United States
                  Environmental Protection
                  Agency
               Air and Radiation
               (EN-341W)
EPA340/1-91-008
September 1991
     vvEPA
Manual for Coordination of VOC
Emissions testing Using EPA
Methods 18> 21, 25, and 25A
V v.
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                         U.S. EPA Headquarters Library
                             Mail code 3604 y^O^f
                         1200 Pennsylvania Avenue NW
                           Washington DC 20460
                               7±> Printed on Recycled Paper

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                                   EPA 340/1-91-008
 MANUAL FOR COORDINATION OF VOC
         EMISSIONS TESTING
USING EPA METHODS 18, 21, 25, AND 25A
   U.S. Environmental Protection Agency
       Office of Air and Radiation
   Stationary Source Compliance Division
         Washington, D.C. 20460
            September 1991
           SESI™«»
           WASHINGTON, D.C.204&0

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4

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                                       TABLE OF CONTENTS

             Chapter                                                                page
'* -
             1.  INTRODUCTION	;.. M

:4            2.     ESTABLISHING TEST OBJECTIVES	 2-1

                   2.1   Review of Applicable Regulations and Background Information	 2-1
                   2.2   Determination of Compliance Limits	 2-2
                   2.3   Determination of Data Necessary to Show Compliance	 2-3
                   2.4   Basis and Comparison of Results for EPA
                        Methods 18, 21, 25, and 25A	:	 2-3

             3.     PREPARATION FOR AND OBSERVATION OF COMPLIANCE TEST .. 3-1

                   3.1   Notification of Compliance Test	.. 3-2
                   3.2   Conduct Pre-test Survey	 3-3
                   3.3   Finalizing Compliance Test Protocol  	 3-4
                   3.4   Procedures Common to Most Types of VOC Testing	 3-5

                        3.4.1  Measurement Errors	 3-5
                        3.4.2  Determination of Flue Gas Flow Rate	  3-6
                        3.4.3  Moisture Determination 	  3-7
                        3.4.4  Organic Compound Identification and Quantification
                              by Gas Chromatography	  3-8

                   3.5   On-Site Observation Procedures 	  3-9

                        3.5.1  First Sampling  Run	'.	3-10
                        3.5.2  Second Sampling Run	3-10
                        3.5.3  Third Sampling Run	3-10
                        3.5.4  Sample Recovery and Transport  	3-11
                        3.5.5  Analysis	3-11
                        3.5.6  Observation Report	3-12

            4.     MEASUREMENT OF GASEOUS ORGANIC COMPOUND EMISSIONS
                   BY GAS CHROMATOGRAPHY - METHOD 18	  4-1

                  4.1   Applicability	  4-1
                  4.2   Method Description	  4-1
                  4.3   Precision, Accuracy, and Limit of Detection of the Method 	  4-2
                  4.4   Measurement and Location of Sampling Points 	  4-2

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                       TABLE OF CONTENTS (Continued)
 Chapter

       4.5
                                                              Page
Observation Procedures for Method 18 Testing  	  4-3
             4.5.1  Selection of Proper Sampling and Analytical Technique	  4-3
             4.5.2  Preliminary Measurements and Setup 	  4-3
             4.5.3  Observation of On-site Testing 	  4-4

       4.6    Observation Procedures for Method 18 Analysis	4-10

             4.6.1  Preparation of Calibration Standards	4-10
             4.6.2  Sample Analysis  	4-11

       4.7    Use of Audit Materials and Interpretation of Data	4-12

             4.7.1  Performance Audits  	4-12
             4.7.2  Systems Audit	4-15

5.     DETERMINATION OF VOLATILE ORGANIC COMPOUND LEAKS
       - METHOD 21	  5-1

       5.1    Applicability	  5-1
       5.2    Method Description	  5-1

             5.2.1  Regulations and Leak Definition	  5-1
             5.2.2  Portable Instrument Operating Principles  	,.  5-2

       53    Calibration Precision	  5-6

             5.3.1  Calibration of VOC Analyzers	  5-6
             5.3.2  Laboratory Calibrations	  5-7
             5.33  Field Span Check Procedure	5-10
             5.3.4  Thermocouple	5-11

       5.4    Location of Sampling Points	5-11

       5.5    Observation Procedures and Checklists for VOC Testing	5-13

             5.5.1   Performance Criteria and Evaluation Procedures for
                   Portable  VOC Detectors		5-13
11

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                       TABLE OF CONTENTS (Continued)

Chapter                                                                   Page

            5.5.2  Laboratory and Shop Support Facilities	5-17
            5.53  Routine Field-Oriented Evaluations of Instrument
                  Conditions and Performance	5-17

      5.6   Typical Sampling Problems and Solutions  	5-19

6.     TOTAL GASEOUS NON-METHANE ORGANICS AS CARBON -
      METHOD 25	  6-1

      6.1   Applicability	  6-1
      6.2   Method Description	  6-2

            6.2.1  Sampling Procedures	  6-2
            6.2.2  Sampling Equipment	  6-2
            6.2.3  Analytical Procedures	  6-3
            6.2.4  Analytical Equipment	  6-4

      63   Precision and Accuracy	  6-4
      6.4   Location of Sampling Points	  6-4
      6.5   Observation Procedures for Method 25 Testing	  6-5

            6.5.1  Equipment Specifications  	  6-5
            6.5.2  Pre-test Leak Checks  	X	  6-5
            6.5.3  Pre-test Sampling Train Purge	  6-7
            6.5.4  Sampling Procedures	  6-7
            6.5.5  Post Sampling  Procedures	  6-8

      6.6   Sampling Problems, Errors, Solutions, and Action Required	  6-9

            6.6.1  High Gas  Sample Moisture Content and Freezing of Trap ....  6-9
            6.6.2  Use of Electrical Service Not Permitted for Probe and Filter .. 6-10
            6.6.3  Probe Exit or Filter Temperatures Not Within Specification .. 6-10
            6.6.4  Non-constant Sample Flow Rate	6-10
            6.6.5  Use of Method 25 for Measuring Low Levels of Organics	6-11
            6.6.6  Sampling and Analysis by Different Companies	6-12
            6.6.7  Measurement in Ducts Containing Organic Droplets	6-12
                                                                             111

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                      TABLE OF CONTENTS (Continued)

 Chapter                                                                 Page

       6.7   Analysis	6-12

            6.7.1  Analytical System Performance Checks  	6-12
            6.72  Calculations	6-16

       6.8 Audit Procedures  	6-17

            6.8.1  Performance Audits	 6-17
            6.8.2  Systems Audit	6-21

 7.     TOTAL GASEOUS ORGANIC CONCENTRATION USING A FLAME
       IONIZATION ANALYZER - METHOD 25A	  7-1

       7.1   Applicability	  7-1
       7.2   Method Description	;	  7-1
       7.3   Precision and Accuracy	  7-3
       7.4   Sampling Point Location	  7-4
       7.5   Observation Procedures for Method 25A Sampling  	  7-4

            7.5.1  Leak Check	  7-4
            7.5.2  Calibration	  7-5
            7.5.3  Response Time Test	  7-6
            7.5.4  Sampling  Procedures	  7-7
            7.5.5  Establishing Response Factors	  7-8

      7.6   Sampling Problems and Solutions  	7-10

            7.6.1  Cold Spots in Sampling System	 7-10
            7.6.2  Sampling  System Leaks	7-10
            7.6.3  High Moisture  	7-10
            7.6.4  Adjustments to Gain or Zero Offset	7-11
            7.6.5  High THC Concentrations	7-11

      7.7   Audits		7-12
IV

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                     TABLE OF CONTENTS (Continued)

    tei                                                               Page.
8.     REVIEW PROCEDURES FOR VOC TEST REPORTS	  8-1

      8.1   VOC Compliance Testing Report Format 	  8-1
      8.2   Report Review 	  8-1

           8.2.1  Cover, Certification, and Introduction	  8-2
           82.2  Emission Results and Performance Audit Results	  8-2
           8.2.3  Facility Operations	  84
           8.2.4  Sampling and Analytical Procedures 	  8-5
           $.2.5  Compliance Report Appendices  	  8-6

Appendix •                                                             Page

A.    ORGANIC COMPOUND IDENTIFICATION AND QUANTIFICATION

      .XI  Organic Compound Identification by Retention Time  	A-l
      A.2  Adequate Peak Resolution	A-2
      A.3  Proper Response Factors   	A-2

           A.3.1 Different Response Factors for Different Detectors	A-3
           A.3.2 Different Response Factors for Different Compounds 	A-3
           A.3.3 Different Response Factors for the Same Compound	A-5

B.    VOC OBSERVATION PROCEDURES

      B.I  Agency Use of Screening Measurement Methods During
           Compliance Test	 B-l
      B.2  On-site Observation Procedures Coupled with the Use of
           Agency Screening Methods  	  B-2

           B.2.1 First Sampling Run	\	  B-2
           B.2.2 Second Sampling Run	  B-3
           B.2.3 Third Sampling Run	B-4

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                      TABLE OF CONTENTS (Continued)

 Appendix

 C    METHOD 18 OBSERVATION PROCEDURES
Page
       C.1   Selection of Proper Sampling and Analytical Technique
            for Method 18	 C-l
       C.2   Observation of On-site Testing  	  C-14

            G2.1  Evacuation Container Sampling (Heated and Unheated)	C-15
            C22  Direct Interface Sampling	  C-27
            C.2.3  Dilution Interface Sampling	  C-30
            C.2.4  Adsorption Tube Sampling  	  C-32

       C.3   VOC Sample Analysis	  C-36

            C.3.1  Preparation of Calibration Standards	C-36
            C3.2  Analysis of Direct Interface Samples	  C-42
            C.33  Analysis of Dilution Interface Samples  	  C-43
            C.3.4  Analysis of Adsorption Tube Samples	  C-45

       C.4   Auditing Procedures  	  C-48
       C.5   References	  G49

D.     METHOD 25 OBSERVATION PROCEDURES

      D.I   Specifications for Method 25 Sampling Equipment	D-l
      D.2   Specifications for Method 25 Analytical Equipment	D-4
      D.3   Method 25 Nomenclature and Equations	D-4
VI

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                              LIST OF FIGURES


Figure                                                                    Page


3.1   Preliminary Survey Data Forms	3-13


4.1   Integrated Bag Sampling System  	4-16


42   Field Sampling Data Form for Container Sampling	 4-17


4.3   Data Form for Analysis of Method 18 Field Samples	 4-18


4.4   Field Audit Report Form	4-19


6.1   Method 25 Sampling Train	 6-22


6.2   Method 25 Filter Housing	6-24


6.3   Method 25 Condensate Trap	6-25


6.4   NMO Analytical Cycle	6-26


6.5   NMO Sample Delivery Schematic	 6-27


6.6   Condensate Recovery System	6-29
                                                                . t,

6.7   Liquid Sample Injection Unit	 6-30


6.8   Field Audit Report Form	6-32


6.9   Schematic of Method 25 Audit System	6-33


7.1   Method 25A Sampling Train	7-14


7.2   Method 25A Sampling Checklist	7-15


73   Calibration/Sample Valve Assembly with Ambient Dump  	7-16


8.1   VOC Compliance Test Report Format	 8-8


8.2   Compliance Test Report Review Form - Report Contents  	8-10


A.1   Adequate Peak Resolution	A-4
                                                                            vu

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                         LIST OF FIGURES (Continued)

 Figure                                                                   Page

 C.1   General Scheme for Selection of Appropriate Sampling Techniques	 C-13

 C2   On-site Measurement Checklist	 C-17

 C3   Direct Pump Sampling System	 C-23

 C.4   Explosion Risk Area Sampling System Option Using an Evacuated
      Steel Container	 C-24

 C5   Direct Interface Sampling System	 C-28

 C.6   Direct Interface Sampling Form	 C-29

 C.7   Dilution Interface Sampling System	 C-31

 C.8   Adsorption Tube Sampling System	 C-34 •

 C.9   Field Sampling Data Form for Adsorption Tube Sampling	 C-35

 CIO  Post Sampling Operations Checklist	 C-37

 D.I   Recommended Standard Format for Reporting Method 25
      Data and Results	D-8
vui

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                               LIST OF TABLES

Table                                                                     Page

2-1   Partial Listing of Data for Compliance Test Protocol	 2-4

5-1   Source Categories that Emit Fugitive VOCs	 5-2

5-2   Portable Instruments Range, Sensitivity, and Response Time	 5-4

5-3   Recommended Calibration Gases for Routine Instrument Service	5-8

5-4   Calibration Time Requirements	 5-9

5-5   Performance Criteria for Portable VOC Detectors	5-14

6-1   Method 25 Sampling Equipment Component and Calibration
      Specifications	6-23

6-2   Analytical Component and Calibration Schedule	6-28

6-3   Activity Matrix for Method 25 Auditing Procedures	6-31

C-l   Status of Selected Organic Compounds for Method 18 Sampling and
      Analysis Techniques	C-2
                                                                 '             Kg
C-2   Method 18 Sampling Techniques for Selected Volatile Organic Compounds . C-4

C-3   GC Detectors for Selected Volatile Organic Compounds by Method 18  	C-6

G4   Recommended Calibration Techniques for Selected Volatile Organic
 '     Compounds by Method 18	C-8

D-l   Method 25 Equipment Checklist  	D-2

D-2   Method 25 Sampling Checklist	D-3
                                                                            IX

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                                    CHAPTER 1
                                 INTRODUCTION

       Under current environmental regulations, a plant or facility that emits volatile
organic compounds (VOCs) into the atmosphere must maintain emissions at or below
certain levels, as set forth in the applicable Federal, State, and local standards.
Compliance testing, in which emissions are sampled while the plant operates under those
normal maximum operational levels which are expected to produce maximum emissions,
is the "means by which emissions are documented and permits to operate are obtained.
Agency personnel observing the execution of compliance testing, and reviewing the test
protocol and compliance test report are Test Coordinators."*
                                        /  .
       The purpose of this report is to provide the test coordinator with procedures to
(1) identify the data necessary to determine compliance, (2) oversee the compliance test,
and (3) review the compliance test report written by the testing firm.  This manual is
intended to provide guidance to agency representatives with various levels of experience
in coordinating VOC compliance tests. A detailed overview of the methods has been
provided for the more experienced test coordinator.

       While the facility is responsible for the proper conduction of the compliance test,
it is the agency representative's responsibility to ascertain that the  test is  conducted in
accordance with established conditions. It is the agency representative's responsibility to
ascertain that the test is conducted in  accordance with established  conditions.  The test
coordinator determines whether the test protocol, probably prepared by a testing firm
and submitted by the facility, will provide the data necessary to determine compliance
with a  reasonable degree of certainty;  conducts a pretest meeting,  or other pretest
communication, to finalize the test conditions; coordinates the compliance test; and
reviews the data submitted in the compliance test report.

       A performance test consists of the  following steps:

       1.    The source owner/operator notifies the agency (responsible for
            determining compliance) of the proposed test.
       2.    The proposed test plan is submitted to the agency.
       3.    A pretest meeting, or in some circumstances a pretest teleconference, is
            held at the affected facility to finalize the test conditions.
       4.    The conditions  established at the pretest meeting are formally documented
            in writing by the agency, by letter,  or a form suitable for this purpose, or
            other acceptable means.
"The use of this terminology (i.e., Test Coordinators") instead of the more commonly
used terminology "observers," reflects the expanded role, hi addition to observing the
actual test, of EPA representatives in having a test performed in an acceptable manner.
                                                                               1-1

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       5.     The performance tests are conducted as coordinated by the agency
             representative.
       6.     Preparation of a report by the agency coordinator to document the events
             concerning the tests.
       7.     Receipt and review of the test report and documentation of the official test
             results.

       This manual deals with the coordination of compliance testing for volatile organic
 compounds. A volatile organic compound (VOC) is defined in 40 CFR Subpart A,
 General Provisions, 60.2, as any compound of carbon, excluding carbon monoxide,
 carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium
 carbonate, which participates in atmospheric photochemical reactions or which is
 measured by a reference method, an equivalent method, or an alternative method; or
 which is ^determined by procedures specified under any subpart.  Negligibly
 photochemically reactive solvents used hi inks to decrease drying time or other purposes
 do not contribute to the total VOC emissions tally. These materials should not count
 toward VOC emission levels if they are "exempt" from the applicable regulation.  These
 negligibly-reactive compounds shall not be considered VOC if the amount of such
 compounds can be  and is accurately quantified. The  EPA considers the following
 organic solvents to  have negligible photochemical reactivity, and therefore does not
 consider them to be VOCs.
             Methane
             Ethane
             1,1,1-Trichloroethane (methyl chloroform)
             Methylene chloride (dichloromethane)
             Trichlorofluoromethane (CFC-11)
             Dichlorodifluoromethane (CFC-12)
             Chlorodifluoromethane (CFC-22)
             Trifluoromethane (CFC-23)
             Trichlorotrifluoroethane (CFC-113)
             Dichlorotetrafluoroethane (CFC-114)
             Chloropentafluoroethane (CFC-115)
             1,1,1-Trifluoro 2,2-dichloroethane (HCFC-123)
             1,1,1,2-Tetrafluoroethane (HFC-134a)
             1,1-Dichloro 1-fluoroethane (HCFC-141b)
             1-Chloro 1,1-difluoroethane (HCFC-142b)
             2-Chloro-l, 1,1,2-tetrafluoroethane (HCFC-124)
             Pentafluoroethane (HFC-125)
             1,1,2,2-Tetrafluoroethane (HFC-134)
             1,1,1-Trifluoroethane (HFC-143a)
             1,1-Difluoroethane (HFC-152a)
1-2
                                                                                        4

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       •      Perfluorocarbon compounds which fall into these classes:  (1) cyclic,
             branched, or linear, completely fluorinated alkanes, (2) cyclic, branched, or
             linear, completely fluorinated ethers with no unsaturations, (3) cyclic,
             branched, or linear, completely fluorinated tertiary amines with no
             unsaturations, and (4) sulfur containing perfluorocarbons with no
             unsaturations and with sulfur bonds only to carbon and fluorine

Many States also do not consider some or all these materials to be VOCs.

       Chapter 2 of this report provides the  coordinator with procedures and references
for establishing the test objectives. Chapter 3 discusses the pretest survey and the
procedures for coordinating the compliance  test.  Chapters 4, 5, 6, and 7 present
sampling and analysis observation procedures for Methods 18, 21, 25, and 25A,
respectively. Chapter 8 presents review procedures for the compliance test report
submitted by the facility.  The test coordinator must be familiar with the regulations and
the test methodology.
                                                                                 1-3

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                                   CHAPTER 2
                       ESTABLISHING TEST OBJECTIVES

       Under Federal regulations, the facility is required to provide at least thirty days
prior notice of the scheduled compliance test The requirement for submission of a
proposal test protocol is usually established by the agency. To develop the test protocol
and conduct emissions measurements, the facility usually retains the services of a testing
firm.  The test protocol is used as a starting point in establishing test conditions. The
test coordinator reviews the test protocol, requests changes if necessary, and approves
the final test protocol.  This chapter provides the procedures for establishing the test
objectives and for determining the acceptability of the written test protocol.

2.1    REVIEW OF APPLICABLE REGULATIONS AND BACKGROUND
       INFORMATION

       The test coordinator must be familiar with the regulations which are applicable to
the facility to be tested.  A more thorough understanding of all applicable regulations
and guidelines typically can be obtained through discussions with each of the applicable
agency groups.  Typical agency groups (agency organizations vary) and types of
information needed from these groups are discussed below. The test coordinator
generally has copies of the regulations and is usually familiar with them.

       Compliance Group - Copies of all applicable regulations should be obtained.
Previous compliance history and current compliance problems should  be determined.

       Permit Group - The test coordinator should obtain a copy of the existing permit
to operate, if one exists, and a copy of the permit to construct. These permits are
necessary because, depending on the agency, they list process and control equipment
operating requirements.  All conditions and requirements for an existing permit should
be understood.  If no previous operating permit exists, the construction permit is used.

       Inspection or Enforcement Group - The test coordinator should determine what
measurements and other parameters are necessary to establish representative facility
operations.

       Obtaining Background Information • If needed, the test coordinator may obtain
additional background information on testing methodology and process and control
equipment operations through State agency personnel, EPA technical  manuals, and EPA
contact personnel. EPA has a computer bulletin board which  agency test coordinators
can use to obtain background information. The Emissions Measurement Technical
Information Center (EMTIC) computer bulletin board service (BBS) can be reached by
calling, on a computer modem, (919) 541-5742. A listing of EPA manuals and contact
personnel related to emissions measurement can be found on the EMTIC BBS. The
agency emissions test coordinator must be a registered user of the BBS.

                                                                              2-1

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       The agency contacts and the EMT1C BBS may provide the following types of
information:

       1.     Background information on how the regulation was established and the
             intent of the regulation.
       2.     Legal determinations and policy memorandums for facility operations,
             interpretation of the regulation, and testing methodology.
       3.     Problems generally associated with facility operation and testing
             methodology.
       4.     Process operational procedures  and control equipment operation
             procedures that provide short term emission reductions.  These procedures
             are occasionally used by source  personnel to reduce emissions during
             compliance testing.
       5.     Compliance test reports from similar sources.
       6.     Source history information. This will include all permits, compliance test
             reports, and inspections. If the  facility has been cited for noncompliance, it
             is extremely important that the test coordinator be aware of these actions
             and their status and that no discussion with facility personnel regarding
             these problems occur without prior knowledge of the agency.

22    DETERMINATION OF COMPLIANCE LIMITS

       The compliance limit will be specified  in the applicable regulations or permit.  It
is critical that the test coordinator understand the measurement units of the applicable
emission standard or limit and how they are determined. If process rate or weight is
used in expressing the limit, then the definitions for process rate or weight must be
understood. Many regulations exempt certain compounds from the limits  (e.g., methane
or ethane may be exempted as VOC). These exemptions should be determined and
understood.

       For limits expressed as a concentration, the units of the standards are generally
parts per million by volume (ppmv).  If the emissions are expressed as parts per million
by weight (ppmw), significantly different values will be obtained. Also, the standards
typically require (1) correction of measurements expressed as parts per million by
volume to a dry basis at a standard temperature and pressure and (2) no dilution air.

       The EPA Methods for VOC determination produce emission results on several
different units of measurement bases. Therefore, results from Methods 18, 21, 24, 25,
and 25A may not be directly comparable, unless additional procedures and calibrations
are performed.  Emission measurements, uncontrolled emissions, and methods for
measuring collection efficiency, must yield data on the same unit basis.  The basis of
results for EPA Methods for VOC determination and a comparison of VOC data
obtained by the use of different methods are discussed later. ,
2-2

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2J   DETERMINATION OF DATA NECESSARY TO SHOW COMPLIANCE

      The test coordinator should determine whether the test protocol submitted to the
agency provides the framework to collect data necessary to demonstrate compliance with
a reasonable degree of certainty.  The test coordinator should: (1) understand the
requirements of the compliance test and (2) match requirements of the compliance test
to the specifications in the written test protocol.

      The test coordinator may also find  it helpful to use the pretest survey form,
presented and  discussed in Chapter 3, to outline the requirements of the compliance test
A partial listing of necessary data requirements is presented in Table 2-1, page 2-4.

2.4   BASIS AND COMPARISON OF RESULTS FOR EPA METHODS 18,21, 25,
      AND 25A

      When the results from two VOC measurement methods are to be compared, the
test coordinator must understand the unit  basis of method results (type of calibration
standards and emissions correlation to calibration standards) for Methods 18, 21, 25, and
25A. Method  18 identifies only those compounds for which sampling and analysis is
specifically conducted; results are  expressed in terms of concentration of those specific
organic compounds. Method 18 does not  identify or quantify unknown compounds.

      Methods 21, 25, and 25A do not provide results on an organic compound specific
basis (i.e., the exact organic compounds measured cannot be determined from the
emission results); measurement results from these methods are expressed in terms of the
calibration standard (e.g.,  ppm as  propane or ppm as carbon) or as in the .case of
Method 24, on a total organic basis (percent volatile organics).          -.-

      When the facility proposes  the use of two different methods for collection
efficiency determination, the test coordinator must determine the acceptability of the
testing protocol.

      The sampling and analytical methods used at each sampling location must provide
emission results on the same unit measurement basis.
                                           ^

      Ensuring that measurements are obtained on the same unit measurement basis
can be complicated. When the test coordinator is uncertain of procedures, the EMTIC
representative who is listed as the VOC contact can be consulted.
                                                                            2-3

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      TABLE 2-1. PARTIAL LISTING OF DATA FOR COMPLIANCE TEST
                  PROTOCOL
            Safety Considerations

            •     Required by EPA
            •     Required by plant
            •     Recommended by OSHA
            Process
                  Facility identification and description
                  Parameters to be monitored and recorded (including recording times
                  time intervals)
                  Acceptable range for each parameter monitored
                  Raw materials to be used
                  Fuel
                  Process samples to be taken and analyzed
                  Process rate
                  Mode of operation
                        Manual or automatic operation
                        Cleaning and auxiliary systems
                        Normal period for process cycle
                        Materials processed - coverage and/or shape
                        Diversion or circumvention of pollutants from air pollution
                        control equipment
                        Operational personnel (Must be the same as scheduled for
                        normal day-to-day operations of facility)
                  Instruments to be added and/or calibrated
      3.,    Control Equipment
                  Description of control equipment
                  Parameters to be monitored and recorded (including recording
                  tunes)
                  Acceptable values for each parameter
                  Control equipment effluent samples to be taken and analyzed
2-4

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TABLE 2-1. PARTIAL LISTING OF DATA FOR COMPLIANCE TEST
            PROTOCOL (Concluded)


      *     Mode of operation

            *     Manual or automatic operation
            *     Collected pollutant removal cycle
            *     Cleaning cycle
            *     Auxiliary or gas conditioning systems

      *     Instruments to be used in monitoring operation
      •     Instruments used in monitoring operation to be calibrated

4.     Measurement Methodology

      •     Basis of results
      •     Sample run time
      •     Portion of the process cycle to be'tested
      •     Portion of the control equipment cycle to be tested
      •     Sampling locations with drawing showing bends, obstructions,
            control equipment, etc.
      •     QA audit samples  to be provided by agency
      •     Fugitive emissions (not discussed in this manual)
      •     Transfer efficiency (not discussed in this manual)
      •     Sampling procedures to be used (emission, process and control
            equipment samples)       ,                       '-«.
      *     Hood capture efficiency (not discussed in this manual)
      •     Material balance (not discussed in this manual)
      •     Sampling procedures not required -by method but required by
            control agency
      •     Analytical procedures to be used (emission, process and control
            equipment samples)
      •     Analytical procedures not required by method but required by
            control agency
      •     QA/QC procedures required (e.g., performance audit samples)
      •     Report format and required data
      •     Time restrictions for submittal of report
                                                                     2-5

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                                   CHAPTERS
        PREPARATION FOR AND OBSERVATION OF COMPLIANCE TEST

       This Chapter addresses preparation and procedures for the on-site observation of
the compliance test.  Preparation for the test observations includes scheduling personnel,
scheduling equipment and ordering performance audit gases. A pretest meeting should
be conducted at the facility at least 15 days prior to the commencement of testing. This
gives the test coordinator the opportunity to inspect the facility, including any air
pollution control equipment and test location, determine which operational parameters
should be monitored, and obtain information to finalize the test conditions.  Preparation
also includes conducting a pretest survey when necessary. The  sampling procedures
common to all EPA VOC Methods are discussed in Section 4 of this chapter. The
specific sampling and analytical  procedures for Methods 18,21,25, and 25A are
presented in Chapters 4, 5, 6, and 7, respectively.

       Observation of VOC compliance tests is typically more difficult than for  tests for
other criteria pollutants. Because of the complex nature of compliance testing for VOC,
Method 18 recommends that the tester conduct site specific and, if applicable, compound
specific pretest preparations.  The test coordinator may also find it useful to conduct a
pretest survey.

      The function of the test coordinator is to ascertain that the test are conducted in
accordance with the conditions established at the pretest meeting. The test coordinator
has the authority to require changes in the testers' procedures if they are not in
accordance with the regulatory requirements or not in agreement with the established
conditions.

      The test coordinator's principle function is to evaluate the representativeness of
compliance testing. In other words, the compliance test results  should represent
emissions typical of maximum operating conditions which produce maximum emissions.
Representativeness is typically evaluated  in terms of five criteria; if any of the criteria
are not met, the compliance test is considered nonrepresentative:

      1.  Process and control equipment must be operated in such a manner as to
          produce representative samples of controlled and uncontrolled emissions.  By
          measuring the emissions before and after control devices, the removal or
          control efficiency can be determined.
      2.  Locations of the sampling ports and points must provide samples which are
          representative of the total uncontrolled (if applicable) and controlled process
          emissions.
      3.  Samples collected in a sampling train must be representative of the
          concentration(s) at the sampling point(s).
      4.  Samples recovered and analyzed must be representative of samples collected
          in the sampling train.


