 
facility documented as meeting the provisions of sections 10.1.1 
(velocity pressure cross-check) and 10.1.2 (axial flow verification) 
using the procedures described in these sections or alternative 
procedures determined to be technically equivalent.
    3.23  Yaw Angle. The angle between the axis of the stack or duct 
and the yaw component of flow, i.e., the component of the total 
velocity vector in a plane perpendicular to the traverse line at a 
particular traverse point. (Figure 2G-1 illustrates the ``yaw 
plane.'') From the standpoint of a tester facing a test port in a 
vertical stack, the yaw component of flow is the vector of flow 
moving to the left or right from the center of the stack as viewed 
by the tester. (This is sometimes referred to as ``vortex flow,'' 
i.e., flow around the centerline of a stack or duct.) The yaw angle 
is the angle described by this yaw component of flow and the 
vertical axis of the stack. The algebraic sign convention is 
illustrated in Figure 2G-2.
    3.24  Yaw Nulling. A procedure in which a Type-S pitot tube or a 
3-D probe is rotated about its axis in a stack or duct until a zero 
differential pressure reading (``yaw null'') is obtained. When a 
Type S probe is yaw-nulled, the rotational position of its impact 
port is 90 deg. from the direction of flow in the stack or duct and 
the  P reading is zero. When a 3-D probe is yaw-nulled, 
its impact pressure port (P1) faces directly into the 
direction of flow in the stack or duct and the differential pressure 
between pressure ports P2 and P3 is zero.

4.0  Interferences. [Reserved]

5.0  Safety

    5.1  This test method may involve hazardous operations and the 
use of hazardous materials or equipment. This method does not 
purport to address all of the safety problems associated with its 
use. It is the responsibility of the user to establish and implement 
appropriate safety and health practices and to determine the 
applicability of regulatory limitations before using this test 
method.

[[Page 26525]]

6.0  Equipment and Supplies

    6.1  Two-dimensional Probes. Probes that provide both the 
velocity pressure and the yaw angle of the flow vector in a stack or 
duct, as listed in sections 6.1.1 and 6.1.2, qualify for use based 
on comprehensive wind tunnel and field studies involving both inter-
and intra-probe comparisons by multiple test teams. Each 2-D probe 
shall have a unique identification number or code permanently marked 
on the main probe sheath. Each probe shall be calibrated prior to 
use according to the procedures in section 10. Manufacturer-supplied 
calibration data shall be used as example information only, except 
when the manufacturer calibrates the probe as specified in section 
10 and provides complete documentation.
    6.1.1  Type S (Stausscheibe or reverse type) pitot tube. This is 
the same as specified in Method 2, section 2.1, except for the 
following additional specifications that enable the pitot tube to 
accurately determine the yaw component of flow. For the purposes of 
this method, the external diameter of the tubing used to construct 
the Type S pitot tube (dimension Dt in Figure 2-2 of 
Method 2) shall be no less than 9.5 mm (3/8 in.). The pitot tube 
shall also meet the following alignment specifications. The angles 
1, 2, 1, 
and 2, as shown in Method 2, Figure 2-3, shall 
not exceed 2 deg.. The dimensions w and z, shown in 
Method 2, Figure 2-3 shall not exceed 0.5 mm (0.02 in.).
    6.1.1.1  Manual Type S probe. This refers to a Type S probe that 
is positioned at individual traverse points and yaw nulled manually 
by an operator.
    6.1.1.2  Automated Type S probe. This refers to a system that 
uses a computer-controlled motorized mechanism to position the Type 
S pitot head at individual traverse points and perform yaw angle 
determinations.
    6.1.2  Three-dimensional probes used in 2-D mode. A 3-D probe, 
as specified in sections 6.1.1 through 6.1.3 of Method 2F, may, for 
the purposes of this method, be used in a two-dimensional mode 
(i.e., measuring yaw angle, but not pitch angle). When the 3-D probe 
is used as a 2-D probe, only the velocity pressure and yaw-null 
pressure are obtained using the pressure taps referred to as 
P1, P2, and P3. The differential 
pressure P1-P2 is a function of total velocity 
and corresponds to the P obtained using the Type S probe. 
The differential pressure P2-P3 is used to yaw 
null the probe and determine the yaw angle. The differential 
pressure P4-P5, which is a function of pitch 
angle, is not measured when the 3-D probe is used in 2-D mode.
    6.1.3  Other probes. [Reserved]
    6.1.4  Probe sheath. The probe shaft shall include an outer 
sheath to: (1) provide a surface for inscribing a permanent 
reference scribe line, (2) accommodate attachment of an angle-
measuring device to the probe shaft, and (3) facilitate precise 
rotational movement of the probe for determining yaw angles. The 
sheath shall be rigidly attached to the probe assembly and shall 
enclose all pressure lines from the probe head to the farthest 
position away from the probe head where an angle-measuring device 
may be attached during use in the field. The sheath of the fully 
assembled probe shall be sufficiently rigid and straight at all 
rotational positions such that, when one end of the probe shaft is 
held in a horizontal position, the fully extended probe meets the 
horizontal straightness specifications indicated in section 8.2 
below.
    6.1.5  Scribe lines.
    6.1.5.1  Reference scribe line. A permanent line, no greater 
than 1.6 mm (1/16 in.) in width, shall be inscribed on each manual 
probe that will be used to determine yaw angles of flow. This line 
shall be placed on the main probe sheath in accordance with the 
procedures described in section 10.4 and is used as a reference 
position for installation of the yaw angle-measuring device on the 
probe. At the discretion of the tester, the scribe line may be a 
single line segment placed at a particular position on the probe 
sheath (e.g., near the probe head), multiple line segments placed at 
various locations along the length of the probe sheath (e.g., at 
every position where a yaw angle-measuring device may be mounted), 
or a single continuous line extending along the full length of the 
probe sheath.
    6.1.5.2  Scribe line on probe extensions. A permanent line may 
also be inscribed on any probe extension that will be attached to 
the main probe in performing field testing. This allows a yaw angle-
measuring device mounted on the extension to be readily aligned with 
the reference scribe line on the main probe sheath.
    6.1.5.3  Alignment specifications. This specification shall be 
met separately, using the procedures in section 10.4.1, on the main 
probe and on each probe extension. The rotational position of the 
scribe line or scribe line segments on the main probe or any probe 
extension must not vary by more than 2 deg.. That is, the difference 
between the minimum and maximum of all of the rotational angles that 
are measured along the full length of the main probe or the probe 
extension must not exceed 2 deg..
    6.1.6  Probe and system characteristics to ensure horizontal 
stability.
    6.1.6.1  For manual probes, it is recommended that the effective 
length of the probe (coupled with a probe extension, if necessary) 
be at least 0.9 m (3 ft.) longer than the farthest traverse point 
mark on the probe shaft away from the probe head. The operator 
should maintain the probe's horizontal stability when it is fully 
inserted into the stack or duct. If a shorter probe is used, the 
probe should be inserted through a bushing sleeve, similar to the 
one shown in Figure 2G-3, that is installed on the test port; such a 
bushing shall fit snugly around the probe and be secured to the 
stack or duct entry port in such a manner as to maintain the probe's 
horizontal stability when fully inserted into the stack or duct.
    6.1.6.2  An automated system that includes an external probe 
casing with a transport system shall have a mechanism for 
maintaining horizontal stability comparable to that obtained by 
manual probes following the provisions of this method. The automated 
probe assembly shall also be constructed to maintain the alignment 
and position of the pressure ports during sampling at each traverse 
point. The design of the probe casing and transport system shall 
allow the probe to be removed from the stack or duct and checked 
through direct physical measurement for angular position and 
insertion depth.
    6.1.7  The tubing that is used to connect the probe and the 
pressure-measuring device should have an inside diameter of at least 
3.2 mm (\1/8\ in.), to reduce the time required for pressure 
equilibration, and should be as short as practicable.
    6.1.8  If a detachable probe head without a sheath [e.g., a 
pitot tube, typically 15.2 to 30.5 cm (6 to 12 in.) in length] is 
coupled with a probe sheath and calibrated in a wind tunnel in 
accordance with the yaw angle calibration procedure in section 10.5, 
the probe head shall remain attached to the probe sheath during 
field testing in the same configuration and orientation as 
calibrated. Once the detachable probe head is uncoupled or re-
oriented, the yaw angle calibration of the probe is no longer valid 
and must be repeated before using the probe in subsequent field 
tests.
    6.2  Yaw Angle-measuring Device. One of the following devices 
shall be used for measurement of the yaw angle of flow.
    6.2.1  Digital inclinometer. This refers to a digital device 
capable of measuring and displaying the rotational position of the 
probe to within 1 deg.. The device shall be able to be 
locked into position on the probe sheath or probe extension, so that 
it indicates the probe's rotational position throughout the test. A 
rotational position collar block that can be attached to the probe 
sheath (similar to the collar shown in Figure 2G-4) may be required 
to lock the digital inclinometer into position on the probe sheath.
    6.2.2  Protractor wheel and pointer assembly. This apparatus, 
similar to that shown in Figure 2G-5, consists of the following 
components.
    6.2.2.1  A protractor wheel that can be attached to a port 
opening and set in a fixed rotational position to indicate the yaw 
angle position of the probe's scribe line relative to the 
longitudinal axis of the stack or duct. The protractor wheel must 
have a measurement ring on its face that is no less than 17.8 cm (7 
in.) in diameter, shall be able to be rotated to any angle and then 
locked into position on the stack or duct test port, and shall 
indicate angles to a resolution of 1 deg..
    6.2.2.2  A pointer assembly that includes an indicator needle 
mounted on a collar that can slide over the probe sheath and be 
locked into a fixed rotational position on the probe sheath. The 
pointer needle shall be of sufficient length, rigidity, and 
sharpness to allow the tester to determine the probe's angular 
position to within 1 deg. from the markings on the protractor wheel. 
Corresponding to the position of the pointer, the collar must have a 
scribe line to be used in aligning the pointer with the scribe line 
on the probe sheath.
    6.2.3  Other yaw angle-measuring devices. Other angle-measuring 
devices with a manufacturer's specified precision of 1 deg. or 
better may be used, if approved by the Administrator.
    6.3  Probe Supports and Stabilization Devices. When probes are 
used for determining flow angles, the probe head should be kept in a 
stable horizontal

[[Page 26526]]

position. For probes longer than 3.0 m (10 ft.), the section of the 
probe that extends outside the test port shall be secured. Three 
alternative devices are suggested for maintaining the horizontal 
position and stability of the probe shaft during flow angle 
determinations and velocity pressure measurements: (1) monorails 
installed above each port, (2) probe stands on which the probe shaft 
may be rested, or (3) bushing sleeves of sufficient length secured 
to the test ports to maintain probes in a horizontal position. 
Comparable provisions shall be made to ensure that automated systems 
maintain the horizontal position of the probe in the stack or duct. 
The physical characteristics of each test platform may dictate the 
most suitable type of stabilization device. Thus, the choice of a 
specific stabilization device is left to the judgement of the 
testers.
    6.4  Differential Pressure Gauges. The velocity pressure 
(P) measuring devices used during wind tunnel calibrations 
and field testing shall be either electronic manometers (e.g., 
pressure transducers), fluid manometers, or mechanical pressure 
gauges (e.g., Magnehelic gauges). Use of electronic 
manometers is recommended. Under low velocity conditions, use of 
electronic manometers may be necessary to obtain acceptable 
measurements.
    6.4.1  Differential pressure-measuring device. This refers to a 
device capable of measuring pressure differentials and having a 
readability of 1 percent of full scale. The device shall 
be capable of accurately measuring the maximum expected pressure 
differential. Such devices are used to determine the following 
pressure measurements: velocity pressure, static pressure, and yaw-
null pressure. For an inclined-vertical manometer, the readability 
specification of 1 percent shall be met separately using 
the respective full-scale upper limits of the inclined and vertical 
portions of the scales. To the extent practicable, the device shall 
be selected such that most of the pressure readings are between 10 
and 90 percent of the device's full-scale measurement range (as 
defined in section 3.4). In addition, pressure-measuring devices 
should be selected such that the zero does not drift by more than 5 
percent of the average expected pressure readings to be encountered 
during the field test. This is particularly important under low 
pressure conditions.
    6.4.2  Gauge used for yaw nulling. The differential pressure-
measuring device chosen for yaw nulling the probe during the wind 
tunnel calibrations and field testing shall be bi-directional, i.e., 
capable of reading both positive and negative differential 
pressures. If a mechanical, bi-directional pressure gauge is chosen, 
it shall have a full-scale range no greater than 2.6 cm (i.e., -1.3 
to +1.3 cm) [1 in. H2O (i.e., -0.5 in. to +0.5 in.)].
    6.4.3  Devices for calibrating differential pressure-measuring 
devices. A precision manometer (e.g., a U-tube, inclined, or 
inclined-vertical manometer, or micromanometer) or NIST (National 
Institute of Standards and Technology) traceable pressure source 
shall be used for calibrating differential pressure-measuring 
devices. The device shall be maintained under laboratory conditions 
or in a similar protected environment (e.g., a climate-controlled 
trailer). It shall not be used in field tests. The precision 
manometer shall have a scale gradation of 0.3 mm H2O 
(0.01 in. H2O), or less, in the range of 0 to 5.1 cm 
H2O (0 to 2 in. H2O) and 2.5 mm H2O 
(0.1 in. H2O), or less, in the range of 5.1 to 25.4 cm 
H2O (2 to 10 in. H2O). The manometer shall 
have manufacturer's documentation that it meets an accuracy 
specification of at least 0.5 percent of full scale. The NIST-
traceable pressure source shall be recertified annually.
    6.4.4  Devices used for post-test calibration check. A precision 
manometer meeting the specifications in section 6.4.3, a pressure-
measuring device or pressure source with a documented calibration 
traceable to NIST, or an equivalent device approved by the 
Administrator shall be used for the post-test calibration check. The 
pressure-measuring device shall have a readability equivalent to or 
greater than the tested device. The pressure source shall be capable 
of generating pressures between 50 and 90 percent of the range of 
the tested device and known to within 1 percent of the 
full scale of the tested device. The pressure source shall be 
recertified annually.
    6.5  Data Display and Capture Devices. Electronic manometers (if 
used) shall be coupled with a data display device (such as a digital 
panel meter, personal computer display, or strip chart) that allows 
the tester to observe and validate the pressure measurements taken 
during testing. They shall also be connected to a data recorder 
(such as a data logger or a personal computer with data capture 
software) that has the ability to compute and retain the appropriate 
average value at each traverse point, identified by collection time 
and traverse point.
    6.6  Temperature Gauges. For field tests, a thermocouple or 
resistance temperature detector (RTD) capable of measuring 
temperature to within 3 deg.C (5 deg.F) of 
the stack or duct temperature shall be used. The thermocouple shall 
be attached to the probe such that the sensor tip does not touch any 
metal. The position of the thermocouple relative to the pressure 
port face openings shall be in the same configuration as used for 
the probe calibrations in the wind tunnel. Temperature gauges used 
for wind tunnel calibrations shall be capable of measuring 
temperature to within 0.6 deg.C (1 deg.F) of 
the temperature of the flowing gas stream in the wind tunnel.
    6.7  Stack or Duct Static Pressure Measurement. The pressure-
measuring device used with the probe shall be as specified in 
section 6.4 of this method. The static tap of a standard (Prandtl 
type) pitot tube or one leg of a Type S pitot tube with the face 
opening planes positioned parallel to the gas flow may be used for 
this measurement. Also acceptable is the pressure differential 
reading of P1-Pbar from a five-hole prism-
shaped 3-D probe, as specified in section 6.1.1 of Method 2F (such 
as the Type DA or DAT probe), with the P1 pressure port 
face opening positioned parallel to the gas flow in the same manner 
as the Type S probe. However, the 3-D spherical probe, as specified 
in section 6.1.2 of Method 2F, is unable to provide this measurement 
and shall not be used to take static pressure measurements. Static 
pressure measurement is further described in section 8.11.
    6.8  Barometer. Same as Method 2, section 2.5.
    6.9  Gas Density Determination Equipment. Method 3 or 3A shall 
be used to determine the dry molecular weight of the stack or duct 
gas. Method 4 shall be used for moisture content determination and 
computation of stack or duct gas wet molecular weight. Other methods 
may be used, if approved by the Administrator.
    6.10  Calibration Pitot Tube. Same as Method 2, section 2.7.
    6.11  Wind Tunnel for Probe Calibration. Wind tunnels used to 
calibrate velocity probes must meet the following design 
specifications.
    6.11.1  Test section cross-sectional area. The flowing gas 
stream shall be confined within a circular, rectangular, or 
elliptical duct. The cross-sectional area of the tunnel must be 
large enough to ensure fully developed flow in the presence of both 
the calibration pitot tube and the tested probe. The calibration 
site, or ``test section,'' of the wind tunnel shall have a minimum 
diameter of 30.5 cm (12 in.) for circular or elliptical duct cross-
sections or a minimum width of 30.5 cm (12 in.) on the shorter side 
for rectangular cross-sections. Wind tunnels shall meet the probe 
blockage provisions of this section and the qualification 
requirements prescribed in section 10.1. The projected area of the 
portion of the probe head, shaft, and attached devices inside the 
wind tunnel during calibration shall represent no more than 4 
percent of the cross-sectional area of the tunnel. The projected 
area shall include the combined area of the calibration pitot tube 
and the tested probe if both probes are placed simultaneously in the 
same cross-sectional plane in the wind tunnel, or the larger 
projected area of the two probes if they are placed alternately in 
the wind tunnel.
    6.11.2  Velocity range and stability. The wind tunnel should be 
capable of maintaining velocities between 6.1 m/sec and 30.5 m/sec 
(20 ft/sec and 100 ft/sec). The wind tunnel shall produce fully 
developed flow patterns that are stable and parallel to the axis of 
the duct in the test section.
    6.11.3  Flow profile at the calibration location. The wind 
tunnel shall provide axial flow within the test section calibration 
location (as defined in section 3.21). Yaw and pitch angles in the 
calibration location shall be within 3 deg. of 0 deg.. 
The procedure for determining that this requirement has been met is 
described in section 10.1.2.
    6.11.4  Entry ports in the wind tunnel test section.
    6.11.4.1  Port for tested probe. A port shall be constructed for 
the tested probe. This port shall be located to allow the head of 
the tested probe to be positioned within the wind tunnel calibration 
location (as defined in section 3.21). The tested probe shall be 
able to be locked into the 0 deg. pitch angle position. To 
facilitate alignment of the probe during calibration, the test 
section should include a

[[Page 26527]]

window constructed of a transparent material to allow the tested 
probe to be viewed.
    6.11.4.2  Port for verification of axial flow. Depending on the 
equipment selected to conduct the axial flow verification prescribed 
in section 10.1.2, a second port, located 90 deg. from the entry 
port for the tested probe, may be needed to allow verification that 
the gas flow is parallel to the central axis of the test section. 
This port should be located and constructed so as to allow one of 
the probes described in section 10.1.2.2 to access the same test 
point(s) that are accessible from the port described in section 
6.11.4.1.
    6.11.4.3  Port for calibration pitot tube. The calibration pitot 
tube shall be used in the port for the tested probe or in a separate 
entry port. In either case, all measurements with the calibration 
pitot tube shall be made at the same point within the wind tunnel 
over the course of a probe calibration. The measurement point for 
the calibration pitot tube shall meet the same specifications for 
distance from the wall and for axial flow as described in section 
3.21 for the wind tunnel calibration location.

