EPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-82-020
August 1982
Air
Addition of Test
Methods 6A and 6B
to Appendix A of 40
CFR Part 60
Summary of
Comments and
Responses
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EPA-450/3-82-020
Addition of
Test Methods 6A and 6B to
Appendix A of 40 CFR Part 60
(Proposed January 26, 1981,
46 FR 8352)
Summary of Comments and
Responses
Emission Measurement Branch
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
August 1982
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This report has been reviewed by the Emission Standards and Engineering Division of the Offfce of Air
Quality Planning and Standards, EPA, and approved for publication. Mention of trade names or commercial
products is not intended to constitute endorsement or recommendation for use. Copies of this report are
available through the Library Services Office (MD-35), U. S. Environmental Protection Agency, Research
Triangle Park, N.C. 27711, or from National Technical Information Services, 5285 Port Royal Road,
Springfield, Virginia 22161.
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TABLE OF CONTENTS
Page
Chapter 1. INTRODUCTION
Chapter 2. SUMMARY OF CHANGES SINCE PROPOSAL.
Chapter 3. SUMMARY OF COMMENTS AND RESPONSES.
Table 1. List of Acronyms Used in Summary
of Comments and Responses 17
Table 2. List of Commenters 18
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CHAPTER 1
INTRODUCTION
On January 26, 1981, the U.S. Environmental Protection
Agency (EPA) published in the FEDERAL REGISTER (46 FR 8352) "Method 6A -
Determination of Sulfur Dioxide, Moisture, and Carbon Dioxide
Emissions from Fossil Fuel Combustion Sources" and "Method 6B -
Determination of Sulfur Dioxide and Carbon Dioxide Daily Average
Emissions from Fossil Fuel Combustion Sources." These methods were
proposed under authority of Sections 111, 114, and 301(a) of the
Clean Air Act as amended.
Public comments were solicited at the time of proposal. To
provide interested persons the opportunity for oral presentation
of data, views, or arguments concerning the proposed specifications,
a public hearing was scheduled for February 19, 1981, beginning at
9:00 a.m. The hearing, however, was not held because no one
requested to speak. The public comment period was from January 26,
1981 to March 27, 1981.
Eleven comment letters on the proposed methods were received
from industry, Federal agencies, State air pollution control agencies,
trade associations, and equipment manufacturers. The comments that
were submitted, along with EPA's responses, are summarized in this
document. The summary of comments and responses serves as a basis
for the revisions that have been made to the test methods between
proposal and promulgation.
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CHAPTER 2
SUMMARY'OF CHANGES SINCE PROPOSAL
1. Method 6A, Section 2.1.2. An additional midget bubbler
has been added to the Method 6A sampling train to accommodate the
addition of an isopropanol bubbler.
2. Section 2.1.3. The COg absorber design has been revised.
3. Section 4. Parts of Sections 4.1.1, 4.2.1, 4.2.2, and
4.2.3 have been revised to describe the use of the isopropanol
bubbler and the redesigned CO^ absorber.
4. Sections 7.2 and 7.4. These paragraphs are revised to
include the isopropanol bubbler in the discussion of the sampling
train.
5. Figures 6A-1 and 6A-2. The figures are revised to show
the redesigned COg absorber and the extra bubbler for the isopropanol
6. Method 6B, Sections 2, 3, and 4. Changes are made to these
sections to explain that the isopropanol bubbler is not used in
Method 6B.
7. Sections 2, 3, and 4. These paragraphs are revised to
clarify the use of the sampling timer and the required sequence.
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CHAPTER 3
SUMMARY OF COMMENTS AND RESPONSES
Commenter IV-D-1
2.1 Comment: Section 60.46(a)(4). Although we have reservations
concerning the accuracy of Method 6A, our primary objection is to the
whole concept associated with the resulting CO^ determination. The
inherent inaccuracies of manual sampling for C02 make it unacceptable
as a method for accurately converting source test results. Our
experience in comparison testing and in reviewing reports from
consultants, some of whom were conducting tests under contract to
EPA, indicates that differences between calculated results
using (1) the F-factor method and (2) the effluent volumetric
flow rate determination and heat input based on fuel feed
rate or heat balance, can usually be traced to invalid diluent data.
Very little consultant Orsat data meet the FQ criteria listed in "APTI,
Course 474, Continuous Emissions Monitoring, Student Manual, Appendix C,
Section C.2." The quality assurance (QA) procedures for manual sampling
of COg or 02 are not sufficient to assure the same data quality as can
be obtained with instrumental methods. Thus, the F-factor method should
not be allowed until additional QA procedures have been developed.