                                                                              3-1

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       5.   Reported results must be representative of facility operations and the samples
           recovered and analyzed.

3.1    NOTIFICATION OF COMPLIANCE TEST

       For Federal New Source Performance Standards (NSPS), the general
requirements for performance (compliance) testing are presented in Title 40 Part 60.8 of
the Code of Federal Regulations.  The requirements are as follows:

       1.   Performance (compliance)  testing within 60 days after achieving the maximum
           production rate at which the facility will operate, but not later than 180 days
           after initial startup.
       2.   Performance testing and data reduction in accordance with the test methods
           and procedures contained in each applicable subpart unless the Administrator
           allow one of the four options listed.
       3.   Performance testing conducted under such conditions as the Administrator
           shall specify to the plant operator based on representative performance of the
           affected facility.                                                    r
       4.   At a least 30 days prior notice of any performance testing to the
           Administrator.
       5.   Provision of (1) sampling ports, (2) safe sampling platforms, (3) safe access to
           sampling platforms, and (4) utilities for sampling by the facility.
       6.   Three separate runs per compliance test. In the event of the items listed in
           60.8(f) the Administrator may accept two sample runs as a test.

       The Federal requirements ensure that the agency is notified prior to the test and
that the sampling site is acceptable. Many States have developed similar guidelines to
ensure proper notification of compliance tests. Testing arrangements and scheduling of
staff and equipment for the observation are also facilitated by an agency guideline. A
typical State agency guideline requires or includes the following:

       1.  A testing protocol submitted by the facility.
       2.  30 Day notification of testing.
       3.  Testing to be conducted during normal agency business  hours.
       4.  Operational conditions during testing.
       5.  Quality assurance requirements for the compliance testing (e.g., performance
          audit samples).
       6.  Testing procedures required by the State which are deviations from the EPA
          Methods.
       7.  Compliance test report format (see Chapter 8 for example format).
       8.  Safety and sampling access  requirements.

       Notification 30 days prior to the test and submission of a written test protocol
allows the test coordinator sufficient time to review the test protocol, conduct a pretest
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meeting to establish that the requirements for compliance testing will be met, and order
performance audit materials.

       Performance Audit Materials - The test coordinator must obtain the proper audit
materials and/or devices. The testing firm analyzes the audit materials on-site as part of
the compliance test. To select the proper audit gas cylinder(s), the test coordinator will
consult the applicable method, and written test protocol supplied by the tester to
determine the type (specific organic compound) and proper concentration range of the
audit gas  to order.  Table C-l, page C-4, lists audit gases available from EPA for
common target organic compounds. Availability and ranges of audit gases can be
determined by contacting:

          U.S. Environmental Protection Agency
          Environmental Monitoring Systems Laboratory
          Quality Assurance and Technical Support Division
          Research Triangle Park, North Carolina  27711
          Attention:  Audit Cylinder Gas Coordinator

       For audit gases obtained from a commercial gas manufacturer, ensure that the
manufacturer has (1) certified the gas in a manner similar to the procedure described in
40 CFR Part 61, Appendix A,  Method 106, Section 5.2.3.1 and (2)  obtained an indepen-
dent analysis of the audit cylinder to verify that the audit gas concentration is within 5
percent of the manufacturer's stated concentration.

       To accurately assess the emission measurements, the performance audit sample
concentrations should fall within the range of approximately 50 to 200 percent of the
expected emissions concentration.  Interpretation of audit results is discussed in
Chapter 8. Performance audit gases with concentrations 5 times greater or 5 times less
than the expected emission value or an organic compound different than that being
measured should be not used.

3.2     CONDUCT PRE-TEST SURVEY

       Prior to compliance testing, the affected facility is often visited by a representative
of the testing firm and the test coordinator. This information gathering visit is referred
to as the pretest survey.  Agencies  should be strongly urged to conduct pretest meetings
at the affected facilities well in advance of the test date.  During the pretest  survey of
the process and control equipment, the test coordinator may find it useful to conduct
screening  measurements to (1) establish some operating baseline values for process and
air pollution control equipment and (2) to determine problems with the methods to be
applied later in the compliance test. The test coordinator may prepare a form of
information to gather during the  pretest survey.  An example  of a general pretest survey
checklist is shown in Figure 3.1, page 3-13. Because of the complex nature of most
organic processes, the test coordinator may provide the testing firm with the  example


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 checklist to be completed to enhance the probability that the testing will be performed
 as required.

       Since most organic gases are invisible, conducting independent testing to estimate
 the emission levels and other key parameters using a portable organic analyzer (EPA
 Method 21  instrumentation) can be extremely useful. Appendix B provides an example
 of how these instruments can be used.
      i
       One  of the primary concerns for any organic sampling program must be safety.
 The test coordinator should always question the facility representative concerning general
 plant safety requirements and safety in regard to sampling.  Every test protocol should
 address the  safety considerations involved in performing the test. There are numerous
 safety considerations involved in organic sampling, particularly regarding health effects
 and explosion hazards, however, it is beyond the scope of this manual to discuss each
 one in detail. It cannot be over-emphasized that the test coordinator must always be
 aware of the safety hazards.

 3.3    FINALIZING COMPLIANCE TEST PROTOCOL

       Before the compliance testing, it is recommended that the agency test coordinator
 meet with a representative of the testing firm, and a facility representative. At this
 meeting the compliance test protocol can be finalized, the baseline (representative)
 facility operating conditions  can be established, and the testing schedule can be
 coordinated. The pretest meeting agreements, or conditions established, should be
 documented in a final letter from the agency test coordinator to the facility
 owner/operator, or on a form/checklist completed by the test coordinator.

      The testing firm representative must know the exact sampling procedures to be
used, the minimum data and reporting requirements, and the conditions that constitute
an invalid test. If the test coordinator will use a checklist to monitor sampling and
analytical procedures, it is beneficial to provide the checklist to the testing firm to ensure
that all required steps will be completed. Likewise, the facility representative should
explain what process and control equipment data will be recorded, the intervals of data
collection, the raw materials to be used, tested, and the  conditions that could constitute
an invalid test.  Since it is  the facility representative's responsibility to obtain the
baseline operational parameters, it is the agency's responsibility to designate which
parameters will be monitored and recorded.  Execution  of the compliance test  in
accordance with the established test protocol should constitute a valid test.

      The lines of communication for the compliance test should be defined.   It is
recommended that all official communications regarding facility operations, testing
methodology, and agency policy be limited to the test coordinator, facility representative,
and testing firm representative.  It can be useful to know the names of the  supervisors of
these individuals in the event of poor cooperation or when requests for information are
questioned.
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       As a minimum for relatively simple processes, a teleconference should be
conducted to establish the test conditions, followed by formal documentation.  In all
cases, whether the process and sampling is simple or complex, it is the test coordinator's
responsibility to be certain that all details of the test procedure are understood and
accepted before the test begins.
   / •
       Procedures common to most types of VOC testing and relevant to on-site
observation are presented below.  The sampling and analytical procedures specific for
.Methods 18, 21, 25, and 25A are addressed  in Chapters 4, 5, 6, and 7, respectively.

3.4    PROCEDURES COMMON TO MOST TYPES OF VOC TESTING

       Determination of measurement errors, measurement of flue gas flow rate,
moisture determination, organic compound identification by retention time,  proper gas
chromatography (GC) peak resolution, and application of proper response factors are
required for most VOC testing. Each is discussed below.

3.4.1   Measurement Errors

       The procedure for determining pollutant emission rates by stack sampling involves
measurement of a number of parameters. Errors of measurement associated with each
parameter combine to produce an error in the calculated emission rate.  Measurement
errors are of three types: bias, blunders, and random errors.  Bias errors, usually a result
of poor sampling and analytical technique, cause the measured value  to differ from the
true value in one direction.  Many bias errors can be eliminated through proper
calibration of the  equipment. Most blunders occur during sampling, sample transport,
and sample preparation for analysis.  Elimination of blunders should be a main concern.
Random errors (precision), which result from a variety of factors, cause measured values
to be either higher or lower  than the true value. Such errors result from the inability of
sampling personnel to read scales precisely,  poor equipment performance, and lack of
sensitivity in measurement devices. The usual assumption is that random errors are
normally distributed about the mean or true value and can be represented statistically in
terms of probabilities.  All methods have some inherent random error (precision).

      To make on-site decisions based on the significance of error, the test coordinator
must know three things to determine the importance of the error.

       1.  Does the facility have to prove compliance with the standards (Federal
          regulations) or does the agency have to prove a violation of the standards
          (State regulations)?
      2.  What are the direction and magnitude of any biases?
      3.  What is the acceptable bias that will be  allowed before rejecting the results?
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        If a facility is attempting to prove itself in compliance with most Federal
 regulations, any magnitude of high bias in an outlet emission measurement (measured
 emissions higher than actual emissions) conclusively showing compliance would be
 allowed. However, these high biased results might not be valid for use in emissions
. trading or banking. A low bias  in an outlet emission measurement would be acceptable
 if it did not cause the reported results to show compliance rather than violation.  Since
 the final results are not generally known during the on-site testing, it is preferable for the
 test coordinator to have a fixed  value to apply in allowing or disallowing a test run while
 on-site. EPA method development testing reports indicate that most VOC test methods
 have a precision of about 10 percent.  A listing of EPA method development reports and
 the method's precision are on the EMTIC BBS.  Therefore,  a good rule of thumb for
 allowing biases determined on-site is up to 10 percent high bias and 5 percent low bias.

        When the State or local agency has the burden of proving that the source is in
 violation with the applicable regulation, any low bias in a measurement (measured
 results less than the true value)  that still proves the source in violation would be
 acceptable. The low bias will not be challenged by the facility unless the testing does not
 comply with legal requirements  as stated by the applicable test method.  When the
 agency bears  the proof of violation, a good rule of thumb for acceptable bias is up to
 5 percent high bias and 10 percent low bias. Again, it should be stressed that for proof
 of violation, meeting the requirements of the applicable test  method is mandatory.

       Errors from the measurement of most sampling parameters have very little effect
 on the final data results. The test coordinator or tester may be able to calculate the
 direction and magnitude of a measurement error.

 3.4.2  Determination of Flue Gas Flow Rate

       For ducts equal to or greater than 12 inches in diameter, the number of sampling
 points necessary to determine the flow rate is specified by EPA Method 1, Figure 1-2,
 "Minimum number of traverse points for velocity (nonparticulate) traverses."  For ducts
 less than 12 inches in diameter,  EPA Method 1A should be used to determine the point
 location for velocity measurements.  Sampling port locations  upstream of air pollution
 control equipment do  not typically meet Method 1 requirements. If a sampling location
 does not meet minimum requirements and the system is closed with no air entering or
 leaving, then the flow  rate at the outlet location (after control equipment) can be
 measured and the standardized flow rate used for the inlet location.

       Flow rate is determined by EPA Method 2 for large ducts equal to or greater
 than 12 inches in diameter. Method 2 uses a "S" type pilot tube to determine the
 average velocity pressure.  The velocity pressure and the stack gas molecular weight
 (from  Method 3) and stack gas moisture content (from Method 4) are used to determine
 the flue gas flow rate.  For ducts less than 12 inches in diameter within the temperature
 range  of 0 to 50°C, Method 2A can be used to measure the gas volume flow rate directly
 3-6

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with a gas meter. Method 2B is used to measure gas volume flow rate from gasoline
vapor incinerators. This method determines the flue gas flow rate prior to combustion
and then calculates flue gas flow rate after combustion based on a carbon balance.
Method 2C applies to ducts less than 12 inches in diameter and measures flue gas flow
rate with a standard pitot tube instead of a type S pitot tube. Method 2D also applies to
ducts less than 12 inches in diameter and uses the same approach as 2A by measuring
flow rate directly with a rotameter or orifice plate.

    *   Flue gas flow rates measured using Methods 1 and 2 are typically within
10 percent  of the true flow rate values for all the methods shown above (Methods 2A,
2B, 2C, and 2D). Sections 3.0 and 3.1 of EPA's Quality Assurance Handbook, Volume
HI, EPA-600/4-77-027b, discusses errors associated with velocity measurements.

3.4.3   Moisture Determination

       Stack gas moisture content must be determined when (1) flue gas flow rate is
determined or (2) stack gas concentration is  measured (container sampling or direct
interface sampling). The moisture content is used to correct the emission concentration
or mass emission rate to a dry basis. EPA Method 4, Section 3.3 of EPA's Quality
Assurance Handbook, Volume in, EPA-600/4-77-027b,  is used to measure stack gas
moisture content Section 3.3 of the Quality Assurance  Handbook, Volume HI, provides
detailed information on the application of Method 4.

       For flue gas streams at or below 60°C (140dF), flue gas moisture content can be
determined using wet bulb/dry bulb thermometers and the partial pressure equation
shown  below. This is an approximation method, as described in Method 4.  Obtain the
wet bulb/dry bulb temperatures as follows:

       1.  Moisten the wet bulb thermometer wick with deionized distilled water.
       2.  Insert thermometers into flue gas  stream and monitor wet bulb temperature.
       3.  When wet bulb temperature has stabilized, record both wet bulb and dry
          bulb thermometer temperatures.
       4.  Calculate flue gas moisture content (%H2O) using the equations listed below.
                                                                    Equation 3-1
                                    P. + 
-------
                                          x (I+(J*w-32yi571)) x 100   Equation 3-2
          where:
             w2 • Calculated constant, saturation % H2O at Tw
             Tw = Wet bulb temperature, °F
             Td = Dry bulb temperature, °F
             Pb - Barometric pressure, in. Hg
             Ps = Static pressure of duct, in. H2O
 3.4.4  Organic Compound Identification and Quantification by Gas Chromatography

       When using Method 18, the organic compounds to be measured must be known
 prior to the test.  To identify and quantify the major components of the organic
 compounds known to exist in the sample, the retention time of each component is
 matched with the retention times of the known compounds (the standard reference
 material or calibration standard) under identical conditions. Separation of organic
 compounds is performed with gas chromatographic columns, referred to as GC analysis.
 The retention time is the time between sample injection into the GC and when the
 organic compound reaches the detector. If GC conditions remain constant, the retention
 time for each compound will be constant as well, and will serve as the identifying
 parameter for each peak.  Care  must be taken to assure that two compounds do not
 share the same retention time. The retention time shall be within 0.5 seconds or
 1 percent of the retention time of the known compound's (calibration standard)
 retention time (whichever is greater) to be considered acceptable. The retention time
 will vary with (1) type of column or column material, (2) length of column, (3)
 temperature of column, (4) organic compound, and (5) several other factors.  The exact
 seconds or minutes of the retention time do not matter, except the longer the retention
 time, the longer the analysis time.

       To obtain proper quantitative values, sample peaks (the result of organic
 compounds as they reach the detector) must be properly separated to enable the
 detector to analyze only the compound of interest.

       Understanding the use of the response factor is important because (1) different
 detectors can have a different response factor for the same  compound, (2) each detector
 can have a different response factor for different compounds, and (3) the same detector
 can give a different response factor for the same compound at different conditions.  The
response factor for each compound on any detector can be  determined by dividing the
area units from the integrator printout of the standards by the concentration of the
standard (area units/ppm of standard). This is done for all concentrations of standards
used to calibrate the detector.
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       Method 25 was developed to eliminate the reduced response factor problem when
the organic compounds are unknown.  When the organic compounds in the sample are
unknown (e.g., after an incineration process), then proper calibration gases cannot be
selected. To minimize this problem, Method 25 removes all the elements that give
reduced response factors and analyzes the compound as methane in terms of carbon.
The results are then reported as parts per million as carbon.  Unfortunately, the true
molecular weight of the compound is lost and a concentration or mass emission rate
cannot be calculated.

       A detailed discussion of organic compound identification and quantification is.
presented in Appendix A.

3.5    ON-SITE OBSERVATION PROCEDURES

       The attitude and behavior of the agency test coordinator during the pretest
meeting and compliance test, are of the utmost importance.  The test coordinator should
conduct his/her duties thoughtfully and thoroughly, not disrupting the testers as they
perform the tests.  The test coordinator must also avoid appearing meek or reluctant to
authoritatively represent the agency's interest. If problems with facility operation or
sampling are noted by the test coordinator during the compliance test, it is recommended
that the test coordinator deal solely with the designated testing firm representative and
facility representative; he/she should have a clear understanding with them if it  is
necessary to communicate with other testing firm personnel or facility operations
personnel.  Conversely, it may be advisable to refrain from answering inquiries from the
testing firm personnel and facility operations personnel concerning agency enforcement
policy.                                                              T

       During the test, the test coordinator should check to ensure representative facility
operations  and adherence to specified sampling procedures.  To eliminate the possibility
of overlooking necessary checks and to provide the  agency with  documentation to use in
later enforcement actions, the  test coordinator can use checklists covering details of
process operations, control equipment operations, and sampling procedures.  The
pretest survey forms previously discussed in Chapter 3.2 can be used to develop  the
process and control equipment checklist. Sampling checklists for Methods 18, 25, and
25A are presented in the applicable discussions later in this manual.

       Since additional measurements  are typically not made by the agency, the
recommended procedures for conducting on-site observations do not include use of
agency conducted screening measurements. Independent screening measurements
conducted by an  agency during the compliance test  are discussed in Appendix B.

       The remainder of this Chapter presents a recommended scheme for the test
coordinator to use in conducting the test observation.
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 3.5.1  First Sampling Run

       Applicable methods include Method 18, 25, and 25A.  If analyses are to be
 conducted on-site, acceptable results must be obtained for audit sample(s) prior to any
 field sample analyses.  An inspection of the sample recovery area and observation of the
 sampling train(s) assembly by the test coordinator may be useful in detecting and
 eliminating errors before they occur.  If only one agency test coordinator is present, the
 schedule below will make the most effective use of observation time. These procedures
 are provided to assist less experienced test coordinators in establishing a routine for on-
 site observations.  More experienced test coordinators will follow their established
 routine.

       For the first test run, after determining that the facility operations are as specified
 in the test protocol, the test coordinator should go to the sampling location to observe
 the test team recording the initial data. The initial sampling system leak check should
 be observed.  When the test coordinator is satisfied with the sampling train preparation
 and the facility operation, he should allow the testing to begin.  He should observe the
 sampling procedures for the first 15 minutes of sampling and then conduct a check on
 the facility operations.  If the process and control equipment are operating satisfactorily
 and the data are being recorded as specified, the test coordinator can return to the
 sampling location to observe the completion of sampling, giving close attention to the
 final readings and the  final leak check.  If conducted on-site, the sample analysis should
 be observed closely during analysis of the  audit gas cylinder and the first field sample.
 The  analyst should be  required to conduct all necessary calculations to determine the
 field results in terms of the units of the allowable emissions standard (e.g;, ppmv on a
 dry, standard condition basis for the specified organic compound).  All procedures and
 calculations should be  validated by the test coordinator. The distance between the
 control room, or area,  and the test  location may create restrictions, which may be
 compounded by difficult procedures. The agency coordinator again must use sound
judgement in determining his/her activities during the tests.

 3.52   Second Sampling Ron

       Applicable methods include  Method 18, 25, and 25A.  If the test coordinator is
 satisfied that the sampling procedures applied during the first test run are proper, he
 should spend most of the second run observing process operations,  with intermittent
 checks on the sampling procedures. At the end of the run, the test coordinator should
 return to the sampling location and observe recording of the final data, the final leak
 check, transport of the sampling train to the cleanup area, and sample recovery, as
 applicable.
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3.53  Third Sampling Run

       Applicable methods include Method 18, 25, and 25A. The focus of observation
for the third sampling run is based on observations made during the first and second
runs. The test coordinator's attempts to determine which element(s), facility operations,
sampling procedures, sample recovery procedures, and/or analytical procedures may
introduce the greatest degree of error in the emission measurements. The test
coordinator should then place the most emphasis on these elements.  However, at least a
brief check of each should be included in observations made during the third run.

3.5.4  Sample Recovery and Transport

       It is important that sample recovery, sample transport, and analysis are conducted
according to applicable method procedures and are well-documented.  To reduce the
possibility of invalidating the test results, all of the samples should be placed in sealed,
nonreactive, properly identified containers.  The samples must then be delivered to the
laboratory and analyzed within the sample stability time specified by the method or
determined by the preliminary evaluations.  Each container must be uniquely identified,
at the time of sample recovery, to preclude the possibility of interchange.  The number
of each container must be recorded on the sample recovery form (which documents the
chain of custody) and the analytical data sheet.
                                                                   i
3.5.5  Analysis

       When the analysis is conducted at the testing firm's laboratory or an outside
laboratory rather than in the field, the use of performance audit samples is the best
method for determining if the sampling and analytical procedures were followed.
Consult the applicable Method to determine the allowable error (acceptable results) for
the audit sample analysis.  Acceptable audit sample results cannot assure acceptable
results on the field samples. Acceptable audit sample results only indicate that the
method was conducted properly and that the calibration standard values were correct.

      Analytical errors are generally difficult to detect by reviewing the compliance test
report without the aid of performance audit information.  Instrument integrators which
record and calculate  laboratory data should reduce analytical laboratory error.
Computers used to calculate emissions data can greatly reduce calculated analytical
errors. The laboratory data, calibrations, and calculations must be well-documented and
presented in the compliance test report in such a manner that the test coordinator can
evaluate the validity of the data using procedures presented in the chapters on the
specific methods (e.g., Chapter 4 for Method 18).
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3.5.6  Observation Report

       Chapter 8 discusses review of the compliance test report Information gathered
during the pretest survey, if performed by the test coordinator, can be useful in reviewing
the compliance test report  The test coordinator may also find  it beneficial to organize
the on-site observations upon returning from the field. The test coordinator should
prepare a formal report concerning the performance tests.  This is a narrative report
with field notes and forms/checklists attached.
3-12
                                                                                            4

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       General Information

       Name of company	Date_
       Address
      Contact	Title.
      Phone	
      Process to be tested
       Source ID No.	  Permit No.	Other ID No.
       Duct or vent to be sampled	
      Current permit requirements (attach copy of operating or other permit)

n.    General Plant Requirements

      Plant safety requirements_	
      Vehicle traffic rules
      Plant entry requirements_
      Security agreements_
      Potential problems_
      Safety equipment requirements (glasses, hard hats, shoes, etc.)
      Can photographs be taken?_
ffl.   Process and Product Information

      Process description	
      Raw material and fuels that produce the potentially highest
      emissions
      Raw materials and fuels for compliance test
                     Figure 3.1.  Preliminary survey data forms.

Note: These forms apply to Methods 18, 25, and 25A.  Some changes or modifications
      are necessary to them when applying to Method 21.
                                                                            3-13

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       Will raw materials be sampled and analyzed?
      If yes, describe procedures
       Estimated precision and accuracy of procedures	
       Methods that the agency will use in analysis of raw materials
       Do plant records demonstrate the raw materials used?	
       Are the normal recording intervals satisfactory for test?	
       Should these records be kept on file for future inspections?
       Remarks:
       Products that potentially produce the highest emissions

       Products selected for compliance test
       Products sampled and analyzed by source?
  If yes, describe procedures
       Estimated precision and accuracy of procedures	
       Methods that the agency will use in analysis of the products
      Do plant records demonstrate the products produced?
      Are normal record intervals satisfactory for test?
      Should these records be kept on file for future inspections?_
      Operating cycle
      Check: Batch	Continuous	Cyclic	
      How is the cycle determined?	
      Timing of batch or cycle (hours and/or minutes)	
      Portion of cycle to be tested	
      Portion of cycle represented by each run
      Maximum process rate or capacity
      Method to determine process weight or rate
      Estimated precision and accuracy of method
      Dd~any instruments need calibration?_
changed for test ?
      Methods that agency will demonstrate to check rate or weight_
      Do plant records reflect process weight/rate?	
      Are normal record intervals satisfactory for test?	
      Should these records be kept on file for future inspections?	
      Other process parameters to be recorded (e.g., temperatures, air flow rate)

                               Figure 3.1. (Continued)
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Parameter	How determined?	Recorded
Estimated precision	accuracy	calibrated _
Acceptable value for parameter	 units	
Method that agency will conduct to check parameter	
Are normal record intervals satisfactory for test?
Parameter	How determined?	Recorded
Estimated precision	accuracy	calibrated	
Acceptable value for parameter	units	
Method that agency will conduct to check parameter	
Are normal record intervals satisfactory for test?
Parameter	How determined?	•    Recorded
Estimated precision	accuracy	calibrated	
Acceptable value for parameter	units	
Method that agency will conduct to check parameter	
Are normal record intervals satisfactory for test?
Parameter	How determined?	Recorded
Estimated precision	accuracy	calibrated	
Acceptable value for parameter	units	
Method that agency will conduct to check parameter	
Are normal record intervals satisfactory for test?
Should these records be kept on file for future inspections?	
Physical arrangement of process - doors open, hoods on, covers on
Normal mode of process operation: manual	automatic
Mode of operation for test: manual	automatic _
What constitutes a process malfunction?	•
How are malfunctions handled with regard to process operation and
notification of agency?	

Description of future, planned changes in operations	
Normal maintenance schedule
List of parameter records which should be retained by facility
                        Figure 3.1.  (Continued)
                                                                       3-15

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IV.    Air Pollution Control Equipment
       Description of control equipment
                                           length of cycle
                                                       cyclic
Control equipment operations: continuous
How is the cycle determined?	                 	
Do instruments determine cycle?	 Are control equipment data recorded?
Are these records kept on file for future inspections?
Portion of cycle to be tested	
       Normal mode of operation: manual
       Mode of operation for test: manual
                                                automatic
                                              automatic
       Control equipment parameters to be recorded (temperatures, air flow rate)
       Parameter               How determined?	Recorded	
                                      accuracy         calibrated
Estimated precision
Acceptable value for parameter
                                                     units
       Method that agency will conduct to check parameter
       Are normal record intervals satisfactory for test?
       Should these records be kept on file for future inspections?	
       Parameter	How determined?	Recorded
       Estimated precision	accuracy	calibrated	
       Acceptable value for parameter	units	
       Method that agency will conduct to check parameter	
       Are normal record intervals satisfactory for test?
      Should these records be kept on file for future inspections?	
      Parameter               How determined?	Recorded
                                      accuracy
Estimated precision
Acceptable value for parameter	units
Method that agency will conduct to check parameter
Are normal record intervals satisfactory for test?
calibrated
      Should these records be kept on file for future inspections?
      Removal procedure and sequence for collected materials	
      Collected materials sampled and analyzed: procedures for
      Collected material type	
      Collected material volume or weight	
      Methods used by agency on collected materials: type and/or volume

      Physical arrangement of control equipment: auxiliary systems or ducts

      What constitutes a control equipment malfunction?
                              Figure 3.1.  (Continued)
3-16

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      How are malfunctions normally handled with regard to keeping the process
      and control equipment on line?	
      Describe future, planned changes in operations
      Normal maintenance schedule
V.    Sampling Site and Procedures

      A.  Sampling Site
      Site description	
      Duct shape and size_
      Material(s) of construction	
      Wall thickness	inches
      Upstream distance	inches	No. of diameters
      Downstream distance	inches	No. of diameters
      Size of test port(s)
      Size of access area for test personnel and equipment	
      Hazards	Ambient temp	°F

      B.  Properties of Gas Stream
      Temperature	°C	°F,     Data source	
      Velocity	,     Data source	
      Static pressure	inches H2O,       Data source	
      Moisture content	%,     Data source	
      Paniculate content            ,       Data source
      Gaseous components
      N2 _  % Hydrocarbons (ppm)       Toxics/ Acids (ppm)
      CO _   % _         HQ
                     %                          HF
      SO, _  % _         Other
      C. Sampling Considerations
      Sampling and analytical procedures to be used - attach procedures
      Specific procedures - use check lists presented with Methods
      (i.e., Method 18, Chapter 4; Method 21, Chapter 5; Method 25, Chapter 6
      and Method 25A, Chapter 7)
      Location to set up GC (when applicable)	
                             Figure 3.1.  (Continued)
                                                                            3-17

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       Special hazards to be considered^
      Power available at duct
      Power available for GC (when applicable)
      Potential problems	
      Specific safety equipment (glasses, hard hats, shoes, etc.)
      D. Other Sampling Considerations
      Fugitive emissions: how determined
      How controlled
      Attach copy of method to determine fugitive emissions if present
      Estimated precision and accuracy of method	
      Screening methods to be conducted by agency	
      Hood capture efficiency: how determined
      Attach copy of method to determine hood capture efficiency
      Estimated precision and accuracy of method	
      Screening methods to be conducted by agency	
      Parameters to show continuing compliance with capture efficiency
      Interval of recording parameter for test	
      Are test parameters to be recorded in future and kept on file?
      Transfer efficiency: how determined
      Attach a copy of method to determine transfer efficiency.
      Estimated precision and accuracy of method	
      Screening methods to be .conducted by agency	
      Parameters to show continuing compliance with transfer efficiency
      Interval of recording parameter for test	
      Are test parameters to be recorded in future and kept on file?