7.0  Reagents and Standards. [Reserved]

8.0  Sample Collection and Analysis

8.1  Equipment Inspection and Set Up

    8.1.1  All 2-D and 3-D probes, differential pressure-measuring 
devices, yaw angle-measuring devices, thermocouples, and barometers 
shall have a current, valid calibration before being used in a field 
test. (See sections 10.3.3, 10.3.4, and 10.5 through 10.10 for the 
applicable calibration requirements.)
    8.1.2  Before each field use of a Type S probe, perform a visual 
inspection to verify the physical condition of the pitot tube. 
Record the results of the inspection. If the face openings are 
noticeably misaligned or there is visible damage to the face 
openings, the probe shall not be used until repaired, the 
dimensional specifications verified (according to the procedures in 
section 10.2.1), and the probe recalibrated.
    8.1.3  Before each field use of a 3-D probe, perform a visual 
inspection to verify the physical condition of the probe head 
according to the procedures in section 10.2 of Method 2F. Record the 
inspection results on a form similar to Table 2F-1 presented in 
Method 2F. If there is visible damage to the 3-D probe, the probe 
shall not be used until it is recalibrated.
    8.1.4  After verifying that the physical condition of the probe 
head is acceptable, set up the apparatus using lengths of flexible 
tubing that are as short as practicable. Surge tanks installed 
between the probe and pressure-measuring device may be used to 
dampen pressure fluctuations provided that an adequate measurement 
system response time (see section 8.8) is maintained.
    8.2  Horizontal Straightness Check. A horizontal straightness 
check shall be performed before the start of each field test, except 
as otherwise specified in this section. Secure the fully assembled 
probe (including the probe head and all probe shaft extensions) in a 
horizontal position using a stationary support at a point along the 
probe shaft approximating the location of the stack or duct entry 
port when the probe is sampling at the farthest traverse point from 
the stack or duct wall. The probe shall be rotated to detect bends. 
Use an angle-measuring device or trigonometry to determine the bend 
or sag between the probe head and the secured end. (See Figure 2G-
6.) Probes that are bent or sag by more than 5 deg. shall not be 
used. Although this check does not apply when the probe is used for 
a vertical traverse, care should be taken to avoid the use of bent 
probes when conducting vertical traverses. If the probe is 
constructed of a rigid steel material and consists of a main probe 
without probe extensions, this check need only be performed before 
the initial field use of the probe, when the probe is recalibrated, 
when a change is made to the design or material of the probe 
assembly, and when the probe becomes bent. With such probes, a 
visual inspection shall be made of the fully assembled probe before 
each field test to determine if a bend is visible. The probe shall 
be rotated to detect bends. The inspection results shall be 
documented in the field test report. If a bend in the probe is 
visible, the horizontal straightness check shall be performed before 
the probe is used.
    8.3  Rotational Position Check. Before each field test, and each 
time an extension is added to the probe during a field test, a 
rotational position check shall be performed on all manually 
operated probes (except as noted in section 8.3.5 below) to ensure 
that, throughout testing, the angle-measuring device is either: 
aligned to within 1 deg. of the rotational position of 
the reference scribe line; or is affixed to the probe such that the 
rotational offset of the device from the reference scribe line is 
known to within 1 deg.. This check shall consist of 
direct measurements of the rotational positions of the reference 
scribe line and angle-measuring device sufficient to verify that 
these specifications are met. Annex A in section 18 of this method 
gives recommended procedures for performing the rotational position 
check, and Table 2G-2 gives an example data form. Procedures other 
than those recommended in Annex A in section 18 may be used, 
provided they demonstrate whether the alignment specification is met 
and are explained in detail in the field test report.
    8.3.1  Angle-measuring device rotational offset. The tester 
shall maintain a record of the angle-measuring device rotational 
offset, RADO, as defined in section 3.1. Note that 
RADO is assigned a value of 0 deg. when the angle-
measuring device is aligned to within 1 deg. of the 
rotational position of the reference scribe line. The 
RADO shall be used to determine the yaw angle of flow in 
accordance with section 8.9.4.
    8.3.2  Sign of angle-measuring device rotational offset. The 
sign of RADO is positive when the angle-measuring device 
(as viewed from the ``tail'' end of the probe) is positioned in a 
clockwise direction from the reference scribe line and negative when 
the device is positioned in a counterclockwise direction from the 
reference scribe line.
    8.3.3  Angle-measuring devices that can be independently 
adjusted (e.g., by means of a set screw), after being locked into 
position on the probe sheath, may be used. However, the 
RADO must also take into account this adjustment.
    8.3.4  Post-test check. If probe extensions remain attached to 
the main probe throughout the field test, the rotational position 
check shall be repeated, at a minimum, at the completion of the 
field test to ensure that the angle-measuring device has remained 
within 2 deg. of its rotational position established 
prior to testing. At the discretion of the tester, additional checks 
may be conducted after completion of testing at any sample port or 
after any test run. If the 2 deg. specification is not 
met, all measurements made since the last successful rotational 
position check must be repeated. Section 18.1.1.3 of Annex A 
provides an example procedure for performing the post-test check.
    8.3.5  Exceptions.
    8.3.5.1  A rotational position check need not be performed if, 
for measurements taken at all velocity traverse points, the yaw 
angle-measuring device is mounted and aligned directly on the 
reference scribe line specified in sections 6.1.5.1 and 6.1.5.3 and 
no independent adjustments, as described in section 8.3.3, are made 
to device's rotational position.
    8.3.5.2  If extensions are detached and re-attached to the probe 
during a field test, a rotational position check need only be 
performed the first time an extension is added to the probe, rather 
than each time the extension is re-attached, if the probe extension 
is designed to be locked into a mechanically fixed rotational 
position (e.g., through the use of interlocking grooves), that can 
re-establish the initial rotational position to within 
1 deg..
    8.4  Leak Checks. A pre-test leak check shall be conducted 
before each field test. A post-test check shall be performed at the 
end of the field test, but additional leak checks may be conducted 
after any test run or group of test runs. The post-test check may 
also serve as the pre-test check for the next group of test runs. If 
any leak check is failed, all runs since the last passed leak check 
are invalid. While performing the leak check procedures, also check 
each pressure device's responsiveness to changes in pressure.
    8.4.1  To perform the leak check on a Type S pitot tube, 
pressurize the pitot impact opening until at least 7.6 cm 
H2O (3 in. H2O) velocity pressure, or a 
pressure corresponding to approximately 75 percent of the pressure 
device's measurement scale, whichever is less, registers on the 
pressure device; then, close off the impact opening. The pressure 
shall remain stable (2.5 mm H2O, 
0.10 in. H2O) for at least 15 seconds. Repeat 
this procedure for the static pressure side, except use suction to 
obtain the required pressure. Other leak-check procedures may be 
used, if approved by the Administrator.
    8.4.2  To perform the leak check on a 3-D probe, pressurize the 
probe's impact (P1) opening until at least 7.6 cm 
H2O (3 in. H2O) velocity pressure, or a 
pressure corresponding to approximately 75 percent of the pressure 
device's measurement scale, whichever is less, registers on the 
pressure device; then, close off the impact opening. The pressure 
shall remain stable (2.5 mm

[[Page 26528]]

H2O, 0.10 in. H2O) for at least 15 
seconds. Check the P2 and P3 pressure ports in 
the same fashion. Other leak-check procedures may be used, if 
approved by the Administrator.
    8.5  Zeroing the Differential Pressure-measuring Device. Zero 
each differential pressure-measuring device, including the device 
used for yaw nulling, before each field test. At a minimum, check 
the zero after each field test. A zero check may also be performed 
after any test run or group of test runs. For fluid manometers and 
mechanical pressure gauges (e.g., Magnehelic gauges), 
the zero reading shall not deviate from zero by more than 
0.8 mm H2O (0.03 in. 
H2O) or one minor scale division, whichever is greater, 
between checks. For electronic manometers, the zero reading shall 
not deviate from zero between checks by more than: 0.3 
mm H2O (0.01 in. H2O), for full 
scales less than or equal to 5.1 cm H2O (2.0 in. 
H2O); or 0.8 mm H2O 
(0.03 in. H2O), for full scales greater than 
5.1 cm H2O (2.0 in. H2O). (Note: If negative 
zero drift is not directly readable, estimate the reading based on 
the position of the gauge oil in the manometer or of the needle on 
the pressure gauge.) In addition, for all pressure-measuring devices 
except those used exclusively for yaw nulling, the zero reading 
shall not deviate from zero by more than 5 percent of the average 
measured differential pressure at any distinct process condition or 
load level. If any zero check is failed at a specific process 
condition or load level, all runs conducted at that process 
condition or load level since the last passed zero check are 
invalid.
    8.6  Traverse Point Verification. The number and location of the 
traverse points shall be selected based on Method 1 guidelines. The 
stack or duct diameter and port nipple lengths, including any 
extension of the port nipples into the stack or duct, shall be 
verified the first time the test is performed; retain and use this 
information for subsequent field tests, updating it as required. 
Physically measure the stack or duct dimensions or use a calibrated 
laser device; do not use engineering drawings of the stack or duct. 
The probe length necessary to reach each traverse point shall be 
recorded to within 6.4 mm (\1/4\ in.) and, 
for manual probes, marked on the probe sheath. In determining these 
lengths, the tester shall take into account both the distance that 
the port flange projects outside of the stack and the depth that any 
port nipple extends into the gas stream. The resulting point 
positions shall reflect the true distances from the inside wall of 
the stack or duct, so that when the tester aligns any of the 
markings with the outside face of the stack port, the probe's impact 
port shall be located at the appropriate distance from the inside 
wall for the respective Method 1 traverse point. Before beginning 
testing at a particular location, an out-of-stack or duct 
verification shall be performed on each probe that will be used to 
ensure that these position markings are correct. The distances 
measured during the verification must agree with the previously 
calculated distances to within \1/4\ in. For manual 
probes, the traverse point positions shall be verified by measuring 
the distance of each mark from the probe's impact pressure port (the 
P1 port for a 3-D probe). A comparable out-of-stack test 
shall be performed on automated probe systems. The probe shall be 
extended to each of the prescribed traverse point positions. Then, 
the accuracy of the positioning for each traverse point shall be 
verified by measuring the distance between the port flange and the 
probe's impact pressure port.
    8.7  Probe Installation. Insert the probe into the test port. A 
solid material shall be used to seal the port.
    8.8  System Response Time. Determine the response time of the 
probe measurement system. Insert and position the ``cold'' probe (at 
ambient temperature and pressure) at any Method 1 traverse point. 
Read and record the probe differential pressure, temperature, and 
elapsed time at 15-second intervals until stable readings for both 
pressure and temperature are achieved. The response time is the 
longer of these two elapsed times. Record the response time.
    8.9  Sampling.
    8.9.1  Yaw angle measurement protocol. With manual probes, yaw 
angle measurements may be obtained in two alternative ways during 
the field test, either by using a yaw angle-measuring device (e.g., 
digital inclinometer) affixed to the probe, or using a protractor 
wheel and pointer assembly. For horizontal traversing, either 
approach may be used. For vertical traversing, i.e., when measuring 
from on top or into the bottom of a horizontal duct, only the 
protractor wheel and pointer assembly may be used. With automated 
probes, curve-fitting protocols may be used to obtain yaw-angle 
measurements.
    8.9.1.1  If a yaw angle-measuring device affixed to the probe is 
to be used, lock the device on the probe sheath, aligning it either 
on the reference scribe line or in the rotational offset position 
established under section 8.3.1.
    8.9.1.2  If a protractor wheel and pointer assembly is to be 
used, follow the procedures in Annex B of this method.
    8.9.1.3  Curve-fitting procedures. Curve-fitting routines sweep 
through a range of yaw angles to create curves correlating pressure 
to yaw position. To find the zero yaw position and the yaw angle of 
flow, the curve found in the stack is computationally compared to a 
similar curve that was previously generated under controlled 
conditions in a wind tunnel. A probe system that uses a curve-
fitting routine for determining the yaw-null position of the probe 
head may be used, provided that it is verified in a wind tunnel to 
be able to determine the yaw angle of flow to within 
1 deg..
    8.9.1.4  Other yaw angle determination procedures. If approved 
by the Administrator, other procedures for determining yaw angle may 
be used, provided that they are verified in a wind tunnel to be able 
to perform the yaw angle calibration procedure as described in 
section 10.5.
    8.9.2  Sampling strategy. At each traverse point, first yaw-null 
the probe, as described in section 8.9.3, below. Then, with the 
probe oriented into the direction of flow, measure and record the 
yaw angle, the differential pressure and the temperature at the 
traverse point, after stable readings are achieved, in accordance 
with sections 8.9.4 and 8.9.5. At the start of testing in each port 
(i.e., after a probe has been inserted into the flue gas stream), 
allow at least the response time to elapse before beginning to take 
measurements at the first traverse point accessed from that port. 
Provided that the probe is not removed from the flue gas stream, 
measurements may be taken at subsequent traverse points accessed 
from the same test port without waiting again for the response time 
to elapse.
    8.9.3  Yaw-nulling procedure. In preparation for yaw angle 
determination, the probe must first be yaw nulled. After positioning 
the probe at the appropriate traverse point, perform the following 
procedures.
    8.9.3.1  For Type S probes, rotate the probe until a null 
differential pressure reading is obtained. The direction of the 
probe rotation shall be such that the thermocouple is located 
downstream of the probe pressure ports at the yaw-null position. 
Rotate the probe 90 deg. back from the yaw-null position to orient 
the impact pressure port into the direction of flow. Read and record 
the angle displayed by the angle-measuring device.
    8.9.3.2  For 3-D probes, rotate the probe until a null 
differential pressure reading (the difference in pressures across 
the P2 and P3 pressure ports is zero, i.e., 
P2 = P3) is indicated by the yaw angle 
pressure gauge. Read and record the angle displayed by the angle-
measuring device.
    8.9.3.3  Sign of the measured angle. The angle displayed on the 
angle-measuring device is considered positive when the probe's 
impact pressure port (as viewed from the ``tail'' end of the probe) 
is oriented in a clockwise rotational position relative to the stack 
or duct axis and is considered negative when the probe's impact 
pressure port is oriented in a counterclockwise rotational position 
(see Figure 2G-7).
    8.9.4  Yaw angle determination. After performing the applicable 
yaw-nulling procedure in section 8.9.3, determine the yaw angle of 
flow according to one of the following procedures. Special care must 
be observed to take into account the signs of the recorded angle 
reading and all offsets.
    8.9.4.1  Direct-reading. If all rotational offsets are zero or 
if the angle-measuring device rotational offset (RADO) 
determined in section 8.3 exactly compensates for the scribe line 
rotational offset (RSLO) determined in section 10.5, then 
the magnitude of the yaw angle is equal to the displayed angle-
measuring device reading from section 8.9.3.1 or 8.9.3.2. The 
algebraic sign of the yaw angle is determined in accordance with 
section 8.9.3.3. [Note: Under certain circumstances (e.g., testing 
of horizontal ducts) a 90 deg. adjustment to the angle-measuring 
device readings may be necessary to obtain the correct yaw angles.]
    8.9.4.2  Compensation for rotational offsets during data 
reduction. When the angle-measuring device rotational offset does 
not compensate for reference scribe line rotational offset, the 
following procedure shall be used to determine the yaw angle:

[[Page 26529]]

    (a) Enter the reading indicated by the angle-measuring device 
from section 8.9.3.1 or 8.9.3.2.
    (b) Associate the proper algebraic sign from section 8.9.3.3 
with the reading in step (a).
    (c) Subtract the reference scribe line rotational offset, 
RSLO, from the reading in step (b).
    (d) Subtract the angle-measuring device rotational offset, 
RADO, if any, from the result obtained in step (c).
    (e) The final result obtained in step (d) is the yaw angle of 
flow.

[Note: It may be necessary to first apply a 90 deg. adjustment to 
the reading in step (a), in order to obtain the correct yaw angle.]

