United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-79-030C
July 1980
Air
Reference Methods
24 and 25 —
Background  Information
for Promulgated Test
Methods

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                              EPA-450/3-79-030C

         Reference Method 24 —
Determination of Volatile Matter Content,
 Water Content, Density, Volume Solids,
  and Weight Solids of Surface Coatings

         Reference Method 25 —
     Determination of Total Gaseous
Nonmethane Orqanic  Emissions as Carbon

         Background Information
      for Promulgated Test Methods
            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

                    July 1980

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This report has been reviewed by the Emission Standards and Engineering
Division, Office of Air Quality Planning and Standards, Office of Air,
Noise, and Radiation, Environmental Protection Agency, and approved for
publication.   Mention of company or product names does not constitute
endorsement by EPA.  Copies are available free of charge to Federal
employees, current contractors and grantees, and non-profit organizations -
as supplies permit - from the Library Services Office, MD-35, Environmental
Protection Agency, Research Triangle Park, NC 27711; or may be obtained,
for a fee, from the National Technical Information Service, 5285 Port Royal
Road, Springfield, VA 22161.
                   Publication No. EPA-450/3-79-030c
                                   ii

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                           TABLE OF CONTENTS

                                                                  Page
Chapter 1.   SUMMARY	    1-1
            1.1  SUMMARY OF CHANGES SINCE PROPOSAL 	    1-2

Chapter 2.   SUMMARY OF PUBLIC COMMENTS 	    2-1
            2.1  TEST METHODS	    2-1

                 TABLE 2-1.  LIST OF COMMENTERS ON PROPOSED
                 TEST METHODS	    2-7

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                               CHAPTER 1
                                SUMMARY

     On October 5, 1979, as an appendix to the proposed standards of
performance for automobile and light-duty truck surface coating opera-
tions, the U.  S.  Environmental Protection Agency published in the
FEDERAL REGISTER (44 FR 57792) reference methods for analyzing the
solvent content of  oatings [Reference Method 24 (Candidate 1) and
(Candidate 2)] and for determining the percentage reduction of volatile
organic compound (VOC) emissions achieved by emission control devices
(Reference Method 25).  These test methods were proposed under the
authority of Sections 111 and 114 of the Clean Air Act as amended.
Public comments were requested on the proposal in the FEDERAL REGISTER
publication, and a public hearing was held on November 9, 1979.  There
were 15 commenters representing coatings manufacturers and suppliers,
trade and professional associations, and State air pollution control
agencies.  The comments that were submitted, along with EPA's responses,
are summarized in this document.  The summary of comments and responses
serves as the basis for most of the revisions that have been made to the
test methods between proposal and promulgation.  Some of the changes to
the proposed test methods are based on additional information obtained
by EPA from experience with the methods.

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1.1  SUMMARY OF CHANGES SINCE PROPOSAL
     A number of changes of varying Importance have been made since
proposal.   One of the most significant of these changes is the
Administrator's decision to reject the proposed Method 24 (Candidate 1),
Determination of Volatile Content (as Carbon) of Paint, Varnish, Lacquer,
or Related Products.  Data submitted by coatings manufacturers showed
that there are certain coatings which cannot be analyzed using
Candidate 1.  Therefore, the Administrator has concluded that Candidate 1
is not applicable to all coatings and should not be selected as the
reference method.
     Several procedural and editorial changes have been made to
Reference Methods 24 (Candidate 2), "Determination of Volatile Matter
Content, Water Content, Density, Volume Solids, and Weight Solids of
Surface Coatings," and Reference Method 25, "Determination of Total
Gaseous Nonmethane Organic Emissions as Carbon," in order to clarify
and to improve the sampling and analytical procedures.  These changes
are based on additional information obtained by EPA from experience
with the methods and on the public comments received.
Reference Method 24
     The following discussion summarizes the procedural changes made to
proposed Reference Method 24, Candidate 2.  The procedures were added
to protect the source owner from invalid results that might result from
poor analytical techniques, application of the method to a coating not
suitable for analysis with Reference Method 24, or imprecision in
Reference Method 24 resulting from a high percentage of water in the
solvent.
                                   1-2