      E.  Site Diagrams (attach additional sheets if required)

      F.  Quality Assurance Performance Audit Samples
      Quality assurance audit samples taken?	
      Audit samples: proper compound	
proper range(s)
                              Figure 3.1.  (Continued)
                                                                                          4
348

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      G.  Emission Measurement Screening Techniques
      Detector tubes or other screening techniques used_
      Screening technique conducted: prior to testing
      during testing	between testing	
      Remarks
                             Figure 3.1. (Concluded)
Note: Some of the information in Figure 3.1 may be presented in tabular format, if
      desired.
                                                                             349

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                                  CHAPTER 4
       MEASUREMENT OF GASEOUS ORGANIC COMPOUND EMISSIONS
                  BY GAS CHROMATOGRAPHY ~ METHOD 18

4.1   APPLICABILITY

      Method 18 as promulgated on October 8, 1983 and revised on February 19,1987
is a generic method which is structured to analyze approximately 90 percent of the total
gaseous organics emitted from an industrial source.  This method is used to measure
known organics that are in excess of 1 part per million by volume.  It does not include
techniques to identify and measure trace amounts (less than 1 ppm) of organic
compounds, such as those found in building air and  fugitive emission sources. Also, this
method will not determine compounds that (1) are polymeric (high molecular weight
compounds such as dioxins and furans), (2) polymerize before analysis (such as glues or
resins), or (3) have very low vapor pressures at stack or instrument conditions (such as
anilines).

4.2   METHOD DESCRIPTION
      i
      Method 18 is based on extracting a gas sample from the stack at a rate
proportional to the stack gas velocity using one of four techniques: (1) withdrawing the
gases directly from the stack into the analyzer (direct interface sampling), (2) collecting
gases in a container (integrated bag sampling), (3) dilution interface sampling, or (4)
collecting gases on a sorbent tube (adsorption tube sampling). The major gaseous
organic components of a gas mixture are then separated by gas chromatography, and
measured with a suitable detector.

      For the first three techniques,  the sample or diluted sample is introduced directly
into the sample loop of the gas chromatograph (GC). The measured sample is then
carried into the GC column with a carrier gas where the organic compounds are
separated. The organic compounds are each quantified by a GC detector such as a
flame ionization, photoionization, or electron capture detector. The qualitative analysis
is made by comparing the retention times (from  injection to detection) of known
calibration standards to the retention times of the sample components. The quantitative
analysis is made by comparing the detector response for the sample compound to a
known quantity of that compound in a corresponding standard. Gas samples collected
on adsorption tubes are desorbed from the adsorption media using a solvent.  A
measured volume of the desorption solution is injected into a heated injection port
where the mixture is vaporized and carried into the  GC column with a carrier gas.  The
sample is separated into the individual components,  then qualitatively and quantatively
analyzed in the same manner as a gas sample.

      Gas samples are analyzed immediately as taken from the stack or within a set
period of time after being collected in a container or on an adsorption tube. To select


                                                                             4-1

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 the correct GC column and establish proper GC analytical conditions, the analyst must
 identify approximate concentrations of organic compounds to be measured beforehand.
 With this information, the analyst can then prepare or purchase commercially available
 standard mixtures to calibrate the GC under physical conditions identical to those that
 are used for the samples. The analyst must also have prior information concerning
 interferences arising from other compounds present in the emissions, the need for
 sample dilution to avoid detector saturation, gas stream filtration to eliminate particulate
 matter, and prevention of sample loss due to moisture condensation in the sampling
 apparatus.

 43    PRECISION, ACCURACY, AND LIMIT OF DETECTION OF THE METHOD

       Precision of analytical procedures is quantified based on duplicate sample
 analysis.* All EPA's Method 18 evaluation studies have demonstrated a relative standard
 deviation of less than 5 percent for the analytical precision which is required by
 Method 18.

       Accuracy of sampling and analysis is quantified based on the required analysis of
 two audit gas cylinders obtained through the EPA's audit sample repository.  Field
 validations of Method 18 conducted by EPA and numerous compliance test audits have
 demonstrated, that when proper procedures and checks are conducted, Method 18 is
 accurate within 10 percent of the true value (as required by the method).

       The limit of detection, of Method 18 is typically about 1 part per million by
 volume (ppmv) for most organic compounds. The actual limit of detection will vary for
 each organic compound and type of detector and is defined as the minimum detectable
 concentration of that compound, or the concentration that produces a signal-to-noise
 ratio of 3:1.

 4.4    MEASUREMENT AND LOCATION OF SAMPLING POINTS

       The agency representative must determine if the final results need to be presented
 on a concentration basis or a mass emission basis. For data presentation on a
 concentration basis,  only the concentrations of the specified organics and the  stack gas
 moisture content must be measured.  If the mass emission rate of any compound is to be
 presented, the flow rate of the stack gas must also be determined using the velocity
 traverse.  The number and locations velocity  traverse points are selected according to
 Method 1; the traverse is conducted according to Methods 2, 2A, 2C, or 2D, as
 applicable. Although Method 18 requires sampling at a single point, it may be necessary
 to perform a velocity traverse to obtain the emission data in the units of the standard.

       Method 18 requires that samples are collected proportionally, meaning that the
sampling rate must be kept proportional to the stack gas velocity at the sampling point
during the sampling period.  If the process has a steady state flow (constant),  then the
4-2

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flow rate does not have to be varied during sampling.  The majority of sources of organic
emissions are of this type because they use constant rate fans. If the testing firm can
confirm that the emission source of interest has a steady state flow (e.g., it uses a
constant rate fan), then sampling can be conducted at a constant rate and no concurrent
velocity measurements need to be made.  If it cannot be determined whether the process
is steady state, .then velocity measurements (based on the velocity head, AP) must be
made at the point to be sampled. The average velocity head (phot reading, AP) and
range of fluctuation is determined and then utilized to establish the proper flow rate
settings during sampling.

4.5    OBSERVATION PROCEDURES FOR METHOD 18 TESTING

       As previously mentioned, one of the primary concerns for any organic sampling
program must be safety. It is beyond the scope of this manual to discuss safety aspects
of organic sampling and analysis. However, it cannot be over-emphasized that the test
coordinator must always be aware of the safety hazards.  The major two hazards  are
explosion and health effects.  For all source performance tests, there may be hazards in
gaining access to the test location and in moving about the facility to complete the
required activities in observing the tests.

4.5.1   Selection of Proper Sampling and Analytical Technique
                                                                  • -t
       Because of the number of different combinations of sampling procedures,  sample
preparation procedures, calibration  procedures, GC column packing materials, GC
operating conditions, and GC detectors covered under this method, a set of tables has
been developed to assist the tester in selecting (and the test coordinator in  evaluating)
acceptable sampling and analytical techniques. The organic compounds included in
these tables were selected based on their current status as either presently regulated or
being evaluated for future regulation by the EPA and State and  local agencies. Table
C-l, page C-2, provides the user with the following information for the selected
compounds: (1) the International Union of Pure and Applied Chemistry (IUPAC) name,
any synonyms,  the chemical formula, the Chemical  Abstracts Service (CAS) number; (2)
method, classification and  corresponding references for more information; and (3)
information on whether EPA currently has an audit cylinder for  this compound.  Also,
detailed discussions on how to select the proper sampling and analytical techniques are
presented in Appendix C.

4.52   Preliminary Measurements and Setup

       Method 18 recommends that a pretest survey and/or laboratory evaluation be
conducted by the testing firm prior to sampling and analysis. The pretest survey
measurements are needed to properly design the emission test protocol.  The primary
objective of the preliminary survey is to collect a pretest survey sample for
(1) determining which sampling procedure is most appropriate and (2) optimizing the

                                                                              4-3

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 analytical procedures.  Using the pretest survey sample, estimates of the emission
 concentration(s) are made and the organic compounds in the gas stream are identified.
 Also, any compounds that may interfere with the quantification of the target analyte(s)
 are identified and appropriate modifications can be made to the analytical procedures.

       Table C-l, page C-2, provides data on availability and ranges of EPA audit gases
 for the target organic compounds.  Further information can be obtained by contacting
 EPA.

       For audit gases obtained from a commercial gas manufacturer, check that the
 manufacturer has (1) certified the gas in a manner similar to the procedure described in
 40 CFR Part 61, Appendix B, Method 106, Section 5.2.3.1 and (2) obtained an
 independent analysis of the audit cylinder that verifies  that the audit gas concentration is
 within 5; percent of the manufacturer's stated concentration.

 4.53   Observation of On-site Testing

       The on-site observation techniques and reference tables provided in Appendix C
 should assist the test coordinator in determining if the  testing firm has selected an
 acceptable sampling and analysis technique. Data quality should be enhanced if the
 testing firm conducts the recommended quality assurance/control checks and procedures
 provided in this chapter and Appendix C. At some facilities, the testing firm may need
 to use two or more sampling trains (different sampling techniques) to accurately measure
 all the organic compounds of interest.

       Because of the large number of approaches to the three different sampling
 techniques (container sampling, adsorption tube sampling, and direct interface sampling),
 only the most commonly used (evaluated  container or Tedlar bag sampling) is discussed
 in this chapter. The  other sampling approaches are addressed in Appendix C in the
 locations shown below. The test coordinator can use listing below to locate and review
 the sampling approach of interest.
Chapter,,.    Sampling Approaches
4.5.3
   A
   B
   C
   D
   E
   F
   G
Evacuated Container Sampling
Sampling System Preparation
Proportional Sampling
Indirect Pumping Bag Sampling
Sample Recovery and Transport to Laboratory
Common Problems
Stability Check
Retention Check
Page

  4-5
  4-6
  4-6
  4-7
  4-9
  4-9
  4-9
  4-9
4-4

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Appendix    Sampling Procedures                                             Page

C2.1        Evacuated Container Sampling (heated and unheated)               C-15
   H        Direct Pumping Bag Sampling                                    C-22
   I         Explosion Risk Area Bag Sampling                                C-23
   J         Prefilled Bag Sampling                                           C-23
   K        Heated Syringe  Sampling                                         C-26
C22        Direct Interface Sampling                                        C-27
C23        Dilution Interface Sampling                                       C-30
C2A        Adsorption Tube Sampling                                       C-32

      Evacuated Container Sampling (Heated and Unheated) - In this sampling
technique, sample bags are filled by evacuating rigid air-tight containers that hold them.
The suitability of the bags for sampling is confirmed by permeation and retention checks
using the specific organic compounds of interest during the pretest survey
operations. The permeation and retention checks (discussed later) must be performed
on the field samples to ensure that the container sampling technique is acceptable.

   On-site sampling includes the  following steps:

      1.     Conducting preliminary measurements and setup.             ~
      2.     Preparing and setup of sampling system.
      3.     Preparing of the probe.
      4.     Connecting electrical service and conducting leak check of sampling system.
      5.     Inserting probe into duct and sealing port.
      6.     Purging sampling system.                                   '- -
      7.     Conducting proportional sampling.
      8.     Recording data.
      9.     Recovering sample  and transporting to laboratory.

      The "On-site Checklist" (Figure C.2, page C-17) includes checks for each  of the
steps above and can be used by the test coordinator as an instructional guide. To assist
the test  coordinator, the most critical  items are printed in bold lettering.

      It is the responsibility of the testing firm to ensure that the sampling and
analytical procedures are performed correctly. The following detailed information is
given only as training guide for the less experienced test coordinator  and does not imply
mandatory actions by the test coordinator except when the discussions state that the test
coordinator "shall" conduct a given procedure.

      Method 18 requires that samples be collected proportionally, meaning that the
sampling rate must be kept proportional to the stack gas velocity at the sampling point
during the sampling period. If the process has a  steady state flow (constant), then the
flow rate does not have to be varied during sampling.  The average velocity head (pitot

                                                                              4-5

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reading) and range of fluctuation is determined and then utilized to establish the proper
flow rate settings during sampling.  If it is found that the process is not steady state, then
the velocity head must be monitored during sampling to maintain a constant proportion
between the sample flow rate and the flow rate in the duct.

       A total sampling time greater than or equal to the minimum total sampling time
specified in the applicable emission standard must be selected. The number of minutes
between readings while sampling should be recorded as an integer. It is desirable for the
time between readings to be such that the flow rate does not change more than 20
percent during this period.

       If the sampling system must be heated during sample collection and analysis, the
system temperature should not decrease below the specified temperature. The average
stack temperature is used as the reference temperature for initial heating of the system
and should be determined.  Then, the stack temperature at the sampling point is
measured and recorded during sampling to adjust the heating system just above the stack
temperature or above the dew point. The use of a heated sampling system requires on-
site analysis.

      A. Sampling System Preparation - The test coordinator should observe the
preparation of the probe  and sampling train in the laboratory area (&ee~Figure 4.1, page
4-16).  The sampling apparatus must meet the following criteria (on-site measurements
checklist, Figure C.2, page C-17):

       1.     The probe must be constructed of stainless steel, glass or Teflon.
      2.     All connections must be either stainless steel or Teflon.
      3.     The probe, if required, must be capable of keeping the stack gases at or
             just above the stack temperature.
      4.     The sample line must be Teflon.
      5.     The sample bags must be Tedlar or Teflon, leak checked and blank
             checked.
      6;     A permeation check and retention  check should have been conducted prior
             to testing.  If these checks have not been made, then they should be
             conducted on the field samples.
      7.     The flowmeter must be calibrated,  be in the proper range, and heated, if
             applicable.
      8.     If located between the probe and bag, the pump must be of the Teflon
             coated diaphragm  type and heated, if applicable. If the pump is after the
             rigid container, it may be any type of pump that provides the proper flow
             rate.
      9.     If a dilution system is used and the probe must be heated,  the dilution
             system must be in  a heated box.
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       B. Proportional Sampling - Sampling must be conducted at a rate in constant
proportion to the stack gas flow at the sampling point Thus, for a steady state operation,
the sampling flow rate is not varied during the run. For a nonsteady state process, the
sampling flow rate is varied in proportion to the changing velocity.  The velocity is
monitored by measuring the velocity head (AP) which is linearly related to the square of
the velocity. A recommended method for determining proportional sampling rates is as
follows:

       1.     Conduct a single point velocity check as previously specified, and deter-
             mine the average velocity head  (AP^g) to be sampled.
       2.     The average sampling flow rate for the test is .determined prior to the start
             of the run.  Typically, the average sampling flow rate  is about  0.5 1/min
             yielding approximately 30 liters of sample. The flow rate chosen in the
             laboratory should fill the bag to about three-fourths of its capacity during
             the  sample run.  The average flow rate chosen is then assigned to the
             average velocity head measured.
       3.     The flow rate to be used during sampling when the velocity head varies
             from the average is calculated using the following equation.

                         AP*                                         Equation 4-1
      where:
             Qm    =  Average sampling rate, 1/min (r^/min),
             Qs    =  Calculated sampling rate, 1/min (rrYmin),
             AP    =  Actual velocity head, mm (in.) H2O, and
                   =  Average velocity head, mm (in.) H2O.
      4.     Determine the rotameter setting for the sampling rate (Q5) from the rota-
             meter calibration curve, and adjust the rotameter accordingly.

      C.  Tedlar Bag Sampling Procedures using an Indirect Pumping Technique - Use
of proportional sampling will provide for the correct sampling rate and the proper filling
of the sample bag.  The tester should follow the procedure below to obtain an integrated
sample when the pump is located after a rigid container (Figure 4.1, page 4-16).

      1.     If a-heating system is required, turn on the heating system and set
             container temperature at the average stack temperature determined from
             the pretest measurements.  If probe heating is required, then bag heating
            would also likely be required.
      2.    Leak check the sampling train just prior to sampling by connecting a U-
             tube,  inclined manometer, or equivalent at the probe inlet and pulling a


                                                                              4-7

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       vacuum of a  10 in. H2O. Close the needle valve and then turn the pump
       off. The vacuum should remain stable for at least 30 seconds.  If a leak is
       found, repair  before proceeding; if not, slowly release the vacuum gauge.
       This leak check is optional. The most critical place for a leak is between
       the probe and the bag. Air inleakage into the sample bag will produce low
       results.  If the rigid sample container develops a small leak which only
       effects the pumping rate, this should not cause a significant bias in the
       results.
3.     If the system is being heated, wait for it to come to the proper tempe-
       rature.  Place the probe in the stack at the sampling point: centroid of the
       stack or no closer to the walls than 1 meter.  Seal the sampling port to
       prevent dilution of the stack gas by inleakage of ambient air.  It can be
  *•    important that the port is sealed to prevent  air inleakage. Also, if the
  '•''    system must be heated, a significant loss of organics can result from poor
       heating. It is better to heat the system above than below the specified
       temperature.
4.     Disconnect the flexible bag. Purge the system by turning on the pump and
       drawing at least 5 times the sampling system volume through the train, or
       purge for 10 minutes, whichever is greater.  The system is purged to
       equilibrate and remove ambient air. If the system is not purged, then a
       negative error may be introduced.
5.     Adjust the flow rate to the proper setting based on the velocity pressure
       (measured during the purging, for nonsteady state processes).  Proportional
       sampling should be conducted for nonsteady state systems, but constant
       rate sampling generally will not cause a significant bias unless the
       concentration and flow rate are changing significantly.
6.     Connect the flexible bag to the sampling train (the connections should
       ensure a leakfree system), and begin sampling. The sampling rate must
       remain proportional to the stack gas velocity for the total sampling time
       specified by the applicable standard. Although Method  18 recommends a
       rate of about  1 1pm be used, slower sampling rates and smaller sample
       bags have been shown to be as accurate and precise.
       Record all data required (at 5 minute intervals, minimum) on the field
  H    sampling data form similar to Figure 4.2, page 4-17. The flow rate and
       sampling train heating system should be adjusted after every pitot and
       temperature reading to the correct level.  A shorter sampling time for each
       point is typically used when the flow rate is changing significantly. For
       emission sources with small changes in the flow rate, the sampling time
       per point may be longer.
8.     Disconnect and seal the flexible bag upon completion of sampling. Take
       care not to dilute the contents with ambient air.  Hie bag should be sealed
       well to prevent leakage.
         -
      7.v
4-8

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      9.     Label eacb bag clearly and uniquely to identify it with its corresponding
             data form and/or run.  If the sampling system was heated, the sample bag
             must be maintained at the stack temperature through sample analysis.

      D.  Sample Recovery and Transport to Laboratory - Sample recovery should be
performed so as to prevent contamination of the bag sample and maintain sample
integrity.  The bag should remain leakfree, be protected from direct sunlight, be main-
tained at a temperature that will prevent condensation of any of the gases, and be stored
in a safe place to prevent damage or tampering prior to analysis.  It is recommended
that bag samples be analyzed within two hours of sample collection; however, many of
the organic compounds are  stable enough to allow a few days prior to analysis. Upon
completion of the testing and sample recovery, all the data forms should be checked for
completeness and the sample bags re-examined for proper identification. It is important
to check the bags for problems with  permeation and retention of the sample.

      E.  Common Problems - The most common problems encountered with bag
sampling techniques are (1) adsorption of the gases on the bag, (2) permeation of the
gases through the bag, (3) reaction of gases in the bag, (4) condensation of the gases or
water vapor  in the  bag, and (5) leaks developing in the bag during testing, transport,
and/or analysis. The bags must be checked for stability and retention of the target
compound.

      F.  Stability Check - To assess the stability of the gas sample in Tedlar bagSj
perform a second analysis after a time period equalling the period between sample
collection and the first analysis.  If the concentration of the sample collected in a Tedlar
bag decreases by more than 10 percent between the first and second analyses, then an
accepted sampling method other than Tedlar bags should be considered.

      G.  Retention Check - Perform a retention check on the bag sample by
successively evacuating the bag and refilling it with hydrocarbon-free air or nitrogen one
or more times.  Analyze the bag contents for the target compound(s), then allow the gas
to sit  in the bag overnight and reanalyze bag contents for the target compound(s). If any
target compound is detected in the bag at a concentration greater than 5 percent of the
original concentration, then an accepted sampling method other than Tedlar bags
should be considered.

      One technique that can be used to reduce both retention and/or condensation in
the bag is addition of a heating system.  Heating is generally applied during sample
collection and maintained through analysis.  However, heating may increase the
permeation rate. Another option is the use of heat lamps applied to the sample bags
after sample collection and during sample analysis. Two other techniques that have been
used to prevent condensation are (1) addition of a knockout trap to remove water vapor
and heavy organics from the sample  stream, and (2) use of sorbents such as Tenax to
remove the high boiling point organics.  In these cases, the testing firm must demonstrate


                                                                              4-9

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 that the organic compound(s) of interest are not removed. Alternatively, sample and/or
 water vapor condensation may be reduced by the use of the prefilled bag technique.  The
 prefilling  of the bag lowers the concentrations of the organic and/or water vapor, thereby
 eliminating condensation.

       If gases are reacting in the bag, then the bag material can be changed, the time
 between sample collection and analysis reduced, or a different sampling technique used
 such as direct interface sampling. Methods to reduce bag leak problems are proper
 construction of the sample bags, conducting additional runs, using a backup sample
 collection technique such as an another  bag sampling system or an adsorption tube
 sampling  system, and care in handling the sampling bags.  Also, steel canisters can be
 used in place of bags. If the organic compounds are stable with time, the use of steel
 canistersjmay improve preservation of the samples especially if they must be air freighted
 to the laboratory for analysis.          ;

 4.6    OBSERVATION PROCEDURES FOR METHOD 18 ANALYSIS

       Unless it is conducted on-site, the test coordinator will not typically have an
 opportunity to observe the analysis. The test coordinator should therefore check the
 data and other documentation in the compliance test report for:

       1.     Audit sample results within 10 percent of true value (see Chapter 4.7 for
             more details).
       2.     Proper preparation of calibration standards.
      . 3.     Proper resolution of compounds.
       4.     Additional unidentified peaks.
       5.     Proper analytical precision.
       6.     Acceptable collection efficiency for adsorption tube sampling.
       7.     Acceptable desorption efficiency for adsorption tube sampling.
       8.     Proper calculation of analytical data results.

       A:test coordinator's postsampling operations checklist (Figure CIO, page C-37) is
provided; to assist in the review of the procedures for on-site analysis and the compliance
test report for off-site analysis.

4.6.1   Preparation of Calibration Standards

       Calibration standards are prepared prior to sample  analysis following the
procedures described in the following chapters.  Refer to Table C-4, page C-8, for
recommendations on the  procedures suitable for selected compounds.  Note that there
are two basic types of standards, gaseous or liquid; the type prepared depends on the
type  of sample collected.  Gaseous calibration standards are needed for analysis of
pretest survey samples collected in glass  flasks or bags, and final  samples collected in
bags, by direct, or by dilution interface sampling. There are three techniques for
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preparing gaseous standards, depending on availability and the chemical characteristics
of the standard compound(s); gas cylinder standards may also be used directly, if the
proper concentration ranges are available.  Liquid calibration standards are required for
the analysis of adsorption tube samples from the pretest survey and/or the final
sampling, as well as to determine the desorption efficiency; there are two techniques for
preparing liquid calibration standards. The concentrations of the calibration standards
should bracket the expected concentrations of the target compound(s) in the emissions
being sampled.  Specific procedures for preparing and analyzing each type of standard
are described in Appendix C.3.

4.6.2  Sample Analysis

      After the GC has been calibrated and the analysis of the audit sample(s) has been
conducted successfully, the samples are analyzed. The following are the key procedures
used to analyze emission samples collected in Tedlar bags using a GC calibrated with
gaseous calibration standards.  The analytical procedures for adsorption  tube sampling
and direct interface sampling are presented in Appendix C.3.

      1.     Note the time of injection on the strip chart recorder and/or actuate the
             electronic integrator. Record the sample identity, detector attenuation
             factor, chart speed, sample loop temperature, column temperature and
             identity, and the carrier gas type and flow rate on a data form. It is also
             recommended that the same information be recorded directly on the
             chromatogram and on an analytical data sheet similar to Figure 4.3, page
             4-18.  Record the operating parameters  for the particular detector being
             used.
      2.     Examine the chromatogram to  ensure that adequate resolution is being
             achieved for the major components of the sample.  If adequate resolution
             is not being achieved, vary the  GC conditions until resolution is achieved,
             and reanalyze the standards to recalibrate the GC at the new conditions.
      3.     After conducting the analysis with acceptable peak resolution, determine
             the retention time of the sample components and compare them to the
             retention times for the standard compounds. To qualitatively identify an
             individual sample component as a target compound, the retention time for
             the component must match within 0.5 seconds or 1 percent, whichever is
             greater,  of the retention time of the target compound determined with the
             calibration standards.
      4.     Repeat injection of the first sample until the area counts for each
             identified target compound from two consecutive injections are within
             5 percent of their average.
      5.     Multiply the average area count of the consecutive injections by the attenu-
             ation factor to get the area value for that sample, and record the area
             value on the data form.
                                                                              4-11

-------
       6.     Immediately following the analysis of the last sample, reanalyze the cali-
              bration- standards, and compare the area values for each standard to the
              corresponding area values from the first calibration analysis.  If the
              individual area values are within 5 percent of their mean value, use the
              mean values to generate  a final calibration curve for determining the
              sample concentrations. If the individual values are not within 5 percent of
              their mean values, generate a calibration curve using the results of the
              second analysis of the calibration standards,  and report the sample results
              compared to both standard curves.

       Determine the bag sample moisture content by measuring the temperature and
 the barometric pressure near the bag. Use water saturation vapor pressure chart, assum-
 ing the .relative humidity of the bag to  be 100 percent unless a lower value is known, to
 determine the water vapor content as a decimal figure (percent divided by 100). If the
 bag has been heated during sampling and analysis, the flue gas or duct moisture content
 should be determined using Method 4.

 4.7   USE OF AUDIT MATERIALS AND INTERPRETATION OF DATA

       An audit is an independent assessment of data quality. Based on the
 requirements of Method 18 and the results of collaborative testing of other EPA
 Methods, two specific performance audits are recommended:

       1.     An audit of the sampling and analysis procedures of Method 18 is required
              under NSPS and recommended for other purposes.
       2.     An audit of the data processing is recommended.

       A systems audit may be conducted by the test coordinator in addition to these
 performance audits.  Performance audits are described in detail in Chapter 4.7.1 and the
 systems  audit is explained in Chapter 4.7.2.

 4.7.1  Performance Audits
         r , •
        -* -
       Performance audits are conducted to evaluate quantitatively the quality of data
. produced by the total measurement system (sample collection, sample analysis,  and data
 processing).  It is required that cylinder gas performance audits be performed once
 during every NSPS compliance test utilizing Method 18, and it is recommended that a
 cylinder gas audit be performed once during any compliance test utilizing Method 18
 conducted under regulations other than NSPS.

       Performance Audit of the Field Test - As stated in Section 6.5 of 40 CFR 60,
 Appendix A, Method 18, immediately after the preparation of the calibration curves and
 prior to  the sample analysis, the analysis audit described in 40 CFR 61, Appendix C,
 Procedure 2: "Procedure for Field Auditing GC Analysis," should be performed. The
 4-12

-------
information required to document the analysis of the audit sample(s) has been included
on the example data sheet shown in Figure 4.4, page 4-19. The audit analyses shall
agree within 10 percent (or other specified value, as explained below) of the true values.
The test coordinator may obtain audit cylinders by contacting: U.S. Environmental
Protection Agency, Atmospheric Research and Exposure Assessment Laboratory, Quality
Assurance and Technical Support Division, Research Triangle Park, North Carolina
27711.  Audit cylinders obtained from a commercial gas manufacturer may be used
provided that (1) the gas manufacturer certifies the audit cylinder in a manner similar to
the procedure described in 40 CFR 61, Appendix B, Method 106, Section 5.2.3.1, and
(2) the gas manufacturer obtains an independent analysis.  Independent analysis is
defined as an analysis performed by an individual other than the individual who performs
the gas manufacturer's analysis, using calibration standards and analysis equipment dif-
ferent from those used for the gas manufacturer's analysis. Verification is completed and
acceptable when the independent analysis concentration is within 5 percent of die gas
manufacturer's concentration.