    8.9.4.3  Record the yaw angle measurements on a form similar to 
Table 2G-3.
    8.9.5  Impact velocity determination. Maintain the probe 
rotational position established during the yaw angle determination. 
Then, begin recording the pressure-measuring device readings. These 
pressure measurements shall be taken over a sampling period of 
sufficiently long duration to ensure representative readings at each 
traverse point. If the pressure measurements are determined from 
visual readings of the pressure device or display, allow sufficient 
time to observe the pulsation in the readings to obtain a sight-
weighted average, which is then recorded manually. If an automated 
data acquisition system (e.g., data logger, computer-based data 
recorder, strip chart recorder) is used to record the pressure 
measurements, obtain an integrated average of all pressure readings 
at the traverse point. Stack or duct gas temperature measurements 
shall be recorded, at a minimum, once at each traverse point. Record 
all necessary data as shown in the example field data form (Table 
2G-3).
    8.9.6  Alignment check. For manually operated probes, after the 
required yaw angle and differential pressure and temperature 
measurements have been made at each traverse point, verify (e.g., by 
visual inspection) that the yaw angle-measuring device has remained 
in proper alignment with the reference scribe line or with the 
rotational offset position established in section 8.3. If, for a 
particular traverse point, the angle-measuring device is found to be 
in proper alignment, proceed to the next traverse point; otherwise, 
re-align the device and repeat the angle and differential pressure 
measurements at the traverse point. In the course of a traverse, if 
a mark used to properly align the angle-measuring device (e.g., as 
described in section 18.1.1.1) cannot be located, re-establish the 
alignment mark before proceeding with the traverse.
    8.10  Probe Plugging. Periodically check for plugging of the 
pressure ports by observing the responses on the pressure 
differential readouts. Plugging causes erratic results or sluggish 
responses. Rotate the probe to determine whether the readouts 
respond in the expected direction. If plugging is detected, correct 
the problem and repeat the affected measurements.
    8.11  Static Pressure. Measure the static pressure in the stack 
or duct using the equipment described in section 6.7.
    8.11.1  If a Type S probe is used for this measurement, position 
the probe at or between any traverse point(s) and rotate the probe 
until a null differential pressure reading is obtained. Disconnect 
the tubing from one of the pressure ports; read and record the 
P. For pressure devices with one-directional scales, if a 
deflection in the positive direction is noted with the negative side 
disconnected, then the static pressure is positive. Likewise, if a 
deflection in the positive direction is noted with the positive side 
disconnected, then the static pressure is negative.
    8.11.2  If a 3-D probe is used for this measurement, position 
the probe at or between any traverse point(s) and rotate the probe 
until a null differential pressure reading is obtained at 
P2-P3. Rotate the probe 90 deg.. Disconnect 
the P2 pressure side of the probe and read the pressure 
P1-Pbar and record as the static pressure. 
(Note: The spherical probe, specified in section 6.1.2 of Method 2F, 
is unable to provide this measurement and shall not be used to take 
static pressure measurements.)
    8.12  Atmospheric Pressure. Determine the atmospheric pressure 
at the sampling elevation during each test run following the 
procedure described in section 2.5 of Method 2.
    8.13  Molecular Weight. Determine the stack or duct gas dry 
molecular weight. For combustion processes or processes that emit 
essentially CO2, O2, CO, and N2, 
use Method 3 or 3A. For processes emitting essentially air, an 
analysis need not be conducted; use a dry molecular weight of 29.0. 
Other methods may be used, if approved by the Administrator.
    8.14  Moisture. Determine the moisture content of the stack gas 
using Method 4 or equivalent.
    8.15  Data Recording and Calculations. Record all required data 
on a form similar to Table 2G-3.
    8.15.1  2-D probe calibration coefficient. When a Type S pitot 
tube is used in the field, the appropriate calibration coefficient 
as determined in section 10.6 shall be used to perform velocity 
calculations. For calibrated Type S pitot tubes, the A-side 
coefficient shall be used when the A-side of the tube faces the 
flow, and the B-side coefficient shall be used when the B-side faces 
the flow.
    8.15.2  3-D calibration coefficient. When a 3-D probe is used to 
collect data with this method, follow the provisions for the 
calibration of 3-D probes in section 10.6 of Method 2F to obtain the 
appropriate velocity calibration coefficient (F2 as 
derived using Equation 2F-2 in Method 2F) corresponding to a pitch 
angle position of 0 deg..
    8.15.3  Calculations. Calculate the yaw-adjusted velocity at 
each traverse point using the equations presented in section 12.2. 
Calculate the test run average stack gas velocity by finding the 
arithmetic average of the point velocity results in accordance with 
sections 12.3 and 12.4, and calculate the stack gas volumetric flow 
rate in accordance with section 12.5 or 12.6, as applicable.

9.0  Quality Control

    9.1  Quality Control Activities. In conjunction with the yaw 
angle determination and the pressure and temperature measurements 
specified in section 8.9, the following quality control checks 
should be performed.
    9.1.1 Range of the differential pressure gauge. In accordance 
with the specifications in section 6.4, ensure that the proper 
differential pressure gauge is being used for the range of 
P values encountered. If it is necessary to change to a 
more sensitive gauge, replace the gauge with a gauge calibrated 
according to section 10.3.3, perform the leak check described in 
section 8.4 and the zero check described in section 8.5, and repeat 
the differential pressure and temperature readings at each traverse 
point.
    9.1.2  Horizontal stability check. For horizontal traverses of a 
stack or duct, visually check that the probe shaft is maintained in 
a horizontal position prior to taking a pressure reading. 
Periodically, during a test run, the probe's horizontal stability 
should be verified by placing a carpenter's level, a digital 
inclinometer, or other angle-measuring device on the portion of the 
probe sheath that extends outside of the test port. A comparable 
check should be performed by automated systems.

10.0  Calibration

    10.1  Wind Tunnel Qualification Checks. To qualify for use in 
calibrating probes, a wind tunnel shall have the design features 
specified in section 6.11 and satisfy the following qualification 
criteria. The velocity pressure cross-check in section 10.1.1 and 
axial flow verification in section 10.1.2 shall be performed before 
the initial use of the wind tunnel and repeated immediately after 
any alteration occurs in the wind tunnel's configuration, fans, 
interior surfaces, straightening vanes, controls, or other 
properties that could reasonably be expected to alter the flow 
pattern or velocity stability in the tunnel. The owner or operator 
of a wind tunnel used to calibrate probes according to this method 
shall maintain records documenting that the wind tunnel meets the 
requirements of sections 10.1.1 and 10.1.2 and shall provide these 
records to the Administrator upon request.
    10.1.1  Velocity pressure cross-check. To verify that the wind 
tunnel produces the same velocity at the tested probe head as at the 
calibration pitot tube impact port, perform the following cross-
check. Take three differential pressure measurements at the fixed 
calibration pitot tube location, using the calibration pitot tube 
specified in section 6.10, and take three measurements with the 
calibration pitot tube at the wind tunnel calibration location, as 
defined in section 3.21. Alternate the measurements between the two 
positions. Perform this procedure at the lowest and highest velocity 
settings at which the probes will be calibrated. Record the values 
on a form similar to Table 2G-4. At each velocity setting, the 
average velocity pressure obtained at the wind tunnel calibration 
location shall be within 2 percent or 2.5 mm 
H2O (0.01 in. H2O), whichever is less 
restrictive, of the average velocity pressure obtained at the fixed 
calibration pitot tube location. This comparative check shall be 
performed at 2.5-cm (1-in.), or smaller,

[[Page 26530]]

intervals across the full length, width, and depth (if applicable) 
of the wind tunnel calibration location. If the criteria are not met 
at every tested point, the wind tunnel calibration location must be 
redefined, so that acceptable results are obtained at every point. 
Include the results of the velocity pressure cross-check in the 
calibration data section of the field test report. (See section 
16.1.4.)
    10.1.2  Axial flow verification. The following procedures shall 
be performed to demonstrate that there is fully developed axial flow 
within the wind tunnel calibration location and at the calibration 
pitot tube location. Two options are available to conduct this 
check.
    10.1.2.1  Using a calibrated 3-D probe. A probe that has been 
previously calibrated in a wind tunnel with documented axial flow 
(as defined in section 3.22) may be used to conduct this check. 
Insert the calibrated 3-D probe into the wind tunnel test section 
using the tested probe port. Following the procedures in sections 
8.9 and 12.2 of Method 2F, determine the yaw and pitch angles at all 
the point(s) in the test section where the velocity pressure cross-
check, as specified in section 10.1.1, is performed. This includes 
all the points in the calibration location and the point where the 
calibration pitot tube will be located. Determine the yaw and pitch 
angles at each point. Repeat these measurements at the highest and 
lowest velocities at which the probes will be calibrated. Record the 
values on a form similar to Table 2G-5. Each measured yaw and pitch 
angle shall be within 3@ of 0@. Exceeding the limits 
indicates unacceptable flow in the test section. Until the problem 
is corrected and acceptable flow is verified by repetition of this 
procedure, the wind tunnel shall not be used for calibration of 
probes. Include the results of the axial flow verification in the 
calibration data section of the field test report. (See section 
16.1.4.)
    10.1.2.2  Using alternative probes. Axial flow verification may 
be performed using an uncalibrated prism-shaped 3-D probe (e.g., DA 
or DAT probe) or an uncalibrated wedge probe. (Figure 2G-8 
illustrates a typical wedge probe.) This approach requires use of 
two ports: the tested probe port and a second port located 90 deg. 
from the tested probe port. Each port shall provide access to all 
the points within the wind tunnel test section where the velocity 
pressure cross-check, as specified in section 10.1.1, is conducted. 
The probe setup shall include establishing a reference yaw-null 
position on the probe sheath to serve as the location for installing 
the angle-measuring device. Physical design features of the DA, DAT, 
and wedge probes are relied on to determine the reference position. 
For the DA or DAT probe, this reference position can be determined 
by setting a digital inclinometer on the flat facet where the 
P1 pressure port is located and then identifying the 
rotational position on the probe sheath where a second angle-
measuring device would give the same angle reading. The reference 
position on a wedge probe shaft can be determined either 
geometrically or by placing a digital inclinometer on each side of 
the wedge and rotating the probe until equivalent readings are 
obtained. With the latter approach, the reference position is the 
rotational position on the probe sheath where an angle-measuring 
device would give a reading of 0 deg.. After installation of the 
angle-measuring device in the reference yaw-null position on the 
probe sheath, determine the yaw angle from the tested port. Repeat 
this measurement using the 90 deg. offset port, which provides the 
pitch angle of flow. Determine the yaw and pitch angles at all the 
point(s) in the test section where the velocity pressure cross-
check, as specified in section 10.1.1, is performed. This includes 
all the points in the wind tunnel calibration location and the point 
where the calibration pitot tube will be located. Perform this check 
at the highest and lowest velocities at which the probes will be 
calibrated. Record the values on a form similar to Table 2G-5. Each 
measured yaw and pitch angle shall be within 3 deg. of 
0 deg.. Exceeding the limits indicates unacceptable flow in the test 
section. Until the problem is corrected and acceptable flow is 
verified by repetition of this procedure, the wind tunnel shall not 
be used for calibration of probes. Include the results in the probe 
calibration report.
    10.1.3  Wind tunnel audits.
10.1.3.1  Procedure. Upon the request of the Administrator, the 
owner or operator of a wind tunnel shall calibrate a 2-D audit probe 
in accordance with the procedures described in sections 10.3 through 
10.6. The calibration shall be performed at two velocities that 
encompass the velocities typically used for this method at the 
facility. The resulting calibration data shall be submitted to the 
Agency in an audit test report. These results shall be compared by 
the Agency to reference calibrations of the audit probe at the same 
velocity settings obtained at two different wind tunnels.
10.1.3.2  Acceptance criterion. The audited tunnel's calibration 
coefficient is acceptable if it is within 3 percent of the reference 
calibrations obtained at each velocity setting by one (or both) of 
the wind tunnels. If the acceptance criterion is not met at each 
calibration velocity setting, the audited wind tunnel shall not be 
used to calibrate probes for use under this method until the 
problems are resolved and acceptable results are obtained upon 
completion of a subsequent audit.
10.2  Probe Inspection.
10.2.1  Type S probe. Before each calibration of a Type S probe, 
verify that one leg of the tube is permanently marked A, and the 
other, B. Carefully examine the pitot tube from the top, side, and 
ends. Measure the angles (1, 
2, 1, and 
2) and the dimensions (w and z) illustrated in 
Figures 2-2 and 2-3 in Method 2. Also measure the dimension A, as 
shown in the diagram in Table 2G-1, and the external tubing diameter 
(dimension Dt, Figure 2-2b in Method 2). For the purposes 
of this method, Dt shall be no less than 9.5 mm (\3/8\ 
in.). The base-to-opening plane distances PA and 
PB in Figure 2-3 of Method 2 shall be equal, and the 
dimension A in Table 2G-1 should be between 2.10Dt and 
3.00Dt. Record the inspection findings and probe 
measurements on a form similar to Table CD2-1 of the ``Quality 
Assurance Handbook for Air Pollution Measurement Systems: Volume 
III, Stationary Source-Specific Methods' (EPA/600/R-94/038c, 
September 1994). For reference, this form is reproduced herein as 
Table 2G-1. The pitot tube shall not be used under this method if it 
fails to meet the specifications in this section and the alignment 
specifications in section 6.1.1. All Type S probes used to collect 
data with this method shall be calibrated according to the 
procedures outlined in sections 10.3 through 10.6 below. During 
calibration, each Type S pitot tube shall be configured in the same 
manner as used, or planned to be used, during the field test, 
including all components in the probe assembly (e.g., thermocouple, 
probe sheath, sampling nozzle). Probe shaft extensions that do not 
affect flow around the probe head need not be attached during 
calibration.
10.2.2  3-D probe. If a 3-D probe is used to collect data with this 
method, perform the pre-calibration inspection according to 
procedures in Method 2F, section 10.2.
10.3  Pre-Calibration Procedures. Prior to calibration, a scribe 
line shall have been placed on the probe in accordance with section 
10.4. The yaw angle and velocity calibration procedures shall not 
begin until the pre-test requirements in sections 10.3.1 through 
10.3.4 have been met.
10.3.1  Perform the horizontal straightness check described in 
section 8.2 on the probe assembly that will be calibrated in the 
wind tunnel.
10.3.2  Perform a leak check in accordance with section 8.4.
10.3.3  Except as noted in section 10.3.3.3, calibrate all 
differential pressure-measuring devices to be used in the probe 
calibrations, using the following procedures. At a minimum, 
calibrate these devices on each day that probe calibrations are 
performed.
10.3.3.1  Procedure. Before each wind tunnel use, all differential 
pressure-measuring devices shall be calibrated against the reference 
device specified in section 6.4.3 using a common pressure source. 
Perform the calibration at three reference pressures representing 
30, 60, and 90 percent of the full-scale range of the pressure-
measuring device being calibrated. For an inclined-vertical 
manometer, perform separate calibrations on the inclined and 
vertical portions of the measurement scale, considering each portion 
of the scale to be a separate full-scale range. [For example, for a 
manometer with a 0-to 2.5-cm H2O (0-to 1-in. 
H2O) inclined scale and a 2.5-to 12.7-cm H2O 
(1-to 5-in. H2O) vertical scale, calibrate the inclined 
portion at 7.6, 15.2, and 22.9 mm H2O (0.3, 0.6, and 0.9 
in. H2O), and calibrate the vertical portion at 3.8, 7.6, 
and 11.4 cm H2O (1.5, 3.0, and 4.5 in. H2O).] 
Alternatively, for the vertical portion of the scale, use three 
evenly spaced reference pressures, one of which is equal to or 
higher than the highest differential pressure expected in field 
applications.
10.3.3.2  Acceptance criteria. At each pressure setting, the two 
pressure readings made using the reference device and the pressure-
measuring device being calibrated shall agree to within #2 percent 
of full scale of the device being calibrated or 0.5 mm 
H2O (0.02 in. H2O), whichever is less 
restrictive. For an inclined-vertical manometer, these