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     The promulgated reference method requires the analyst to complete
duplicate analyses on each sample tested.   A comparison is then made
between these results and the within-laboratory precision statements for
each parameter.   Duplicate analyses are made until the results fall
within the range established for the within-laboratory precision statements.
The purpose of the procedure is to verify that the analyst can achieve a
level of precision for the coating under analysis equal to or better than
the precision obtained by experienced analysts participating in the ASTM
studies of the method.   Because of the variety of coatings that may be
subject to analysis, it is possible that certain coatings may not be
amenable to analysis using Reference Method 24; that is, in certain
cases it may not be possible to achieve results which meet the precision
limits.  In this case,  the method provides for a case-by-case evaluation
and development of a suitable procedure.
     An additional procedure for waterborne coatings was added to the
promulgated reference method to protect the source owner or operator from
a determination of noncompliance when the owner is actually in compliance.
This procedure is needed because the results of Reference Method 24 are
dependent on the difference between the weight of total solvents and the
weight of water.  As the percent weight of water increases, the difference
decreases.  As a result, any imprecision in the measurement of the weight
of total solvent in water is magnified in the calculation of organic solvent
content.  For example, if the total solvent of a coating is measured as
100 ± 2 units and the water content is measured at 90 ± 2 units, the
organic solvent content would be in the range of 6 to 14 units.  The
magnitude of the range, as a percent of the true organic solvent content,
increases with increasing water content and could, as shown in the example,
lead to a conclusion of noncompliance even when the owner is in compliance.
                                   1-3

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The procedure added to Reference Method 24 for waterborne coatings
protects the owner or operator from this erroneous determination by
minimizing the calculated value for VOC content.  This is done, for
example, by subtracting the between-laboratory precision statement from
the average value of total solvent and adding the between-laboratory
precision statement to the average value for water content.   Thus, if a
source owner is in compliance based on average coating values, the
compliance method will automatically show a lower VOC content because of
the adjustments made to the average values based on the between-laboratory
precision statements.
     Based on comments from manufacturers that ASTM D-2697 has only
been shown to be applicable to architectural coatings, the experimental
procedure for determining volume solids has been eliminated.   Method
24 requires that the volume solids be calculated from manufacturer's
formulation data.
     The coatings classification step in the proposed method was
eliminated because industry comments indicated that it was only
necessary to separate waterborne (water reducible) and solvent-borne
(solvent reducible) coatings.   Therefore, the "Procedure" discussed in
Section 4 of the method has been simplified.  The elimination of coating
classes means that all coatings will be analyzed by the same procedure
except for the additional step of measuring the water content of waterborne
coatings.
Reference Method 25
     The majority of the procedural changes relate to calibration
requirements and are meant to improve quality assurance and at the same
time simplify the daily operation of the analytical equipment.  This is
accomplished by requiring a performance test of the analytical equipment
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(nonmethane organic analyzer and condensate recovery and conditioning
apparatus) prior to initial use; specific criteria for the performance
tests are provided.  Routine daily calibrations (much less time consuming
than previously required) are conducted and the results are compared to
performance test reference values to determine whether the performance
of the analytical equipment is still acceptable.
     Other procedural changes include the following:   (1) the addition
of pure oxygen carrier gas just prior to the catalyst in the condensate
recovery and conditioning system - the auxiliary oxygen is required to
assure complete oxidation; (2) the simplification of the pretest and
post-test sampling train leak checks; and (3) the calculation changes
which are made by including the subtraction of blank values from the
measured values.
     In the promulgated test method, several important system components
are not specified; instead, minimum performance specifications for
these components are provided.  The method is written in this manner to
allow individual preference in choosing components, as well as to
encourage development and use of improved components.  Therefore,
Addendum I which lists specific information regarding system components
found to be acceptable has been added to the method to provide guidance
for users.
     Specifics of the most important procedural changes that have been
included in the promulgated test method are as follows:
     1.  Section 1.1  Applicability.  This section was rewritten
to clarify the applicability of Method 25 in relation to several other
organic measurement methods.
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     2.   Section 2.2.2  Nonmethane Organic Analyzer.   The reference
to the analyzer is changed from "total gaseous nonmethane organic
analyzer" to nonmethane organic analyzer (NMO).   The description is
clarified to indicate that the NMO analyzer is also used to quantify
COp from trap condensate recovery.  Furthermore, a requirement that
the NMO analyzer meet an initial performance test with specific criteria
is added.  Previously, only demonstration of "proper separation,
oxidation, reduction and measurement" was required.
     3.   Section 4.1.3  Pretest Leak Check.  The leak check procedure
is simplified.   Instead of evacuating the sample train, the sample
probe is plugged and then the sample valve is opened; the sample tank
vacuum gauge is monitored for a change in vacuum.
     4.   Section 4.1.4  Sample Train Operation.   This section is
clarified to indicate that any probe extension used must be positioned
totally  in the stack effluent; any portion of the sample probe outside
the stack wall  must be analyzed as part of the condensate trap.
     5.   Section 4.1.5  Post Test Leak Check.  The leak check procedure
is simplified (see "3" above).
     6.   Section 4.3.3  Recovery of Condensate Trap Sample.  A
requirement for mixing auxiliary oxygen with the carrier gas just
prior to the catalyst is added.  The procedures are clarified to
indicate that the condensate trap is placed 1n a muffle furnace at
500°C (changed from 600°C) and that the probe must be heated.
     7.   Section 5.1  Initial Performance Check for Condensate
Recovery and Conditioning Apparatus.   A requirement is added for an
initial performance test of the system which Includes a carrier gas
blank value determination (section 5.1.1), an oxidation catalyst
                                  1-6