      Responsibilities of the Test Coordinator - The primary responsibilities of the test
coordinator are to ensure that the proper audit gas cylinder(s) are ordered and safe-
guarded, and to interpret the results obtained by the analyst.

      When auditing sampling systems that do not dilute the stack gas during sampling,
the audit gases ordered must consist of the same organic compound(s) that are being
measured; for emission standards on a concentration basis, the audit gas concentration^)
must be in the range of 25 percent to 250 percent of the applicable standard. The audit
should include analysis of two concentration levels. If two cylinders are not available,
then one cylinder can be used.  It is strongly recommended that audit cylinder values
below 5 ppm not be used.  For emission standards which specify a control efficiency, the
concentration of the  audit gases should be in the range of 25 percent to 250 percent  of
the expected stack gas concentration.  The audit should include analysis of two
concentration levels.  If two cylinders are not available, the audit can be conducted using
one cylinder.

      The test coordinator must ensure that the audit gas cylinder(s) are shipped to the
correct address, and to prevent vandalism, verify that they are stored in a safe location
both before and  after the  audit.  Audit cylinders should not be analyzed when their
pressure drops below 200 psi  because the cylinder gas value may be unreliable.

      The audit results must agree within 10 percent of the stated audit cylinder value
or true value. Agreement within 15 percent is allowed  for cylinders between 5 and
20 ppm. When the measured value agrees within these limits, the test coordinator
directs the analyst to begin analyzing the field samples. For on-site analysis, when the
measured concentration does not agree, the analyst should first recheck the analytical
system and calculations, and then repeat the audit.  When the results of the repeat audit
are within the limits, the analyst may conduct the field sample analysis.  If the analyst


                                                                               4-13

-------
li
 fails the second audit, the agency may reject the compliance test results. Method 18
 states "Audit supervisor judgement and/or supervisor policy determine action when
 agreement in not within ± 10 percent."  "When a consistent bias in excess of 10 percent is
 found, it may be possible to proceed with the sample analysis, with a corrective factor to
 be applied to the results at a later time."  The test coordinator should therefore know
 the policy of the agency related to audit failure.

       During the audit, the test coordinator should record the appropriate cylinder
 number(s), cylinder pressure(s) (at the end of the audit), and the calculated concen-
 trations on the "Field audit report form,11 Figure 4.4, page 4-19.  The individual being
 audited must not, under any circumstances, be told the actual audit concentrations) until
 the calculated concentration(s) have been submitted to the test coordinator and are
 considered acceptable.

       When auditing sampling systems that dilute the emissions during collection, the
 audit gas concentration value used in  the calculations can either be based on (1) the
 undiluted concentration using the criteria discussed above or (2) the expected
 concentration of the gases following dilution during collection using the same dilution
 factor as used for the emission samples.

       The audit procedures that follow are used for the evacuated container sampling
 approach with either on-site or off-site analysis. Auditing procedures for the other
 sampling techniques are presented in  Appendix C according to the sampling approach
 used to collect the organic emissions and whether the samples are analyzed on-site or
 off-site.

       Container (Bag, Syringe, and Canister) Sampling with On-site Analysis - The
 cylinder gas performance audit for bag,  syringe, or canister sampling with on-site  analysis
is conducted on-site just prior to the analysis of the field samples. The recommended
procedures for conducting the audit are:

       1: -    The audit samples should  be collected in the type of container used during
        *»   sample collection.  However, to conserve audit gas, it is usually not
        V   necessary to involve the  rest of the sampling system in audit sample
             collection for unheated container sampling. Problems related to the
             reaction or retention of  the organic compounds will occur in the container.
             Interferents in the stack gas such as water vapor and other organics are not
             present in the audit cylinders and thus, related problems are not assessed
             by the audit. For heated container systems, it may be necessary to use the
             whole sampling system to collect the audit gas. However, if a gas must be
             heated to prevent its condensation in the sampling system, it is likely that
             audit gas cylinders are not available for this compound or level of
             compound.
           4-14

-------
       2.     Prior to analysis, the audit samples should remain in the appropriate
             container approximately the same length of time as the field samples.
             After the preparation of the calibration curve, a minimum of two
             consecutive analyses of each audit cylinder gas should be conducted. The
             analyses must agree within 5 percent of the average.  The audit results
             should be calculated by the analyst (or his representative) and given to the
             test coordinator. The test coordinator will record all the information and
             data on the "Field  Audit Report Form" and then inform the analyst of the
             status of the audit.  The equations for calculation of error are  included on
             the form.

       Container (Bag and Canister) Sampling with Off-site Analysis - For cylinder gas
performance audits associated with container samples analyzed off-site, it is
recommended that the audit be conducted off-site just prior to the compliance test (if
the agency desires) and then repeated during the off-site sample analysis  as a quality
control measure. The  use of the pretest audit will help ensure that the analytical system
will be acceptable  prior to testing. Alternatively, the audit gases can be collected in the
appropriate containers on-site or off-site, and then analyzed just prior to the field sam-
ples analysis. It is recommended that the tester fill at least two containers with the audit
gas to guard against a container  leak causing a failed  audit.  Since the use of the
performance audit is to both assess and improve the data quality, the use of .the pretest
audit will provide the tester/analyst with a better chance of obtaining acceptable data.
The recommended procedure for conducting the audit is the same as described above for
the on-site audit with the exception that the test coordinator will likely not be present
and the data will have  to be reported by telephone.

       Performance Audit of Data Processing - Calculation errors  are prevalent in
processing data. Data processing errors can be determined by auditing the recorded data
on the field and laboratory forms.  The original and audit (check) calculations should
agree within round-off error; if not, all of the remaining data should be checked.  The
data processing may also be audited by providing the  testing laboratory with specific data
sets (exactly as would appear in the field), and by requesting that the data calculation be
completed and that the results be returned to the agency.  This audit is useful in
checking both computer programs and manual methods of data processing.

4.72   Systems Audit

       A systems audit involves checking to ensure that the proper equipment and
procedures are used. The observation of the sampling and analytical procedures by the
test coordinator described in Chapters 4.5 and 4.6 constitutes a systems audit for Method
18.  The systems audit results may be recorded on the sampling and analytical checklists
referenced in Chapters 4.5 and 4.6.
                                                                               4-15

-------
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                                                                                                           4-17

-------
Date: 	
Location:
                  Analyst:
Type of Calibration Standard: 	
Number of Standards: 	  Date Prepared:
                                      	  Plant:
                                       Sample Type:
                                                                                      1
                                             Target Compound:
                                                     Prepared By:
                            Column Used:
GC Used: 	
Carrier Gas Used: ___	
Column Temperatures, Initial: ___^__  	
Sample Loop Volume: 	  Loop Temperature:
Detector Temp.: 	  Auxiliary Gases:
                                 Carrier Gas Flow Rate:
                                       Program Rate:
                                                               Final:
                                                  Inject. Port Temp.
Calibration Data                    Standard 1
 First analysis/second analysis
   Standard concentration (C^,)      	
   Flow rate through loop(ml/min)        /	
   Liquid injection volume (tubes)       /	
   Injection time (24-hr clock)      	
   Chart- speed (cm/min)                  /	
   Detector attenuation                  /	
   Peak retention time (min)             I	
   Peak 'retention time range  (min)   	
   Peak area                            /	
   Peak area x attenuation factor        /	
  Average peak area value (Y)       	
   Percent deviation from average    	
   Calculated concentration (CM)    	
   %  deviation from actual (%DM)    	
                                                   Standard 2
                                                                  standard 3
   Linear regression equation; slope (m):
                                                   y-intercept
Sample Analysis Data
   First analysis/second analysis
   Sample identification
   Interface dilution factor
   Flow rate through loop  (ml/min)
   Liquid injection volume (tubes)
   Injection time (24-hr clock)
   Chart speed (cm/min)
   Detector attenuation
   Peak retention time
   Peak retention time range
   Peak area
   Peak.area x atten.  factor
                                     Samle 1
                                                    Sample 2
                                                                  Sample 3
% deviation from average
Calculated concentration
c«d

or C, -
(Y - b)
m
(%D,
(C.)

-J


At - Y
Y
Xi no*: *n — ... ,. V i nni

           Figure 43.  Data form for analysis of Method 18 field samples.
4-18

-------
  Part A. - To be  filled out using information from organization
supplying audit cylinders.

  1. Organization  supplying audit sample(s)  and shipping address

  2. Audit supervisor,  organization,  and phone number

  3. Shipping instructions:  Name,  Address,  Attention

  4. Guaranteed arrival date for  cylinders  - 	
  5. Planned shipping date  for cylinders -
  6. Details on audit cylinders  from last analysis

a. Date of last analysis 	


d. Audit gas (es) /balance gas*
e. Audit gas(es) > ppm 	
f. Cylinder construction 	

Low cone.







High cone.







Part B. - To be filled  out  for  audit analysis.
1. Process sampled 	
2. Audit location 	
3
4,            	
5. Audit Results:
Name of individual audit
Audit date 	




d. Measured concentration, ppm
e. Actual audit concentration, ppm "
f . Audit accuracy : *

Percent accuracy* =
Measured Cone. - Actual Cone, x 100
Actual Cone.

Low
cylinder









High
cylinder









^Results of two consecutive injections that meet the criteria.

                    Figure 4.4. Field audit report form.
                                                               4-19

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                                   CHAPTERS
                   DETERMINATION OF VOLATILE ORGANIC
                       COMPOUND LEAKS - METHOD 21*

5.1    APPLICABILITY

       Method 21 applies to the determination of volatile organic compound (VOC)
leaks from process equipment that is in VOC service. In VOC service includes any
fugitive emission source that contains or contacts a fluid composed of equal to or greater
than 10 percent VOC by weight.  For the benzene fugitive emission regulation, in
benzene service includes any source that contains or contacts a fluid equal to or greater
than 10 percent benzene by weight.

       VOC service can further be divided into light liquid or heavy liquid service. Light
liquid VOC service is defined as one or more of the stream components having a vapor
pressure greater than 0.3 Kpa (0.04 psia) at 20° (68°F). All VOC sources with a  stream
component vapor pressure equal to or less than 0.3 Kpa at 20°C are in heavy liquid
service. The NSPS (New Source Performance Standard)  for "Refinery Leaks" defines
heavy liquid as kerosene or heavier liquid.

       Leaks are classified as fugitive emissions. Sources of fugitive emissions  include,
but are not limited to, valves, flanges and other connections, pumps and compressors,
pressure relief devices, process drains, open-ended valves, pump and compressor  sealing
systems, degassing vents, accumulator vessel vents, agitator seals, and access door seals.

5.2    METHOD DESCRIPTION

       A portable instrument is used to detect VOC leaks from individual sources.  The
instrument detector type is not specified, but it must meet certain specifications and
performance criteria contained in EPA Method 21, Section 3. This procedure  is
intended to locate and classify leaks only, and is not to be used as a direct measure of
mass emission rates from individual sources.

5.2.1   Regulations  and Leak Definition

       Industries that emit fugitive VOCs and are affected by federal regulations  are
shown in Table 5-1. The sources of fugitive emissions, methods by which emissions are
detected and repaired, and control procedures are very similar for each of these
industries.
"The majority of this Chapter is taken directly from EPA-340/1-86-015, "Portable
Instruments User's Manual for Monitoring VOC Sources." To reduce the references to
the cited manual, reference markings have been left out.

                                                                            5-1

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        TABLE 5-1. SOURCE CATEGORIES THAT EMIT FUGITIVE VOCs
Source Category
Type of Control Guidance*
Petroleum refineries
Synthetic organic chemicals
  manufacturing industry
Polymers and resin manufacturing
Natural gas and natural gasoline
  processing plants
Benzene in coke ovens/by-products
  plants
Vinyl-_chloride sources
Benzene fugitive sources
CTG, NSPS

CTG, NSPS
CTG, NSPS

CTG, NSPS

NESHAPs
NESHAPs
NESHAPs
 CTG: Control Technique Guideline
NSPS: New Source Performance Standard
NESHAPs: National Emission Standard for Hazardous Air Pollutants

       A leak definition can be based on either a concentration value or a "no detectable
emissions." The "no detectable emission" standard is applied to sources designed to
operate in a leakless manner, such as pressure-relief devices with rupture or sealless
pumps. The concentration-based value most often used to define a leak is a
concentration equal to or greater than 10,000 ppmv. The "no detectable emission"
standard is not an absolute zero reading. A violation of the "no  detectable emission"
limit is defined in Method 21 as a concentration greater than five percent of the
concentration-based leak definition. For example, based on the  10,000 ppmv definition
of a leak, a concentration greater the 500 ppmv would be in violation of the "no
detectable emission" standard.

522   Portable Instrument Operating Principles

       Various types of instruments are available for detecting organic vapors. These
operate on different principles. Each detector has its own advantages, disadvantages,
and sensitivity.

       In addition to the portable VOC detectors, other portable equipment used during
Method 21 testing includes temperature sensors, flow monitors, and pressure gauges.
This equipment is much smaller, less expensive, and easier to use than the portable VOC
detectors.
5-2

-------
       Several types of portable VOC detectors can be used either as screening tools or
 to meet the requirements of EPA Method 21.  These include:

       *     Flame ionization detector (FID)
       •     Photoionization (ultraviolet) detector (PDD)
       •     Catalytic combustion or hot wire detector
       •     Nondispersive infrared detector (NDIR)

       The specifications of these instruments vary significantly with regard to sensitivity,
 range, and responsiveness. Table 5-2 lists the most common instruments currently in use
 and the associated detection principle, range, sensitivity, and response time.

       Flame Ionization Detector - In an FID, the sample is introduced into a hydrogen
 flame. A concentration of as little as 0.1 ppm of hydrocarbon produces measurable
 ionization, which is a function of the number of carbon ions present. A positively
 charged collector surrounds the flame, and the ion current between the flame and the
 collector is measured electronically.  Pure  hydrogen burning in air produces very little
 ionization, so background effects are essentially masked by the hydrogen flame. The
 calibration output current is read on a panel meter or chart recorder.

       Organic compounds containing nitrogen, oxygen, or halogen atoms give a reduced
 response in a FID when compared to compounds without these atoms.  The FID
 hydrocarbon analyzers  are usually calibrated in terms of a gas such as methane or
 hexane, and the output is  read in parts per million of carbon measured as methane or
 hexane.

       Although nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), and water
vapor (H2O) do not produce significant interferences, condensed water vapor can block
the sample entry tube and cause erratic readings.  Also, when the oxygen (O2)
concentration exceeds 4 percent, it can significantly reduce the detector output.  The
relative response of the FID to various organic compounds, including those with attached
oxygen, chlorine, and nitrogen  atoms, varies from compound to compound.

       Photoionization Detector - In the photoionization detector, ultraviolet light ionizes
a molecule as follows:  R  + hv'> R+ + e", where R* is the ionized species and hv
represents a photon with energy less than or equal to the ionization potential of the
molecule: Generally, all species with an ionization potential less than the ionization
energy of the lamp are detected. Because  the ionization potential of all major
components of air (03, N^ CO, CO& and H2O) is greater than the ionization energy of
the lamps in general use, they are not detected.

      The detector consists of an argon-filled, ultraviolet (UV) light source that emits
photons.  A chamber adjacent to the sensor contains a pair of electrodes.  When a
positive potential is applied to  one electrode, the field that is created drives any ions
formed by the  absorption of UV light to the collector electrode, where the current
(proportional to the concentration) is measured.
                                                                              5-3

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TABLE 5-2.
Instrument
Trade Names
550, 551, 555
(AID, Inc.)
OVA 108, 128
Centuiy'Systems
(Foxboro)
PI - 101
(Hnu Systems,
Inc.)
TLV Sniffer
(Bacharach)
Ecolyzer 400
(Energetics
Science)
Miran 1A
(Foxboro)
PORTABLE
Detection
Principle
FID
FID
pro
Catalytic
combustion
Catayltic
combustion
NDIR
INSTRUMEK
RESPONSE
Range, ppm
0-200
0-2,000
0-10,000
0-10
0-100
0-1,000
0-20
0-200
0-2,000
0-500
0-5,000
0-50,000
0-100%
LEL
ppm to %
ITS RANGE, SENSITIVE
TIME
Sensitivity
0.1 ppm at
0-200 ppm
0.2 ppm (Model 128)
0.5 ppm (Model 108)
1 ppm
2 ppm
1% LEL
1 ppm
Y, AND
Response
Times
5
2
2
5

15
1, 4, 10
and 40*
* Response times for different ranges.
5-4

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       Nondispersive Infrared Detector - Nondispersive infrared (NDIR) spectrometry Is
 a technique based on the broadband absorption characteristics of certain gases. Infrared
 radiation is typically directed through two separate absorption cells: a reference cell and
 a sample cell.  The sealed reference cell  is filled with nonabsorbing gas, such as nitrogen
 or argon. The sample cell is physically identical to the reference cell and receives a
 continuous stream of the gas being analyzed. When a particular hydrocarbon is present,
 the IR absorption is proportional to the molecular concentration of that gas. The
 detector consists of a double chamber separated by an impermeable diaphragm. Radiant
 energy passing through the two absorption cells heats the two portions of the detector
 chamber differentially. The pressure difference causes  the diaphragm between the cells
 in a capacitor to distend  and vary. This variation in capacitance, which is proportional to
 the concentration of the component of gas present, is measured electronically.

       Interferences in NDIR measurements are usually a result of other gases in the
 sample absorbing at the same wavelength as the gas of interest. Efforts to eliminate
 these interferences by use of reference cells or optical filters are only partially successful.
 For hydrocarbon (HC) monitoring, the detector is filled with one or several different
 hydrocarbons, which may be different from the HC contained hi the sample; this causes
 a disproportionate response.  Other sources of errors include gas leaks in the detector
 and reference cells, inaccurate zero and span gases, nonlinear response, and electronic
 drift.

       Catalytic Combustion or Hot Wire Detector - The  heat of combustion of a gas is
 sometimes used for quantitative detection of that gas. Suffering the same limitations as
 thermal conductivity, this method is nonspecific, and satisfactory results depend on
 sampling and measurement conditions.

       One type of thermal combustion cell uses a resistance bridge containing arms that
 are heated filaments. The combustible gas is ignited in a gas cell upon contact with a
 heated filament; the resulting heat release changes the filament resistance, which is
 measured and related to the gas concentration.

       Another combustion method uses catalytic heated filaments or oxidation catalysts.
 Filament temperature change or resistance is measured and related to gas
 concentrations.

       Thermocouple - The temperature sensor most  commonly used is  the direct-
 readout hand-held thermocouple.   The thermocouple is composed of two wires of
 dissimilar metals that are joined at one end.  When the joined end is heated, a voltage
 flow can be observed.  A voltmeter is attached to the thermocouple, and the observed
voltage is proportional to the measured temperature. A portable thermocouple assembly
 consists of a shielded probe, a connecting wire, and a voltmeter. The voltmeter may be
 a temperature conversion unit on  a multimeter or a dedicated direct readout
temperature unit.  The voltmeter is battery-operated, small, and easily portable.


                                                                               5-5

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I
        Static Pressure Gauges - Among the several different available static pressure
 gauges, the most commonly used for this type of field work are the inclined manometer
 and the diaphragm gauge.  A pressure tap is necessary for use of a portable static
 pressure gauge. Hie primary feature of the pressure tap is a small opening in the wall of
 a duct, which can be fitted with a connection and a hose to make pressure
 measurements. The tap should be far enough away from such disturbances as elbows
 and internal obstructions to make the effects of such disturbances negligible.
                                                >   ...        '.
        The appropriate side, positive or negative, of the manometer or pressure gauge is
 connected by a rubber hose at the tap,  and a pressure reading can be taken.  It is often
 advantageous to disconnect a permanent pressure gauge and take a pressure reading at
 that point to  compare it with the facility's instrumentation.

 S3    CALIBRATION PRECISION

        Calibration precision is the degree of agreement between measurements  of the
. same known value. To ensure that the readings obtained are repeatable, a calibration
 precision test must be completed before placing the analyzer in service, and at 3 month
 intervals, or at the next use, whichever is later. The calibration precision must be equal
 to or less than 10 percent of the calibration gas value.

        To perform the calibration precision test, .a total of three test runs are  required.
 Measurements are made by first introducing zero gas and adjusting the analyzer to zero.
 The specified calibration gas (reference) is then introduced and the meter reading is
 recorded.  The average algebraic difference between" the meter reading and the known
 value of the calibration gas is then computed. This average  difference is then divided by
 the known calibration value and multiplied by 100 to express the resulting calibration
 precision in percentages.

 53.1  Calibration of VOC Analyzers

       Calibration requirements for VOC instrumentation are specified in Method 21
 and in  the specific NSPS applicable to sources of fugitive VOC emissions.  The
 requirements  pertaining to calibration are briefly summarized here.
                         The instrument should be calibrated daily.
                         The gas concentrations used for calibration should be close to the leak
                         definition concentration.
                         The calibrant gas should be either methane or hexane.
                         A calibration precision test should be conducted every 3 months.
                         If gas blending is used to prepare gas standards, it should provide a known
                         concentration with an accuracy of ± 2 percent.
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O
O
O
       The daily calibration requirement specified in Method 21 and in the various NSPS
gives individual instrument operators some flexibility. The calibration could consist of a
multipoint calibration in the lab, or it could be a single-point "span-check."

       Neither Method 21 nor the applicable NSPS specifies where the calibration must
•take place.  It is simpler to conduct the calibration in the laboratory than at the facility
being tested; however, there is the possibility that the calibration may shift sufficiently to
affect the accuracy of the leak detection measurements.  The degree of shift has not yet
been documented for the various commercially available instruments.  Because of the
potential for calibration shift, one should consider conducting, at a Tninirnpni, a single-
point span check after the instrument arrives on-site. It is also suggested that a span test
be run at the midpoint of the day and at the conclusion of the field work.

       Although the span checks discussed above would in most cases qualify as the daily
calibrations required by the NSPS, a separate calibration test for organic vapor analyzers
should be conducted whenever possible. Because uniform day-to-day calibration gas
temperatures and calibration gas flow rates-can be  maintained in the laboratory,
calibrations performed in the regulatory agency laboratory are conducted under more
controlled conditions than those conducted in the field. Furthermore,  the initial
calibration test provides an excellent opportunity to confirm that the entire instrument
system is working properly before it is taken in the field.  The laboratory calibration data
should be carefully recorded in the instrument calibration/maintenance notebook. This
calibration should be considered the official calibration required by the regulations.

533   Laboratory Calibrations

      As specified in the EPA-promulgated NSPS, the instruments used in accordance
with Method 21 must be calibrated by using either  methane or hexane at concentrations
that are close to the leak-detection limits.  In most cases, the leak-detection limit is
10,000 ppmv, however, for certain sources, it is 500 ppmv above the background levels.

      Methane-in-air is generally the  preferred calibrant gas for the high concentration
range. A hexane-in-air concentration of 10,000 ppmv should not be prepared because it
is too close to the lower explosive limit. Also, hexane may condense on the calibration
bag surface at this high concentration.  If hexane-in-air calibrations are necessary, the
chosen concentration should reflect a compromise between the need for adequate
calibration of leak detection levels and the practical safety and reproducibility problems
inherent in the use of hexane.  The EPA's position is that the choice of calibrant gas
does not affect the ability of the instruments to detect fugitive leaks.
                                                                                               5-7

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       When charcoal beds are used to provide the VOC-free air, a routine check should
be made to assess breakthrough of organic compounds. This is done by passing a low-
hydrocarbon-concentration gas stream (approximately 10 to 50 ppmv) through the bed
for a period of 5 to 10 minutes.  If the bed has not become saturated, the outlet
hydrocarbon concentration should be low.  Methane should not be used as the
hydrocarbon because charcoal is ineffective in adsorbing methane.

533  Field Span Check Procedure

       The following are some of the various ways to calibrate the portable instrument in
'the field:                          .

       •     Use large pressurized gas cylinders transported to inspection site.
      '"-•'     Use certified gas cylinders provided by the facility being inspected.
      ; •'•'•    Use disposable gas cylinders with the appropriate gas composition and
      """•"••    concentration.
       •     Use a gas sampling cylinder with a gas blending system.

       Transporting large pressurized gas cylinders is generally impractical because most
agencies do not have the necessary vehicles.  It is not safe to transport unsecured,
'pressurized gas cylinders in personal or State-owned cars. Furthermore, there are
specific Department of Transportation (DOT) regulations governing the shipping  of
compressed gases.

       Using the facility's gas  cylinders is certainly the least expensive approach for a
regulatory  agency; however, the  appropriate gas cylinders are not always available. Also,
use of the  facility's cylinders prevents the agency from making a completely independent
assessment of the VOC fugitive  leaks and from evaluating the adequacy of the facility's
leak-detection program.

       Using disposable cylinders of certified calibration gas mixtures is relatively simple
because no on-site blending is necessary and the cylinders are easily transported.  The
calibration gas mixture may be fed to the instrument directly by using a preset regulator
that provides constant gas flow and pressure; or the gas can be fed into a Tedlar or
Teflon bag, from which it is drawn into the portable instrument

       A fourth  approach involves the use of a stainless steel gas sample cylinder  with a
small Tedlar sample bag. A small quantity of calibration gas is drawn from a large
cylinder of certified gas mixture  (at the agency's main laboratory) into the small
transportable gas sample cylinder.  The calibration gas is kept at a relatively low pressure
to minimize safety problems during transport of the material  to the job site. The
compressed gas  is transferred  to the Tedlar bag through a regulator and needle valve.
At a pressure of 325 psig, a 1  liter sample cylinder should provide enough span  check gas
for two field checks.  Zero air can be supplied by drawing ambient air through a small
5-10

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 charcoal filter. This approach is very inexpensive because the agency is using small
 quantities of the  certified calibration gas mixture from the main cylinder at the
 laboratory and they are not purchasing any disposable cylinders.  Some additional
 development work on this simple approach is necessary to ensure that a regulator is
 available to transfer the gas from the main cylinder to the sample cylinder at pressures
 reaching several hundred psig. Most regulators have a delivery pressure limit of
 100 psig.  It is also necessary to confirm that the compressed gas can be transferred
 safely.  It should  be noted, however, that this is the same approach used to fill the
 hydrogen fuel cylinders on the portable flame ionization analyzers.

       The field span check should be performed at the greater distance possible from
 potential  sources of fugitive VOC.  It should also be performed in an area where there is
 nojarge AC motors or other equipment that generate strong electrical fields, as such
 equipment can have an adverse effect on certain types of instruments (e.g.,
 photoionization analyzers).  The charcoal filter used in the "clean air" supply should be
 routinely  regenerated to avoid the possibility of saturation. It should be checked
 occasionally for saturation by supplying a moderate, known concentration of VOC and
 then checking the measured exit concentration after several minutes.

       Data concerning the span checks should be recorded in the field notes. If gauges
 are provided with the instrument, the tester  also should occasionally note the instrument
 sample gas flow rate.

 53.4  Thermocouple

       Thermocouples may be calibrated in several ways.  The simplest method is
 immersion in an ice bath and boiling distilled water. Electronic "ice point" reference
 circuits are also commercially  available to check thermocouple operation.  An isothermal
 zone box may be  used to test the thermocouple in a different range.

       There are  several suggestions for thermocouple operations. These include:
 -*M
       1.     Use the largest wire possible that will not shunt heat away from the
             measurement area.
       2.     Avoid mechanical stress and vibration that could strain the wires.
       3.     Avoid steep temperature gradients.
       4.     Use'the thermocouple wire well within its temperature rating.
       5.     Use the proper sheathing materials in hostile environments.

 5.4    LOCATION OF SAMPLING POINTS

       There are  many potential sources of fugitive VOC emissions hi a given facility.
The sources that will be considered here include: pump seals, compressor seals, process
valves, pressure relief devices,  and  agitator seals.


                                                                              5-11.

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       Pumps are used extensively by the target industries to move organic liquid. The
 most widely used pump is the centrifugal pump. Other pumps used are the positive
 displacement, reciprocating and rotary action, canned-motor, and diaphragm pumps.
 Most pumps have a moving shaft which is exposed to the atmosphere. The fluid being
 moved inside the pump must be isolated from the atmosphere.  This requires a seal.
 Leaks can occur at the point of contact between the moving shaft and the stationary
 casing.  The canned-motor and the diaphragm pumps do not have seals; therefore, they
 more effectively prevent leaks.