[[Page 26531]]

requirements shall be met separately using the respective full-scale 
upper limits of the inclined and vertical portions of the scale. 
Differential pressure-measuring devices not meeting the #2 percent 
of full scale or 0.5 mm H2O (0.02 in. H2O) 
calibration requirement shall not be used.
10.3.3.3  Exceptions. Any precision manometer that meets the 
specifications for a reference device in section 6.4.3 and that is 
not used for field testing does not require calibration, but must be 
leveled and zeroed before each wind tunnel use. Any pressure device 
used exclusively for yaw nulling does not require calibration, but 
shall be checked for responsiveness to rotation of the probe prior 
to each wind tunnel use.
10.3.4  Calibrate digital inclinometers on each day of wind tunnel 
or field testing (prior to beginning testing) using the following 
procedures. Calibrate the inclinometer according to the 
manufacturer's calibration procedures. In addition, use a triangular 
block (illustrated in Figure 2G-9) with a known angle, '', 
independently determined using a protractor or equivalent device, 
between two adjacent sides to verify the inclinometer readings. 
(Note: If other angle-measuring devices meeting the provisions of 
section 6.2.3 are used in place of a digital inclinometer, 
comparable calibration procedures shall be performed on such 
devices.) Secure the triangular block in a fixed position. Place the 
inclinometer on one side of the block (side A) to measure the angle 
of inclination (R1). Repeat this measurement on the 
adjacent side of the block (side B) using the inclinometer to obtain 
a second angle reading (R2). The difference of the sum of 
the two readings from 180 deg. (i.e., 180R1R2) 
shall be within #2 of the known angle, ``.
10.4  Placement of Reference Scribe Line. Prior to the first 
calibration of a probe, a line shall be permanently inscribed on the 
main probe sheath to serve as a reference mark for determining yaw 
angles. Annex C in section 18 of this method gives a guideline for 
placement of the reference scribe line.
10.4.1  This reference scribe line shall meet the specifications in 
sections 6.1.5.1 and 6.1.5.3 of this method. To verify that the 
alignment specification in section 6.1.5.3 is met, secure the probe 
in a horizontal position and measure the rotational angle of each 
scribe line and scribe line segment using an angle-measuring device 
that meets the specifications in section 6.2.1 or 6.2.3. For any 
scribe line that is longer than 30.5 cm (12 in.), check the line's 
rotational position at 30.5-cm (12-in.) intervals. For each line 
segment that is 12 in. or less in length, check the rotational 
position at the two endpoints of the segment. To meet the alignment 
specification in section 6.1.5.3, the minimum and maximum of all of 
the rotational angles that are measured along the full length of 
main probe must not differ by more than 2 deg.. (Note: A short 
reference scribe line segment [e.g., 15.2 cm (6 in.) or less in 
length] meeting the alignment specifications in section 6.1.5.3 is 
fully acceptable under this method. See section 18.1.1.1 of Annex A 
for an example of a probe marking procedure, suitable for use with a 
short reference scribe line.)
    10.4.2  The scribe line should be placed on the probe first and 
then its offset from the yaw-null position established (as specified 
in section 10.5). The rotational position of the reference scribe 
line relative to the yaw-null position of the probe, as determined 
by the yaw angle calibration procedure in section 10.5, is the 
reference scribe line rotational offset, RSLO. The 
reference scribe line rotational offset shall be recorded and 
retained as part of the probe's calibration record.
    10.4.3  Scribe line for automated probes. A scribe line may not 
be necessary for an automated probe system if a reference rotational 
position of the probe is built into the probe system design. For 
such systems, a ``flat'' (or comparable, clearly identifiable 
physical characteristic) should be provided on the probe casing or 
flange plate to ensure that the reference position of the probe 
assembly remains in a vertical or horizontal position. The 
rotational offset of the flat (or comparable, clearly identifiable 
physical characteristic) needed to orient the reference position of 
the probe assembly shall be recorded and maintained as part of the 
automated probe system's specifications.
    10.5  Yaw Angle Calibration Procedure. For each probe used to 
measure yaw angles with this method, a calibration procedure shall 
be performed in a wind tunnel meeting the specifications in section 
10.1 to determine the rotational position of the reference scribe 
line relative to the probe's yaw-null position. This procedure shall 
be performed on the main probe with all devices that will be 
attached to the main probe in the field [such as thermocouples, 
resistance temperature detectors (RTDs), or sampling nozzles] that 
may affect the flow around the probe head. Probe shaft extensions 
that do not affect flow around the probe head need not be attached 
during calibration. At a minimum, this procedure shall include the 
following steps.
    10.5.1  Align and lock the angle-measuring device on the 
reference scribe line. If a marking procedure (such as described in 
section 18.1.1.1) is used, align the angle-measuring device on a 
mark within 1 deg. of the rotational position of the 
reference scribe line. Lock the angle-measuring device onto the 
probe sheath at this position.
    10.5.2  Zero the pressure-measuring device used for yaw nulling.
    10.5.3  Insert the probe assembly into the wind tunnel through 
the entry port, positioning the probe's impact port at the 
calibration location. Check the responsiveness of the pressure-
measurement device to probe rotation, taking corrective action if 
the response is unacceptable.
    10.5.4  Ensure that the probe is in a horizontal position, using 
a carpenter's level.
    10.5.5  Rotate the probe either clockwise or counterclockwise 
until a yaw null [zero P for a Type S probe or zero 
(P2-P3) for a 3-D probe] is obtained. If using 
a Type S probe with an attached thermocouple, the direction of the 
probe rotation shall be such that the thermocouple is located 
downstream of the probe pressure ports at the yaw-null position.
    10.5.6  Use the reading displayed by the angle-measuring device 
at the yaw-null position to determine the magnitude of the reference 
scribe line rotational offset, RSLO, as defined in 
section 3.15. Annex D in section 18 of this method gives a 
recommended procedure for determining the magnitude of 
RSLO with a digital inclinometer and a second procedure 
for determining the magnitude of RSLO with a protractor 
wheel and pointer device. Table 2G-6 gives an example data form and 
Table 2G-7 is a look-up table with the recommended procedure. 
Procedures other than those recommended in Annex D in section 18 may 
be used, if they can determine RSLO to within 1 deg. and 
are explained in detail in the field test report. The algebraic sign 
of RSLO will either be positive if the rotational 
position of the reference scribe line (as viewed from the ``tail'' 
end of the probe) is clockwise, or negative, if counterclockwise 
with respect to the probe's yaw-null position. (This is illustrated 
in Figure 2G-10.)
    10.5.7  The steps in sections 10.5.3 through 10.5.6 shall be 
performed twice at each of the velocities at which the probe will be 
calibrated (in accordance with section 10.6). Record the values of 
RSLO.
    10.5.8  The average of all of the RSLO values shall be 
documented as the reference scribe line rotational offset for the 
probe.
    10.5.9  Use of reference scribe line offset. The reference 
scribe line rotational offset shall be used to determine the yaw 
angle of flow in accordance with section 8.9.4.
    10.6  Velocity Calibration Procedure. When a 3-D probe is used 
under this method, follow the provisions for the calibration of 3-D 
probes in section 10.6 of Method 2F to obtain the necessary velocity 
calibration coefficients (F2 as derived using Equation 
2F-2 in Method 2F) corresponding to a pitch angle position of 
0 deg.. The following procedure applies to Type S probes. This 
procedure shall be performed on the main probe and all devices that 
will be attached to the main probe in the field (e.g., 
thermocouples, RTDs, sampling nozzles) that may affect the flow 
around the probe head. Probe shaft extensions that do not affect 
flow around the probe head need not be attached during calibration. 
(Note: If a sampling nozzle is part of the assembly, two additional 
requirements must be satisfied before proceeding. The distance 
between the nozzle and the pitot tube shall meet the minimum spacing 
requirement prescribed in Method 2, and a wind tunnel demonstration 
shall be performed that shows the probe's ability to yaw null is not 
impaired when the nozzle is drawing sample.) To obtain velocity 
calibration coefficient(s) for the tested probe, proceed as follows.
    10.6.1  Calibration velocities. The tester may calibrate the 
probe at two nominal wind tunnel velocity settings of 18.3 m/sec and 
27.4 m/sec (60 ft/sec and 90 ft/sec) and average the results of 
these calibrations, as described in sections 10.6.12 through 
10.6.14, in order to generate the calibration coefficient, 
Cp. If this option is selected, this calibration 
coefficient may be used for all field applications where the 
velocities are 9.1 m/sec (30 ft/sec) or greater. Alternatively, the 
tester may customize the probe calibration for a particular field 
test application (or for a series of applications), based on the 
expected average velocity(ies) at the test

[[Page 26532]]

site(s). If this option is selected, generate the calibration 
coefficients by calibrating the probe at two nominal wind tunnel 
velocity settings, one of which is less than or equal to and the 
other greater than or equal to the expected average velocity(ies) 
for the field application(s), and average the results as described 
in sections 10.6.12 through 10.6.14. Whichever calibration option is 
selected, the probe calibration coefficient(s) obtained at the two 
nominal calibration velocities shall meet the conditions specified 
in sections 10.6.12 through 10.6.14.
    10.6.2  Connect the tested probe and calibration pitot tube to 
their respective pressure-measuring devices. Zero the pressure-
measuring devices. Inspect and leak-check all pitot lines; repair or 
replace them, if necessary. Turn on the fan, and allow the wind 
tunnel air flow to stabilize at the first of the selected nominal 
velocity settings.
    10.6.3  Position the calibration pitot tube at its measurement 
location (determined as outlined in section 6.11.4.3), and align the 
tube so that its tip is pointed directly into the flow. Ensure that 
the entry port surrounding the tube is properly sealed. The 
calibration pitot tube may either remain in the wind tunnel 
throughout the calibration, or be removed from the wind tunnel while 
measurements are taken with the probe being calibrated.
    10.6.4  Check the zero setting of each pressure-measuring 
device.
    10.6.5  Insert the tested probe into the wind tunnel and align 
it so that the designated pressure port (e.g., either the A-side or 
B-side of a Type S probe) is pointed directly into the flow and is 
positioned within the wind tunnel calibration location (as defined 
in section 3.21). Secure the probe at the 0 deg. pitch angle 
position. Ensure that the entry port surrounding the probe is 
properly sealed.
    10.6.6  Read the differential pressure from the calibration 
pitot tube (Pstd ), and record its value. Read the 
barometric pressure to within 2.5 mm Hg (0.1 
in. Hg) and the temperature in the wind tunnel to within 0.6 deg.C 
(1 deg.F). Record these values on a data form similar to Table 2G-8.
    10.6.7  After the tested probe's differential pressure gauges 
have had sufficient time to stabilize, yaw null the probe (and then 
rotate it back 90 deg. for Type S probes), then obtain the 
differential pressure reading (P). Record the yaw angle and 
differential pressure readings.
    10.6.8  Take paired differential pressure measurements with the 
calibration pitot tube and tested probe (according to sections 
10.6.6 and 10.6.7). The paired measurements in each replicate can be 
made either simultaneously (i.e., with both probes in the wind 
tunnel) or by alternating the measurements of the two probes (i.e., 
with only one probe at a time in the wind tunnel).
    10.6.9  Repeat the steps in sections 10.6.6 through 10.6.8 at 
the same nominal velocity setting until three pairs of P 
readings have been obtained from the calibration pitot tube and the 
tested probe.
    10.6.10  Repeat the steps in sections 10.6.6 through 10.6.9 
above for the A-side and B-side of the Type S pitot tube. For a 
probe assembly constructed such that its pitot tube is always used 
in the same orientation, only one side of the pitot tube need be 
calibrated (the side that will face the flow). However, the pitot 
tube must still meet the alignment and dimension specifications in 
section 6.1.1 and must have an average deviation () value 
of 0.01 or less as provided in section 10.6.12.4.
    10.6.11  Repeat the calibration procedures in sections 10.6.6 
through 10.6.10 at the second selected nominal wind tunnel velocity 
setting.
    10.6.12  Perform the following calculations separately on the A-
side and B-side values.
    10.6.12.1  Calculate a C value for each of the three 
replicates performed at the lower velocity setting where the 
calibrations were performed using Equation 2-2 in section 4.1.4 of 
Method 2.
    10.6.12.2  Calculate the arithmetic average, 
Cp(avg-low), of the three Cp values.
    10.6.12.3  Calculate the deviation of each of the three 
individual values of Cp from the A-side average 
Cp(avg-low) value using Equation 2-3 in Method 2.
    10.6.12.4  Calculate the average deviation () of the 
three individual Cp values from Cp(avg-low) 
using Equation 2-4 in Method 2. Use the Type S pitot tube only if 
the values of  (side A) and  (side B) are less 
than or equal to 0.01. If both A-side and B-side calibration 
coefficients are calculated, the absolute value of the difference 
between Cp(avg-low) (side A) and Cp(avg-low) 
(side B) must not exceed 0.01.
    10.6.13  Repeat the calculations in section 10.6.12 using the 
data obtained at the higher velocity setting to derive the 
arithmetic Cp values at the higher velocity setting, 
Cp(avg-high), and to determine whether the conditions in 
10.6.12.4 are met by both the A-side and B-side calibrations at this 
velocity setting.
    10.6.14  Use equation 2G-1 to calculate the percent difference 
of the averaged Cp values at the two calibration 
velocities.
[GRAPHIC] [TIFF OMITTED] TR14MY99.062

The percent difference between the averaged Cp values 
shall not exceed 3 percent. If the specification is met, 
average the A-side values of Cp(avg-low) and 
Cp(avg-high) to produce a single A-side calibration 
coefficient, Cp. Repeat for the B-side values if 
calibrations were performed on that side of the pitot. If the 
specification is not met, make necessary adjustments in the selected 
velocity settings and repeat the calibration procedure until 
acceptable results are obtained.
    10.6.15  If the two nominal velocities used in the calibration 
were 18.3 and 27.4 m/sec (60 and 90 ft/sec), the average 
Cp from section 10.6.14 is applicable to all velocities 
9.1 m/sec (30 ft/sec) or greater. If two other nominal velocities 
were used in the calibration, the resulting average Cp 
value shall be applicable only in situations where the velocity 
calculated using the calibration coefficient is neither less than 
the lower nominal velocity nor greater than the higher nominal 
velocity.
    10.7  Recalibration. Recalibrate the probe using the procedures 
in section 10 either within 12 months of its first field use after 
its most recent calibration or after 10 field tests (as defined in 
section 3.3), whichever occurs later. In addition, whenever there is 
visible damage to the probe head, the probe shall be recalibrated 
before it is used again.
    10.8  Calibration of pressure-measuring devices used in the 
field. Before its initial use in a field test, calibrate each 
pressure-measuring device (except those used exclusively for yaw 
nulling) using the three-point calibration procedure described in 
section 10.3.3. The device shall be recalibrated according to the 
procedure in section 10.3.3 no later than 90 days after its first 
field use following its most recent calibration. At the discretion 
of the tester, more frequent calibrations (e.g., after a field test) 
may be performed. No adjustments, other than adjustments to the zero 
setting, shall be made to the device between calibrations.
    10.8.1  Post-test calibration check. A single-point calibration 
check shall be performed on each pressure-measuring device after 
completion of each field test. At the discretion of the tester, more 
frequent single-point calibration checks (e.g., after one or more 
field test runs) may be performed. It is recommended that the post-
test check be performed before leaving the field test site. The 
check shall be performed at a pressure between 50 and 90 percent of 
full scale by taking a common pressure reading with the tested probe 
and a reference pressure-measuring device (as described in section 
6.4.4) or by challenging the tested device with a reference pressure 
source (as described in section 6.4.4) or by performing an 
equivalent check using a reference device approved by the 
Administrator.
    10.8.2  Acceptance criterion. At the selected pressure setting, 
the pressure readings made using the reference device and the tested 
device shall agree to within 3 percent of full scale of 
the tested device or 0.8 mm H2O (0.03 in. 
H2O), whichever is less restrictive. If this 
specification is met, the test data collected during the field test 
are valid. If the specification is not met, all test data collected 
since the last successful calibration or calibration check are 
invalid and shall be repeated using a pressure-measuring device with 
a current, valid calibration. Any device that fails the calibration 
check shall not be used in a field test until a successful

[[Page 26533]]

recalibration is performed according to the procedures in section 
10.3.3.
    10.9  Temperature Gauges. Same as Method 2, section 4.3. The 
alternative thermocouple calibration procedures outlined in Emission 
Measurement Center (EMC) Approved Alternative Method (ALT-011) 
``Alternative Method 2 Thermocouple Calibration Procedure'' may be 
performed. Temperature gauges shall be calibrated no more than 30 
days prior to the start of a field test or series of field tests and 
recalibrated no more than 30 days after completion of a field test 
or series of field tests.
    10.10  Barometer. Same as Method 2, section 4.4. The barometer 
shall be calibrated no more than 30 days prior to the start of a 
field test or series of field tests.

11.0  Analytical Procedure

    Sample collection and analysis are concurrent for this method 
(see section 8.0).

12.0  Data Analysis and Calculations

    These calculations use the measured yaw angle and the 
differential pressure and temperature measurements at individual 
traverse points to derive the near-axial flue gas velocity 
(a(ii)) at each of those points. The near-axial velocity 
values at all traverse points that comprise a full stack or duct 
traverse are then averaged to obtain the average near-axial stack or 
duct gas velocity a(avg).

12.1  Nomenclature

A = Cross-sectional area of stack or duct at the test port location, 
m2 (ft2).
Bws = Water vapor in the gas stream (from Method 4 or 
alternative), proportion by volume.
Cp = Pitot tube calibration coefficient, dimensionless.
F2(i) = 3-D probe velocity coefficient at 0 pitch, 
applicable at traverse point i.
Kp = Pitot tube constant,
[GRAPHIC] [TIFF OMITTED] TR14MY99.063

for the metric system, and
[GRAPHIC] [TIFF OMITTED] TR14MY99.064

for the English system.

Md = Molecular weight of stack or duct gas, dry basis 
(see section 8.13), g/g-mole (lb/lb-mole).
Ms = Molecular weight of stack or duct gas, wet basis, g/
g-mole (lb/lb-mole).
[GRAPHIC] [TIFF OMITTED] TR14MY99.065

Pbar = Barometric pressure at velocity measurement site, 
mm Hg (in. Hg).
Pg = Stack or duct static pressure, mm H2O 
(in. H2O).
Ps = Absolute stack or duct pressure, mm Hg (in. Hg),
[GRAPHIC] [TIFF OMITTED] TR14MY99.066

Pstd = Standard absolute pressure, 760 mm Hg (29.92 in. 
Hg).
13.6 = Conversion from mm H2O (in. H2O) to mm 
Hg (in. Hg).
Qsd = Average dry-basis volumetric stack or duct gas flow 
rate corrected to standard conditions, dscm/hr (dscf/hr).
Qsw = Average wet-basis volumetric stack or duct gas flow 
rate corrected to standard conditions, wscm/hr (wscf/hr).
ts(i) = Stack or duct temperature,  deg.C ( deg.F), at 
traverse point i.
Ts(i) = Absolute stack or duct temperature,  deg.K 
( deg.R), at traverse point i.
[GRAPHIC] [TIFF OMITTED] TR14MY99.067

for the metric system, and
[GRAPHIC] [TIFF OMITTED] TR14MY99.068

for the English system.