Response: The EPA has published QA guidelines in a handbook
(EPA-6QO/4-77-027b, August 1977). One procedure involves the use of
the FQ criterion. Your experience does not indicate that this QA procedure
is inadequate, but that many testers fail to use it in validating their
technique with the Orsat.
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The COg determination of Method 6A is based on the American
Society for Testing and Materials (ASTM) D 3178 and is not inherently
inaccurate. It appears that the fault lies with the testers.
The Agency is presently in the process of reviewing its test
methods and will incorporate appropriate QA procedures as needed.
2.2 Comment: Section 60.47a. We object to a method which has
not been proven accurate or reliable. An impinger procedure as an
automated, unattended field monitor is over-ambitious. There are
serious problems associated with condensation, evaporation, pressure
gradients and environmental factors, particularly the exposure
of the sampling train to ambient changes in temperature over the
sampling period.
Response: The bibliography section of Methods 6A and 6B lists
reports written during the development of these methods. Other
similar tests have been conducted since these publications to
document the capabilities of the method. These tests compared
results of Methods 6A and 6B with the results of Methods 6 and 3 in
determining the adequacy of the proposed methods. The results were
shown to be comparable for the test conditions encountered and
Methods 6A and 6B were determined to be adequate alternative procedures.
Some revisions to Methods 6A and 6B have been included in the
promulgated version to address the potential problems. The
Agency's experience is that environmental effects can be minimized
to the point that the methods can produce reliably accurate results.
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The changes to the methods include heated probe for prevention
of condensation; increased concentration of hydrogen peroxide,
absorbing solution to 10 percent; and redesign of the ascarite
absorbing device.
2.3 Comment: We question the need for less accurate or any
"backup" systems. In cases where monitoring is conducted for
determination of compliance with emission regulations, there is no
valid reason for accepting data from a system that could not be
certified as a primary CEMS. Although data from "backup" systems
may be better than no data at all for noncompliance monitoring,
the effects of allowing less accurate systems to be used would be
felt by State agencies. Agencies are already receiving pressure
from sources to certify the less accurate systems as primary
continuous emission monitoring systems (CEMS). If allowed as "backup"
systems, sources would not be encouraged to maintain the primary CEMS.
Response: The comment is made on the assumption that Method
6B is less accurate than the CEMS. See Responses 2.1 and 2.2.
The proposal does not state that Method 6B cannot be certified
as a primary CEMS. The present regulations require hourly averages,
whereas Method 6B provides a 24-hour average. The Agency feels that
with certain QA procedures and with an appropriate objective, Method
6B could be used in place of the CEMS.
Commenter IV-D-2
4.1 Comment: The proposed methods are simplications of the
existing requirements and should be adopted.
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Response: None required.
4.2 Comment: Section 7 of Method 6A, the abbreviated sampling
train for the determination of emission rate values, should be
specified as a separate method for fossil fuel combustion sources.
Response: Methods 6A and 6B are applicable only for fossil
fuel combustion sources in either of the test train configurations.
Inclusion or elimination of the dry gas meter does not change the
applicability of the method, only the form of the calculation procedures.
A separate method is not necessary for this type of variation.
4.3 Comment: I recommend that Method 6B should be adopted.
Response: None required.
Commenter IV-D-3
6.1 Comment: What data has been established to show that these
methods are equal to or better than their original counterparts?
Response: See Response 2.2.
6.2 Comment: Why is there not any qualification of each particular
implementation and exercise using blind gas samples similar to the CEMS
criteria? It seems that because of EPA's vested interest in these
techniques and their expertise in using such wet chemistry techniques,
that CEMS are the only subject of scrutiny. In particular, with respect to
using Method 6B in lieu of an operating CEMS, why should this unqualified
Method 6B data be more acceptable than that obtained by a substitute CEMS
which can be qualified with National Bureau of Standards gases?
Response: In the opinion of the Agency, Method 6B sampling
and analysis procedures are clearly detailed and, with some minor
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revisions, provide adequate quality controls if strict adherence is
maintained. Gas audits of Methods 6A and 6B are not practical and are
costly for most field test applications.
The CEMS is not the only subject of scrutiny. The EPA is
reviewing the need for other QA measures for the reference methods
and will publish procedures as appropriate.
Method 6B is not unqualified. See Response 2.2.
A substitute CEMS may be acceptable. Paragraph 60.47a(f) allows
the use of "other monitoring systems as approved by the Administrator."
Commenter IV-D-4
7.1 Comment: The condensation of moisture presents special problems.
Due to the low flow rates, the scrubbing of SCL from the sample gas has a
significant effect on the measured emissions rate. Therefore, it is
suggested that either heat or insulation be provided on the line right
into the first impinger.