       Compressors are, basically, pumps that are used in gas service.  Gas compressors
 used in process units can be driven by rotary or reciprocating shafts and therefore need
 shaft seals to isolate the process gas from the atmosphere.  Rotary shafts may use either
 packed  or mechanical seals, while reciprocating shafts must use packed seals.  As with
 the seals in pumps, the seals in compressors are the most likely source of fugitive
 emissions from these units.

       One of the most common pieces of equipment in an industrial plant is  the valve.
 Individually, process valves have a low emission rate. However, because of the large
 number of valves present in most plants, as a group they usually constitute the largest
 percentage of fugitive VOC emissions. For example, in a 100,000 gallon per day
 petroleum refinery, there are usually 25,000 process valves as compared to about 250
 pump seals.  In some instances, valves may make up 90 percent of the process
 components that must be checked for leaks.

       Many different types of valves exist, such as globe, gate, plug, ball and check
 valves.  However, they can be grouped into three functional categories:

       •      Block: used for on/off control. Generally, these valves are used only
              occasionally, such as when there is a process change (i.e., unit shutdown).
       •      Control: used for flow rate control.
       *      Check: used for directional control. Since check valves are enclosed within
        .     process piping, they have no stem or packing gland and are not considered
              to be a potential source of fugitive emissions.

.The most common valves in use are the gate  valve and the globe valve. These valves
 can be found either in-line or at the end of a process line.

       Engineering codes require that pressure-relieving devices or systems be used in
 applications where the process pressure may exceed the maximum allowable working
 pressure of the vessel.  The most common pressure-relieving device used in process units
 is the pressure relief valve. Typically, a relief valve is spring loaded. It is designed to
 open when the process exceeds a set pressure. This allows the release of vapors or
 liquids until the system pressure is reduced to a normal operating level. When the
 normal pressure is retained, the valve reseats and a seal is again formed. There are two
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potential causes of leakage from relief valves.  Simmering occurs when the operating
pressure is similar to the set pressure of the valve, while popping occurs when the
operating pressure exceeds the set pressure, generally for an extremely short period of
time. The other cause of leakage is improper valve reseating after a relieving operation.

      Agitators are commonly used to stir or blend chemicals. Like pumps and
compressors, agitators may leak organic chemicals at the point where the shaft
penetrates the casing. Consequently, seals are required to minimi^ fugitive emissions
from agitators.

      Flanges are bolted, gasket-sealed junctions between sections of pipe and pieces of
equipment. They are used whenever pipe or equipment components (vessels, pumps,
valves, heat exchangers, etc.) may require  isolation or removal. The possibility of a leak
through the gasket seal makes flanges a potential source of fugitive emissions. However,
the results of EPA's refinery sampling programs have shown that flanges have a very low
emission factor.  Even though there are many of them in any refinery or chemical plant,
their overall contribution to fugitive emissions is  small.

5.5   OBSERVATION PROCEDURES AND CHECKLISTS FOR VOC TESTING

5.5.1 Performance Criteria and Evaluation Procedures for Portable VOC Detectors

      As  previously stated, any portable VOC detector may be used as long as it meets
the performance criteria specified in Method 21.   The performance criteria and detector
evaluation procedure is summarized in Table 5-5.

      In addition to the performance criteria, Method 21 also requires that the analyzer
meet the following specifications:

      •     The VOC detector shall respond to those organic compounds processed at
            the facility (determined by the response factor).
      •     The analyzer shall be  capable of measuring the leak definition specified in
            the regulation (i.e., 10,000 ppmv or "no detectable limit").
      •     The scale of the analyzer shall be readable to  ± 5 percent of the specified
            leak definition concentratioa
      •     The analyzer shall be  equipped with a  pump so that a continuous sample is
            provided at a nominal flow rate of between 0.5 and 3 liters per minute.
      •     The analyzer shall be  intrinsically safe  for operation in explosive
            atmospheres as defined by the applicable standards.
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   TABLE 5-5. PERFORMANCE CRITERIA FOR PORTABLE VOC DETECTORS
                Criteria
           Response factor
           Response time
           Calibration
           precision
  Requirement
Must be <10
Must be .<30
seconds
Must be .<10%
of calibration gas
value
      Time Interval
One time, before detector
is put in service
One time, before detector
is put in service; if
modification to sample
pumping or flow
configuration is made, a
new test is required
Before detector is put in
service and at 3 month
intervals or next, use,
whichever is later
       Also, criteria for the calibration gases to be used are specified in Method 21.
 Two calibration gases are required for both monitoring and analyzer performance
 evaluation. One is a zero gas which is air with less than 10 ppmv VOC.  The other
 calibration gas uses a reference compound/air mixture.  This calibration gas is also
 referred to as the reference gas. The concentration of the reference gas is approximately
 equal to the leak definition.  The leak definition and the reference compound are both
 specified in the applicable regulations. Calibration may be performed using a compound
 other than the reference compound if a conversion factor is determined for the alternate
 compound. The resulting meter readings during source  surveys can be converted to
 reference compound results.  Often instrument manufacturers list conversion factors for
 other gases in their operator's manuals. Because of the nonlinear responses, however,
 care must  be taken to use the conversion factor at the action level.

       Selection of the Necessary Types of Instruments - Selection of the types of
 instruments needed for source evaluation is based primarily on a review of the types of
 industrial facilities within the agency's jurisdiction and an evaluation of the measurement
'requirements inherent in the  promulgated VOC regulations. Agencies should also
 determine if it is possible to select instruments that can be used for future air toxic
 control requirements as well as the already existing VOC regulations.

       Organic Vapor Analyzers - One important criterion in the selection of organic
 vapor detectors is the response of the instrument to the  specific chemical or chemicals
 present in  the gas stream. The abilities of the major classes of organic vapor analyzers
 to detect different organic chemicals differ substantially. The response factor provides a
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convenient index of this property.  The response factor (RF) is defined by:

     Response factor »  Actual concentration of cpropount;}               Equation 5-1
                       Observed concentration from detector

       A response factor must be determined for each compound that is to be measured,
either by testing of from reference sources. The analyzer response factor for individual
compounds to be measured must be less than 10.0. The response factor tests are
required before placing the analyzer in service, but do not have to be repeated at
subsequent intervals.

       Response factors can be determined by the following method. First the analyzer
is calibrated using the reference gas.  Then, for each organic species that is to be
measured, a known standard in air is obtained or prepared The standard should be at a
concentration of approximately 80 percent of the leak definition unless limited by
volatility or explosivity.  In these cases, a standard at either 90 percent of the saturation
concentration or 70 percent of the lower explosive limit (LEL) is prepared.  This mixture
is then injected into the analyzer and the observed meter reading is recorded. The
analyzer is then zeroed by injecting zero air until a stable reading is obtained.  The
procedure is repeated by alternating between the mixture and zero air until a total of
three measurements have been obtained. A response factor is calculated for each
repetition and then averaged over three runs.

       Alternately, if response factors have been published for the compounds of interest
for the type of detector, the response factor determination is not required, and existing
results may be referenced.  When published response factors of the organic compound
being monitored are greater than 1 (approaching 10) or much smaller than 1
(approaching 0.1), it is prudent to measure the response factor for these specific
compounds. When screening for leaks from a source containing cumene, and FID can
be used (RF=1.87), while the  catalytic oxidation detector cannot (no RF value). The
same data shows that neither of these devices would be capable of detecting leaks from a
source containing carbon tetrachloride.

       The concept of using response factors as a general guide to analyzer applicability
is especially important when dealing with chemical mixtures.  Since many process streams
in industrial plants are composed of a mixture of compounds, having a simple method to
determine the response factor for a given detector type is important. One EPA study
has concluded that analyzer response factors for a mixture fall between the responses
expected for the pure components. Therefore, if desired, an interpolated or weighted
average can be  used to predict the response for mixtures based on known responses for
individual compounds.  For further information see EPA 600/2-81-110, "Response of
Portable VOC Analyzers to Chemical  Mixtures."
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       Range and Accuracy - The ability of an instrument to measure 10,000 ppmv
should be carefully considered if the instrument will be used to determine compliance
with EPA Method 21 regulations.  As indicated in Table 5-1, only a few of the currently
available units can operate at 10,000 ppmv or above. Other units can operate at this
concentration only by using dilution probes.  Although dilution probes can be used
accurately, they can also be a large source of error.  Both changes in flow rate through
the dilution probe and saturation of the charcoal tubes used to remove organic vapors
from the dilution air can lead to large errors in the indicated organic vapor
concentration. Dilution probes also complicate calibration and field span checks. For
these reasons, they should be avoided whenever possible.

      . Generally, an instrument should have the desired  accuracy at the concentration of
interest.  It should be noted that an accuracy of ± 5 percent is required for Method 21
work. "'*

       Response Time - The response time of an analyzer is defined as the time interval
from a step change in VOC  concentration at the input of a sampling system to the time
at which 90 percent of the corresponding final value is reached as displayed on the
analyzer readout meter. The response time must be equal to or less than 30 seconds.
The response time must be determined for the analyzer configuration that will be used
during testing. The response time  test is required before placing and analyzer in service.
If a modification to the sample pumping system or flow configuration is made that would
change the response time, a new test is required before further use.

      The response time of an analyzer is determined by first introducing zero gas into
the sample probe. When the meter has stabilized, the system is quickly switched to the
specified calibration gas. The time, from the switching to when 90 percent of the final
stable reading is reached, is noted  and recorded. This test sequence must be performed
three times. The reported response time is the average of the three tests.

      Safety - All instruments used during field inspections of VOC emission sources
and air toxics emission sources must be intrinsically safe  if they are to be used in
potentially explosive  atmospheres.  Localized pockets of gas (and even particulates)
within the explosive range can result from fugitive leaks and malfunctioning control
devices.  Intrinsically safe means that the instrument will not provide a source of ignition
for the explosive materials when used properly.  Instrument designs are certified as
intrinsically safe for certain types of atmospheres by organizations such as the Factory
Mutual Research Corporation.

      The large majority of the organic vapor analyzers  are designed to be intrinsically
safe in Class I areas.  Factory Mutual, however, has certified only a few of the currently
available commercial instruments to be intrinsically safe for Class n areas.
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       It should also be noted that battery-powered thermocouple are not designed as
 intrinsically safe for either Qass I or Qass n atmospheres.  Therefore, these instruments
 cannot be taken into or through areas where there is a possibility of encountering
 explosive mixtures of organic vapors and/or dust Conventional flashlights are also not
 intrinsically safe, and they should be replaced by explosion-proof flashlights.
                •>''
 5.5.2  Laboratory And Shop Support Facilities

       Because of their level of sophistication,  organic vapor analyzers require laboratory
 and instrument shop support facilities.  Regulatory agency inspectors should not attempt
 to store and calibrate the instruments in their offices, as this practice can lead to
 significant safety problems and complicate the  routine maintenance of the instruments.

       Gas Flow Evaluation - Many of the organic vapor analyzers, especially the flame
 ionization detectors, are sensitive to the sample flow rate.  Routine confirmation of
 proper flow rate is important, especially for those instruments that do not include a flow
 sensor. Flow rates are normally measured by use of a rotameter designed for flow rates
 between 0.5 and 5.0 liters per minute. The rotameter should be calibrated against a
 soap bubble flow meter.

       Electrical Diagnostic Equipment - The extent to which malfunctioning organic
 vapor analyzers can be serviced by agency personnel is limited because the ^intrinsic
 safety of the instrument can be voided inadvertently.  Nevertheless, qualified agency
 instrument technicians should be equipped to check such operating parameters as the
 lamp voltage of photoionization units and the battery output voltage of all portable
 instruments.

       Thermocouple Calibration Equipment - The thermocouple readout device and
 thermocouple probes should be calibrated at least twice  a year.  For convenience, the
 calibrations should be performed in-house with a conventional tube furnace. The field
 instrument and probes are compared against National Institute of Standards and
 Technology (NIST) traceable thermocouple probes.

       Static Pressure Calibration Equipment - All diaphragm-type static.pressure
 gauges must be calibrated on at least a weekly basis.  A relatively large U-tube
 manometer can be permanently mounted in the agency laboratory for calibration of
 0 to 10 inch W.C. and 0 to 60 inch W.C. gauges.  An inclined manometer is  needed for
 calibration of the 0 to 2 inch W.C. gauges.

 5.53  Routine Field-Oriented Evaluations of Instrument Conditions and Performance

       Several instrument performance checks should be made before the inspector
leaves for the job site and during the routine screening of possible fugitive VOC sources.
The field-check procedures are in addition to, not a replacement for, the calibration


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 procedures discussed earlier. The daily calibration, the field span check, and the routine
 field performance checks are necessary to confirm that the instrument is operating
 properly. Preferably, the initial instrument checks should be made by the agency's
 instrument specialist assigned responsibility for the analyzers.  Brief notes concerning
 each day's initial instrument checks should be included in the main instrument
 evaluation/maintenance notebook kept in the instrument laboratory. The inspectors
 make the field checks by using the instruments at the job site and documentation of
 these field checks should be a part of the inspectors' field notes.

       Initial Instrument Checks - It is very important that a few simple instrument
 checks be made before the inspector leaves for the job site. The appropriate field
 checks for each instrument can be found in the instruction manual supplied by the
 instrument manufacturer.  The following common factors, however, should be checked
 regardless of the type of instrument:

       •.     Leak checks including integrity of sample line and adequacy of pump
             operation
       *     Probe condition
       •     Battery pack status
       •     Detector conditions
       •     Spare parts and supplies
These checks can be made in a period of 5 to 15 minutes.  Repairs to the detectors,
batteries, and probes usually can be accomplished quickly if a set of spare parts is kept
on hand.  Some of the checks that should be made before field work is begun are
discussed in the following discussions.

      Leak Checks - To leak check the probes on units with flow meters, the probe
outlet should be plugged for 1 to 2 seconds while the sample pump is running. If the
sample flow rate drops to zero, there are no significant leaks in the entire sampling line.
If any detectable sample flow rate is noted, further leak checks will be necessary to
prevent dilution of the VOC sample gas during sampling.  The leak checks involve a
step-by-step disassembly of the probe/sample line starting at the  probe inlet and working
back toward the instrument.  At each step, the probe/sample line is briefly plugged to
determine if inleakage is still occurring at an upstream location.  Once the site of
leakage has been determined, the probe/sample line is repaired and reassembled. To
confirm that the probe/sample line is now free of air infiltration, the probe is again
briefly plugged at the inlet to demonstrate that the sample flow rate drops to zero.

      When leaks are detected, there is sometimes a tendency to over-tighten the
fittings, especially those between the instrument body and the end of  the sample line.
With some types of fittings (e.g., Swagelok fittings) over-tightening can damage the fitting
and even lead to persistent leaks.
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        Units that do not have flow monitors should be leak-tested by installing a
  rotameter on the sample line as close as possible to the inlet to the instrument body.
  The leak-testing procedure described above can then be followed. Also, the sound of the
  pump should be noted, as this provides one qualitative means of identifying clogs.  It
  should be noted, however, that pump noise is useless for identification of probe leakage
 ^because the pump continues to receive  air due to the  infiltration.

        Some catalytic combustion units  should not be  leak tested by plugging the probe.
  Short-term loss of sample flow would reportedly lead to high detector temperatures.

        When more than one probe can  be attached to the same instrument body, each
  probe should be tested. Only those  that can be sealed properly should be packed for
  field use.

        Probe Condition - The probes for some instruments can contain a number of
  independent components, especially  those that dilute the sample before analysis. The
  physical condition of the probe should be checked visually before use.  These checks
  include, but are  not limited to, an examination for:

        •     Presence of any organic deposits on the  inside of the probe
        •     Presence of clean a particulate filter in the probe               :
        •     Condition of orifice

  5.6    TYPICAL SAMPLING PROBLEMS AND SOLUTIONS

        One of the main problems in monitoring organic vapors is locating or pinpointing
  the leaking source. Organic vapors are dispersed by the wind, sometimes making it
  difficult to determine their source. It is important that the probe be moved slowly; the
  slower the instrument response time, the slower the probe must be moved.  Placing a
  notebook or something similar (to block the wind) on the upward  side of the suspected
  leaking source may help locate the leak, but is not required by Method 21.
..'•
        In  some cases, it may be difficult to determine  whether .a meter response is
  caused by high ambient air hydrocarbons or by a source leak, particularly when the
* ambient reading is highly variable. This problem is commonly experienced in enclosed
  areas. One method to determine if a source is leaking is to place  the probe at the leak
  source and then remove it from the leak source. This operation is repeated at regular
  intervals.  If the movement of the needle corresponds to the placement and removal of
  the probe (keeping in mind the analyzer response time), the source is probably leaking.
•" The screening value is then determined by subtracting the ambient reading from the
  measured screening results.  A variety of such situations may be encountered and
  judgement on the part of the operator may be required to obtain a representative
  reading.
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       Occasionally, a source may be encountered which has a highly variable leak rate.
 In general, the maximum sustained reading or the maximum repeatable reading should
 be recorded. Again, judgement on the part of the operator may be required to obtain a
 representative reading.

       Further difficulty may arise when emission sources contain heavier hydrocarbon
 streams, particularly hot sources.  When these sources are sampled, some of the organic
 vapor tends to condense on the internal surfaces of the probe or sample hoses.  The
 response of the meter is considerably slower for the heavier hydrocarbons than for the
 lighter ones. And, the meter may require more time  to return to zero. When sampling
 heavier hydrocarbons, the meter should be allowed to stabilize before reading the results.
 Before sampling the next source, sufficient time should be allowed for the meter to
 stabilize or return to zero.  Often the meter will not return completely to zero and a
 considerable adjustment may be required.

    ',:.'- Under no circumstances should the end of the probe be placed in contact with
 liquid. If liquid is drawn into the system through the  sample hose, it may damage the
 analyzer. A liquid trap, connected between the analyzer and the sample probe, can be
 used. In addition, the equipment being sampling may be covered with a film of grease
 or dirt If the probe touches  these components, the grease may plug the probe. The
 inspector can carry a package of pipe cleaners to clean out the probe.  Alternatively, a
 Teflon probe extension can be used and the end cut off if it becomes clogged.

       When using a portable VOC detector, the following safety practices are suggested:

       1.     Do not place a  rigid probe in contact with a moving part such as a rotating
             pump shaft.  A  short, flexible probe extension may be used.
       2.     Do not place the umbilical cord from the detector on a heated surface such
             as a pipe, valve, heat exchanger, or furnace.
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                                  CHAPTER 6
    TOTAL GASEOUS NON-METHANE ORGAN1CS AS CARBON - METHOD 25

 6.1    APPLICABILITY

,-     Method 25 is designed to measure Total Gaseous Non-Methane Organics
 (TGNMO's). Organic' compounds which exist as a gas or which have significant vapor
 pressure at or below 250°F are subject to measurement by this method.  Methane is
 excepted from regulation and is not included in the reported organic emissions. During
 analysis of the samples, all organics are catalyzed to methane.  With proper analytical
 procedures methane in the sample does not bias the TGNMO result The catalyzed
 methane generated during sample analysis corresponds one-to-one with the carbon
.content of the sample, therefore the TGNMO results are reported in "ppm as carbon.11

       Method 25 exhibits a 1:1 response for all carbon present in the sample and
 therefore shows no bias due to differing response factors for different compounds.
 Method 25 should be used when multiple organics are present or when the make-up of
 the gas stream is not known. Products of incomplete combustion can be present at any
 combustion source, therefore the make-up of the exhaust gas cannot be known with
 certainty. For this reason Method 25 should be used for most combustion sources.

       During Method 25  analysis, all carbon present is catalyzed to methane.  Because
 of this, the relative contribution to the total carbon content from different compounds
 cannot be determined. If specific organic compounds are to be identified  and quantified,
 EPA Method 18 or some other method must employed, as Method 25 is not a compound
 specific method.

       Method 25 is applicable to sources with VOC concentrations of 100 ppm to
 several percent by volume as carbon. The general application of the method allows
 detection of concentrations as low as 100 ppmv, but with modifications cited in
 Section 3.17 of EPA's "Quality Assurance Handbook, Volume HI" (EPA-600/4-77-027b)
 and prior approval of these modification by the Administrator, a lower detectable limit
 of 50 ppmv can be achieved.

       Organic compound concentrations are expressed as carbon by adjusting the ppm
values for the number of carbon atoms per molecule. For example, an audit cylinder
 containing 50 ppmv of toluene would have a concentration of 350 ppm as  carbon
 because toluene has seven carbons per molecule. A mixture of 50 ppm CO, 50 ppm
 CH4, 2 percent CO2, and 20 ppm propane would have an organic concentration of 60
ppm as carbon.  The 50 ppm CH4 is not counted because Method 25 excludes methane,
20 ppm propane is counted three times because there are three carbons per molecule in
propane. CO and CO2 are not counted because they are not organic constituents.
                                                                            6-1

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 62    METHOD DESCRIPTION

 62.1  Sampling Procedures

       EPA Method 25 uses an evacuated cylinder or tank to draw gas from the emission
 source at a constant rate from a single point in the gas stream.  The sample is integrated
 evenly over the period of the test run. The sample is withdrawn from the source through
 a heated probe, passed through a heated particulate filter and cold condensate trap, and
 drawn into the evacuated cylinder. Heavy molecular weight organics are condensed out
 of the sample into the chilled trap, and lighter organics are trapped in the evacuated
 cylinder.  The contents of both the condensate trap and the evacuated cylinder are
 analyzed for organics following the test run.

       A gaseous organic is defined as any organic which is in the gaseous state at
 standard pressure and 121°C (250°F).  Therefore, the probe is kept at a temperature
 above 121°C at 129°C (265°F)  and the filter housing is kept at 121±3°C (250±5°F).  The
 filter ensures that only gaseous organics  and no organic particulate matter or mist passes
 through to the sample. Particulate matter or mist could significantly bias the results
 high. A thermocouple well should be placed at the probe exit and the filter housing.
 The temperatures at these locations are  monitored every 5 minutes during testing.

       After passing through the filter, "heavy" organics condense in the chilled
 condensate trap. The trap is kept on dry ice to maintain the coldest possible
 temperature.  The dry ice should be kept in an insulated container to ensure that it does
 not sublime during the run. The dry ice level should be checked periodically during the
 run. After the condensate trap, the remaining sample flows through a rotameter and
 fine metering valve used to control the sampling rate, then into  the evacuated tank or
 cylinder.  Method 25 states that the sample flow rate shall be between 60 cc/min and
 100 cc/min. For a one hour ran at a sampling rate of 60 cc/min, a sample volume of
 3600 cc or 3.6 liters will be collected. At a flow rate of 100 cc/min, the sample volume
will be 6 liters. The evacuated tank should have a volume of at least 4.5 liters to allow
 for a minimum of 3.6 liters sample with room for error.  The tank should not exceed 12
 liters unless the sampling time is planned to be greater than one hour. If the volume of
 the tank^is too large,  the sample becomes diluted when the tank is pressurized, and the
sensitivity of the analysis is decreased. A diagram of the Method 25 sampling  train is
shown in Figure 6.1 at the end of the chapter, page 6-22. All other figures and tables
 are also presented at the  end of the chapter.

 622   Sampling Equipment

      The sampling system consists of a heated probe, heated filter, condensate trap,
flow control system, sample purge pump, and evacuated sample  tank.  Complete systems
are commercially available, however a system can be fabricated from easily obtained
materials. Any system should meet the specifications listed below.  Table 6-1,  page 6-23,
6-2

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lists the calibration specifications and frequencies for the sampling system. Specifications
for the sampling equipment are presented in Table D-l, page D-2. Figure 6.2, page
6-24, is an example of an acceptable filter housing. Figure 6.3, page 6-25, is an example
of an acceptable condensate trap design.

6.2 J  Analytical Procedures

      Both the condensate trap and the sample tank are analyzed for nonmethane
organics (NMO's). The condensible organics are recovered from the trap by volatilizing
the organics and catalytically oxidizing them to carbon dioxide and collecting the CO3 in
an intermediate collection vessel (ICV).  The carbon dioxide concentration in the ICV is
then measured.  The non-condensible NMO's are recovered from the sample tank by
pressurizing the tank and analyzing the contents by using a flame ionization detector
(FID).

      Both the CO2 evolved from the condensibles recovery and the non-condensible
NMO's are analyzed by using a gas chfomatograph with an FID. This analysis differs
from other VOC methods because the sample is first conditioned such that all organics
are reduced to methane before being introduced to the FID.  A separation column is
used tc separate methane, carbon monoxide, carbon dioxide, and NMO's.  As each
compound elutes from  the separation column, it is catalytically oxidized to CO2. The
CO2 is then passed over a reduction catalyst in the presence of hydrogen. The CO2 is
reduced to methane. In this process,  only methane is passed to the detector.  The FID
response is assigned to CO, CO2, methane and NMO's by the elution time in the cycle.
Figure 6.4, page  6-26, is a schematic of the analysis cycle, and Figure 6.5, page 6-27, is  a
schematic of the sample delivery valve and flow path for the analysis.

      The condensible organics are recovered  by "burning " the trap, i.e., heating the
trap in an oven to 200°C.  After burning the trap, the CO2 generated by catalytic
oxidation is measured.  Any CO2 present in the trap prior to burning will bias  the results
high.  To eliminate this bias, a "cold purge " is done. The cold purge consists of purging
the trap with pure  air while the trap is immersed in dry  ice to drive; off any CO2 present.
The purge effluent is monitored with a non-dispersive infrared (NDER) analyzer to
assure that all the CO2 is gone before ending the purge. The NDIR analysis is non-
destructive, and the purge effluent is collected at the exit of the NDIR in a second ICV.
As the NDIR response approaches zero, a 10 ml syringe is used to extract a sample from
an injection port located before the NDIR.  The 10 ml sample is analyzed using the
NMO analyzer for CO2 concentration. The purge is considered complete when the CO2
concentration is below  10 ppm. This ICV is analyzed for NMO's as some organics may
volatilize during  the purge.

      After the  cold purge, the trap bum is done. The  trap is placed in the oven at
room temperature. Then it is heated to 200°C.   During  the burn, the trap is purged with
pure oxygen. As the trap is heated, organics are carried by the purge to  the catalyst bed

                                                                              6-3

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where they are oxidized to CO2.  The purge is again monitored for end-point using the
NDIR, and 10 ml samples are withdrawn from the injection port and checked until the
CO2 concentration is less than 1 ppm.  The purge gas is collected in the ICV and
analyzed for CO2 and NMO's (in case some organics passed through the catalyst).  Care
must be taken that the  organics are not volatilized too fast or the catalyst may become
saturated. If this happens, some organics will pass through to the ICV.  They might not
be accounted for by NMO analysis. However, If the organics have high boiling points,
they may condense on the side of the ICV and bias the results low.  This can be avoided
by heating the trap slowly or by adding auxiliary oxygen to the system through a tap
between the oven and the oxidation catalyst.  Each analytical system should be equipped
with such a tap for handling samples with high organic catches. High NMO
concentrations in the ICV vessel may indicate breakthrough of unoxidized hydrocarbons.
           NMO concentrations from the sample tank, the ICV from the cold purge,
and the ICV from the trap burn, as well as the CO2 concentration from the trap burn are
weighted according to the vessel volume associated with each concentration to determine
the carbon content of the original sample.

6.2.4  Analytical Equipment

      Since most Method 25 analyses are done post-test in a laboratory, it will be
difficult to observe the equipment and procedures.  A list of the major equipment
components needed for analysis is presented in Appendix D.2, page D-4.  Table 6-2,
page 6-28, contains the major components of the analytical system and the calibration
schedule for each.

6.3   PRECISION AND ACCURACY

      Very little data is available concerning the precision and accuracy of Method 25.
A limited number of laboratories actively perform the NMO analysis and interlaboratory
studies are not complete as of this writing.  The generally accepted limits for precision
and accuracy are both 20 percent of the mean value. Preliminary results of
interlaboratory studies indicate that at lower concentrations, less than 200 ppm, the
accuracy limit becomes much higher than 20 percent. At high concentrations, greater
than 1000 ppm, the accuracy limit should be less than 20 percent. High concentrations
of CO2 and water will further increase the limits of the  accuracy and precision, especially
at low organic concentrations.

6.4   LOCATION OF SAMPLING POINTS

      Method 25 sampling is performed at a constant rate from a single point in the
duct.  No traversing or isokinetic sampling is required.  The nozzle on the sample probe
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can be of any size, but should be constructed such that it can be turned away from the
direction of flow in the stack to avoid collecting paniculate matter.  The nozzle should
be placed at the point in the stack or duct with average velocity.