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efficiency check (section 5.1.2), and an overall system performance
check via liquid injections (section 5.1.3).   Previously, only a
catalyst efficiency check was required.
     8.   Section 5.2  Initial NMO Analyzer Performance Test.   The
calibration criteria for the NMO analyzer are changed to include
an initial performance test.   This performance test requires  an
oxidation catalyst check (5.2.1), an analyzer linearity check (5.2.2),
determination of a NMO calibration response factor (5.2.2),  determina-
tion of a COp calibration response factor (5.2.3), determination of a
NMO blank value (5.2.4) and a system check using several gaseous
organic compounds (5.2.5).
     9.   Section 5.3  NMO Daily Calibration.   This section requires
that a daily calibration of the NMO analyzer be conducted.   The
calibration involves one COp calibration gas and one propane
calibration gas.  Response factors are determined for both COp and
NMO, and a NMO blank value is measured.   This calibration is  conducted
with the oxidation and reduction catalysts in full operation.  The
results obtained are compared to the reference values obtained during
the initial performance test in order to determine if the analyzer
performance is acceptable.   This daily calibration procedure is greatly
simplified compared to the procedure previously required which included
bypassing the oxidation and reduction catalysts and using several
different concentration levels of methane, carbon dioxide and propane
calibration gases.
     10.  Section 6.2  Noncondensible Organics.  The calculation for the
NMO concentration of the contents of each collection tank 1s changed by
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rewriting the equation to include the subtraction of the daily NMO blank
value from the measured concentration.
     11.   Section 6.3  Condensible Organics.  The calculation for the
NMO concentration of the contents of each condensate trap is changed by
rewriting the equation to include the subtraction of the daily condensate
recovery and conditioning system carrier blank value from the measured
C0  concentration.
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                            CHAPTER 2
                   SUMMARY OF PUBLIC COMMENTS