Response: This has been added to the method.
7.2 Comment: Rather than specification of midget impingers with
15 ml of hydrogen peroxide (H^Og). allow the use of larger impingers with
larger volumes of HpO^. We have used both 125 ml Mae West impingers
with 75 ml of HgOg and 500 ml Greenburg-Smith impingers and modified
Greenburg-Smith impingers with 100 ml of ^2 with good success. The
intention of this modification is to allow an increase in sample rate
and sample volume. This increase will improve the accuracy of the
test method as sample recovery and analysis will be less critical as
larger amounts of SO and CO have been collected. To allow this increase
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in sample rate, the following additional modifications must be made:
(a) Use 10 percent h^Og rather than 3 percent ^2' T'lis W1^ assure
adequate oxygen is available for the conversion to sulfate. In
addition, this will reduce the cooling requirements specified in the
proposed methods, (b) Use three impingers containing HgOg. This will
assure the capture of all SOo- (c) Increase the amounts of drierite and
ascarite to 200-300 grams. This will allow the capture of all moisture
and carbon dioxide.
Response: The Agency agrees .that some of these changes will
definitely improve the reliability of the methods. The revised methods
include an increase in hydrogen peroxide concentration and increases
in drierite and ascarite amounts for assurance of complete collection
of S02» moisture, and carbon dioxide. The cost of materials should be
considered in determining the volume flow rate and total volume collected.
Ascarite and hydrogen peroxide are not reusable and drierite can be
recycled a limited number of times. For this reason, the Agency will
not require larger volume samplers such as described in Method 8, but
such equipment with appropriate increased reagent amounts may be used
at the user's discretion.
7.3 Comment: Include a statement in Methods 6A and 6B
specifically disallowing the use of silica gel as some COg will be
collected by silica gel.
Response: This is included in the revised methods.
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7.4 Comment: Include a statement allowing modified test
methods if approved by the Administrator.
Response: Alternative test methods are allowed under
Section 60.8(b).
Commenter IV-D-5
10.1 Comment: We note that in Method 6A the 80 percent
isopropanol solution for S03 and FUSO, is not required. We are
concerned that the two Methods, 6 and 6A, will not
produce comparable results. The SO^ concentrations determined by
Method 6A will be of a greater magnitude than those determined by
Method 6.
Response: Method 6A is revised to include an isopropanol
impinger. This is not appropriate for Method 6B as the longer
sampling period will allow some of the isopropanol solution to pass
through the train and collect in the ascarite absorber thus affecting the
collection of C02. If sulfuric acid mist is a significant interference,
a heated filter placed in front of the first hydrogen peroxide impinger
will remove most of the acid. If this is not satisfactory, other test
methods should be used.
10.2 Comment: It is unclear to us why an expression in English
units (lb/10 Btu) was not included in Section 7.6.2 of Method 6A as it
has been done in other methods.
Response: The EPA and other agencies are converting to
standard international units for all standards and regulations. The
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test methods are written to be consistent with the regulations and
the intentions of the Agency. Method 19 contains the required
conversion factors, if they are needed.
Commenter IV-D-6
11.1 Comment: We find it difficult to evaluate the precision
and accuracy of the proposed methods based on information supplied
in the Federal Register. We recommend that EPA prepare a background
information document similar to the document prepared for reference
Methods 24 and 25.
Response: See Response 2.2.
11.2 Comment: The description methodology for preparing the
collection train is unclear. Specific reference that the drierite
should be added to the third bubbler should be included.
Response: The method has been revised to be more specific.
11.3 Comment: Since EPA test methods are
adopted by many States, we recommend that factors be included to
express the sulfur dioxide emission rate in Ib SOp/lO Btu of heat
input. We believe that these alternate units would be beneficial
since most State emission regulations express limitations in English
units.
Response: See Response 10.2.
Commenter IV-D-7
12.1 Comment: The proposal is unclear as to whether Method 6B
can be used as an alternate CEMS method in lieu of other types of
monitors. We understand that Method 6B is mainly intended for use on
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an interim basis when an installed CEMS malfunctions to satisfy the
requirement in Section 60.47a(f) of 40 CFR Part 60, Subpart Da,
to obtain emission data during CEMS breakdowns. However, the logical
extension to this, since Method 6B can obtain a 24-hour sample on a
continuous basis, is to allow installation of a Method 6B train as an
acceptable alternate CEMS. The data obtained could satisfy 1-hour,
3-hour, or 24-hour (or rolling 24-hour) averaging times by use of the
timer or pump as appropriate. We recommend that the option of using
the Method 6B train as a continuous monitor over long time periods be
approved by the EPA and incorporated into the final version of this
proposal.