      A velocity traverse should be done prior to sampling, and the average impact
pressure differential of the gas stream should be determined. The nozzle should be
placed at the point where the delta P (AP) is closest to the average  AP.  If the velocity
profile across the duct is level, place  the nozzle at the center of the  duct.

63   OBSERVATION PROCEDURES FOR METHOD 25 TESTING

      It is the responsibility of the testing firm to ensure that the sampling and
analytical procedures are performed correctly. The following detailed information is
given only as training  guide for the less experienced test coordinator and does not imply
mandatory actions by  the test coordinator except when the discussions state that the test
coordinator "shall" conduct a given procedure.

6.5.1  Equipment Specifications

      All equipment used during sampling should be checked to ensure that it conforms
to the requirements of Method 25. Table D-l, page D-2, is  a checklist for sampling
equipment specifications and calibration which may be completed or used as a guide by
the test coordinator or testing firm. Thermocouples and rotameters should be calibrated
and the calibration values and last date of calibration should be noted. Rotameters
should have a gamma between 0.9 and  1.1, and thermocouples must agree with the
calibration standard within 3°C (5°F). The sample tanks should have been calibrated for
standard volume and tagged with a unique identification code. The  volume and tag
number for each tank should be recorded by the testing firm.

6.5.2  Pre-test Leak Checks

       A leak check must be conducted on the entire sampling system prior to sampling.
Table D-2, page D-4, is for sampling  operations checklist which may be completed or
used as  a guide by the test coordinator. The allowable leak rate is 1 percent of the
sample flow rate.  The system is assembled and the probe and filter  housing are heated
to their respective set-points. A system which is leak tight when cold may not be leak
tight when hot, so leak checks should be conducted with the system heated. The
condensate trap is placed in the container of dry ice. The top of the trap should be 2.5
to 5 cm above the top of the dry ice.  If the 1/8 inch tubing  connecting the trap to the
filter is covered with dry ice, water and  CO2 will freeze in the tubing and block the flow
during sampling. As the trap temperature reaches equilibrium with the dry ice, frost will
form on the trap.  The frost  line should not extend onto the  connecting tubing. The inlet
tubing to the condensate trap should extend into the filter housing so that organics don't
condense in the tubing, but  condense  in the packing of the trap.


                                                                              6-5

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       The leak rate is determined by attaching a mercury manometer to the inlet of the
 probe and evacuating the system to within 10 mm Hg of absolute. The metering valve
 used to control sample flow rate should be wide open to allow the system to evacuate as
 quickly as possible. Each sampling system will allow diversion of sample flow to a purge
 pump.  This is usually done with a 3-way valve. Be sure that the 3-way valve is turned
 toward the sampling position.

       As the system is evacuated, the air moving from the sampling train to the
 evacuated tank can be monitored with the rotameter. The flow through the rotameter
 should drop to zero, indicating that all the air is out of the system, before the leak check
 is started. If no flow is initially seen on the rotameter,  the flow control valve may be
 closed or the sample/purge valve might be at the neutral or purge position.  The sample
 valve at the sample tank is switched off to isolate the system from the tank.  The system
 should maintain the same vacuum, as read on the Hg manometer, for 5 or 10 minutes.
 The allowable leak rate is based on a check time of 10  minutes, so if 5 minutes is used,
 divide the allowable leak rate by 2. A tank other than  the one intended for sample
 should be used for the leak check because the air initially present in the sampling system
 is drawn into the leak check tank.  The allowable leak rate is calculated by the following
 equation:
       A P = 0.01 x F x Pb x t/ Vt
Equation 6-1
where:
       A P   =  allowable pressure change, mm Hg
       F     =  sample flow rate, cc/min
       Pb    =  barometric pressure, mm Hg
       t      =  leak check time, minutes
       Vt    =  volume of the sampling train, cc

       For example, if the sampling train volume were 30 cc's, the intended flow rate
60 cc/min, and 760 mm Hg and 10 minutes are used for barometric pressure and leak
check time.  Then the maximum allowable pressure change over the 10 minute period is:
      AP = 0.01 x 60 cc/min x 760 mm Hg x 10 mins/30 cc
          = 152mmHg = 5.98 in. Hg
Equation 6-2
      After the leak check, the sample/purge valve is turned to the neutral position to
prevent in-Ieakage of ambient air. The flow control valve is closed all the way so that
the sample flow rate can be accurately controlled when the run is started. The leak
check tank is replaced with a fresh sample tank. When the probe exit temperature and
filter housing temperature  are at their set points ±3°C (±5°F), remove the manometer
fitting from the tip of the probe and place the probe in the stack at the previously
determined sampling point.
6-6

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       Each sample tank should also be leak checked. This is most easily accomplished
by evacuating the sample tanks one day prior to the test date. The absolute pressure in
each tank as well as the barometric pressure and tank temperature are recorded.  On the
day of testing, the tank pressure and temperature are measured again. After allowing for
differences in barometric pressure and tank  temperature, the tank absolute pressure
should be identical to the previous day's reading.  If the  sample tanks cannot be
evacuated on the day preceding testing, they should be evacuated and left for at least
one hour. The  absolute pressure in the tank should not  change in that hour. If the tank
leak checks are started the day prior to testing, the absolute pressure change should be
no more than 5 mm Hg.  For a one hour leak check, the pressure change should be no
more than 1 mm Hg.

6.5.3   Pre-test Sampling Train Purge

       A minimum of 10 minutes before the start of the  run, the sample/purge valve is
turned to purge,, and the purge pump is turned on. The  purge rate should be set at 60 to
100 cc/min. The purge pump draws stack gas through the probe  and filter, but not the
condensate trap or sample tank. Just before sampling starts, the purge pump is turned
off and the sample/purge valve is  returned to the neutral position.

6.5.4   Sampling Procedures

       To start the run, the sampler needs to perform the next four steps nearly
simultaneously:

       1.    Start the run timer.
       2.    Open the sample/purge valve to the sample position
       3.    Open the valve to the sample tank.  If a sealing quick connect is used, push
            the quick connect to the "locked-in" position.
       4.    Open the flow control valve to the desired flow rate.

       The pressure differential between the duct and the sample tank is the driving
force in the sampling train. As the sample tank vacuum decreases, the flow rate will
decrease if left unattended. The sample flow rate, probe exit temperature, and filter
housing temperature should be monitored and recorded  every 5 minutes during the run.
The flow control valve should be used to adjust the sample flow rate such that it stays
constant to ± 10 percent of the intended flow rate.

       If the vacuum in the sample tank decreases to the point that the flow rate can no
longer be maintained, the following procedure should be followed: Turn off the tank
sample valve. Disconnect the tank from the system without disconnecting any other part
of the system. Take another leak  check and evacuate the  sample tank. Record the tank
vacuum and temperature.  Attach  it to  the sampling train and resume sampling until the
required run time has been met or exceeded.

                                                                              6-7

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       To end the sampling run, the sample/purge valve is moved to the neutral position
and the sample tank valve is turned off.  Before the train is taken apart, the condensate
trap and sample tank should be tagged with the date, ran number, facility and sampling
location designations, and the reference number assigned to the project by the testing
company. This will assure that no mix-up or confusion arises over sample identity during
analysis. The condensate trap and sample tank identification numbers must be recorded
on the data sheet for that run.

       A post-test leak check is not required by Method 25.  Under no circumstances
should a leak check be done using a fresh sample tank or a leak check tank, or the purge
pump. Since sampling is completed at a vacuum much lower than that of a completely
evacuated sample tank, organics will volatilize and be carried from the cold trap to the
leak check tank or purge pump. An alternative that is  acceptable to verify the integrity
of the sampling system at the end of the run is as follows:

      Turn the sample/purge valve to the neutral position.  Reconnect the sample tank
or open the sample tank valve.  Wait for the rotameter to drop to zero.  Record the
system vacuum on the gauge installed in the system (this may be close to zero, but is
usually 10 mm Hg).  Turn off the sample tank valve and remove the sample tank from
the system. Wait 5 minutes and check the system vacuum again. The vacuum should
not decrease  by more than 2 mm Hg.

      This procedure is not required and is at the option of the test coordinator. This
procedure will not cause sample loss because it is conducted at the lowest vacuum in the
system during the run.  If any lighter organics are drawn from the trap to the sample
tank, they will be recorded in the non-condensible NMO analysis.

6.5.5  Post Sampling Procedures

      Proper procedures must be followed on-site to insure the samples are recovered
for analysis. The sample tank is removed from the train and the final tank absolute
pressure is recorded to the nearest mm Hg.  The condensate trap is removed from the
sampling system promptly and both the inlet and outlet are plugged to prevent leakage
into or out of the trap.  The trap must be kept cold until condensate recovery. To
accomplish this, sufficient dry ice must be available to keep the traps cold until they are
transported to the analytical lab. The dry ice should be kept in specially designed
coolers which will maintain dry ice for several days. The sample tanks may be
pressurized on-site.  If they are, the final positive pressure must be recorded as well as
the tank temperature at that time.

      Pressurizing the  sample tanks is done by using a "Y" connector to attach the
sample tank to both a cylinder of carrier grade air, and the mercury manometer. An
on/off valve is located in the leg of the "Y" between the sample tank and the air
cylinder. The on/off valve must be closed at this point.  The tank pressure is read on
6-8

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the manometer and the tank temperature is measured and recorded. The on/off valve is
opened and air is pushed into the sample tank until approximately 300 mm Hg pressure
is indicated by the manometer. The on/off valve is closed again to isolate the sample
tank from the air cylinder and the new tank temperature and pressure are measured and
recorded.  The sample tank is removed from the T" and prepared for shipment to the
laboratory.

      Inspection of the test data sheets before leaving the site may disclose omissions or
problems which can easily be remedied now, but which could cause the data to be
unacceptable if undetected until  later. A copy of an acceptable data sheet is included in
Figure D.I, page D-8.  Items which must be recorded are:

      Date                           •     Run Number
      Company  Name                •     Source Designation
      Test Start Time                 •     Test Finish Time
      Operator                       •     Sample Train I.D.
      Sample Tank I.D.               •     Sample Tank Nominal Volume
      Trap I.D.                       •     System Leak Check Rate
      Train Volume                   •     Tank Temperatures &  Pressures -
                                           pre-test and post-test

      Some missing data may be filled in at the end of the test run with the correct
values. Failure to record other values at the appropriate time may be cause for
repeating a run.  One such item  is the pre-test or post-test tank pressure  and
temperature.  If the tank was pressurized before this data was recorded, the run must be
repeated, because the sample volume cannot be calculated without it. A missing tank
I.D. or trap I.D. may be  recovered from the tags on the tanks and traps, but if the traps
and tanks were not tagged and no other way exists to assign the proper tanks or traps to
the proper runs, the runs must be repeated.

6.6   SAMPLING PROBLEMS, ERRORS, SOLUTIONS, AND ACTION REQUIRED

      Because of the large number and variety of organic processes, it is not possible to
discuss all of the sampling problems related to Method 25 sampling.  Only the most
common problems will be addressed.

6.6.1  High Gas  Sample Moisture Content and Freezing of Trap

      Due to the condensate trap temperature maintained by the dry ice, any moisture
and some CO2 present in the sample will freeze in the  trap. If the tubing leading to the
trap becomes  too cold, water will freeze in the tubing causing a plug. This condition is
indicated by a sudden loss of flow during  sampling or by difficulty in maintaining
proper flow with  the flow control valve entirely open. If a plug develops, the timer
should be  stopped. The  purge/sample valve is turned to the neutral position and the


                                                                             6-9

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 sample tank valve is closed. Any simultaneous trains must also be stopped. The trap is
 then raised out of the dry ice until the connecting tubing is 2.5 to 5 cm above the dry ice.
 When the frost film on the connecting tubing melts, sampling can be resumed.

       If the sample gas has a high moisture content, the freezing problem at the inlet  to
 the trap may become chronic. If raising the trap out of the dry ice bath does not
 alleviate the problem, the inlet line can be insulated. Also, a second trap may be placed
 in front of the condensate trap.  The second trap should be kept  in an ice water bath.
 The water will condense out in this trap without freezing and the condensate trap will
 not collect as much moisture.  This second trap must be analyzed in the same manner  as
 the condensate trap.  Both traps are kept on dry ice during shipping and storage.

 6.62  Use of Electrical Service Not Permitted for Probe and Filter

       If for safety reasons, the plant cannot allow the use of electrical service at the
 sampling site, sampling should be conducted using an in-stack filter.  The filter should
 consist of a stainless steel tube packed with quartz wool. The condensate trap is then
 connected directly to the in-stack filter.

 6.63  Probe Exit or Filter Temperatures Not Within Specification

       The temperature at the probe exit and the filter housing are measured every
 5 minutes during the test run.  Method 25 requires that these temperatures be
 maintained above 129°C and at 121 ±3°C, respectively. If specifications, the test
 coordinator may allow or disallow the run.  Since an NMO is defined as a non-methane
 organic existing at or below 121°C, a probe temperature or filter  temperature
 significantly below 121°C may allow some organics to condense in the  sampling  train.
 Therefore, if the probe exit or filter temperature is maintained at or falls below  121°C
 for an appreciable length of time, the  run should be considered invalid. If, however, the
 probe exit or filter temperature exceeds the limits, organics which have higher boiling
 points may pass through the filter.  If the temperature specifications are exceeded, the
 bias  willvbe toward higher organic concentrations and the agency  may choose to accept
 the runs.:
       x.'
 6.6.4  Non-constant Sample Flow Rate

       Method 25 sampling requires a constant flow rate.  The flow rate is monitored
 every 5 minutes throughout the run. However, because of the variable driving force
 from the sample tank, the flow may not have been maintained at  the proper setting
 ± 10 percent  This can be detected at the end of the run by examining the vacuum gauge
 readings for each five minute point. The difference between readings should be  constant
 over the course of the run. For instance, if a 4.5 liter tank is used for a 1 hour run, the
vacuum change over each 5 minute period should be between 3 and 5 cm Hg.  If the
 flow rate falls below the set point the vacuum change would be less than 3 cm Hg. If
6-10

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the flow is higher than the set point the vacuum change will be greater than 5 cm Hg.
Vacuum gauges normally have increments of 1 cm Hg.  So, a vacuum reading is only
'accurate to within about 1 cm Hg, and this should be considered when reviewing the
data A difference of greater than 2 cm Hg from the normal vacuum change for any
5 minute period would indicate a problem with that reading.

       The appropriate response when inconsistent flow is detected is dependent on the
emission source characteristics.  If the emission source is a batch operation where one
full batch comprises one test run, the flow problems would weight the results toward the
period of highest flow and away from the period of lowest flow. This could be significant
depending on process conditions. If the source operates in a steady state condition, then
each 5 minute sampling period would be fairly equivalent in terms of the emission rate,
and the inconsistent flow would have little effect on the results.

       One situation which is serious regardless of process conditions is very high flow.
The condensate'trap is designed for a flow rate of 60 to 100 cc/min. If the flow  is much
higher, then breakthrough of heavy organics may occur.  The heavy organics would then
condense on the sides of the sample tank and not be included in the NMO analysis. If
the vacuum change for any period indicates that the flow rate during that period was
greater than 200 cc/min, die run should be repeated. High flows are commonly seen at
the start of sampling.  If the flow control valve is not closed after being wide open during
sampling a large amount of gas will be drawn through the system before the flow can be
set properly.

6.6.5  Use of Method 25 for Measuring Low Levels of Organics

       The lower detectable limit of Method 25 is 100 ppm as carbon.  Due to the large
number of factors contributing to imprecision in both sampling and analysis, the accuracy
of the  results is questionable at concentrations near the lower limit.  A simple way to
increase  the accuracy at lower concentrations is to extend the sampling time from
1 to 2  hours. This will require that the vacuum in the sample tank be sufficient to draw
sample for twice as long.  This can be accomplished by using a larger sample tank
( >9 liters) or by changing sample tanks halfway through the run.  When the vacuum in
the first sample tank becomes too low to maintain the proper flow rate, stop sampling
and  disconnect the sample tank. The condensate trap should not be  disconnected. The
same condensate trap is used  for the entire test run.  The tester should then install a
new sample tank and record its volume and I.D. number on the data sheet  Do not
perform a leak check with the new sample tank in place.  Organics will be drawn from
the condensate trap to the sample tank by the higher vacuum. Proceed with the
extended test run.

       If the source emissions have a high moisture content, the extended test period
may cause the condensate trap to fill up with water or ice. This can be avoided by using
an auxiliary trap placed in an ice water bath prior to the condensate trap (see


                                                                             6-11

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 Section 6.6.1). Both traps must be analyzed.  The NMO contribution from both tanks
 and traps is summed.

       Method 25 was not intended to measure organics at levels below 100 ppm as
 carbon.  However, if the tester has no other options, Method 25 can be used under the
 following conditions:  (1) extreme caution must be used in preparing the traps and tanks
 and (2) two traps and two tanks should be set aside as field blanks with the analytical
 results subtracted from the field sample values.  This approach will improve
 measurements at low level sources, but the accuracy and precision will  be poor.

 6.6.6  Sampling and Analysis by Different Companies

       Because of the small number of laboratories that conduct Method 25 analysis, a
 large-portion of the Method 25 sampling and  analysis is conducted by two different
 companies. This creates problems in  assigning responsibility when audit sample results
 are not acceptable. If the sampling company  wants to check the consistency of the
 analytical results, they should obtain extra traps and cylinders from the  laboratory.
 These clean traps and cylinders should not be opened, marked as if they were a sample,
 and submitted for analysis.
                        X

 6.6.7  Measurement in Ducts Containing Organic Droplets

       If the gas stream to be sampled contains organic droplets, Method 25 results can
 be significantly biased-high.  The testing firm  should first try to find  another sampling
 location.  If this is not possible, an in-stack filter may be added to the sampling system
 with both the  in-stack and out-of-stack filters being replaced after each  run. The addition
 of an in-stack  filter should help collect organic droplets and will reduce the loading on
 the out-of-stack filter.

 6.7   ANALYSIS

 6.7.1  Analytical System Performance Checks

      Method 25 analysis is rarely conducted on-site. Therefore, direct observation of
 the analytical procedures is seldom possible. However, documentation of the quality
 control checks required by Method 25 should  be included in the compliance test report.
 Method 25 requires the following checks to be done at system start-up or after any
period where the analytical system has been unused for 6 months or longer:

             Oxidation Catalyst Efficiency Test
            Reduction Catalyst Efficiency Test
            NMO Response Linearity Test
            CO2 Response Linearity Test
            NMO Analyzer Performance Check
6-12

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       •     Condensible Organic Recovery System Check

       Although these tests and checks are only required at system start-up,
documentation showing each test to be within the specifications of the method should be
included with each report.  The checks are described below.

       The last portion of this chapter addresses performance checks that should be
conducted each day that the system is used for NMO analysis.

       Oxidation Catalyst Efficiency Test - With both the oxidation and reduction
catalysts unbeated, analyze the high level methane standard (nominal 1 percent CH4 in
air) in triplicate.  With only the oxidation catalyst heated to its operating temperature,
reanalyze the high level methane standard in triplicate.  Record data and calculate the
oxidation catalyst efficiency using the following equation:

      Oxidation Catalyst Efficiency = (Rl -  R2)/R1 x 100                 Equation 6-2

where:

      Rl = response with both catalysts unheated
      R2 = response with only oxidation catalyst heated

       If the oxidation catalyst is working properly, the methane is all oxidized to CO2
when the catalyst is heated.  The system response would then be zero during condition
R2. The average response with the oxidation catalyst heated should be less than
1 percent of the average response obtained with  both catalysts unheated.

       Reduction Catalyst Efficiency Test - With the oxidation catalyst unheated and the
reduction catalyst heated to  its operating temperature, analyze the high level methane
standard in triplicate. Repeat the analysis in triplicate with both catalysts heated to their
operating temperatures.  Record the data and calculate  the reduction catalyst efficiency
using the equation below:

      Reduction Catalyst Efficiency = R4/R3 x  100              •        Equation 6-3

where:
      R3 = response with reduction catalyst only heated
      R4 = response with both catalysts heated

       When the oxidation catalyst is heated (condition R4), the methane is oxidized to
CO2 and the reduction catalyst must then reduce the CO2 back to methane. If the
reduction catalyst is not 100 percent efficient, then the CO2 will pass through to the FED
and the response will be lower than the response at condition R3. The responses
observed under these two conditions should agree within 5 percent.


                                                                               6-13

-------
       NMO Response Linearity Test and Initial Calibration - With both catalysts at
 their operating temperatures, perform triplicate injections of each of the following  .
 propane standards: 20 ppm, 200 ppm, and 3,000 ppm in air nominal.  Convert certified
 concentrations in ppm to ppm C by multiplying the ppm concentrations by 3.  Record
 these concentrations on a data sheet, along with the area responses observed for each
 injection. Calculate  the mean response factor as ppm C/mean area for each standard
 and the overall mean response factor for all three standards.  The NMO response
 linearity is acceptable if the average response factor of each calibration gas standard is
 within 2.5 percent of the overall mean response factor and if the relative standard
 deviation for each set of triplicate injections is less than 2 percent. The overall mean
 response factor is used as the initial NMO calibration response factor
       CO2 Response Linearity Test and Initial Calibration - Perform the linearity test
as described above, except use CO2 calibration standards of 50 ppm, 500 ppm, and
1 percent in air. The overall mean response factor is used as the initial CO2 calibration
response factor (RF^).  The CO2 calibration response factor (RFC02) should be within
10 percent of the NMO calibration response factor
       NMO Analyzer Performance Test - After calibration of the NMO response as
described above, analyze each of the following four gas standard mixtures in triplicate.
Standard 1 is nominally 50 ppm CO, 50 ppm CH4, 2 percent CO2, and 20 ppm propane
in air; Standard 2 is nominally 50 ppm hexane in air; Standard 3 is nominally 20 ppm
toluene in air; and Standard 4 is nominally 100 ppm methanol in air.  Record the NMO
area responses for each standard on the data sheet. Convert the certified organic
compound concentrations of the standards to ppm C by multiplying by the carbon
number of the compound (3 for propane, 6 for hexane, and 7 for toluene). Record these
concentrations on the data sheet as the expected concentrations. Calculate the mean
NMO concentration of the test gas.  The analyzer performance is acceptable if the
average measured NMO concentration for each mixture or standard is within 5 percent
of the expected value.

       Condensible Organic Recovery System Check - This check is conducted in three
stages. First, the carrier gas is checked for its blank concentration. The carrier gas
blank value should be less than 5 ppm.  Second, the oxidation catalyst is checked, then
the system is checked by spiking with a known organic concentration.  A schematic of the
condensate recovery system is shown in Figure 6.6, page 6-29.

       The oxidation catalyst efficiency is tested by the following sequence.

       1.    The system is  set-up as normal using a clean condensate trap, and clean
            immediate collection vessel (ICV) which has been evacuated.
      2.    The recovery valve is  set to the vent position, and  the carrier gas is
            replaced with  the 1 percent methane in air cylinder.
      3.    Set the flow from the  1 percent methane standard equal to the normal
6-14

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             carrier gas flow rate. Allow the NDIR response to stabilize, then turn the
             recovery valve to the ICV. Using the flow control valve on the ICV,
             maintain the system pressure near atmospheric. Continue flow until the
             ICV has been pressurized to 300 mm Hg.
       4.     Analyze the CO2 concentration in the ICV using the NMO analyzer. The
             CO2 concentration should agree with the certified concentration of the 1
             percent methane standard within 2 percent

       Hie condensible organic recovery efficiency is checked by setting the recovery
system up as normal, except the condensate trap is replaced with a liquid sample
injection unit similar to that shown in Figure 6.7, page 6-30. The recovery valve is
turned to the collect position, then 50 ftl of hexane  is injected into the liquid sample
injection unit The liquid organic is  collected by the normal procedures of the method.
Hexane has six carbons and the percent recovery is calculated using the following
equation:
                       Percent Recovery=1.604 x -  J^gt          Equation 6-4
where:

      M           =     molecular weight of compound injected, g/g-mole
      Vv           =     volume of ICV tank, m3
      Pf           =     final pressure of ICV tank, mm Hg absolute
      COB         =     measured concentration (NMO analyzer) for the condensate
                         trap ICV, ppm CO2
      L           =     volume of liquid injected, ftl
      p           =     density of liquid  injected, g/cc
      Tf           =     final temperature of ICV, °K
      N           =     carbon number of liquid compound injected (N = 12 for
                         decane, N = 6 for hexane).

      The recovery efficiency should be checked in triplicate with 50 fd hexane, then in
triplicate with 10 /A hexane, 50 fA decane, and 10 pi decane. The percent recovery is
acceptable if the average percent recovery is 100 ± 10 percent with a relative standard
deviation of less than 5 percent for each set of triplicate injections.

      The following set of performance checks  should be performed each day that the
system is used for NMO analysis.

      Leak Test of Condensibles Recovery System - A clean trap should be installed in
the system, then the vacuum pump is used to evacuate the system to 10 mm Hg absolute.


                                                                              6-15

-------
 The system is closed off and the system pressure is monitored for 10 minutes.  The
 system pressure should change by no more than 2 mm Hg over this time period.

       System Background Check for Condensibles Recovery System - The carrier air
 and auxiliary air are set to their normal operating parameters.  The recovery valve is set
 to the vent position and a 10 ml syringe is used to extract a sample from the injection
 port upstream of the NDIR.  The 10 ml sample is injected into the NMO analyzer and
 the CO2 concentration is recorded.  The CO2 concentration should be less than 10 ppm.

       Oxidation Catalyst Efficiency - This test is performed  in the same manner as
 described previously for system start-up.

       CO2 Analyzer Response - The highest level CO2 calibration gas is analyzed  in
 triplicate.  The average peak area is used to calculate a daily response factor for CO2.
 The daily CO2 response factor should agree with the system CO2 response factor
 determined during system start-up.

       NMO Response Check - The gas mixture containing nominally 50 ppm CO,
 50 ppm CH4, 2 percent CO^ and 20 ppm propane in air is analyzed in triplicate.  The
 average area count value is used to  calculate a daily response factor as carbon. The
 daily response factor should be within 5 percent of the initial NMO response factor.

       If audit cylinder samples are  included with the field samples to be analyzed, the
 test results may be accepted or rejected on the basis of the audit results, and the
 performance check documentation may be optional.  However, if no audit is performed,
 the test results cannot be evaluated  without proper documentation of system
 performance and calibration.

 6.72   Calculations

       The calculations required to compute the TGNMO concentration of the original
 sample from the sampling and analytical data recorded are reproduced in Appendix D.3,
 page D^t.  The number of variables is large and some of the equations are complex. It
 is recommended that a computer program or spreadsheet software be used to handle all
 calculations. A copy of the program used for calculations should be included with  the
 test results. Also, example calculations using data from one of the test runs for each test
 series should be included.  The run number of the example calculation must be stated.
 Check to be sure that the example calculation agrees with the reported concentration
within reasonable round-off error. Choose a different test run and perform the
 calculations yourself. The answer should again agree with the reported result to within
reasonable round-off error.

       Calculations should be carried out to at least one extra decimal place beyond that
of the acquired data and should be rounded off after final calculation to two significant
6-16

-------
digits for each run or sample. All rounding of numbers should conform to ASTM 380-76
procedures.

6.8   AUDIT PROCEDURES

      An audit is an independent assessment of data quality. Independence is achieved
if the individual(s) administering the audit and their standards and equipment are
different from the regular field team and their standards and equipment.  Routine
quality assurance checks by a field team are necessary to generate good quality data, but
they are not part of the auditing procedure. Table 63, page 6-31, summarizes the quality
assurance functions for auditing.

      Based on the requirements of Method 25 and the results of collaborative testing
of other EPA Test Methods,  one performance audit is required when testing for
compliance for Standards of New Source Performance and is recommended when testing
for other purposes; and a second performance audit is recommended.  The 2
performance audits are:

      1.    An audit of the sampling and analysis of Method 25 is required for  NSPS
            and recommended for other purposes.
      2.    An audit of the data processing is recommended.

It is  suggested that a systems audit be conducted as specified by the test coordinator in
addition to these performance audits.  The two performance audits and the systems audit
are described in detail in Chapters 6.8.1 and 6.8.2, respectively.

6.8.1  Performance Audits

      Performance audits are conducted to evaluate quantitatively the quality of  data
produced by the total measurement system (sample collection, sample analysis, and data
processing).  It is required that a cylinder gas performance audit be performed once
during every NSPS compliance test utilizing Method 25  and it is recommended that a
cylinder gas audit be performed once during any test utilizing Method 25 conducted
under regulations other than  NSPS.