Ts(avg)=Average absolute stack or duct gas temperature 
across all traverse points.
Tstd=Standard absolute temperature, 293 deg.K 
(528 deg.R).
va(i)=Measured stack or duct gas impact velocity, m/sec 
(ft/sec), at traverse point i.
va(avg)=Average near-axial stack or duct gas velocity, m/
sec (ft/sec) across all traverse points.
Pi=Velocity head (differential pressure) of 
stack or duct gas, mm H2O (in. H2O), 
applicable at traverse point i.
(P1-P2)=Velocity head (differential pressure) 
of stack or duct gas measured by a 3-D probe, mm H2O (in. 
H2O), applicable at traverse point i.
3,600=Conversion factor, sec/hr.
18.0=Molecular weight of water, g/g-mole (lb/lb-mole).
y(i)=Yaw angle of the flow velocity vector, at 
traverse point i.
n=Number of traverse points.

    12.2  Traverse Point Velocity Calculations. Perform the 
following calculations from the measurements obtained at each 
traverse point.
    12.2.1  Selection of calibration coefficient. Select the 
calibration coefficient as described in section 10.6.1.
    12.2.2  Near-axial traverse point velocity. When using a Type S 
probe, use the following equation to calculate the traverse point 
near-axial velocity (va(i)) from the differential 
pressure (Pi), yaw angle 
(y(i)), absolute stack or duct standard 
temperature (Ts(i)) measured at traverse point i, the 
absolute stack or duct pressure (Ps), and molecular 
weight (Ms).
[GRAPHIC] [TIFF OMITTED] TR14MY99.069

Use the following equation when using a 3-D probe.
[GRAPHIC] [TIFF OMITTED] TR14MY99.070

    12.2.3  Handling multiple measurements at a traverse point. For 
pressure or temperature devices that take multiple measurements at a 
traverse point, the multiple measurements (or where applicable, 
their square roots) may first be averaged and the resulting average 
values used in the equations above. Alternatively, the individual 
measurements may be used in the equations above and the resulting 
calculated values may then be averaged to obtain a single traverse 
point value. With either approach, all of the individual 
measurements recorded at a traverse point must be used in 
calculating the applicable traverse point value.
    12.3  Average Near-Axial Velocity in Stack or Duct. Use the 
reported traverse point near-axial velocity in the following 
equation.
[GRAPHIC] [TIFF OMITTED] TR14MY99.071

    12.4  Acceptability of Results. The acceptability provisions in 
section 12.4 of Method 2F apply to 3-D probes used under Method 2G. 
The following provisions apply to Type S probes. For Type S probes, 
the test results are acceptable and the calculated value of 
va(avg) may be reported as the average near-axial 
velocity for the test run if the conditions in either section 12.4.1 
or 12.4.2 are met.
    12.4.1  The average calibration coefficient Cp used 
in Equation 2G-6 was generated at

[[Page 26534]]

nominal velocities of 18.3 and 27.4 m/sec (60 and 90 ft/sec) and the 
value of va(avg) calculated using Equation 2G-8 is 
greater than or equal to 9.1 m/sec (30 ft/sec).
    12.4.2  The average calibration coefficient Cp used 
in Equation 2G-6 was generated at nominal velocities other than 18.3 
or 27.4 m/sec (60 or 90 ft/sec) and the value of va(avg) 
calculated using Equation 2G-8 is greater than or equal to the lower 
nominal velocity and less than or equal to the higher nominal 
velocity used to derive the average Cp.
    12.4.3  If the conditions in neither section 12.4.1 nor section 
12.4.2 are met, the test results obtained from Equation 2G-8 are not 
acceptable, and the steps in sections 12.2 and 12.3 must be repeated 
using an average calibration coefficient Cp that 
satisfies the conditions in section 12.4.1 or 12.4.2.
    12.5  Average Gas Volumetric Flow Rate in Stack or Duct (Wet 
Basis). Use the following equation to compute the average volumetric 
flow rate on a wet basis.
[GRAPHIC] [TIFF OMITTED] TR14MY99.072

    12.6  Average Gas Volumetric Flow Rate in Stack or Duct (Dry 
Basis). Use the following equation to compute the average volumetric 
flow rate on a dry basis.
[GRAPHIC] [TIFF OMITTED] TR14MY99.073

13.0  Method Performance. [Reserved]

14.0  Pollution Prevention. [Reserved]

15.0  Waste Management. [Reserved]

16.0  Reporting.

16.1  Field Test Reports. Field test reports shall be submitted to 
the Agency according to applicable regulatory requirements. Field 
test reports should, at a minimum, include the following elements.
16.1.1  Description of the source. This should include the name and 
location of the test site, descriptions of the process tested, a 
description of the combustion source, an accurate diagram of stack 
or duct cross-sectional area at the test site showing the dimensions 
of the stack or duct, the location of the test ports, and traverse 
point locations and identification numbers or codes. It should also 
include a description and diagram of the stack or duct layout, 
showing the distance of the test location from the nearest upstream 
and downstream disturbances and all structural elements (including 
breachings, baffles, fans, straighteners, etc.) affecting the flow 
pattern. If the source and test location descriptions have been 
previously submitted to the Agency in a document (e.g., a monitoring 
plan or test plan), referencing the document in lieu of including 
this information in the field test report is acceptable.
16.1.2  Field test procedures. These should include a description of 
test equipment and test procedures. Testing conventions, such as 
traverse point numbering and measurement sequence (e.g., sampling 
from center to wall, or wall to center), should be clearly stated. 
Test port identification and directional reference for each test 
port should be included on the appropriate field test data sheets.
16.1.3  Field test data.
16.1.3.1  Summary of results. This summary should include the dates 
and times of testing, and the average near-axial gas velocity and 
the average flue gas volumetric flow results for each run and tested 
condition.
16.1.3.2  Test data. The following values for each traverse point 
should be recorded and reported:

(a) Differential pressure at traverse point i 
(Pi)
(b) Stack or duct temperature at traverse point i (ts(i))
(c) Absolute stack or duct temperature at traverse point i 
(Ts(i))
(d) Yaw angle at traverse point i (y(i))
(e) Stack gas near-axial velocity at traverse point i 
(va(i))

    16.1.3.3  The following values should be reported once per run:

(a) Water vapor in the gas stream (from Method 4 or alternative), 
proportion by volume (Bws), measured at the frequency 
specified in the applicable regulation
(b) Molecular weight of stack or duct gas, dry basis (Md)
(c) Molecular weight of stack or duct gas, wet basis (Ms)
(d) Stack or duct static pressure (Pg)
(e) Absolute stack or duct pressure (Ps)
(f) Carbon dioxide concentration in the flue gas, dry basis 
(%d CO2)
(g) Oxygen concentration in the flue gas, dry basis (%d 
O2)
(h) Average near-axial stack or duct gas velocity 
(va(avg)) across all traverse points
(i) Gas volumetric flow rate corrected to standard conditions, dry 
or wet basis as required by the applicable regulation 
(Qsd or Qsw)

    16.1.3.4  The following should be reported once per complete set 
of test runs:

(a) Cross-sectional area of stack or duct at the test location (A)
(b) Pitot tube calibration coefficient (Cp)
(c) Measurement system response time (sec)
(d) Barometric pressure at measurement site (Pbar)

    16.1.4  Calibration data. The field test report should include 
calibration data for all probes and test equipment used in the field 
test. At a minimum, the probe calibration data reported to the 
Agency should include the following:

(a) Date of calibration
(b) Probe type
(c) Probe identification number(s) or code(s)
(d) Probe inspection sheets
(e) Pressure measurements and calculations used to obtain 
calibration coefficients in accordance with section 10.6 of this 
method
(f) Description and diagram of wind tunnel used for the calibration, 
including dimensions of cross-sectional area and position and size 
of the test section
(g) Documentation of wind tunnel qualification tests performed in 
accordance with section 10.1 of this method

    16.1.5  Quality assurance. Specific quality assurance and 
quality control procedures used during the test should be described.

17.0   Bibliography.

(1) 40 CFR Part 60, Appendix A, Method 1--Sample and velocity 
traverses for stationary sources.
(2) 40 CFR Part 60, Appendix A, Method 2--Determination of stack gas 
velocity and volumetric flow rate (Type S pitot tube) .
(3) 40 CFR Part 60, Appendix A, Method 2F--Determination of stack 
gas velocity and volumetric flow rate with three-dimensional probes.
(4) 40 CFR Part 60, Appendix A, Method 2H--Determination of stack 
gas velocity taking into account velocity decay near the stack wall.
(5) 40 CFR Part 60, Appendix A, Method 3--Gas analysis for carbon 
dioxide, oxygen, excess air, and dry molecular weight.
(6) 40 CFR Part 60, Appendix A, Method 3A--Determination of oxygen 
and carbon dioxide concentrations in emissions from stationary 
sources (instrumental analyzer procedure).
(7) 40 CFR Part 60, Appendix A, Method 4--Determination of moisture 
content in stack gases.
(8) Emission Measurement Center (EMC) Approved Alternative Method 
(ALT-011)

[[Page 26535]]

``Alternative Method 2 Thermocouple Calibration Procedure.''
(9) Electric Power Research Institute, Interim Report EPRI TR-
106698, ``Flue Gas Flow Rate Measurement Errors,'' June 1996.
(10) Electric Power Research Institute, Final Report EPRI TR-108110, 
``Evaluation of Heat Rate Discrepancy from Continuous Emission 
Monitoring Systems,'' August 1997.
(11) Fossil Energy Research Corporation, Final Report, ``Velocity 
Probe Tests in Non-axial Flow Fields,'' November 1998, Prepared for 
the U.S. Environmental Protection Agency.
(12) Fossil Energy Research Corporation, ``Additional Swirl Tunnel 
Tests: E-DAT and T-DAT Probes,'' February 24, 1999, Technical 
Memorandum Prepared for U.S. Environmental Protection Agency, P.O. 
No. 7W-1193-NALX.
(13) Massachusetts Institute of Technology, Report WBWT-TR-1317, 
``Calibration of Eight Wind Speed Probes Over a Reynolds Number 
Range of 46,000 to 725,000 Per Foot, Text and Summary Plots,'' Plus 
appendices, October 15, 1998, Prepared for The Cadmus Group, Inc.
(14) National Institute of Standards and Technology, Special 
Publication 250, ``NIST Calibration Services Users Guide 1991,'' 
Revised October 1991, U.S. Department of Commerce, p. 2.
(15) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four Prandtl Probes, 
Four S-Type Probes, Four French Probes, Four Modified Kiel Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
#DW13938432-01-0.
(16) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed In-strumentation, Five Autoprobes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
#DW13938432-01-0.
(17) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Eight Spherical 
Probes,'' Prepared for the U.S. Environmental Protection Agency 
under IAG #DW13938432-01-0.
(18) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four DAT Probes, `` 
Prepared for the U.S. Environmental Protection Agency under IAG 
#DW13938432-01-0.
(19) Norfleet, S.K., ``An Evaluation of Wall Effects on Stack Flow 
Velocities and Related Overestimation Bias in EPA's Stack Flow 
Reference Methods,'' EPRI CEMS User's Group Meeting, New Orleans, 
Louisiana, May 13-15, 1998.
(20) Page, J.J., E.A. Potts, and R.T. Shigehara, ``3-D Pitot Tube 
Calibration Study,'' EPA Contract No. 68D10009, Work Assignment No. 
I-121, March 11, 1993.
(21) Shigehara, R.T., W.F. Todd, and W.S. Smith, ``Significance of 
Errors in Stack Sampling Measurements,'' Presented at the Annual 
Meeting of the Air Pollution Control Association, St. Louis, 
Missouri, June 1419, 1970.
(22) The Cadmus Group, Inc., May 1999, ``EPA Flow Reference Method 
Testing and Analysis: Findings Report,'' EPA/430-R-99-009.
(23) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, DeCordova Steam 
Electric Station, Volume I: Test Description and Appendix A (Data 
Distribution Package),'' EPA/430-R-98-015a.
(24) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, Lake Hubbard 
Steam Electric Station, Volume I: Test Description and Appendix A 
(Data Distribution Package),'' EPA/430-R-98-017a.
(25) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Pennsylvania Electric Co., G.P.U. 
Genco Homer City Station: Unit 1, Volume I: Test Description and 
Appendix A (Data Distribution Package),'' EPA/430-R-98-018a.
(26) The Cadmus Group, Inc., 1997, ``EPA Flow Reference Method 
Testing and Analysis: Wind Tunnel Experimental Results,'' EPA/430-R-
97-013.

18.0  Annexes

    Annex A, C, and D describe recommended procedures for meeting 
certain provisions in sections 8.3, 10.4, and 10.5 of this method. 
Annex B describes procedures to be followed when using the 
protractor wheel and pointer assembly to measure yaw angles, as 
provided under section 8.9.1.
    18.1  Annex A--Rotational Position Check. The following are 
recommended procedures that may be used to satisfy the rotational 
position check requirements of section 8.3 of this method and to 
determine the angle-measuring device rotational offset 
(RADO).
    18.1.1  Rotational position check with probe outside stack. 
Where physical constraints at the sampling location allow full 
assembly of the probe outside the stack and insertion into the test 
port, the following procedures should be performed before the start 
of testing. Two angle-measuring devices that meet the specifications 
in section 6.2.1 or 6.2.3 are required for the rotational position 
check. An angle measuring device whose position can be independently 
adjusted (e.g., by means of a set screw) after being locked into 
position on the probe sheath shall not be used for this check unless 
the independent adjustment is set so that the device performs 
exactly like a device without the capability for independent 
adjustment. That is, when aligned on the probe such a device must 
give the same reading as a device that does not have the capability 
of being independently adjusted. With the fully assembled probe 
(including probe shaft extensions, if any) secured in a horizontal 
position, affix one yaw angle-measuring device to the probe sheath 
and lock it into position on the reference scribe line specified in 
section 6.1.5.1. Position the second angle-measuring device using 
the procedure in section 18.1.1.1 or 18.1.1.2.
    18.1.1.1  Marking procedure. The procedures in this section 
should be performed at each location on the fully assembled probe 
where the yaw angle-measuring device will be mounted during the 
velocity traverse. Place the second yaw angle-measuring device on 
the main probe sheath (or extension) at the position where a yaw 
angle will be measured during the velocity traverse. Adjust the 
position of the second angle-measuring device until it indicates the 
same angle (1 deg.) as the reference device, and affix 
the second device to the probe sheath (or extension). Record the 
angles indicated by the two angle-measuring devices on a form 
similar to table 2G-2. In this position, the second angle-measuring 
device is considered to be properly positioned for yaw angle 
measurement. Make a mark, no wider than 1.6 mm (\1/16\ in.), on the 
probe sheath (or extension), such that the yaw angle-measuring 
device can be re-affixed at this same properly aligned position 
during the velocity traverse.
    18.1.1.2  Procedure for probe extensions with scribe lines. If, 
during a velocity traverse the angle-measuring device will be 
affixed to a probe extension having a scribe line as specified in 
section 6.1.5.2, the following procedure may be used to align the 
extension's scribe line with the reference scribe line instead of 
marking the extension as described in section 18.1.1.1. Attach the 
probe extension to the main probe. Align and lock the second angle-
measuring device on the probe extension's scribe line. Then, rotate 
the extension until both measuring devices indicate the same angle 
(1 deg.). Lock the extension at this rotational 
position. Record the angles indicated by the two angle-measuring 
devices on a form similar to table 2G-2. An angle-measuring device 
may be aligned at any position on this scribe line during the 
velocity traverse, if the scribe line meets the alignment 
specification in section 6.1.5.3.
    18.1.1.3  Post-test rotational position check. If the fully 
assembled probe includes one or more extensions, the following check 
should be performed immediately after the completion of a velocity 
traverse. At the discretion of the tester, additional checks may be 
conducted after completion of testing at any sample port. Without 
altering the alignment of any of the components of the probe 
assembly used in the velocity traverse, secure the fully assembled 
probe in a horizontal position. Affix an angle-measuring device at 
the reference scribe line specified in section 6.1.5.1. Use the 
other angle-measuring device to check the angle at each location 
where the device was checked prior to testing. Record the readings 
from the two angle-measuring devices.
    18.1.2  Rotational position check with probe in stack. This 
section applies only to probes that, due to physical constraints, 
cannot be inserted into the test port as fully assembled with all 
necessary extensions needed to reach the inner-most traverse 
point(s).
    18.1.2.1  Perform the out-of-stack procedure in section 18.1.1 
on the main probe and any attached extensions that will be initially 
inserted into the test port.
    18.1.2.2  Use the following procedures to perform additional 
rotational position check(s) with the probe in the stack, each time 
a probe extension is added. Two angle-measuring devices are 
required. The first of