     The list of commenters and their affiliations is shown in
Table 2-1 of this chapter.  Fifteen letters contained comments on
the proposed test methods.  The comments and issues and responses
to them are discussed in the following section of this chapter.
2.1  TEST METHODS
2.1.1  Comment:   Most commenters objected to using the carbon approach
to measuring emissions and to the use of Method 24 (Candidate 1).
       Response:  Based on data submitted by coatings manufacturers,
there are some coatings that cannot be analyzed using Method 24
(Candidate 1).  These coatings cannot be distilled because they foam
vigorously upon heating, thus contaminating the distillate.  In addition,
the data indicated that less than 90 percent of the solvent would be
recovered during the distillation step for certain coatings.  Since the
distillation step is essential for determining the carbon content and
density of the solvent, EPA is withdrawing this procedure from further
consideration at this time.
2.1.2  Comment:   Several commenters objected to the use of ASTM D-2697
to determine the density of the dried coating as required in Method 24
(Candidate 2).  A number of commenters noted that ASTM D-2697
was not specifically applicable to certain coatings.  It was also

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suggested by one commenter that EPA should specify volume fraction of
solids for the various types of coatings similar to the way transfer
efficiencies were listed.
       Response:  Based on comments from manufacturers that ASTM 2697
has only been shown to be applicable to architectural coatings, the
experimental determination of volume fraction of solids has been
eliminated.  Method 24 will require that the volume fraction of solids
be calculated from manufacturer's formulation data.
2.1.3  Comment:   Another commenter noted that the drying time was
different for ASTM D-2369 and ASTM D-2697 and that these procedures were
not consistent with each other.
       Response:  Since ASTM D-2697 has been deleted, this comment is
no longer applicable.
2.1.4  Comment:   One commenter requested that analyzing a single
composite sample (of all coatings used in an operation) be allowed
rather than analyzing each coating and taking an arithmetic average.
Would there be any complications caused by mixing several coatings and
then running a Method 24 (2) analysis on the mixture?
       Response:  EPA has no information on the consequences of mixing
coatings before analysis.  This would be acceptable on a case-by-base
basis as allowed in 40 CFR 60.8(b) if the owner or operator could
demonstrate to the Administrator's satisfaction that the mixing of
coatings before analysis would not produce different results than
analyzing the samples separately.
2.1.5  Comment:  Several commenters recommended that the use of coatings
manufacturers'  data  be allowed in calculating VOC content of coatings
rather than Method 24.
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     Response:   Coatings manufacturers'  data will  be allowed in
calculating VOC content of coatings because this will reduce the burden
on the industry to measure all  coatings  with Method 24.   Method 24 will
be the reference method.  Use of this method to calculate VOC content
of coatings will require industries to closely monitor and record all
organic solvents added to the coatings at the plant.
2.1.6  Comment:  Three commenters recommended that the direct use of a
flame ionization detection (FID) system or similar instrumentation
system be allowed instead of Method 25 because:  (a) direct FID is
simpler and more precise and (b) the ability to conduct on-site analyses
and DOT restrictions associated with shipping organic samples from a
source location to a laboratory make the FID preferable.
     Response:   While the direct use of an FID system is simpler than
Method 25, it will not give accurate results in many situations because
the instrument response varies with different compounds.   Data collected
to date indicate that the FID will give calculated incineration
efficiencies which may be biased high (relative to Method 25) as much
as 5 percent (i.e., 99 percent efficiency with FID vs 94 percent
efficiency with Method 25).  Therefore,  the FID system cannot be
considered an adequate reference method, but may be acceptable as an
alternative compliance procedure on a case-by-case basis as allowed in
40 CFR 60.8(b).
     The ability to use the FID system to conduct on-site analyses is
not itself sufficient justification to allow the use of direct flame
ionization detection.  The DOT regulations for the shipping of
hazardous materials do require that great care be taken in shipping
the test samples.  The DOT regulations impose strict packaging
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requirements on flammable liquids and compressed flammable gases.
Flammable liquids must be marked as such and must be shipped as
hazardous materials.   However, exemptions for the strict packaging
requirements are permitted for most liquids (49 CFR 172.101) if less
than 1 quart is shipped.  The volume of a sample trap is 0.1 pint.
Assuming all traps were completely full of organic liquid, as many as
20 traps could be shipped in one container.  In addition, gas sample
tanks likely to be shipped from an on-site location to a laboratory
do not meet the DOT definition" of a compressed flammable gas (49 CFR
173.300) because they are not under high pressure and, therefore, should
not pose a shipping problem.  For "unknown" environmental samples, the
DOT regulations (49 CFR 172.402) require labeling according to the most
likely class assignment (e.g., flammable liquid) and any additional
knowledge about the sample that the shipper may have.  Therefore, while
the DOT regulations do require careful attention when shipping test
samples, the regulations will not restrict the shipment of test samples
from an on-site location to a laboratory.
2.1.7  Specific comments on the procedures of Method 25 are underlined
below.  EPA's responses follow.
     (a)  The sample probe should contain a heated filter.  Presently,
there is no data available to support the requirement for a filter in
the sampling train.  However, it is recognized that organic particulate
matter will interfere with the analysis and, therefore, in some cases
an in-stack particulate filter will be required (as noted in Section 1.1
of the method).  EPA will continue to investigate this matter and, if
appropriate, a change will be made.
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     (b)  Problems have been encountered with locating suitable
collection vessels.   The method specifies aluminum or stainless steel
tanks.   Several vendors of suitable tanks have been located.   Therefore,
aluminum or stainless steel vessels will continue to be required.
     (c)  An accurate vacuum gauge should be substituted for the
mercury manometer for in-field use.  The data presented with the
comment was not sufficient to justify a change in the proposed method;
therefore, no change was made.  However, a vacuum gauge would be
considered an acceptable alternative as allowed in 40 CFR 60.8(b)  if
the user could demonstrate to the Administrator's satisfaction that it
was as accurate as the mercury manometer.
     (d)  Specific details of the total gaseous nonmethane organic
analyzer should be given in the reference method.  Specific details
of the analyzer were intentionally deleted to permit various designs
to be used.  Only the performance of the analyzer is critical, and
performance criteria are given in the method.  Addendum I, which lists
specific system components, has been added to the promulgated method
to provide guidance for users.
     (e)  Specific catalysts should be cited in the method.  Only
performance specifications for the catalysts are given in order to
permit use of different catalysts.  Some catalysts that have been found
to be acceptable are cited in the addendum to the promulgated Method 25.
     (f)  Initial tank evacuation and pressure measurement should
be made only in the laboratory.  If good technique is followed, this
can be conducted in the field.  Therefore, the recommendation will
not be included in Method 25.
                                  2-5