      Performance Audit of the Field Test - As stated in Section 4.5 of Method 25
(40 CFR 60, Appendix A) and the "Instructions for the Sampling and Analysis of  Total
Gaseous Nonmethane Organics from Quality Assurance Audit Cylinders using EPA
Method 25 Procedures" (supplied with the EPA audit gas cylinders), a set of two audit
samples are to be collected in the field (not laboratory) from two different concentration
gas cylinders at the same time the compliance test samples are being collected. The two
audit samples are then analyzed concurrently and in exactly the same manner as the
compliance samples to evaluate the  tester's and analyst's technique and the instrument
calibration. The information required to document the  collection and analysis of  the

                                                                             6-17

-------
audit samples has been included on the example data sheet shown in Figure 6.8,
page 6-32. The audit analyses shall agree within 20 percent of the actual cylinder
concentrations.  The testing firm may obtain audit cylinders by contacting the agency
responsible for observing and/or evaluating the compliance test and informing the
agency the time and location of the compliance test. The test coordinator will then
contact: U.S. Environmental Protection Agency, Atmospheric Research and Exposure
Laboratory, Quality Assurance and Technical Support Division, Research Triangle Park,
North Carolina 27711 and have the cylinders shipped to the specified site.

       Responsibilities of the Test Coordinator - The primary responsibilities of the
observer are to ensure that the proper audit gas cylinders are ordered and safe-guarded,
and to interpret the results obtained by the analyst

      When notified by the testing firm that a compliance test is to be conducted, the
test coorinator orders the proper cylinders from the EPA's Quality Assurance Division.
Generally the audit cylinders will be shipped (at EPA's expense) directly to the specified
test site. However, if the test coordinator will be  on-site during the compliance test, the
audit cylinders may be shipped to the testing firm for transport to the sampling site.
Since the audit cylinders are sealed by EPA, the testing firm will not be allowed to
collect any audit gas without breaking the seal.

       The audit gas concentration(s) should be in the range of 50 percent below to 100
percent above the applicable standard.  If two cylinders are not available, then one
cylinder can be used. If the applicable regulation is based on removal efficiency rather
than emission limits, an audit cylinder should be provided near the expected
concentration of both the inlet and outlet of the control system.  The testing firm should
provide the test  coordinator with the best available information to approximate the
concentration at the control system inlet. The expected concentration at the control
system outlet can be calculated using the regulated removal efficiency.

       The test coordinator must ensure that the audit gas cylinder(s) are shipped to the
correct-address,  and to prevent vandalism, verify that they are stored in a safe location
both before and after the audit.  Also, audit cylinders should not be analyzed when the
pressurevdrops below 200 psi.  The  test coordinator ensures that the audits are conducted
as described below. At the conclusion of the collection of the audit samples, if the
testing firm will  transport the audit cylinders to the home laboratory for shipment back
to the EPA/QAD contractor, the test coordinator seals both cylinders to ensure that
additional audit  sample gas cannot  be collected without breaking the seal.

       The test coordinator must interpret the  audit results. Indication of acceptable
results may be obtained by the testing firm immediately following analysis by telephoning
the responsible agency with the audit and compliance test results in ppm C. The testing
firm must include the results of both audit samples, their identification numbers, and the
analyst's name along with the results of the compliance test samples in the appropriate
6-18

-------
reports to the EPA regional office or other appropriate agency during the 30 day period
following the test.

       When the measured audit concentration agrees within 20 percent of the true
value, the audit results are considered acceptable. Failure to meet the 20 percent
specification may require reanalysis of the audit samples and compliance test samples,
reauditing, or retests until the audit problems are resolved.  However, if the audit results
do not affect the compliance or noncompliance status of the affected facility, the agency
may waive the reanalysis, further audits, or retest requirements and accept the results of
the compliance test  For example, if the audit results average 38.6 percent low, the
compliance results would be divided by (1 - 0386) to determine the correlated effect. If
the audit results average 58.3 percent high, the compliance sample results would be
divided by (1 + 0.583) to determine the effect.  When the compliance status of the
facility is the same with and without the correlated value,: then the responsible agency
may accept the results of the compliance test. While steps are being taken to resolve
audit analysis problems, the agency may also choose to use the test data to determine
the compliance or noncompliance of the affected facility.

       The same analyst, analytical reagents, and analytical system shall be used for
analysis of the compliance test samples and the EPA audit samples; if this condition is
met, and the same testing firm is collecting other sets of compliance test samples,
auditing  of subsequent compliance analyses for the same agency within 30 days is not
required. An audit sample set may not be used to validate different sets of compliance
test samples under the jurisdiction of different agencies, unless prior arrangements are
made with both agencies.

       During the audit, the test coordinator should  record the coded cylinder number(s)
and cylinder pressure(s) on the "Field Audit Report  Form,"  Figure 6.8, page 6-32.  The
individual being audited must not be told the actual  audit concentrations or the
calculated  audit percent accuracy.

       On-site Collection of Audit Sample(s) - The cylinder gas performance audit
sample collection must be conducted in the field (not laboratory) at the same time the
compliance test samples are being taken. A maximum of 5 liters of audit gas is to be
used for  each test run unless multiple sample tanks are required for sampling. The
testing firm is required to supply a 2 stage regulator (CGA - 350), a glass manifold or
Teflon tee connection, and other suitable Swagelok fittings (they are not supplied) for
use with  the audit gas cylinder. The  recommended procedures for conducting the on-site
audit sample collection are as follows:

       1.     The test coordinator should verify that the seal affixed to the audit cylinder
             by the shipping laboratory is still intact. After the seal has been checked
             by the test coordinator, the testing firm may break the seal. However, if
             the test coordinator is not present at the time  of the audit, the testing firm
             may break the seal and proceed with the audit.


                                                                               6-19

-------
       2.     The tester should set up the Method 25 sampling train and perform the
             leak check.
       3.     The audit gas from the cylinder has to be sampled at atmospheric pressure
             either from a glass manifold or through a Teflon tee connection. This can
             be done by attaching both the cylinder and the probe of the Method 25
             sampling train to two of the manifold or tee connections while excess gas
             flows out through the remaining connection as shown in Figure 6.9,
             page 6-33. This can be accomplished by starting the cylinder gas flow into
             the manifold or tee with the sampling train flow turned off. Then, turn on
             the sampling train flow while adjusting the flow from the audit cylinder to
             ensure excess audit gas flows from the manifold or tee. After the proper
   '''        sampling flow rate has been obtained in the sampling train, adjust the audit
             cylinder so only a few cubic centimeters of excess gas is discharged from
   '"'~" "~     the manifold or tee. The testing firm must ensure that the audit gas is
             conserved.
   '"""'"' 4.     Use the same sampling flow rate and sample volume as used for the field
             test samples.  When a constant flow rate can no longer be maintained by
             the sampling train, it should be turned off and then the audit cylinder shut
             off. Ensure that the audit cylinder is closed tight  to prevent leakage. If
             the compliance test requires more than one sample tank to complete a run,
             each audit sample should use the same number of tanks required by the
             average run.
       5.     The same procedures are repeated for the second audit cylinder using a
             separate sampling train.
       6.     The sampling trains containing the audit samples should be recovered and
             shipped in the same manner as and along with the field test samples.
       7.     In all cases, it is recommended that the test coordinator reseal the audit
             cylinders to ensure against tampering.  However, if the testing firm is to
             return the cylinder to the EPA/QAD contractor, it is mandatory that the
             audit cylinders are resealed by the test coordinator.
       8.     The audit cylinders are  to be shipped back immediately after the test to
             the EPA/QAD contractor at the cost of the responsible agency or the
             testing firm either by ground transportation or air cargo. They are not to
             be shipped collect.

       Analysis of Audit Sample(s) - The collected audit sample fractions (condensate
trap and evacuated tank) are analyzed at the same time as the Method 25 compliance
test samples. Follow the procedures described in Method 25 for sample analysis,
calibration, and calculations.  The same analysts, analytical reagents, and analytical
system shall be used for both the compliance test samples and the EPA audit samples.

       Reporting of Audit Sample(s) Results • The audit sample results are to be
reported to the responsible  agency by the testing firm in terms of condensibles
(condensate trap fraction), noncondensibles (tank fraction), and total (sum of both
6-20

-------
fractions) as ppm C. The agency will in turn report the results to the EPA/QAD
contractor for continuing evaluation of the Method 25 audit program. The testing firm
must also supply the agency with the results of both audit samples as described above,
their identification numbers, and the analyst's name along with the results of the
compliance test samples in written reports to the EPA regional office or the appropriate
agency during the 30 day period.

      Performance Audit of Data Processing - Calculation errors are prevalent in
processing data.  Data processing errors can be identified by auditing the recorded data
on the field and laboratory forms. The original and audit (check) calculations should
agree within round-off error; if not, all of the  remaining data should be checked. The
data processing may also be audited by providing the  testing firm with specific data sets
(exactly as would appear in the field),  and by  requesting that the data calculation be
completed and that the results be returned to the agency. This audit is useful in
checking both computer programs and manual methods of data processing.

6.8.2  Systems Audit

      A systems audit is an on-site, qualitative inspection and review of the total
measurement system (sample collection, sample analysis, etc.). Initially, a systems audit
is recommended for each compliance test, defined here as a series of three runs at one
facility.  After the testing firm gains  experience with the method, the frequency of
auditing may be reduced - for example, to once every four tests.

      While on site, the auditor observes the testing  firm's overall performance,
including the following specific operations:

      1.    Setting up and leak testing the sampling train.
      2.    Collecting the sample at a constant rate at the specified flow rate.
      3.    Conducting the final leak check  and recovery of the samples.
      4.    Sample documentation procedures, sample recovery, and preparation of
            samples for shipment.
                                                                              6-21

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                                               REGULATING
                                                 VALVE
               TEMPERATURE
                CONTROLLER
                          DUAL RANGE
                                                                           MANOMETER
VACUUM PUMP
                                PURGE VALVE

                                      THERMOCOUPLE
                               SAMPLE
                                VALVE
                                      Jl
                           STAINLESS STEEL
                           FILTER HOLDER
                        HEATED BOX
          FLOW
        CONTROL
         VALVE
                                                ROTAMETER
                 STAINLESS
                STEEL PROBE
  •CONDENSATE
      TRAP
                                                                                SAMPLE
                                                                                 TANK
                          Figure 6.1. Method 25 sampling train.
6-22

-------
    TABLE 6-1. METHOD 25 SAMPLING EQUIPMENT COMPONENT
               AND CALIBRATION SPECIFICATIONS
Apparatus
    Limits
  Frequency and Method
 Sample Tank
 Volume

 Sampling Train
 Volume
±5 cc or 5 g


 No Limit
 (suggest ±2 cc)
 Rotameters
     0.9 to 1.1
 Thermometers
Within 3°C
(5.4'F)
 Barometer
 Within 2.5 mm Hg
 (0.1 in Hg)
Initially
Initially and after
replacing any
component; should
have condensate trap
installed during
calibration.

Initially and whenever
calculated sample volume
does not match volume
expected from sample
flow rate (deviation
of > 10%)

Calibrate against
mercury-in-glass
thermometer and in
boiling water;#•
check at ambient temp
before each test;
recalibrate if ambient
check is outside limit

Check against mercury-
in-glass barometer or
National Weather Service
value. Check before and
after each test.
                                                           6-23

-------
                                      VACUUM PUMP
                                        CONNECTOR
                SAMPLE
               SHUT-OFF
                 VALVE
                       25.4
                       1.0
                     RBERFAX
                    INSULATION
            DIMENSIONS:
  PROBE
CONNECTOR
                                    m
                                    m
                                              3.1^5
                                              0.125
                                           CONDENSATE
                                           TRAP PROBE
                                            BULKHEAD
                                           CONNECTOR
                D
             PROBE LINE
            THERMOCOUPLE
          TO TEMPERATURE
             CONTROLLER
    a                    a
 FILTER HEAT            CONDENSATE
 TEMPERATURE            TRAP PROBE
 CONTROLLER    "         CONNECTOR
THERMOCOUPLE           THERMOCOUPLE
                            Figure 6.2. Method 25 filter housing.
   6-24

-------
                                                            : 0.375
                                                                  316 SS NUT
DIMENSIONS:
inn

 in
-WA11 :
WALL
                                                         COARSE QUARTZ

                                                          WOOL PACKING
                                   225
                    Figure 6.3. Method 25 condensate trap.
                                                                               6-25

-------
                                        CARRIER GAS
              CALIBRATION STANDARDS-
                       SAMPLE TANK-
 SAMPLE
INJECTION
  LOOP
 INTERMEDIATE COLLECTION
• VESSEL (CONDmONED
      TRAP SAMPLE)
                                        SEPARATION
                                          COLUMN
                                                     BACKFLUSH
                         CO.CH4lC02
              NONMETHANE
               ORGAN1CS
                                         OXIDATION
                                         CATALYST
                                         REDUCTION
                                         CATALYST
                                           i
                                          FLAME
                                        IONEATJON
                                         DETECTOR
                                           1
               •HYDROGEN
               COMBUSTION
                  AIR
                                      DATA RECORDER
                         Figure 6.4. NMO analytical cycle.
6-26

-------
                       COLUMN OVEN
Figure 6.5. NMO sample delivery schematic.
                                                           6-27

-------
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         6-28

-------
               FLOW METERS
                                            HEAT TRACE (100"C)
                                    SAMPLE
                                   RECOVERY
                                     VALVE
                   FLOW
                 CONTROL
                  VALVE
SYRINGE PORT
VACUUM PUMP
                Figure 6.6.  Condensate recovery system.
                                                                             6-29

-------
          CONNECTING T
                           INJECTION
                           SEPTUM
     FROM 	,
    CARRIER^1
   DIMENSIONS: "
                                                       CONNECTING ELBOW
                                                                  SS TUBING
   TO
CATALYST
                       Figure 6.7. Liquid sample injection unit
6-30

-------
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                   6-31

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Part A. - To be filled out  using information from organization
supplying audit cylinders.
1. Company supplying audit  sample(s) and shipping address

2. Test coordinator, organization, and phone number

3. Shipping instructions: Name, Address, Attention

4. Guaranteed arrival date  for cylinders - 	
5. Planned shipping date for cylinders -
6. Details on audit cylinders from last analysis




d. Audit gas (es) /balance .gas. .


Low cone.



N2
Aluminum

High cone



N2
Aluminum

Part B. - To be filled out by test coordinator.
1. Process sampled	
2. Audit location 	
   Name of individual audit
   Audit date 	
3.
4.	
5. Audit cylinders sealed
6. Audit results:


b. Cylinder pressure before audit, psi. .......
c. Cylinder pressure after audit, psi. ........
d. Measured concentration, ppm C
U— tube fraction ...........................
TanJc fraction .............................
Total concentration .......................
e. Actual audit concentration, ppm C
f. Audit accuracy:1
Low cone . cvlinder .........................
Hi ah cone, cvlinder ........................
Percent accuracy =
Measured Cone. — Actual Conc^ x 100
Actual Cone.
9 Problems detected ( if anvl .................

Low
cone.
cylinder











High
cone.
cylinder










, —
aThe audit accuracy is calculated on the total concentration.

              Figure 6.8.  Field audit report form.
                                                                         I
6-32

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              EXCESS
               FLOW
ROTAMETER
                           ROTAMETErl
         TEFLON TEE*
         OR MANIFOLD
                                            FLOW
                                           CONTROL
                                            VALVE
                                                      MANOMETER
i>      r—i
«»m ^ " ^   i
                                                   SAMPLE
                                                    TANK
                                                   VALVE
                                       CONDENSATE
                                          TRAP
  AUDfT
CYLINDER
     Figure 6.9. Schematic of Method 25 audit svstem.
      SAMPLE
       TANK.
                                                                   6-33

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                                  CHAPTER?
             TOTAL GASEOUS ORGANIC CONCENTRATION USING
               A FLAME IONIZATION ANALYZER - METHOD 25A

7.1   APPLICABILITY

      Method 25A is designed to measure Total Hydrocarbon (THC) concentrations in
flue gas streams. Total hydrocarbons are measured by a flame ionization detector (FID)
on a continuous, real-time basis. No compound separation takes place, so Method 25A
is noncompound specific, like Method 25. Not all hydrocarbons are suitable for analysis
by FID. Highly substituted or halogenated hydrocarbons, in particular, are not amenable
to FID analysis. In general alkanes, alkenes, and aromatics are the most appropriate
compound groups for Method 25A sampling and analysis. Method 25A results are
measured on a wet basis and the concentrations must be adjusted for the percent
moisture in the sample gas stream for the purpose of emissions calculations.

      Method 25A has some advantages over other methods used for measuring organic
compounds.  Specifically, the data is generated continuously in real time.  Method 25A
can only be used in situations where an appropriate response factor for the stack gas can
be determined.  In gas streams that cannot be characterized or which have changing
composition, the response factor for the stream cannot be determined; Method 25A is
not applicable for such a gas stream.

      Method 25A can be used in other situations which require a response factor  to be
established or estimated, for instance, a surface coating operation which uses which four
solvents. The amount of each solvent used as a percentage of the total solvent usage is
known.  A standard is prepared using the weighted percent of each solvent used in the
coating operation. The concentration in ppm as carbon is calculated for the standard.
The standard is introduced to the sampling system and the response factor is calculated.
The analyzed concentrations from the emission  source are then adjusted by  dividing by
the response factor.

7.2   METHOD DESCRIPTION

      Method 25A sampling is performed continuously using a THC monitor.  Sample
gas is extracted from the emission source from a single point in the duct and pumped to
the monitor at a constant rate.  The sample is analyzed by an FID detector and the
resulting electrical signal is proportional to the carbon content of the sample stream
passing through the detector.

      The sample gas is pumped through a Teflon line 1/4 inches to 3/8 inches in
diameter from the sampling point to the  analyzer. The line and the sample pump are
heated to prevent condensation of water vapor or hydrocarbons.  The analyzer and the
detector are also heated. All parts of the sampling system are kept above 121°C (250°F).


                                                                            7-1

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The sample is pumped to the detector at a constant pressure, which is monitored by a
gauge on the analyzer. The analyzer is calibrated and operated at the same sample
delivery pressure to insure equivalent instrument response for the same concentration.

      The FID consists of a flame, fed by hydrogen and air, a  collection ring, and an
amplifier for the electrical signal. A small portion of the sample gas extracted from the
duct is passed through the flame using a capillary tube to restrict the flow.  If the sample
delivery pressure is not kept constant, the flow rate through the capillary is not constant,
and the instrument response will vary accordingly. As the sample passes through the
flame, the organic molecules are burned. The flame and the collector ring are
maintained with a very high electrical potential between them.  As the molecules are
burned, the gas between  the collector ring and the jet becomes conductive due to the
presence of ions given off during combustion.  The ions carry a small current from the
jet to the collector ring.  The current is proportional to the amount of organics being
combusted in the flame.  The current is amplified and output as a 0 to 1 volt signal.

      An FID is capable of measuring hydrocarbons in ranges  varying from 0 to 10 ppm
to 100,000 ppm.  The analyzer is calibrated in the range applicable to the emission limit,
given flow rate estimates. Calibration gases are prepared and the concentrations
certified  by National Institute of Standards and Technology (NIST) methods or EPA
Protocol 1. The gases should be prepared such that three gas concentrations, high, mid-,
and low range, are used for each instrument range. The concentrations should
correspond to 80 to 90 percent of range limit, 45 to 55 percent  of range limit, and 25 to
35 percent of range limit. The range selected (e.g., 0 to 100 ppm ) should correspond to
100 percent of full scale response at one of the available signal amplifier settings. The
highest available response on each range is the range span.  The high range calibration
standard is introduced to the analyzer and the  analyzer output is adjusted so that the
output matches the standard concentration. If the analyzer response is linear, the mid-
and low range gases should give responses equal  to their certified concentrations.

      The analyzer can be calibrated by introducing the calibration gasses directly to the
instrument (direct cal), or by introducing the gases to the inlet of the sampling system
(system cal).  If a direct cal is done, a performance check must  be conducted to validate
the sampling system.  After calibration, the mid-level gas is introduced at the sampling
system inlet and the response is recorded at the analyzer. The  instrument response
should match the calibration gas concentration.  To allow calibration gases to be
introduced into the sampling system as close as possible to the  sample gas inlet, a three-
way valve is installed at the back of the sample probe. The three-way valve is used to
allow either stack gas or  calibration gas to be drawn through the sampling system.  A
diagram of the Method 25A sampling system is shown in Figure 7.1, page 7-14. The
major components of the sampling system are listed below:

      Probe • 1/4 inch or 3/8 inch in diameter.  Constructed of Teflon or stainless steel.
7-2

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       Col/Sample Valve - A three-way valve which allows the analyzer to draw from
either the sampling probe or the calibration line. This should be located at the rear of
the probe and must be heated to 250°F.

       Paniculate Filter - A 25-mm glass mat filter with a cut size of-2 microns or less.  It
must be heated to 250°F.

       Sample Line - 1/4-inch or 3/8-inch Teflon line encased in an insulated shell with
heat tracing.  It must be capable of maintaining 250°F along the entire length of.the line.

       Sample Pump - Teflon-sealed diaphragm piimp capable tif pulling at Least
1 liter/minute and attaining 10 inch Hg vacuum.  The pi'inp-heads .must Jse heated to at
least 250°F.

       THC Analyzer - Hydrocarbon analyzer equipped a flame iomzation detector. The
analyzer should keep the sample stream above 250°F until delivered to the'FID. The
FID must be equipped with an output amplifier compatible wim^ strip chart recorder or
data acquisition system.

       Recorder • A strip chart recorder or data acquisition system capable of recording
the analyzer output continuously or recording the analyzer output average response at
intervals of no greater than 1 minute.  The instrument output voltage should represent
full scale deflection of the strip chart.

73    PRECISION AND ACCURACY                                ~

       The precision and accuracy of Method 25A are defined by the calibration
parameters imposed on  the tester before and after the run. Calibration error is defined
as the deviation of the analyzer response from the true value of a calibration gas.
Method accuracy is commonly determined in this manner. Therefore, the calibration
error can be used to assess the accuracy of Method 25A The specification for
calibration error is ±5 percent of the true value of the calibration gas.

       Calibration  drift  is defined as the deviation between the value determined for a
calibration gas measured before the test run and the value determined for the same gas
after the test run. This is a measure of the reproducibility of the. analysis and represents
the precision of the method. The limit for calibration drift is  ±3 percent of the  span
used for analysis.

      .The precision of the method should remain the same lor all volatile organic
compounds introduced to the system.  However, the accuracy determination is based on
use of a single compound calibration gas.  In situations that require a response .factor to
be used to adjust the analyzed concentrations, the accuracy is  only as good as the
response factor.  If the response factor is generated for a specific compound,-the

                                                                              7-3

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accuracy of the response factor is determined by the care taken in preparing the
compound standard, and the accuracy of the analyzer when used to generate the
response factor. A standard of a different concentration can be used to check the
response factor by comparing the actual reading to the predicted response using the
response factor. The cumulative accuracy limits can be estimated as the square root of
the sum of the squares of contributing limits. If the analyzer accuracy is ±5 percent and
the response factor accuracy is ± 10 percent, the cumulative accuracy limit is (0.052 +
0.102)*4 = 11 percent.  For emission sources where the response factor is estimated, the
accuracy is no better than the estimate of the response factor.

7.4   SAMPLING POINT LOCATION

      Method 25A sampling is conducted nonisokinetically at a constant rate. A
sampling point is selected in one of three ways: (1) the probe can be placed at a single
point in the center of the duct, (2) the probe can be placed at a single point at a position
in the duct with average gas velocity, (3) or a rake-type probe may be used.  If no
stratification is expected in the duct, a single point sample can be extracted.  If the test
location is immediately downstream of the inlet of an auxiliary gas stream or ambient
intake, the concentration may not be constant across the duct.  If this might be the case,
a rake-type probe should be used. The probe is sized to be the same length as  the stack
diameter. Several holes of equal size are drilled in the side of the probe such that the
spacing between the holes is equal. No holes should be placed within an inch of the
duct walls, and it is most important that no holes extend into the port nipple or out of
the duct.  The end of the probe should be blocked, or the majority of sample will enter
the probe through the end.  If paniculate matter is expected  to be present, the holes
should be turned away from the direction of flow to minimize plugging.

7.5   OBSERVATION PROCEDURES FOR METHOD 2SA SAMPLING

7.5.1  Leak Check

      A*leak check of the sampling system is recommended prior to testing.  The .
method does not require a leak check, but it is a good idea to verify the integrity of the
sampling'system before starting a test run.  If the tester can show that the  system
calibration has a calibration error of less than ±5 percent of the certified value of the
cal gas, he may decline to perform a leak check. If a leak check is performed, it can be
done in one of two manners. The first method is to place a vacuum gauge at the probe
tip and draw a vacuum on the system  of 10 inch Hg. A valve is used to isolate the
system from the sample pump. The system vacuum should remain constant for  a period
of 5 minutes. The second method is to plug the probe tip and place a rotameter or
water bubbler at the pump exhaust. The pump should evacuate the system until there is
no flow through the pump.  One disadvantage to this approach is that the system vacuum
will be as high as the pulling capacity of the sample pump, while sampling should never
exceed 10 inch Hg.
7-4

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       The leak check and other sampling procedures are summarized in a sampling
checklist (Figure 7.2, page 7-15) to be completed or used a guide by the test coordinator.

7.5.2  Calibration

       Prior to the start of testing, the hydrocarbon analyzer must be calibrated. The
calibration is done by introducing the high, mid-, and low range calibration gases to the
analyzer to show that the analyzer response reflects the true concentration of the gases.
The analyzer range must be chosen so that the source THC limit is 10 to 100 percent of
the range.  Preliminary traverses may be done to determine the emission source flow
rate so that the allowable concentration limit can be calculated from the mass emission
limits. The allowable concentration limit should be higher than 10 percent of the
analyzer range.  If not, a lower range should be selected until the limit is above
10 percent of the range or the lowest range of the analyzer is reached.  The allowable
concentration limit should not be above 100 percent of the analyzer  range unless the
source concentration is expected to be less than 10 percent of the allowable
concentration limit.

       The calibration gases are usually propane in air or propane in nitrogen. Some
regulatory agencies may require that the calibration gases be methane in air or nitrogen.
If the calibration gases are propane, the propane concentrations should be multiplied by
three to represent the concentration as carbon in the cylinder.  If the calibration cylinder
concentrations are not adjusted to carbon concentration, the test results must later be
multiplied by a K factor of 3.0 to adjust for the number of carbons in the calibration gas.
Any gas standard may be used as a calibration standard if it is National Institute of
Standards and Technology traceable and the K factor is known. The K factor for
methane is 1.0.

       The calibration gas may be introduced directly into the analyzer or through the
sampling system. A  cylinder of carrier grade purity zero air containing no hydrocarbons
is introduced to the analyzer and the back pressure to the FID  is set The zero offset
adjustment of the analyzer is set such that the analyzer output is 0 ppm ±3 percent of
the span.  The high range calibration gas is then introduced to the analyzer. The
amplifier gain adjustment is set such that the analyzer output matches the calibration gas
certified value within 5 percent of that value. The actual analyzer response is  recorded
and a calibration factor is calculated. The calibration factor is  equal to the certified
cylinder concentration divided by the analyzer response in divisions:

                          CF  =    Certified Cylinder Value             Equation 7-1
                                # Divisions Analyzer Response

If the high range cylinder value is 85.7 ppm and the instrument  response is 84.6 divisions,
the calibration factor is:
                                                                                 7-5

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                          CF
                                84.6 Divisions
1/013 ppm
 Division
Equation 7-2
       Since the amplifier gain is set such that the recorded value is ±5 percent of the
true value, the calibration factor should always fall in the range of 0.95 to 1.05.  If higher
instrument ranges are used, the factor will be some factor of ten, e.g., 9.5 to 10.5 (for a
factor of ten) or 950 to 1050 (for a factor of one-thousand).

       The calibration factor is used to predict the  response for the mid- and low range
gases using the following equation:
             Analyzer Response = Cylinder Concentration
                                    Calibration Factor
                       Equation 7-3
      The actual response must be within 5 percent of the predicted response.  This
procedure is a linearity check on the analyzer. A linearity check must be done once for
each set of test runs.  If any range is to be used other than the one in which the linearity
check is performed then a mid-level gas in that range is introduced to confirm the
multiplier for that range. The analyzer response for the mid-level gas in each range
must agree with the cylinder value within 5 percent.