Response: The EPA is considering the use of Method 6B as a
CEMS. Although Method 6B has been successfully used by EPA and other
source testers, several incidents have shown that plant personnel not
accustomed to testing have difficulty with the method. After further
evaluation, EPA will determine whether to allow Method 6B as a CEMS.
12.2 Comment: We are also concerned about the lack of supporting
data and demonstration of how good reference Methods 6A and 6B are.
We recommend that EPA gather suitable data to demonstrate the
effectiveness of these methods, their validity, and their expected
accuracies. These data should then be published for distribution and
review by interested parties.
Response: See Response 2.2.
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Commenter IV-D-8
Comment: We are concerned that our employees will be potentially
subjected to occupational health hazards from handling asbestos
materials.
Response: Ascarite is a potential skin and eye irritant because
of the sodium hydroxide coating and the containers are clearly labeled
as to care and handling of the material as well as first-aid treatment
in case of skin or eye contact. No mention is made of the potential
for asbestos exposure and the Agency is not aware of other documented
t
precautions for the use of ascarite. In addition, the manufacturer
of ascarite has developed a new product, ascarite II, which contains no
asbestos and can be used in place of ascarite. Methods 6A and 6B are
alternative procedures and, if a tester determines that these methods
create a situation that is potentially hazardous, Methods 6 and 3 can
be used.
Commenter IV-D-9
14.1 Comment: We support the use of proposed Method 6B and feel
that its use should not be restricted to time periods of CEMS break-
»
downs, repairs, calibration checks and zero span adjustments. Because
we feel that the proposed reference Method 6B is a more reliable method
of collecting S02 emission data, we recommend Method 6B be adopted
as a CEMS, rather than merely a reference method.
Response: See Response 12.1.
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Commenter IV-D-10
15.1 Comment: We suggest that two C02 absorbers be placed in
series, in lieu of the one bubbler. Our experience indicates that
at times one bubbler may not be adequate to absorb all CCL present.
If the second absorber is not completely absorbed with CCL, it can
be used as the first absorber in the next sample train. The hydrogen
peroxide should be 6 percent rather than 3 percent. Again, our
experience indicates that a 3 percent solution may not insure complete
collection of all sulfur dioxide. The contents of each impinger should
be poured into separate containers and analyzed separately to determine
the collection efficiency. Large impingers should be allowed with
appropriate apparatus and procedures.
Response: See Response 7.1. The EPA has found that one C0?
absorber is sufficient. However, the use of a second absorber has
been included as an option. The concentration of hydrogen peroxide
has been increased.
15.2 Comment: The calculation for volume of water collected in
Method 6B (Eq. 6A-2) should be modified to subtract the mass of sulfur
dioxide caught in the impingers.
Response: Because the moisture volume in the stack gas will
be usually in the volume percent range and the S02 will be only a few
hundred parts per million, the mass of S02 collected in the impingers
will be negligible and can be omitted from the calculation.
Commenter IV-D-11
16.1 Comment: The moisture determination method described in
proposed Method 6A could result in a misrepresentation of the actual
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moisture content of the flue gas sampled. The gravimetric procedure
is inadequate to produce acceptable accuracy. The components of the
sampling train weigh approximately 200 grams. The increase in weight
because of moisture adsorption from a typical flue gas sample will be
approximately 1 gram. Accurate detection of this slight percentage
increase from the tare weight is difficult.
The sampling train components are weighed to the nearest 0.1 gram.
After the test, the train is purged with ambient air and weighed. Under
a realistic laboratory condition, an erroneous weight gain of
approximately 0.35 gram could result from the purge. Since the Method 6A
weighing procedure requires determination of weights to the nearest
0.1 gram, a possible error of about 8 percent is introduced for the
typical weight gain of 1 gram during the test. The error that could
result from the weighing procedure, added to this possible erroneous
weight gain of 0.35 gram, could cause the moisture to be as much as
43 percent higher than the actual moisture content of the flue gas.
This difference could be greater when the realistic assumption is made
that the tared components could have gained weight as a result of handling
the sampling train procedure.
Response: The purpose for collecting moisture data with
Method 6A is to correct the dry SOg or COg measurements to stack conditions,
if needed. In the example given above, the 43 percent error in moisture
determination will lead to a nominal error of 2 percent in the S02 or
O^ measurement. Although the revised Method 6A does include a purging
period because of the addition of the isopropanol impinger, the proposed
version and Method 6B do not.