[[Page 26536]]

these is the device that was used to measure yaw angles at the 
preceding traverse point, left in its properly aligned measurement 
position. The second angle-measuring device is positioned on the 
added probe extension. Use the applicable procedures in section 
18.1.1.1 or 18.1.1.2 to align, adjust, lock, and mark (if necessary) 
the position of the second angle-measuring device to within 
1 deg. of the first device. Record the readings of the 
two devices on a form similar to Table 2G-2.
    18.1.2.3  The procedure in section 18.1.2.2 should be performed 
at the first port where measurements are taken. The procedure should 
be repeated each time a probe extension is re-attached at a 
subsequent port, unless the probe extensions are designed to be 
locked into a mechanically fixed rotational position (e.g., through 
use of interlocking grooves), which can be reproduced from port to 
port as specified in section 8.3.5.2.
    18.2  Annex B--Angle Measurement Protocol for Protractor Wheel 
and Pointer Device. The following procedure shall be used when a 
protractor wheel and pointer assembly, such as the one described in 
section 6.2.2 and illustrated in Figure 2G-5 is used to measure the 
yaw angle of flow. With each move to a new traverse point, unlock, 
re-align, and re-lock the probe, angle-pointer collar, and 
protractor wheel to each other. At each such move, particular 
attention is required to ensure that the scribe line on the angle 
pointer collar is either aligned with the reference scribe line on 
the main probe sheath or is at the rotational offset position 
established under section 8.3.1. The procedure consists of the 
following steps:
    18.2.1  Affix a protractor wheel to the entry port for the test 
probe in the stack or duct.
    18.2.2  Orient the protractor wheel so that the 0 deg. mark 
corresponds to the longitudinal axis of the stack or duct. For 
stacks, vertical ducts, or ports on the side of horizontal ducts, 
use a digital inclinometer meeting the specifications in section 
6.2.1 to locate the 0 deg. orientation. For ports on the top or 
bottom of horizontal ducts, identify the longitudinal axis at each 
test port and permanently mark the duct to indicate the 0 deg. 
orientation. Once the protractor wheel is properly aligned, lock it 
into position on the test port.
    18.2.3  Move the pointer assembly along the probe sheath to the 
position needed to take measurements at the first traverse point. 
Align the scribe line on the pointer collar with the reference 
scribe line or at the rotational offset position established under 
section 8.3.1. Maintaining this rotational alignment, lock the 
pointer device onto the probe sheath. Insert the probe into the 
entry port to the depth needed to take measurements at the first 
traverse point.
    18.2.4  Perform the yaw angle determination as specified in 
sections 8.9.3 and 8.9.4 and record the angle as shown by the 
pointer on the protractor wheel. Then, take velocity pressure and 
temperature measurements in accordance with the procedure in section 
8.9.5. Perform the alignment check described in section 8.9.6.
    18.2.5  After taking velocity pressure measurements at that 
traverse point, unlock the probe from the collar and slide the probe 
through the collar to the depth needed to reach the next traverse 
point.
    18.2.6  Align the scribe line on the pointer collar with the 
reference scribe line on the main probe or at the rotational offset 
position established under section 8.3.1. Lock the collar onto the 
probe.
    18.2.7  Repeat the steps in sections 18.2.4 through 18.2.6 at 
the remaining traverse points accessed from the current stack or 
duct entry port.
    18.2.8  After completing the measurement at the last traverse 
point accessed from a port, verify that the orientation of the 
protractor wheel on the test port has not changed over the course of 
the traverse at that port. For stacks, vertical ducts, or ports on 
the side of horizontal ducts, use a digital inclinometer meeting the 
specifications in section 6.2.1 to check the rotational position of 
the 0 deg. mark on the protractor wheel. For ports on the top or 
bottom of horizontal ducts, observe the alignment of the angle wheel 
0 deg. mark relative to the permanent 0 deg. mark on the duct at 
that test port. If these observed comparisons exceed 
2 deg. of 0 deg., all angle and pressure measurements 
taken at that port since the protractor wheel was last locked into 
position on the port shall be repeated.
    18.2.9  Move to the next stack or duct entry port and repeat the 
steps in sections 18.2.1 through 18.2.8.
    18.3  Annex C--Guideline for Reference Scribe Line Placement. 
Use of the following guideline is recommended to satisfy the 
requirements of section 10.4 of this method. The rotational position 
of the reference scribe line should be either 90 deg. or 180 deg. 
from the probe's impact pressure port. For Type-S probes, place 
separate scribe lines, on opposite sides of the probe sheath, if 
both the A and B sides of the pitot tube are to be used for yaw 
angle measurements.
    18.4  Annex D--Determination of Reference Scribe Line Rotational 
Offset. The following procedures are recommended for determining the 
magnitude and sign of a probe's reference scribe line rotational 
offset, RSLO. Separate procedures are provided for two 
types of angle-measuring devices: digital inclinometers and 
protractor wheel and pointer assemblies.
    18.4.1  Perform the following procedures on the main probe with 
all devices that will be attached to the main probe in the field 
[such as thermocouples, resistance temperature detectors (RTDs), or 
sampling nozzles] that may affect the flow around the probe head. 
Probe shaft extensions that do not affect flow around the probe head 
need not be attached during calibration.
    18.4.2  The procedures below assume that the wind tunnel duct 
used for probe calibration is horizontal and that the flow in the 
calibration wind tunnel is axial as determined by the axial flow 
verification check described in section 10.1.2. Angle-measuring 
devices are assumed to display angles in alternating 0 deg. to 
90 deg. and 90 deg. to 0 deg. intervals. If angle-measuring devices 
with other readout conventions are used or if other calibration wind 
tunnel duct configurations are used, make the appropriate 
calculational corrections. For Type-S probes, calibrate the A-side 
and B-sides separately, using the appropriate scribe line (see 
section 18.3, above), if both the A and B sides of the pitot tube 
are to be used for yaw angle determinations.
    18.4.2.1  Position the angle-measuring device in accordance with 
one of the following procedures.
    18.4.2.1.1  If using a digital inclinometer, affix the 
calibrated digital inclinometer to the probe. If the digital 
inclinometer can be independently adjusted after being locked into 
position on the probe sheath (e.g., by means of a set screw), the 
independent adjustment must be set so that the device performs 
exactly like a device without the capability for independent 
adjustment. That is, when aligned on the probe the device must give 
the same readings as a device that does not have the capability of 
being independently adjusted. Either align it directly on the 
reference scribe line or on a mark aligned with the scribe line 
determined according to the procedures in section 18.1.1.1. 
Maintaining this rotational alignment, lock the digital inclinometer 
onto the probe sheath.
    18.4.2.1.2  If using a protractor wheel and pointer device, 
orient the protractor wheel on the test port so that the  deg. mark 
is aligned with the longitudinal axis of the wind tunnel duct. 
Maintaining this alignment, lock the wheel into place on the wind 
tunnel test port. Align the scribe line on the pointer collar with 
the reference scribe line or with a mark aligned with the reference 
scribe line, as determined under section 18.1.1.1. Maintaining this 
rotational alignment, lock the pointer device onto the probe sheath.
    18.4.2.2  Zero the pressure-measuring device used for yaw 
nulling.
    18.4.2.3  Insert the probe assembly into the wind tunnel through 
the entry port, positioning the probe's impact port at the 
calibration location. Check the responsiveness of the pressure-
measuring device to probe rotation, taking corrective action if the 
response is unacceptable.
    18.4.2.4  Ensure that the probe is in a horizontal position 
using a carpenter's level.
    18.4.2.5  Rotate the probe either clockwise or counterclockwise 
until a yaw null [zero P for a Type S probe or zero 
(P2-P3) for a 3-D probe] is obtained. If using 
a Type S probe with an attached thermocouple, the direction of the 
probe rotation shall be such that the thermocouple is located 
downstream of the probe pressure ports at the yaw-null position.
    18.4.2.6  Read and record the value of 
null, the angle indicated by the angle-
measuring device at the yaw-null position. Record the angle reading 
on a form similar to Table 2G-6. Do not associate an algebraic sign 
with this reading.
    18.4.2.7  Determine the magnitude and algebraic sign of the 
reference scribe line rotational offset, RSLO. The 
magnitude of RSLO will be equal to either 
null or (90 deg.-null), 
depending on the type of probe being calibrated and the type of 
angle-measuring device used. (See Table 2G-7 for a summary.) The 
algebraic sign of RSLO will either be positive if the 
rotational position of the reference scribe line is clockwise or 
negative if counterclockwise with respect to the probe's yaw-null 
position. Figure 2G-10 illustrates how the magnitude and sign of 
RSLO are determined.

[[Page 26537]]

    18.4.2.8  Perform the steps in sections 18.3.2.3 through 
18.3.2.7 twice at each of the two calibration velocities selected 
for the probe under section 10.6. Record the values of 
RSLO in a form similar to Table 2G-6.
    18.4.2.9  The average of all RSLO values is the 
reference scribe line rotational offset for the probe.


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BILLING CODE 6560-50-C

[[Page 26554]]

Method 2H--Determination of Stack Gas Velocity Taking Into Account 
Velocity Decay Near the Stack Wall

1.0  Scope and Application

    1.1  This method is applicable in conjunction with Methods 2, 
2F, and 2G (40 CFR Part 60, Appendix A) to account for velocity 
decay near the wall in circular stacks and ducts.
    1.2  This method is not applicable for testing stacks and ducts 
less than 3.3 ft (1.0 m) in diameter.
    1.3  Data Quality Objectives. Adherence to the requirements of 
this method will enhance the quality of the data obtained from air 
pollutant sampling methods.

2.0  Summary of Method

    2.1  A wall effects adjustment factor is determined. It is used 
to adjust the average stack gas velocity obtained under Method 2, 
2F, or 2G of this appendix to take into account velocity decay near 
the stack or duct wall.
    2.2  The method contains two possible procedures: a 
calculational approach which derives an adjustment factor from 
velocity measurements and a default procedure which assigns a 
generic adjustment factor based on the construction of the stack or 
duct.
    2.2.1  The calculational procedure derives a wall effects 
adjustment factor from velocity measurements taken using Method 2, 
2F, or 2G at 16 (or more) traverse points specified under Method 1 
of this appendix and a total of eight (or more) wall effects 
traverse points specified under this method. The calculational 
procedure based on velocity measurements is not applicable for 
horizontal circular ducts where build-up of particulate matter or 
other material in the bottom of the duct is present.
    2.2.2  A default wall effects adjustment factor of 0.9900 for 
brick and mortar stacks and 0.9950 for all other types of stacks and 
ducts may be used without taking wall effects measurements in a 
stack or duct.
    2.3  When the calculational procedure is conducted as part of a 
relative accuracy test audit (RATA) or other multiple-run test 
procedure, the wall effects adjustment factor derived from a single 
traverse (i.e., single RATA run) may be applied to all runs of the 
same RATA without repeating the wall effects measurements. 
Alternatively, wall effects adjustment factors may be derived for 
several traverses and an average wall effects adjustment factor 
applied to all runs of the same RATA.
    3.0  Definitions.
    3.1  Complete wall effects traverse means a traverse in which 
measurements are taken at drem (see section 3.3) and at 
1-in. intervals in each of the four Method 1 equal-area sectors 
closest to the wall, beginning not farther than 4 in. (10.2 cm) from 
the wall and extending either (1) across the entire width of the 
Method 1 equal-area sector or (2) for stacks or ducts where this 
width exceeds 12 in. (30.5 cm) (i.e., stacks or ducts greater than 
or equal to 15.6 ft [4.8 m] in diameter), to a distance of not less 
than 12 in. (30.5 cm) from the wall. Note: Because this method 
specifies that measurements must be taken at whole number multiples 
of 1 in. from a stack or duct wall, for clarity numerical quantities 
in this method are expressed in English units followed by metric 
units in parentheses. To enhance readability, hyphenated terms such 
as ``1-in. intervals'' or ``1-in. incremented,'' are expressed in 
English units only.
    3.2  dlast. Depending on context, dlast 
means either (1) the distance from the wall of the last 1-in. 
incremented wall effects traverse point or (2) the traverse point 
located at that distance (see Figure 2H-2).
    3.3  drem. Depending on context, drem 
means either (1) the distance from the wall of the centroid of the 
area between dlast and the interior edge of the Method 1 
equal-area sector closest to the wall or (2) the traverse point 
located at that distance (see Figure 2H-2).
    3.4  ``May,'' ``Must,'' ``Shall,'' ``Should,'' and the 
imperative form of verbs.
    3.4.1  ``May'' is used to indicate that a provision of this 
method is optional.
    3.4.2  ``Must,'' ``Shall,'' and the imperative form of verbs 
(such as ``record'' or ``enter'') are used to indicate that a 
provision of this method is mandatory.
    3.4.3  ``Should'' is used to indicate that a provision of this 
method is not mandatory but is highly recommended as good practice.
    3.5  Method 1 refers to 40 CFR part 60, appendix A, ``Method 1--
Sample and velocity traverses for stationary sources.''
    3.6  Method 1 exterior equal-area sector and Method 1 equal-area 
sector closest to the wall mean any one of the four equal-area 
sectors that are closest to the wall for a circular stack or duct 
laid out in accordance with section 2.3.1 of Method 1 (see Figure 
2H-1).
    3.7  Method 1 interior equal-area sector means any of the equal-
area sectors other than the Method 1 exterior equal-area sectors (as 
defined in section 3.6) for a circular stack or duct laid out in 
accordance with section 2.3.1 of Method 1 (see Figure 2H-1).
    3.8  Method 1 traverse point and Method 1 equal-area traverse 
point mean a traverse point located at the centroid of an equal-area 
sector of a circular stack laid out in accordance with section 2.3.1 
of Method 1.
    3.9  Method 2 refers to 40 CFR part 60, appendix A, ``Method 2--
Determination of stack gas velocity and volumetric flow rate (Type S 
pitot tube).''
    3.10  Method 2F refers to 40 CFR part 60, appendix A, ``Method 
2F--Determination of stack gas velocity and volumetric flow rate 
with three-dimensional probes.''
    3.11  Method 2G refers to 40 CFR part 60, appendix A, ``Method 
2G--Determination of stack gas velocity and volumetric flow rate 
with two-dimensional probes.''
    3.12  1-in. incremented wall effects traverse point means any of 
the wall effects traverse points that are located at 1-in. 
intervals, i.e., traverse points d1 through dlast 
(see Figure 2H-2).
    3.13  Partial wall effects traverse means a traverse in which 
measurements are taken at fewer than the number of traverse points 
required for a ``complete wall effects traverse'' (as defined in 
section 3.1), but are taken at a minimum of two traverse points in 
each Method 1 equal-area sector closest to the wall, as specified in 
section 8.2.2.
    3.14  Relative accuracy test audit (RATA) is a field test 
procedure performed in a stack or duct in which a series of 
concurrent measurements of the same stack gas stream is taken by a 
reference method and an installed monitoring system. A RATA usually 
consists of series of 9 to 12 sets of such concurrent measurements, 
each of which is referred to as a RATA run. In a volumetric flow 
RATA, each reference method run consists of a complete traverse of 
the stack or duct.
    3.15  Wall effects-unadjusted average velocity means the average 
stack gas velocity, not accounting for velocity decay near the wall, 
as determined in accordance with Method 2, 2F, or 2G for a Method 1 
traverse consisting of 16 or more points.
    3.16  Wall effects-adjusted average velocity means the average 
stack gas velocity, taking into account velocity decay near the 
wall, as calculated from measurements at 16 or more Method 1 
traverse points and at the additional wall effects traverse points 
specified in this method.
    3.17  Wall effects traverse point means a traverse point located 
in accordance with sections 8.2.2 or 8.2.3 of this method.

4.0  Interferences. [Reserved]

5.0  Safety

    5.1  This method may involve hazardous materials, operations, 
and equipment. This method does not purport to address all of the 
health and safety considerations associated with its use. It is the 
responsibility of the user of this method to establish appropriate 
health and safety practices and to determine the applicability of 
occupational health and safety regulatory requirements prior to 
performing this method.

6.0  Equipment and Supplies

    6.1  The provisions pertaining to equipment and supplies in the 
method that is used to take the traverse point measurements (i.e., 
Method 2, 2F, or 2G) are applicable under this method.

7.0  Reagents and Standards. [Reserved]

8.0  Sample Collection and Analysis

    8.1  Default Wall Effects Adjustment Factors. A default wall 
effects adjustment factor of 0.9900 for brick and mortar stacks and 
0.9950 for all other types of stacks and ducts may be used without 
conducting the following procedures.
    8.2  Traverse Point Locations. Determine the location of the 
Method 1 traverse points in accordance with section 8.2.1 and the 
location of the traverse points for either a partial wall effects 
traverse in accordance with section 8.2.2 or a complete wall effects 
traverse in accordance with section 8.2.3.
    8.2.1  Method 1 equal-area traverse point locations. Determine 
the location of the Method 1 equal-area traverse points for a 
traverse consisting of 16 or more points using Table 1-2 (Location 
of Traverse Points in Circular Stacks) of Method 1.
    8.2.2  Partial wall effects traverse. For a partial wall effects 
traverse, measurements must be taken at a minimum of the following 
two wall effects traverse point locations in all four Method 1 
equal-area sectors closest to the wall: (1) 1 in. (2.5 cm) from the 
wall (except as provided in section 8.2.2.1) and (2)

[[Page 26555]]

drem, as determined using Equation 2H-1 or 2H-2 (see 
section 8.2.2.2).
    8.2.2.1  If the probe cannot be positioned at 1 in. (2.5 cm) 
from the wall (e.g., because of insufficient room to withdraw the 
probe shaft) or if velocity pressure cannot be detected at 1 in. 
(2.5 cm) from the wall (for any reason other than build-up of 
particulate matter in the bottom of a duct), take measurements at 
the 1-in. incremented wall effects traverse point closest to the 
wall where the probe can be positioned and velocity pressure can be 
detected.
    8.2.2.2  Calculate the distance of drem from the wall 
to within \1/4\ in. (6.4 mm) using Equation 2H-1 or 
Equation 2H-2 (for a 16-point traverse).
[GRAPHIC] [TIFF OMITTED] TR14MY99.074

Where:

r = the stack or duct radius determined from direct measurement of 
the stack or duct diameter in accordance with section 8.6 of Method 
2F or Method 2G, in. (cm);
p = the number of Method 1 equal-area traverse points on a diameter, 
p  8 (e.g., for a 16-point traverse, p = 8); dlast 
and drem are defined in sections 3.2 and 3.3 
respectively, in. (cm).