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     (g)  The post-test leak check is overcomplicated, and the same



result could be obtained by simply plugging the probe and monitoring



for a pressure drop.   This approach does simplify the procedure,



and the method has been modified.



     (h)  The final tank pressure/temperature should be measured



following a 24-hour equilibration period.  Such a long equilibration



period should not be necessary.  Except for extreme conditions (i.e.,



winter sampling), a period of  less than 1 hour should be sufficient.



Given the "worst case" conditions, in which the pressure was



immediately measured after sampling at 35°C or -7°C and the incorrect



gas temperature of 20°C was assumed, the errors in the calculated sample



volume would still be only +5.2 percent and -2.5 percent, respectively.



     (i)  An equilibration period should be required before



measuring the final tank pressure.  The tank contains enough surface



area and mass to assure that the internal gas temperature will be at



ambient conditions.  Therefore, no equilibration period will be required.



     (j)  Directions should be provided for heating the sampling



probe because this tubing can  contain organics.  Directions for



heating the probe  have been added to the method.
                                   2-6

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                            TABLE 2-1

      LIST OF COMMENTERS ON PROPOSED TEST METHODS 24 AND 25
                       Docket No.  A-79-05

Document No.              Commenter/Affiliation

    D-l                  William T.  Cavanaugh, Managing Director
                         ASTM
                         1916 Race Street
                         Philadelphia, Pennsylvania  19103

    D-la                 H. J. Stremba, Deputy Managing Director
                         ASTM
                         1916 Race Street
                         Philadelphia, Pennsylvania  19103

D-2 and D-2a             John E. Lowe
                         Environmental Coordinator
                         Finishes Division
                         E.I. DuPont De Nemours & Company
                         Wilmington, Delaware  19898