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16.2 Comment: The gravimetric determination of flue gas carbon
dioxide content used in Method 6A is not subject to as significant an
error as the moisture portion of the test because of the smaller tare
weight and larger mass gain during the test and should be as accurate
as stated in the procedure. However, the only acceptable standard for
determination of flue gas carbon dioxide content is the Orsat analyzer.
Therefore, the carbon dioxide content determined by Method 6A should be
verified with an Orsat analyzer at least once per test series to verify
the accuracy of the method and ensure that the ascarite used is active.
Response: The use of ascarite for CCL determination is also
a standard method (ASTM D 3178).
16.3 Comment: Determination of moisture and carbon dioxide
contents of flue gas by Method 6A could result in excessive and costly
delays during the test procedure. If a leak should develop in the
connections between the tared impingers during transportation from the
laboratory.to the test plane, the leak cannot be repaired at the test
plane. These components must be returned to the laboratory because
they must not be disturbed after being tared.
Response: Most leaks can be repaired without significantly
affecting the tare weight. The tare weights for the impingers and
the COp absorber are measured in tens of grams and the amounts
collected are measured in grams. These large masses will not be
significantly affected by careful handling during leak tests.
16.4 Comment: Method 6B is the Method 6A sampling train operated
over a designated, extended time period. Operation of this sampling
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train on an intermittent basis is impossible in stacks or ducts where
the static pressure is significantly negative. During the deenergized
interval of the test period, the sampling probe tip would be exposed
to a negative pressure when referenced to the remaining components of
the test train. This condition allows for ambient air to flow in a
reverse path through the sampling train, which could cause a mixing
or contamination of reagents used for the test or contamination of
the solid reagents and complete evacuation of the liquid reagents from
their containers through the probe and into the flue gas stream.
Response: Method 6B can be used in the continuous mode
instead of the intermittent, or a solenoid valve separating the train
from the stack during nonsampling periods could be used. Alternatively,
other monitoring systems as approved by the Administrator or the
reference methods may be used.
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Table 1. LIST OF ACRONYMS USED IN THE
SUMMARY OF COMMENTS AND RESPONSES
CEMS - Continuous Emission Monitoring System
QA - Quality Assurance
EPA - Environmental Protection Agency
ASTM - American Society for Testing and Materials
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TABLE 2. List of Commenters
Document Number Commenter
IV-D-1 From James K. Hambright, Director BOAC
State of Pennsylvania to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-2 From Russell 0. Blosser, Technical
Director. NCASI to Roger Shigehara,
ESED. Subject: comments on proposal
of Methods 6A and 6B.
IV-D-3 From Gerald F. McGowan, V.P. Eng. Lear
Seigler, Inc. to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-4 From V.J. Brisini, Pennsylvania Electric
Company to Docket Number OAQPS-79-4.
Subject: comments on proposal of
Methods 6A and 6B.
IV-D-5 From Mark P. Steinberg, Wisconsin Electric
Power Company to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-6 From F.W. Chapman, Environmental and
Energy Conservation to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-7 . From Morris L. Brehmer, Virginia Electric
Power Company to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-8 From J.G. Holmes, TOSCO Corp. to Docket
Number OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-9 From R.E. Kelly, Arizona Public Service
Co. to Docket Number OAQPS-79-4.
Subject: comments on proposal of
Methods 6A and 6B.
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TABLE 2. List of Commenters
(Continued)
Document Number Commenter
IV-D-10 From Allen to Eli Bell, Texas Air
Control Board to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
IV-D-11 From Mohamed T. El-Ashey, Tennessee
Valley Authority to Docket Number
OAQPS-79-4. Subject: comments on
proposal of Methods 6A and 6B.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
tPA-450/3-82-02U
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Addition of Test Metnods 6A and 6B to Appendix A of
40 CFR Part 60 Summary of Comments and Responses
5. REPORT DATE
August 1982
6. PERFORMING ORGANIZATION CODE
7. AUTHOH(S)
Emission Standards and Engineering Division
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Emission Measurement Branch (MD-19) .
Emission Standards and Engineering Division
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Director, Air Quality Planning and Standards (MD^IO)
Office of Air, Noise, and Radiation
U.S. Environmental Protection Sgency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA 7200/04:
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This document includes the comments solicited at the time of proposal of Test Methods
6A and 6B as additions to Appendix A of 40 CFR Part 60. Method 6A is used to determine
sulfur dioxide and carbon dioxide emissions from fossil fuel combustion sources, and
Method 6B is used to determine sulfur dioxide and carbon dioxide daily average emission
from fossil fuel combustion sources.-.
17.
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21. NO. OF PAGES
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