For a 16-point Method 1 traverse, Equation 2H-1 becomes:
[GRAPHIC] [TIFF OMITTED] TR14MY99.075

    8.2.2.3  Measurements may be taken at any number of additional 
wall effects traverse points, with the following provisions.
    (a) dlast must not be closer to the center of the 
stack or duct than the distance of the interior edge (boundary), 
db, of the Method 1 equal-area sector closest to the wall 
(see Figure 2H-2 or 2H-3). That is,

[GRAPHIC] [TIFF OMITTED] TR14MY99.094

Where:
[GRAPHIC] [TIFF OMITTED] TR14MY99.076

Table 2H-1 shows db as a function of the stack or duct 
radius, r, for traverses ranging from 16 to 48 points (i.e., for 
values of p ranging from 8 to 24).
    (b) Each point must be located at a distance that is a whole 
number (e.g., 1, 2, 3) multiple of 1 in. (2.5 cm).
    (c) Points do not have to be located at consecutive 1-in. 
intervals. That is, one or more 1-in. incremented points may be 
skipped. For example, it would be acceptable for points to be 
located at 1 in. (2.5 cm), 3 in. (7.6 cm), 5 in. (12.7 cm), 
dlast, and drem; or at 1 in. (2.5 cm), 2 in. 
(5.1 cm), 4 in. (10.2 cm), 7 in. (17.8 cm), dlast, and 
drem. Follow the instructions in section 8.7.1.2 of this 
method for recording results for wall effects traverse points that 
are skipped. It should be noted that the full extent of velocity 
decay may not be accounted for if measurements are not taken at all 
1-in. incremented points close to the wall.
    8.2.3  Complete wall effects traverse. For a complete wall 
effects traverse, measurements must be taken at the following points 
in all four Method 1 equal-area sectors closest to the wall.
    (a) The 1-in. incremented wall effects traverse point closest to 
the wall where the probe can be positioned and velocity can be 
detected, but no farther than 4 in. (10.2 cm) from the wall.
    (b) Every subsequent 1-in. incremented wall effects traverse 
point out to the interior edge of the Method 1 equal-area sector or 
to 12 in. (30.5 cm) from the wall, whichever comes first. Note: In 
stacks or ducts with diameters greater than 15.6 ft (4.8 m) the 
interior edge of the Method 1 equal-area sector is farther from the 
wall than 12 in. (30.5 cm).
    (c) drem, as determined using Equation 2H-1 or 2H-2 
(as applicable). Note: For a complete traverse of a stack or duct 
with a diameter less than 16.5 ft (5.0 m), the distance between 
drem and dlast is less than or equal to \1/2\ 
in. (12.7 mm). As discussed in section 8.2.4.2, when the distance 
between drem and dlast is less than or equal 
to \1/2\ in. (12.7 mm), the velocity measured at dlast 
may be used for drem. Thus, it is not necessary to 
calculate the distance of drem or to take measurements at 
drem when conducting a complete traverse of a stack or 
duct with a diameter less than 16.5 ft (5.0 m).
    8.2.4  Special considerations. The following special 
considerations apply when the distance between traverse points is 
less than or equal to \1/2\ in. (12.7 mm).
    8.2.4.1  A wall effects traverse point and the Method 1 traverse 
point. If the distance between a wall effects traverse point and the 
Method 1 traverse point is less than or equal to \1/2\ in. (12.7 
mm), taking measurements at both points is allowed but not required 
or recommended; if measurements are taken at only one point, take 
the measurements at the point that is farther from the wall and use 
the velocity obtained at that point as the value for both points 
(see sections 8.2.3 and 9.2 for related requirements).
    8.2.4.2  drem and dlast. If the distance 
between drem and dlast is less than or equal 
to \1/2\ in. (12.7 mm), taking measurements at drem is 
allowed but not required or recommended; if measurements are not 
taken at drem, the measured velocity value at 
dlast must be used as the value for both dlast 
and drem.
    8.3  Traverse Point Sampling Order and Probe Selection. 
Determine the sampling order of the Method 1 and wall effects 
traverse points and select the appropriate probe for the 
measurements, taking into account the following considerations.
    8.3.1  Traverse points on any radius may be sampled in either 
direction (i.e., from the wall toward the center of the stack or 
duct, or vice versa).
    8.3.2  To reduce the likelihood of velocity variations during 
the time of the traverse and the attendant potential impact on the 
wall effects-adjusted and unadjusted average velocities, the 
following provisions of this method shall be met.
    8.3.2.1  Each complete set of Method 1 and wall effects traverse 
points accessed from the same port shall be sampled without 
interruption. Unless traverses are performed simultaneously in all 
ports using separate probes at each port, this provision disallows 
first sampling all Method 1 points at all ports and then sampling 
all the wall effects points.
    8.3.2.2  The entire integrated Method 1 and wall effects 
traverse across all test ports shall be as short as practicable, 
consistent with the measurement system response time (see section 
8.4.1.1) and sampling (see section 8.4.1.2) provisions of this 
method.
    8.3.3  It is recommended but not required that in each Method 1 
equal-area sector closest to the wall, the Method 1 equal-area 
traverse point should be sampled in sequence between the adjacent 
wall effects traverse points. For example, for the traverse point 
configuration shown in Figure 2H-2, it is recommended that the 
Method 1 equal-area traverse point be sampled between 
dlast and drem. In this example, if the 
traverse is conducted from the wall toward the center of the stack 
or duct, it is recommended that measurements be taken at points in 
the following order: d1, d2, dlast, 
the Method 1 traverse point, drem, and then at the 
traverse points in the three Method 1 interior equal-area sectors.
    8.3.4  The same type of probe must be used to take measurements 
at all Method 1 and wall effects traverse points. However, different 
copies of the same type of probe may be used at different ports 
(e.g., Type S probe 1 at port A, Type S probe 2 at port B)

[[Page 26556]]

or at different traverse points accessed from a particular port 
(e.g., Type S probe 1 for Method 1 interior traverse points accessed 
from port A, Type S probe 2 for wall effects traverse points and the 
Method 1 exterior traverse point accessed from port A). The 
identification number of the probe used to obtain measurements at 
each traverse point must be recorded.
    8.4  Measurements at Method 1 and Wall Effects Traverse Points. 
Conduct measurements at Method 1 and wall effects traverse points in 
accordance with Method 2, 2F, or 2G and in accordance with the 
provisions of the following subsections (some of which are included 
in Methods 2F and 2G but not in Method 2), which are particularly 
important for wall effects testing.
    8.4.1  Probe residence time at wall effects traverse points. Due 
to the steep temperature and pressure gradients that can occur close 
to the wall, it is very important for the probe residence time 
(i.e., the total time spent at a traverse point) to be long enough 
to ensure collection of representative temperature and pressure 
measurements. The provisions of Methods 2F and 2G in the following 
subsections shall be observed.
    8.4.1.1  System response time. Determine the response time of 
each probe measurement system by inserting and positioning the 
``cold'' probe (at ambient temperature and pressure) at any Method 1 
traverse point. Read and record the probe differential pressure, 
temperature, and elapsed time at 15-second intervals until stable 
readings for both pressure and temperature are achieved. The 
response time is the longer of these two elapsed times. Record the 
response time.
    8.4.1.2  Sampling. At the start of testing in each port (i.e., 
after a probe has been inserted into the stack gas stream), allow at 
least the response time to elapse before beginning to take 
measurements at the first traverse point accessed from that port. 
Provided that the probe is not removed from the stack gas stream, 
measurements may be taken at subsequent traverse points accessed 
from the same test port without waiting again for the response time 
to elapse.
    8.4.2  Temperature measurement for wall effects traverse points. 
Either (1) take temperature measurements at each wall effects 
traverse point in accordance with the applicable provisions of 
Method 2, 2F, or 2G; or (2) use the temperature measurement at the 
Method 1 traverse point closest to the wall as the temperature 
measurement for all the wall effects traverse points in the 
corresponding equal-area sector.
    8.4.3  Non-detectable velocity pressure at wall effects traverse 
points. If the probe cannot be positioned at a wall effects traverse 
point or if no velocity pressure can be detected at a wall effects 
point, measurements shall be taken at the first subsequent wall 
effects traverse point farther from the wall where velocity can be 
detected. Follow the instructions in section 8.7.1.2 of this method 
for recording results for wall effects traverse points where 
velocity pressure cannot be detected. It should be noted that the 
full extent of velocity decay may not be accounted for if 
measurements are not taken at the 1-in. incremented wall effects 
traverse points closest to the wall.
    8.5  Data Recording. For each wall effects and Method 1 traverse 
point where measurements are taken, record all pressure, 
temperature, and attendant measurements prescribed in section 3 of 
Method 2 or section 8.0 of Method 2F or 2G, as applicable.
    8.6  Point Velocity Calculation. For each wall effects and 
Method 1 traverse point, calculate the point velocity value 
(vi) in accordance with sections 12.1 and 12.2 of Method 
2F for tests using Method 2F and in accordance with sections 12.1 
and 12.2 of Method 2G for tests using Method 2 and Method 2G. (Note 
that the term (vi) in this method corresponds to the term 
(va(i)) in Methods 2F and 2G.) When the equations in the 
indicated sections of Method 2G are used in deriving point velocity 
values for Method 2 tests, set the value of the yaw angles appearing 
in the equations to 0 deg..
    8.7  Tabulating Calculated Point Velocity Values for Wall 
Effects Traverse Points. Enter the following values in a hardcopy or 
electronic form similar to Form 2H-1 (for 16-point Method 1 
traverses) or Form 2H-2 (for Method 1 traverses consisting of more 
than 16 points). A separate form must be completed for each of the 
four Method 1 equal-area sectors that are closest to the wall.
(a) Port ID (e.g., A, B, C, or D)
(b) Probe type
(c) Probe ID
(d) Stack or duct diameter in ft (m) (determined in accordance with 
section 8.6 of Method 2F or Method 2G)
(e) Stack or duct radius in in. (cm)
(f) Distance from the wall of wall effects traverse points at 1-in. 
intervals, in ascending order starting with 1 in. (2.5 cm) (column A 
of Form 2H-1 or 2H-2)
(g) Point velocity values (vd) for 1-in. incremented 
traverse points (see section 8.7.1), including dlast (see 
section 8.7.2)
    (h) Point velocity value (vdrem) at drem (see 
section 8.7.3).

    8.7.1   Point velocity values at wall effects traverse points 
other than dlast. For every 1-in. incremented wall 
effects traverse point other than dlast, enter in column 
B of Form 2H-1 or 2H-2 either the velocity measured at the point 
(see section 8.7.1.1) or the velocity measured at the first 
subsequent traverse point farther from the wall (see section 
8.7.1.2). A velocity value must be entered in column B of Form 2H-1 
or 2H-2 for every 1-in. incremented traverse point from d1 
(representing the wall effects traverse point 1 in. [2.5 cm] from 
the wall) to dlast.
    8.7.1.1  For wall effects traverse points where the probe can be 
positioned and velocity pressure can be detected, enter the value 
obtained in accordance with section 8.6.
    8.7.1.2  For wall effects traverse points that were skipped [see 
section 8.2.2.3(c)] and for points where the probe cannot be 
positioned or where no velocity pressure can be detected, enter the 
value obtained at the first subsequent traverse point farther from 
the wall where velocity pressure was detected and measured and 
follow the entered value with a ``flag,'' such as the notation 
``NM,'' to indicate that ``no measurements'' were actually taken at 
this point.
    8.7.2  Point velocity value at dlast. For 
dlast, enter in column B of Form 2H-1 or 2H-2 the 
measured value obtained in accordance with section 8.6.
    8.7.3  Point velocity value (vdrem) at 
drem. Enter the point velocity value obtained at 
drem in column G of row 4a in Form 2H-1 or 2H-2. If the 
distance between drem and dlast is less than 
or equal to \1/2\ in. (12.7 mm), the measured velocity value at 
dlast may be used as the value at drem (see 
section 8.2.4.2).
    9.0  Quality Control.
    9.1  Particulate Matter Build-up in Horizontal Ducts. Wall 
effects testing of horizontal circular ducts should be conducted 
only if build-up of particulate matter or other material in the 
bottom of the duct is not present.
    9.2  Verifying Traverse Point Distances. In taking measurements 
at wall effects traverse points, it is very important for the probe 
impact pressure port to be positioned as close as practicable to the 
traverse point locations in the gas stream. For this reason, before 
beginning wall effects testing, it is important to calculate and 
record the traverse point positions that will be marked on each 
probe for each port, taking into account the distance that each port 
nipple (or probe mounting flange for automated probes) extends out 
of the stack and any extension of the port nipple (or mounting 
flange) into the gas stream. To ensure that traverse point positions 
are properly identified, the following procedures should be 
performed on each probe used.
    9.2.1  Manual probes. Mark the probe insertion distance of the 
wall effects and Method 1 traverse points on the probe sheath so 
that when a mark is aligned with the outside face of the stack port, 
the probe impact port is located at the calculated distance of the 
traverse point from the stack inside wall. The use of different 
colored marks is recommended for designating the wall effects and 
Method 1 traverse points. Before the first use of each probe, check 
to ensure that the distance of each mark from the center of the 
probe impact pressure port agrees with the previously calculated 
traverse point positions to within \1/4\ in. (6.4 mm).
    9.2.2  Automated probe systems. For automated probe systems that 
mechanically position the probe head at prescribed traverse point 
positions, activate the system with the probe assemblies removed 
from the test ports and sequentially extend the probes to the 
programmed location of each wall effects traverse point and the 
Method 1 traverse points. Measure the distance between the center of 
the probe impact pressure port and the inside of the probe assembly 
mounting flange for each traverse point. The measured distances must 
agree with the previously calculated traverse point positions to 
within \1/4\ in. (6.4 mm).
    9.3  Probe Installation. Properly sealing the port area is 
particularly important in taking measurements at wall effects 
traverse points. For testing involving manual probes, the area 
between the probe sheath and the port should be sealed with a 
tightly fitting flexible seal made of an appropriate material such 
as heavy cloth so that leakage is minimized. For automated probe 
systems, the probe assembly mounting flange area should be checked 
to verify that there is no leakage.
    9.4  Velocity Stability. This method should be performed only 
when the average

[[Page 26557]]

gas velocity in the stack or duct is relatively constant over the 
duration of the test. If the average gas velocity changes 
significantly during the course of a wall effects test, the test 
results should be discarded.

10.0  Calibration

    10.1  The calibration coefficient(s) or curves obtained under 
Method 2, 2F, or 2G and used to perform the Method 1 traverse are 
applicable under this method.

11.0  Analytical Procedure

    11.1  Sample collection and analysis are concurrent for this 
method (see section 8).

12.0  Data Analysis and Calculations

    12.1  The following calculations shall be performed to obtain a 
wall effects adjustment factor (WAF) from (1) the wall effects-
unadjusted average velocity (vavg), (2) the replacement 
velocity (vej) for each of the four Method 1 sectors 
closest to the wall, and (3) the average stack gas velocity that 
accounts for velocity decay near the wall (vavg).
    12.2  Nomenclature. The following terms are listed in the order 
in which they appear in Equations 2H-5 through 2H-21.

vavg=the average stack gas velocity, unadjusted for wall 
effects, actual ft/sec (m/sec);
vii=stack gas point velocity value at Method 1 interior 
equal-area sectors, actual ft/sec (m/sec);
vej=stack gas point velocity value, unadjusted for wall 
effects, at Method 1 exterior equal-area sectors, actual ft/sec (m/
sec);
i=index of Method 1 interior equal-area traverse points;
j=index of Method 1 exterior equal-area traverse points;
n=total number of traverse points in the Method 1 traverse;
vdecd=the wall effects decay velocity for a sub-sector 
located between the traverse points at distances d-1 (in metric 
units, d-2.5) and d from the wall, actual ft/sec (m/sec);
vd=the measured stack gas velocity at distance d from the 
wall, actual ft/sec (m/sec); Note: v0=0;
d=the distance of a 1-in. incremented wall effects traverse point 
from the wall, for traverse points d1 through dlast, 
in. (cm);
Ad=the cross-sectional area of a sub-sector located 
between the traverse points at distances d-1 (in metric units, 
d-2.5) and d from the wall, in.\2\ (cm \2\) ( e.g., sub-sector 
A2 shown in Figures 2H-3 and 2H-4);
r=the stack or duct radius, in. (cm);
 Qd=the stack gas volumetric flow rate for a sub-sector 
located between the traverse points at distances d-1 (in metric 
units, d-2.5) and d from the wall, actual ft-in.\2\/sec (m-cm \2\/
sec);
Ud, 
d=the total 
stack gas volumetric flow rate for all sub-sectors located between 
the wall and dlast, actual ft-in.\2\/sec (m-cm \2\/sec);
dlast=the distance from the wall of the last 1-in. 
incremented wall effects traverse point, in. (cm);
Adrem=the cross-sectional area of the sub-sector located 
between dlast and the interior edge of the Method 1 
equal-area sector closest to the wall, in.\2\ (cm \2\) (see Figure 
2H-4);
p=the number of Method 1 traverse points per diameter,  
p8 (e.g., for a 16-point traverse, p=8);
drem=the distance from the wall of the centroid of the 
area between dlast and the interior edge of the Method 1 
equal-area sector closest to the wall, in. (cm);
Qdrem=the total stack gas volumetric flow rate for the 
sub-sector located between dlast and the interior edge of 
the Method 1 equal-area sector closest to the wall, actual ft-
in.\2\/sec (m-cm \2\/sec);
vdrem=the measured stack gas velocity at distance 
drem from the wall, actual ft/sec (m/sec);
QT=the total stack gas volumetric flow rate for the 
Method 1 equal-area sector closest to the wall, actual ft-in.\2\/sec 
(m-cm \2\/sec);
vej=the replacement stack gas velocity for the Method 1 
equal-area sector closest to the wall, i.e., the stack gas point 
velocity value, adjusted for wall effects, for the 
jth Method 1 equal-area sector closest to the wall, 
actual ft/sec (m/sec);
vavg=the average stack gas velocity that accounts for 
velocity decay near the wall, actual ft/sec (m/sec);
WAF=the wall effects adjustment factor derived from vavg 
and vavg for a single traverse, dimensionless;
vfinal=the final wall effects-adjusted average stack gas 
velocity that replaces the unadjusted average stack gas velocity 
obtained using Method 2, 2F, or 2G for a field test consisting of a 
single traverse, actual ft/sec (m/sec);
WAF=the wall effects adjustment factor that is applied to the 
average velocity, unadjusted for wall effects, in order to obtain 
the final wall effects-adjusted stack gas velocity, vfinal 
or, vfinal(k), dimensionless;
vfinal(k)=the final wall effects-adjusted average stack 
gas velocity that replaces the unadjusted average stack gas velocity 
obtained using Method 2, 2F, or 2G on run k of a RATA or other 
multiple-run field test procedure, actual ft/sec (m/sec);
vavg(k)=the average stack gas velocity, obtained on run k 
of a RATA or other multiple-run procedure, unadjusted for velocity 
decay near the wall, actual ft/sec (m/sec);
k=index of runs in a RATA or other multiple-run procedure.