    D-3                  Larry L.  Thomas, Executive Director
                         National Paint and Coatings Association
                         1500 Rhode Island Avenue, N.W.
                         Washington, D. C.  20005

    D-4                  Robert H. Col lorn, Chief
                         Air Protection Branch
                         State of Georgia
                         Department of Natural Resources
                         Environmental Protection Division
                         270 Washington Street, S.W.
                         Atlanta, Georgia  30334

    D-5                  Victoria Hathaway-Sarver
                         Air Pollution Control Specialist
                         Abatement Unit
                         Regional Air Pollution Control Agency
                         451 W.  Third Street
                         P.O. Box 972
                         Dayton, Ohio  45422

    D-6                  R. J. Anderson, Vice President
                         DeSoto, Inc.
                         1700 South Mount Prospect Road
                         Des Plaines, Illinois  60018

    D-7                  W. R. Johnson, Director
                         Plant Environment
                         Environmental Activities Staff
                         General Motors Corporation
                         Warren, Michigan  48089

                               2-7

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Document No.              Commenter/Affiliation

    D-8                  C.  B.  Potelunfcs, Manager
                         Air and Water Pollution Control
                         American Motors Corporation
                         14250 Plymouth Road
                         Detroit, Michigan  48232

    D-9                  R.  W.  Vorhees, Manager
                         Environmental Engineering & Manufacturing
                           Standards
                         Crysler Corporation
                         P.O. Box 1919
                         Detroit, Michigan  48288

    D-ll                 A.  B.  M. Houston, Manager
                         Compliance and Liaison Department
                         Stationary Source Environmental Control
                         Ford Motor Company
                         One Parklane Boulevard
                         Dearborn, Michigan  48126

    D-12                 Delbert Rector, Chief
                         Air Quality Division
                         State of Michigan
                         Department of Natural Resources
                         Stevens T. Mason Building
                         Box 30028
                         Lansing, Michigan  48909

    D-14                 Daniel J. Goodwin
                         Manager, Division of Air Pollution Control
                         Illinois EPA
                         2200 Churchill Road
                         Springfield, Illinois  62706

    D-15                 J.  C. Weaver, Chairman of D01-21-13
                         Task Group on VOC
                         ASTM
                         1916 Race Street
                         Philadelphia, Pennsylvania  19103
                                2-8

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing!
1. REPORT NO.
 EPA/450-3-79-030C
4. TITLE AND SUBTITLE
 Reference Methods 24 and 25 -  Background Information
 for Promulgated  Test Methods
                                                            3. RECIPIENT'S ACCESSION NO.
              5. REPORT DATE

              June  1980
              6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
                                                            8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS

 Office of Air  Quality Planning  and  Standards
 US Environmental  Protection Agency
 Research Triangle Park, NC  27711
                                                             10. PROGRAM ELEMENT NO.
              11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS

 DAA for Air Quality Planning and  Standards
 Office of Air,  Noise, and Radiation
 US Environmental  Protection Agency
 Research Triangle Park. NC  27711	
              13. TYPE OF REPORT AND PERIOD COVERED
              Final
              14. SPONSORING AGENCY CODE
              EPA 200/04
16. SUPPLEMENTARY NOTES
16. ABSTRACT
      Reference Method 24 is used  to  determine the volatile organic compound (VOC)
 content of coating materials, and Reference Method 25  is  used to determine the
 percentage reduction of VOC emissions  achieved by emission control devices.  These
 methods were proposed on October  5,  1979,  as an appendix  to the proposed  standards
 of performance for automobile and light-duty truck surface coating operations.  This
 document contains  information on  the public comments made after proposal  and EPA
 responses to the comments.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
                                                                          c.  COSATI Field/Group
 Air pollution
 Pollution control
 Surface coating operations
 Test methods
 Volatile organic compounds (VOC)
Air Pollution Control
     13 B
is. DISTRIBUTION STATEMENT
 Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
     20
                                               20. SECURITY CLASS (Thispage)
                                               Unclassified
                            22. PRICE
EPA Form 2220-1 (R«v. 4-77)    PREVIOUS EDITION is OBSOLETE

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