    12.3  Calculate the average stack gas velocity that does not 
account for velocity decay near the wall (vavg) using 
Equation 2H-5.
[GRAPHIC] [TIFF OMITTED] TR14MY99.077

(Note that vavg in Equation 2H-5 is the same as 
v(a)avg in Equations 2F-9 and 2G-8 in Methods 2F and 2G, 
respectively.)
    For a 16-point traverse, Equation 2H-5 may be written as 
follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.078

    12.4  Calculate the replacement velocity, vej, for 
each of the four Method 1 equal-area sectors closest to the wall 
using the procedures described in sections 12.4.1 through 12.4.8. 
Forms 2H-1 and 2H-2 provide sample tables that may be used in either 
hardcopy or spreadsheet format to perform the calculations described 
in sections 12.4.1 through 12.4.8. Forms 2H-3 and 2H-4 provide 
examples of Form 2H-1 filled in for partial and complete wall 
effects traverses.
    12.4.1  Calculate the average velocity (designated the ``decay 
velocity,'' vdecd) for each sub-sector located between 
the wall and dlast (see Figure 2H-3) using Equation 2H-7.
[GRAPHIC] [TIFF OMITTED] TR14MY99.079

For each line in column A of Form 2H-1 or 2H-2 that contains a value 
of d, enter the corresponding calculated value of vdecd 
in column C.
    12.4.2  Calculate the cross-sectional area between the wall and 
the first 1-in. incremented wall effects traverse point and between 
successive 1-in. incremented wall effects traverse points, from the 
wall to dlast (see Figure 2H-3), using Equation 2H-8.
[GRAPHIC] [TIFF OMITTED] TR14MY99.080

For each line in column A of Form 2H-1 or 2H-2 that contains a value 
of d, enter the value of the expression \1/4\ 
(r-d+1)2 in column D, the value of the 
expression \1/4\ (r-d)2 in column E, and the 
value of Ad in column F. Note that Equation 2H-8 is 
designed for use only with English units (in.). If metric units (cm) 
are used, the first term, \1/4\ (r-d+1)2, must 
be changed to \1/4\ (r-d+2.5)2. This change must 
also be made in column D of Form 2H-1 or 2H-2.
    12.4.3  Calculate the volumetric flow through each cross-
sectional area derived in section 12.4.2 by multiplying the values 
of vdecd, derived according to section 12.4.1, by the 
cross-sectional areas derived in section 12.4.2 using Equation 2H-9.
[GRAPHIC] [TIFF OMITTED] TR14MY99.081

For each line in column A of Form 2H-1 or 2H-2 that contains a value 
of d, enter the corresponding calculated value of Qd in 
column G.

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    12.4.4  Calculate the total volumetric flow through all sub-
sectors located between the wall and dlast, using 
Equation 2H-10.
[GRAPHIC] [TIFF OMITTED] TR14MY99.082

Enter the calculated value of Qd1dlast 
in line 3 of column G of Form 2H-1 or 2H-2.
    12.4.5  Calculate the cross-sectional area of the sub-sector 
located between dlast and the interior edge of the Method 
1 equal-area sector (e.g., sub-sector Adrem shown in 
Figures 2H-3 and 2H-4) using Equation 2H-11.
[GRAPHIC] [TIFF OMITTED] TR14MY99.083

For a 16-point traverse (eight points per diameter), Equation 2H-11 
may be written as follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.084

Enter the calculated value of Adrem in line 4b of column 
G of Form 2H-1 or 2H-2.
    12.4.6  Calculate the volumetric flow for the sub-sector located 
between dlast and the interior edge of the Method 1 
equal-area sector, using Equation 2H-13.
[GRAPHIC] [TIFF OMITTED] TR14MY99.085

In Equation 2H-13, drem is either (1) the 
measured velocity value at drem or (2) the measured 
velocity at dlast, if the distance between 
ddrem and dlast is less than or equal to \1/2\ 
in. (12.7 mm) and no velocity measurement is taken at 
drem (see section 8.2.4.2). Enter the calculated value of 
Qdrem in line 4c of column G of Form 2H-1 or 2H-2.
    12.4.7  Calculate the total volumetric flow for the Method 1 
equal-area sector closest to the wall, using Equation 2H-14.
[GRAPHIC] [TIFF OMITTED] TR14MY99.086

Enter the calculated value of QT in line 5a of column G 
of Form 2H-1 or 2H-2.
    12.4.8  Calculate the wall effects-adjusted replacement velocity 
value for the Method 1 equal-area sector closest to the wall, using 
Equation 2H-15.
[GRAPHIC] [TIFF OMITTED] TR14MY99.087

For a 16-point traverse (eight points per diameter), Equation 2H-15 
may be written as follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.088

Enter the calculated value of vej in line 5b of column G 
of Form 2H-1 or 2H-2.
12.5  Calculate the wall effects-adjusted average velocity,, by 
replacing the four values of avg shown in 
Equation 2H-5 with the four wall effects-adjusted replacement 
velocity values, e, calculated according to 
section 12.4.8, using Equation 2H-17.
[GRAPHIC] [TIFF OMITTED] TR14MY99.089

For a 16-point traverse, Equation 2H-17 may be written as follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.090

    12.6  Calculate the wall effects adjustment factor, WAF, using 
Equation 2H-19.
[GRAPHIC] [TIFF OMITTED] TR14MY99.091

    12.6.1  Partial wall effects traverse. If a partial wall effects 
traverse (see section 8.2.2) is conducted, the value obtained from 
Equation 2H-19 is acceptable and may be reported as the wall effects 
adjustment factor provided that the value is greater than or equal 
to 0.9800. If the value is less than 0.9800, it shall not be used 
and a wall effects adjustment factor of 0.9800 may be used instead.
    12.6.2  Complete wall effects traverse. If a complete wall 
effects traverse (see section 8.2.3) is conducted, the value 
obtained from Equation 2H-19 is acceptable and may be reported as 
the wall effects adjustment factor provided that the value is 
greater than or equal to 0.9700. If the value is less than 0.9700, 
it shall not be used and a wall effects adjustment factor of 0.9700 
may be used instead. If the wall effects adjustment factor for a 
particular stack or duct is less than 0.9700, the tester may (1) 
repeat the wall effects test, taking measurements at more Method 1 
traverse points and (2) recalculate the wall effects adjustment 
factor from these measurements, in an attempt to obtain a wall 
effects adjustment factor that meets the 0.9700 specification and 
completely characterizes the wall effects.
    12.7  Applying a Wall Effects Adjustment Factor. A default wall 
effects adjustment factor, as specified in section 8.1, or a 
calculated wall effects adjustment factor meeting the requirements 
of section 12.6.1 or 12.6.2 may be used to adjust the average stack 
gas velocity obtained using Methods 2, 2F, or 2G to take into 
account velocity decay near the wall of circular stacks or ducts. 
Default wall effects adjustment factors specified in section 8.1 and 
calculated wall effects adjustment factors that meet the 
requirements of section 12.6.1 and 12.6.2 are summarized in Table 
2H-2.
    12.7.1  Single-run tests. Calculate the final wall effects-
adjusted average stack gas velocity for field tests consisting of a 
single traverse using Equation 2H-20.
[GRAPHIC] [TIFF OMITTED] TR14MY99.092

The wall effects adjustment factor, WAF, shown in Equation 2H-20, 
may be (1) a default wall effects adjustment factor, as specified in 
section 8.1, or (2) a calculated adjustment factor that meets the 
specifications in sections 12.6.1 or 12.6.2. If a calculated 
adjustment factor is used in Equation 2H-20, the factor must have 
been obtained during the same traverse in which 
avg was obtained.
    12.7.2  RATA or other multiple run test procedure. Calculate the 
final wall effects-adjusted average stack gas velocity for any run k 
of a RATA or other multiple-run procedure using Equation 2H-21.
[GRAPHIC] [TIFF OMITTED] TR14MY99.093

The wall effects adjustment factor, WAF, shown in Equation 2H-21 may 
be (1) a default wall effects adjustment factor, as specified in 
section 8.1; (2) a calculated adjustment factor (meeting the 
specifications in sections 12.6.1 or 12.6.2) obtained from any 
single run of the RATA that includes run k; or (3) the arithmetic 
average of more than one WAF (each meeting the specifications in 
sections 12.6.1 or 12.6.2) obtained through wall effects testing 
conducted during several runs of the RATA that includes run k. If 
wall effects adjustment factors (meeting the specifications in 
sections 12.6.1 or 12.6.2) are determined for more than one RATA 
run, the arithmetic average of all of the resulting calculated wall 
effects adjustment factors must be used as the value of WAF and 
applied to all runs of that RATA. If a calculated, not a default, 
wall effects adjustment factor is used in Equation 2H-21, the 
average velocity unadjusted for wall effects, 
avg(k), must be obtained from runs in which the 
number of Method 1 traverse

[[Page 26559]]

points sampled does not exceed the number of Method 1 traverse 
points in the runs used to derive the wall effects adjustment 
factor, WAF, shown in Equation 2H-21.
    12.8  Calculating Volumetric Flow Using Final Wall Effects-
Adjusted Average Velocity Value. To obtain a stack gas flow rate 
that accounts for velocity decay near the wall of circular stacks or 
ducts, replace s in Equation 2-10 in Method 2, 
or a(avg) a in Equations 2F-10 and 2F-11 in 
Method 2F, or a(avg) in Equations 2G-9 and 2G-10 
in Method 2G with one of the following.
    12.8.1  For single-run test procedures, use the final wall 
effects-adjusted average stack gas velocity, final, 
calculated according to Equation 2H-20.
    12.8.2  For RATA and other multiple run test procedures, use the 
final wall effects-adjusted average stack gas velocity, 
final(k), calculated according to Equation 2H-
21.

13.0  Method Performance. [Reserved]

414.0  Pollution Prevention. [Reserved]

15.0  Waste Management. [Reserved]

16.0  Reporting

    16.1  Field Test Reports. Field test reports shall be submitted 
to the Agency according to the applicable regulatory requirements. 
When Method 2H is performed in conjunction with Method 2, 2F, or 2G 
to derive a wall effects adjustment factor, a single consolidated 
Method 2H/2F (or 2H/2G) field test report should be prepared. At a 
minimum, the consolidated field test report should contain (1) all 
of the general information, and data for Method 1 points, specified 
in section 16.0 of Method 2F (when Method 2H is used in conjunction 
with Method 2F) or section 16.0 of Method 2G (when Method 2H is used 
in conjunction with Method 2 or 2G) and (2) the additional general 
information, and data for Method 1 points and wall effects points, 
specified in this section (some of which are included in section 
16.0 of Methods 2F and 2G and are repeated in this section to ensure 
complete reporting for wall effects testing).
    16.1.1  Description of the source and site. The field test 
report should include the descriptive information specified in 
section 16.1.1 of Method 2F (when using Method 2F) or 2G (when using 
either Method 2 or 2G). It should also include a description of the 
stack or duct's construction material along with the diagram showing 
the dimensions of the stack or duct at the test port elevation 
prescribed in Methods 2F and 2G. The diagram should indicate the 
location of all wall effects traverse points where measurements were 
taken as well as the Method 1 traverse points. The diagram should 
provide a unique identification number for each wall effects and 
Method 1 traverse point, its distance from the wall, and its 
location relative to the probe entry ports.
    16.1.2  Field test forms. The field test report should include a 
copy of Form 2H-1, 2H-2, or an equivalent for each Method 1 exterior 
equal-area sector.
    16.1.3  Field test data. The field test report should include 
the following data for the Method 1 and wall effects traverse.
    16.1.3.1  Data for each traverse point. The field test report 
should include the values specified in section 16.1.3.2 of Method 2F 
(when using Method 2F) or 2G (when using either Method 2 or 2G) for 
each Method 1 and wall effects traverse point. The provisions of 
section 8.4.2 of Method 2H apply to the temperature measurements 
reported for wall effects traverse points. For each wall effects and 
Method 1 traverse point, the following values should also be 
included in the field test report.
    (a) Traverse point identification number for each Method 1 and 
wall effects traverse point.
    (b) Probe type.
    (c) Probe identification number.
    (d) Probe velocity calibration coefficient (i.e., Cp 
when Method 2 or 2G is used; F2 when Method 2F is used).

For each Method 1 traverse point in an exterior equal-area sector, 
the following additional value should be included.
    (e) Calculated replacement velocity, vej, accounting 
for wall effects.
    16.1.3.2  Data for each run. The values specified in section 
16.1.3.3 of Method 2F (when using Method 2F) or 2G (when using 
either Method 2 or 2G) should be included in the field test report 
once for each run. The provisions of section 12.8 of Method 2H apply 
for calculating the reported gas volumetric flow rate. In addition, 
the following Method 2H run values should also be included in the 
field test report.
    (a) Average velocity for run, accounting for wall effects, 
vavg.
    (b) Wall effects adjustment factor derived from a test run, WAF.
    16.1.3.3  Data for a complete set of runs. The values specified 
in section 16.1.3.4 of Method 2F (when using Method 2F) or 2G (when 
using either Method 2 or 2G) should be included in the field test 
report once for each complete set of runs. In addition, the field 
test report should include the wall effects adjustment factor, WAF, 
that is applied in accordance with section 12.7.1 or 12.7.2 to 
obtain the final wall effects-adjusted average stack gas velocity 
vfinal or vfinal(k).
    16.1.4  Quality assurance and control. Quality assurance and 
control procedures, specifically tailored to wall effects testing, 
should be described.
    16.2  Reporting a Default Wall Effects Adjustment Factor. When a 
default wall effects adjustment factor is used in accordance with 
section 8.1 of this method, its value and a description of the stack 
or duct's construction material should be reported in lieu of 
submitting a test report.
    17.0  References.
(1) 40 CFR Part 60, Appendix A, Method 1'Sample and velocity 
traverses for stationary sources.
(2) 40 CFR Part 60, Appendix A, Method 2'Determination of stack gas 
velocity and volumetric flow rate (Type S pitot tube).
(3) 40 CFR Part 60, Appendix A, Method 2F'Determination of stack gas 
velocity and volumetric flow rate with three-dimensional probes.
(4) 40 CFR Part 60, Appendix A, Method 2G'Determination of stack gas 
velocity and volumetric flow rate with two-dimensional probes.
(5) 40 CFR Part 60, Appendix A, Method 3'Gas analysis for carbon 
dioxide, oxygen, excess air, and dry molecular weight.
(6) 40 CFR Part 60, Appendix A, Method 3A--Determination of oxygen 
and carbon dioxide concentrations in emissions from stationary 
sources (instrumental analyzer procedure).
(7) 40 CFR Part 60, Appendix A, Method 4--Determination of moisture 
content in stack gases.
(8) Emission Measurement Center (EMC) Approved Alternative Method 
(ALT-011) ``Alternative Method 2 Thermocouple Calibration 
Procedure.''
(9) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, DeCordova Steam 
Electric Station, Volume I: Test Description and Appendix A (Data 
Distribution Package),'' EPA/430-R-98-015a.
(10) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, Lake Hubbard 
Steam Electric Station, Volume I: Test Description and Appendix A 
(Data Distribution Package),'' EPA/430-R-98-017a.
(11) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Pennsylvania Electric Co., G.P.U. 
Genco Homer City Station: Unit 1, Volume I: Test Description and 
Appendix A (Data Distribution Package),'' EPA/430-R-98-018a.
(12) The Cadmus Group, Inc., May 1999, ``EPA Flow Reference Method 
Testing and Analysis: Findings Report,'' EPA/430-R-99-009.
(13) The Cadmus Group, Inc., 1997, ``EPA Flow Reference Method 
Testing and Analysis: Wind Tunnel Experimental Results,'' EPA/430-R-
97-013.
(14) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four Prandtl Probes, 
Four S-Type Probes, Four French Probes, Four Modified Kiel Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG No. 
DW13938432-01-0.
(15) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Five Autoprobes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG No. 
DW13938432-01-0.
(16) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Eight Spherical 
Probes,'' Prepared for the U.S. Environmental Protection Agency 
under IAG No. DW13938432-01-0.
(17) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four DAT Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG No. 
DW13938432-01-0.
(18) Massachusetts Institute of Technology (MIT), 1998, 
``Calibration of Eight Wind Speed Probes Over a Reynolds Number 
Range of 46,000 to 725,000 per Foot, Text and Summary Plots,'' Plus 
Appendices, WBWT-TR-1317, Prepared for The Cadmus Group, Inc., under 
EPA Contract 68-W6-0050, Work Assignment 0007AA-3.

[[Page 26560]]

(19) Fossil Energy Research Corporation, Final Report, ``Velocity 
Probe Tests in Non-axial Flow Fields,'' November 1998, Prepared for 
the U.S. Environmental Protection Agency.
(20) Fossil Energy Research Corporation, ``Additional Swirl Tunnel 
Tests: E-DAT and T-DAT Probes,'' February 24, 1999, Technical 
Memorandum Prepared for U.S. Environmental Protection Agency, P.O. 
No. 7W-1193-NALX.

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[FR Doc. 99-11796 Filed 5-13-99; 8:45 am]
BILLING CODE 6560-50-C