      When the linearity check is done through  the sampling system using the cal
sample valve at the rear of the sample probe, the integrity of the sampling system is not
in question. However, if the calibration is done directly through the analyzer, a
performance check must be conducted using the  high range gas. The high range gas is
purged through the calibration line to the cal/sample valve.  A T" with a rotameter on
the tap  leg is placed in the calibration line before the cal/sample valve.  The rotameter
allows excess calibration gas to dump to the atmosphere. The flow rate through the
calibration valve is set such that, with the sample pump on, the dump rate at the
rotameter is less than 2 liters per minute.  If no dump were provided in the system, the
calibration gas would pressurize the system and system leaks would not affect the
performance check results.  When the cal/sample valve is switched to sample, the system
is under negative pressure and system leaks will be indicated by the test results. If the
dump rate falls to  zero flow, ambient air will be  drawn in through the rotameter and the
performance check results will be low.  If the dump rate is too high, the ability of the
rotameter to relieve the delivery pressure of the  calibration gas will be exceeded and the
sampling system will still be under positive pressure. A diagram of the
calibration/sample valve with an ambient dump is included in Figure 7.3, page 7-16.
7-6

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 7.5.3  Response Time Test

       Response time is defined as the time required for a step change in system
 conditions to show a response at the analyzer equal to 95 percent of the step change.
 The response time of the sampling system must be checked to assure that the sample is
 delivered from the emission source to the analyzer in an acceptable period of time. No
 limit for response time is set in Method 25A. A typical response time is less than one
 minute, and should not be over two minutes.  A long response time indicates that the
 flow rate of sample being drawn by the sample pump is not high enough for the test
 conditions. Any test which requires more than 100 feet of sample line will probably
 require a pump that can pull at least 1 liter per minute to keep  the response time down
 to an acceptable limit.

    .,  The response time test is accomplished by first purging the sampling system with
 zero air with the calibration/sample valve turned to calibration.  The zero air flow is
 stopped and replaced as quickly as possible with the high level calibration gas.  A
 stopwatch is used  to record the time taken for the instrument response to equal
 95 percent of the high level cal gas value. This procedure is repeated until three step
 changes have been measured.  The three response times are averaged and recorded as
 the response time for the test series.
                          .   •                    '                    .«
 7.5.4  Sampling Procedures                                          . ".

       Sampling is initiated by turning the cal/sample valve to the sample position and
 starting the sample pump and data recorder.  A period of time longer than-the response
 time of the system must be allowed to purge the system with sample gas.  The start time
•for the test run is  marked on the data recorder.  If a strip chart  is used for'recording
 data, a separate data sheet should be used to record one-minute averages from the strip
 .chart trace.  The delivery back pressure to the FID must be maintained at the same
 Tahie used for calibrations. The analyzer and recorder are allowed to operate with no
 adjustments except those needed to maintain FID delivery pressure for the required test
: duration.  Any process changes or interruptions should be recorded on the strip chart or
 in a test log.

       For test runs longer than one hour, it may become necessary to interrupt the test
 run to check the calibration drift and zero drift of the analyzer.  No adjustments to the
 output multiplier may be made between the pretest calibration and the calibration drift
 check.  The drift check is also performed immediately following  completion of the test
 run.  On longer test runs, the drift check may be performed as often as every hour.  If a
 drift check is done and the drift exceeds 3 percent of the span value or the zero drift
 exceeds 3 percent of the span value, the data collected prior to the drift check are
 invalid. The system must be adjusted and recalibrated and the testing repeated. For
 example, if a four-hour test run is in progress with a drift check performed every hour,
.and the drift check after the third hour is outside.the specifications, the  data recorded

                                                                               7-7

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 between the second-hour drift check and the third-hour drift check is considered invalid.
 The analyzer is recalibrated and the testing is resumed.  The third-hour of testing is
 repeated and if the hourly drift check is acceptable, the fourth hour of testing is then
 completed.

       Alternately, the sampling system may be recalibrated without adjustments.  The
 calibration factor from the new calibration is recorded and the results are reported using
 both the pretest calibration factor and the post-test calibration factor. The agency will
 accept the data showing worst case results.

 7.5.5  .Establishing Response Factors

      , Response factors can be established in three ways: (1) using a gas standard of
 known concentration, (2) using a liquid standard of known concentration, and (3) using a
 liquid standard of unknown concentration. The proper approach will be determined by
 the specifics of each test for which Method 25A is applied.  The testing firm should
 insure that the procedures for establishing response factors have been approved by the
 appropriate regulatory agency prior to testing.  The three methods are described below.

       Gas Standard - If the molar fraction of each compound present in the emissions
 is known before testing, a gas standard in the same ratio of mole fractions can be
 prepared for the response factor test. The concentration as carbon is calculated for the
 gas standard. The gas standard is introduced to the calibrated analyzer and the analyzer
 response is recorded. The response factor is equal to the predicted response divided by
 the actual response.

       The response factor should be established on the day of testing. An FID uses a
 flame to oxidize hydrocarbons.  The response factor is a function of the efficiency of the
 flame to perform this oxidation.  Each time the flame is extinguished and relit, its
 efficiency may change. Therefore, the same flame should be used to establish the
 response factor as is used for testing.  If multiple days of testing are planned, the
 response factor should be reestablished each day. An alternative to establishing the
 response factor on the day of testing is to determine the response factor in the lab
 before testing.  The flame must then be extinguished and the system allowed to cool.
The analyzer is then relit from a cold start. The response factor test is performed again,
 and the results compared to the previous test.  If the deviation between the two response
 factors is <5 percent of the first response factor, the two are averaged and the average
 response factor is used for the test.

      Liquid Standard of Known Composition - A liquid standard of known
 composition can be used to make a gaseous standard by volatilizing a small amount of
liquid into a gas cylinder or Tedlar bag. A heated injection port is recommended to
 assure that all of the liquid is volatilized.  The cylinder or Tedlar bag should be filled
with a metered amount of zero grade air  or nitrogen. The composition of the liquid,
7-8

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volume of liquid injected, molecular weight of each component-density of the liquid, and
volume of diluent gas used must be known to calculate the concentration of the resulting
gas standard. The response factor determination is then done exactly as for a gas
standard.  Polar compounds such as alcohols are not stable in Tedlar bags; it is
recommended that cylinders be used for alcohols or that the response factor be
determined immediately after the standard is prepared in a Tedlar bag.

       Liquid Standard of Unknown Composition - If the test program entails measuring
the emissions from a process which uses a solvent which is a complex mixture that
remains constant hi composition, a known mass of the solvent can .be used to generate a
response factor. This is not truly a response factor since there is jio^predicted response.
Normally the response factor has no units.  A response factor produced from a liquid of
unknown concentration has the units of divisions fesponse/mass/vohime. Since ihe
carbon content of the liquid is never determined, this response factor cannot be used
when the emission limit is expressed as Ibs carbon, but may be used for mass balance
determination such as a capture efficiency test.

       The solvent is used to make a gas sample in the same manner as described for
the liquid of known concentration. The  mass of solvent used must be measured or can
be calculated if the density of the solvent is known. The total volume of the air or
nitrogen introduced into to the cylinder or bag  is also measured.  The mass
concentration of the gas standard is calculated by  dividing the mass of solvent injected by
the volume in the container. The concentration units are mass/volume (e.g^ nag/liter).
When the gas standard is introduced into the analyzer, the response is recorded and the
response factor is calculated by dividing  the divisions of response  by the standard
concentrations. Since the composition of the liquid is unknown, the boiling point of the
liquid is also unknown, therefore, a heated injection port must be used to make the gas
standard. The container  should be checked for  condensation and the injection port
temperature should be kept above  250°F.

       An example of this technique follows: The  exhaust over a couniercuriEnl solvent
rinsing station is sampled. As  long as the operation remains steady state, the
concentration in the dip tank remains constant, but it is difficult to estimate the
composition in the tank.  A sample is taken from the tank and 10 ml is weighed to
establish the density of the  solvent. 50 fil of solvent at a specific gravity of 0.88 are used
to make a gas standard in a bag containing  10.5 liters of nitrogen. The resulting gas   -
standard is introduced to the analyzer and the response is 54.5 divs.

             Gas Concentration  =     (50 u\ x 0.88 mg/al
                                           10 J liter                   Equation 7-4
                                      4.19 mg/1

            Response Factor    =     54.5 divs
                                      4.19 mg/1                       Equation 7-5
                                      13.01 divs/mg/1
                                                                               7-9

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The first test run resulted in an average instrument response of 41 divisions and the flow
rate through the exhaust was calculated to be 1000 scfm which translates to
28320 standard liters per minute.  The emission rate of solvent through the exhaust is:
       Concentration of Exhaust
    41 divs
                                      13.01 divs/mg/1

                                      3.15 mg/1
                                Equation 7-6
       Mass Emissions
3.15 mg/1 x 28320 liters/min x 60 min/hr
5352480 mg/hr x 1 lb/454000 mg
11.79 Ib/hr                      Equation 7-7
7.6    SAMPLING PROBLEMS AND SOLUTIONS

7.6.1   Gold Spots in Sampling System

       The sampling system is heated to 250°F for two reasons:  first to prevent
condensation of hydrocarbons in the sampling system. Second, to prevent condensation
of moisture in the system. Some organics are soluble hi water, and water condensed in
the sampling system could act as a scrubber causing sample loss.  Also, water droplets
carried into the analyzer can cause malfunction of the gauge reading the back pressure
to the FID. Although the FID will still be functional, the faulty back pressure reading
could cause the flow to the FID to change and result in incorrect readings.

      No part of the sampling system may drop below 121°C (250°F).  Any part of the
system found to be less than 121°C (250°F) must be heated or replaced. Since heated
lines are insulated, it is hard to tell how hot the sample line is at any one point.  One
quick check is to disconnect the sampling system at die entrance to the analyzer. With
the lines heated and the sample pump operating at its normal flow rate, the exit
temperature from the pump is measured and should be a 121°C (250°F).  Some other
things to-look for are: (1) temperature  drop in unions between two lengths of sample
line, (2) unheated or uninsulated Teflon showing anywhere hi the system, (3) sudden
concentration spikes from what should be  a steady state process, and (4) an inadequately
heated filter or calibration/sample assembly.

      Two inches of unheated stainless steel or four inches of unheated Teflon is
enough to cause condensation in a sample line.  Unions between lines should be  too hot
to touch or they should be wrapped with a heat tape to keep them above 121°C (250°F).
The filter and calibration/sample assembly should also be wrapped in heat tape.  Sudden
concentration spikes which cannot be explained by process changes may indicate
moisture condensation in the line which is passing through the back pressure regulator in
droplets.
7-10

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7.62   Sampling System Leaks

       Anytime a performance check or calibration drift check is conducted and the
results are lower than expected, the cause could be a sampling system leak. If the cause
of the low value cannot be found, a leak check should be done on the system. If a leak
is found, the results from the preceding test run should be invalidated.  A leak cannot be
considered constant, and the results of the preceding test should not be reported using
either the pretest or post-test calibration.

7.6.3   High Moisture

       Because the THC analyzer operates under positive pressure and because the back
pressure gauge is  mounted on the front of the analyzer and acts as a cold sink, a high
moisture content in the sample gas can cause problems using Method 25A. The oven
temperature of the analyzer can be turned up to help alleviate the problem.  However,
the oven temperature should be set before the calibration.  Moisture condensing in the
pressure gauge would be part of the bypass stream and would not be considered a loss of
sample.  However, this moisture will affect the reading on the gauge. The gauge may be
replaced by running a line to a mercury manometer. The line to the manometer should
be heated. A  small amount of condensation in the manometer will not greatly affect the
reading due to the difference in density between mercury and water.  A column of
13.6 inches of  water would have to collect in the manometer before affecting the
manometer reading by one inch of Hg.

       Method 25A may not be applicable for testing emissions containing more than 40
percent by volume of moisture.  These situations should be reviewed on a'case-by-case
basis to determine the most appropriate method of testing.             •—

7.6.4  Adjustments to Gain or Zero Offset

      When multiple test runs are being done, the calibration drift is checked after each
run. If the calibration has drifted, but is still within the limits, the run data is acceptable.
The tester may want to readjust the output gain to eliminate the drift. If the pot is not
reset, the drift may exceed the  limit by the end of the following run. This  may also be
true for the zero offset

      The gain or offset may be adjusted by the following sequence:

       1.    The results of the calibration drift check and zero drift check performed
            prior to adjustment are recorded as the post-test drift check for the
            preceding run.
      2.    The gain and offset may then be adjusted.
      3.    The analyzer calibration and zero offset are checked again.  The results are
            recorded as the calibration and zero offset pretest check for the next run.
                                                                              7-11

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 7.6.5  High THC Concentrations

       Some hydrocarbon analyzers can be used to measure concentrations up to
 10 percent by volume as carbon.  Many, however, are not linear above concentrations of
 4 to 6 percent carbon by volume. When emission concentrations at a facility are higher
 than this, two strategies may be used.

       The first strategy is to dilute the sample before introducing it to the analyzer.
 Any of a variety of dilution techniques may be used. The dilution ratio of the sampling
 system must be calibrated after the analyzer calibration is completed. A high range
 calibration gas of the same compound used for the analyzer calibration is introduced to
 the system through the calibration position of the calibration/sample valve.  The dilution
 ratio is the ratio of the known calibration concentration and the analyzer response.
 Propane standards are available at concentrations as high as 8 percent (24 percent as
 carbon), or liquid propane tanks can be used to provide 100 percent propane gas.  If
 8 percent propane is used as the dilution standard and the instrument response were
 5300 ppm as carbon, then the dilution ratio is:
             Dilution Ratio
240.000 ppm C
 5300 ppm C

45.3
                                                                     Equation 7-8
       The second strategy is to reduce the flow rate of the sample to the FDD. This will
extend the range in which the FID is linear. Conversely, the sensitivity of the FID will
be reduced. The flow rate can be changed most easily by installing a smaller capillary to
the FID.  Using the same back pressure, the flow change through the capillary is
proportional to the ratio of the square of the capillary diameter. The analyzer must be
calibrated after changing  the capillary. The calibration gases must bracket the expected
concentrations from the emission source. Since propane standard upper concentrations
are limited, methane or ethane would provide a more appropriate  calibration standard.

7.7    AUDITS

      A performance evaluation audit is not required by Method 25A because the
calibration gases must be  NIST traceable and serve as an audit each time a system
calibration is performed.  The testing firm should not, however, refuse an audit if the test
coordinator deems one necessary.

      The audit material must be limited to the gas compound in  the calibration
standard(s). Also,  the audit sample concentration must be  in the range used for the test
runs.  In order to assure that the audit samples are appropriate, the test coordinator
must contact the testing firm prior to the test and inform them that an audit will  be
performed. The compound used in the standards and the calibration ranges expected to
be used during testing must be identified.
7-12

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       The audit gases must be prepared according to MIST guidelines or EPA
Protocol 1 guidelines.  The cylinder concentrations should be certified to ±2 percent of
the tag value.  Three to six weeks should be allowed for preparation and shipment of the
audit cylinders.

       The audit gas is introduced into the sampling system in the same manner as the
calibration gas used for calibration drift checks.

       No limit is specified for audit accuracy, however, the audit accuracy should fall
within the 5 percent limit imposed on calibration error. The tester may be allowed to          "^
reset the output gain and zero offset before the audit if the calibration drift and zero          "'
drift checks have been performed and recorded for the previous runs.
                                                                               7-13

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7-14

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                Test coordinator complete once per test series.
                  Check if acceptable;  "X" if not acceptable.
Leak Xest
 Was a Leak Check done   	
      TIES   	     What was the Leak Rate  	   .intended mow Rate	
      NO    _____     See Performance Check

Calibration
 Is applicable limit >10% of analyzer range 	  <100% analyzer .range 	
 Are calibration gasses NBS traceable or EPA Protocol 1  	
   What gae is used as Calibration Standard   	"__
   What is the K factor    Methane = 1      Propane » 3
         	Ethane  = 2      Butane  —-4
 Was calibration direct or system cal   	
   High Range Calibration Gas Tag Value	 Analyzer response	.±5%	
   Mid-Range Gas Tag 	  Predicted Response	..-Analyxer .Response ±5% __
   Low Range Gas Tag 	  Predicted Response	  Analyzer Response ±5%	

Performance Check  -   Not Necessary if Calibration was done Through System
 Tag Value of Calibration Gas  	
   Analyzer Response
   Analyzer Response ± 5% of Tag Value  	

Response Time Test
 Three repetitions performed
   Average Response Time < 2 mini	

Post-test Calibration Checks
 Calibration Drift Check  - Pretest Response  	   Post-test Response	
   Deviation s 3% of Span  	
 Zero Drift Check - Pretest Response  	      ,    Post-test Response  	
   Deviation S 3% of Span  	

Response Factor
 Was a response factor used  	
  How was the Response Factor Generated   Gas Standard  	
                                 Known Liquid Standard  	
                               Unknown Liquid Standard _____
 What is the Response Factor        Units of Response Factor _____
  Unitless if Gas standard or Liquid Standard used.
 . Units of mass/volume/division if Unknown Liquid Standard used.	
                    Figure 7.2. Method 25A sampling checklist
                                                                          7-15

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               SAMPLE
                PROBE
     STACK
                               HEATED
                              THREE-WAY
                                VALVE
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                                                                      AMBIENT
                                                                       DUMP
                                               H ROTAMETER
                                              CALIBRATION
                                                  GAS
                             SAMPLE

                           TO ANALYZER
          Figure 13. Calibration/sample valve assembly with ambient dump.
7-16

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                                   CHAPTERS
                REVIEW PROCEDURES FOR VOC TEST REPORTS

       The compliance test report is written by the testing firm and submitted by the
facility. It is typically the test coordinator's responsibility to review the report. Some
states lack written guidelines that specify the compliance test report format and
          data reporting requirements. This chapter provides a standardized report
format that can be used by the testing firm in the preparation of the compliance test
report and instructions on compliance test report review for the test coordinator.

8.1   VOC COMPLIANCE TESTING REPORT FORMAT

      EPA's NSPS does not have or need a deadline for submission of the report after
completion of the compliance testing, since there is a deadline for submission of the
report without regard to timing of the compliance test.  Unless the state and local
agencies have a deadline for VOC compliance test results to be submitted to the
responsible agency by the facility representative,  it is recommended that a sixty (60) day
limit from completion of the field work is recommended.  The report should include, but
is not limited to, the  following:

      1.     Basis format and information shown in Figure 8.1, Page 8-8.
      2.     Certification by testing firm representative stating that sampling
             procedures, analytical procedures, and data presented in the report are
             authentic and accurate.
      3.     Certification by testing firm representative (preferably by a professional
             engineer) that all testing details and conclusions are accurate and valid.
      4.     Certification by a facility representative that the facility process data are
             correct to the best of his/her knowledge.
      5.     Calculations  made using applicable equations shown in the  applicable
             method. An example calculation should be shown for one run,
      6.     Final results presented in English and metric units and containing  two
             significant digits for each run.  Values may be rounded off to three
             significant digits after calculation of each equation and two digits for the
             final results or all digits may be carried in the computer and rounded to
             two significant digits only for the final results.  All rounding of numbers
             should be performed in accordance with the ASTM 380-76  procedures.

8.2   REPORT REVIEW

      The following discussion of report review procedures assumes that the test
coordinator has (1) reviewed a written test protocol, (2) stated the requirements of the
compliance test to the testing firm and facility, (3) conducted a pretest survey of the
facility, (4) observed facility operations during the test, (5) observed the sampling
procedures during the test, and (6) required the testing firm to conduct a performance audit.


                                                                             8-1

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       Figure 8.2, page 8-10, is an example compliance test report review form.  The test
 coordinator may complete the form or use it as a guide for the report review. This
 report review form contains three sections:  "Report Contents," "Report Comments," and
 "Summary of Results."  The first section of the form is presented in order of the report
 format. The test coordinator should verify whether each item was included by checking
 "yes," "no," or "OK."  "OK" means the information is not complete, but it does not effect
 the report review.  When the "no" or "OK" column is marked, the test coordinator should
 state the reason for that mark.  Deficiencies should be noted and specific
 recommendations and conclusions made in the "Report Comments" Section.  The test
 report should be reviewed in its entirety.

       The following subsections provide some discussion of the content and review of
 specific parts of the compliance test report.

 8.2.1  Coyer, Certification, and Introduction

       The cover and certifications are self explanatory.  The following items should be
 in the  Introduction of the report.

       Test Purpose - The purpose for testing will typically be to comply with  one or
 more of the state or federal regulations. A complete description of purpose(s) and/or
 applicable regulation numbers should be given, for example:  state  regulation  (list
 regulation No.), federal regulation (list regulation No.), obtain a permit, certify a
 monitor, establish an alternative emission limit, or establish a control or transfer
 efficiency.

       Test Location * The test location description should provide sufficient information
 to ensure  that there is no confusion as to which process and control equipment emissions
were tested.

       Source Identification No. - Many agencies assign a source identification number
 to each facility and each process or emission point in the facility. If an ED  number exists,
 the correct number should be used.

       Test Dates,  Pollutants Tested, Plant Representative Name, and Any  Other
Background Information - This  is self-explanatory.

8.2.2   Emission Results and Performance Audit Results

        A quick review of the results, including appendices, to assure completeness of
the reported results and determine if the values seem reasonable (i.e., correct moisture,
 temperature, and pressure corrections) may be helpful. Report revisions should be made
by die testing firm.
8-2

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       Comparison of compliance test emission results with screening method emission
results, if performed, should reveal obvious errors.

       The performance audit results should be compared to the EPA audit sample
values. For Method 18, audit results should fall within 10 percent of EPA audit sample
values. This method allows for discretionary acceptance for any audit value which does
not fall within the 10 percent range based on the effect on the facility's compliance
status.

       The is another consideration in interpreting results form analysis of EPA audit
gases. Acceptable results on EPA performance audit gases does not ensure correct field
sample results. The atmosphere surrounding any compound of interest is referred to as
a "sample matrix." The sample matrix for audit gases is typically pure nitrogen.  The
target compound in a stack gas will have a more complicated matrix.  Occasionally there
is a component in the stack gas matrix which causes an analytical interference.  If this
interferant has the same retention time as the target compound (the volatile organic
compound found in the audit gas cylinder),  then the analyzed audit gas concentration
could be correct, while the  additive effect of the interferant compound would cause the
analyzed concentration of the compound in the stack gas to be biased high.  The target
compound and the interferant compound would create a single peak.  The concentration
value supplied by the area of this peak, would not be representative of the true
concentration of either component.

       EPA audit gas "true  value" results are accurate to about ±5 percent.  EPA audit
materials are obtained from and analyzed by an EPA contractor.  Yearly audits of these
contractors and their audit materials have shown error and Variance as great.as
5 percent.  EPA audit reports issued annually summarize all audits conducted, and when
necessary, assign new values to each audit cylinder. The test coordinator can use the
EPA audit summary report to assess the variation in the  reported audit value for the
actual cylinder used. The test coordinator may make the acceptability criteria the  10
percent allowable error plus the deviation in EPA audit values for that cylinder.

       Audit sample results should never be used to correct field data results. To
determine the effect the audit results have on the compliance status of the facility, the
test coordinator should mathematically adjust the field results to determine if the
compliance status would change.  For example: the allowable emissions were 100 ppm,
the average emission results were 80 ppm, and  the audit  results were 25 percent low (75
percent of the true value).  Corrected, the 80 ppm emission (results which are in
compliance) would become (80 divided by 0.75) 107 ppm, which shows noncompliance.
The test data, for this example, should be rejected because the audit results were outside
of the acceptable range and the results of the audit samples affect the compliance status
of the facility. Use of the same values with audit results  with 25 percent high would
yield adjusted data showing the facility in compliance, but by a greater margin.  The test
coordinator could accept  the results, if desired.

                                                                               8-3

-------
       Process and Control Equipment Data - The test coordinator can review his field
 observation notes to ensure that the reported process data are consistent with agency
 observations.  If data regarding raw materials, product, or collected materials are related
 to determination of compliance, they should also be presented.

       Allowable Emissions - The facility should restate the emissions standards. This
 demonstrates  an understanding of the applicable regulation(s).  It is beneficial for the
 test coordinator to make an independent assessment of the allowable emissions. Any
 differences should be noted and the report corrected accordingly.

       Discussion of Errors (real and apparent) - This discussion is important to the
 future validity of the data. If the testing firm and the facility state that the data is valid,
 then they-will not be able to easily  discredit the data at a later time.  Testing firms do
 not like to admit errors.  However,  when they do state that the data is invalid, the
 agency typically requires a retest. If no errors were noted by the testing firm or facility,
 it should be recorded in the report  that "no errors were noted." If errors are noted, the
 test coordinator writes his observations regarding these errors on the review  form.

 8,2.3   Facility Operations

       Facility operations may be critical in establishing compliance with the emission
 standard(s). The following items should be evaluated.

       Description of Process and Control Equipment - The process and control
 equipment descriptions in the test report must be sufficient to (1) identify the process
 and control equipment in comparison to the permit to operate and (2) allow the agency
 enforcement inspector to determine if the facility does make major modification to
 process or control equipment.

       Process and Control Equipment Flow Diagrams - The report should include a
 flow diagram which shows all ducts  leading in and out of the process and control
 equipment of  interest and any auxiliary systems that can be enabled or disabled. The
 diagram will allow the test coordinator to determine whether the system has  been
 modified since it was last tested.

       Process Parameter, Materials and Product Results (with example calculations) -
 The process operating parameter, raw materials, and product results should be presented
 as required to determine compliance with applicable regulation(s). Some facilities
 cannot directly determine process rates and use indirect measurements with  assumed
 factors to calculate process rates.  For example, if a facility assumes that the  final
product contains 5 percent of the organics input as residues, then they must  state
whether they consider this to be a constant factor or a variable factor. The effect on the
 compliance status may be small, but it is to the advantage of the agency that the facility
 not be allowed to change their assumptions to fit their needs at a later date.
8-4

-------
       Calculations should be checked to ensure that reported values include the proper
assumptions, are based on the correct equations, and are~mathematicaliy correct. The
test coordinator may wish to assign a confidence limit to each value.

       Describe Process Operations Tested - If the process is cychc or a batch operation,
the report should describe the portion(s) of process cycle covered by the testing and the
rationale for selecting them. This is important because facility could stretch out a cycle
to reduce emissions during sampling. When cycles .of operation or batches are
compressed or reduced, emissions are typically higher. The portion of the process cycle
tested should be approved by the agency prior to sampling.

       Representativeness of Process Parameters, Raw Material, and Products - It is
preferable if the facility representative or testing firm state that the process parameters,
raw materials, and products were representative.  If this information Js.notistated.ia a
report showing  noncompliance, facility representative may later claim that the facility
was tested under conditions of upset or malfunction.

       Two items not typically presented in a compliance test report^tiiat should be
determined during the pretest survey are (1) the normal process maintenance schedule
and (2) how malfunctions are handled.  These may be specified in the permit to operate
and should be checked by inspectors in the future.

       Describe Control Equipment Operations Tested - Many VOC control systems
involve cyclic operations. For  example, two carbon bed absorbers in parallel may be
used as a control device. One is cleaned while the other is collecting emissions.
Depending on the methods of bed cleaning and switching from one  bed to^the  other,
emission rates may be the highest at the beginriing or end of the cycle. Removal or
recycling of the collected material is another area of concern.  The faculty should not be
allowed to change their cycle of operation or method of removing collected .material for
the compliance test.

       Representativeness of Control Equipment Parameters and QUtected^Materials -
The same concerns apply here as for the process parameters.

8.2.4   Sampling and Analytical Procedures

       Sampling Port Location(s) and Dimensions of Cross-section -Ensure that the
sampling location drawings are accurate and that the mass emission.rates are directly
related to the area of the stack.

       Sampling Point Description (including labeling) - Check on the accuracy of the
description.
                                                                               8-5

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       Brief Description of Sampling Procedures (including equipment and diagram of
the sampling train) - Hie EPA Methods include many options regarding equipment and
procedures. For example, Method 18 sampling can be performed by at least six
approaches. A detailed and accurate diagram of sampling equipment and a description
of the sampling procedures used should be included in the compliance test report

       Deviations of Sampling Procedures from  Method -The compliance test report
should address any deviations (planned or not) from the standard method including an
explanation justifying the deviation(s).  Planned  deviations to the standard test method
should obtain pretest approval from the agency.

       For accidental deviations, the report should provide a description of the deviation
and expected effect  When appropriate,  the test coordinator should comment on what
effect the accidental  deviation had on the validity of and the degree of confidence in the
emission results. If the test coordinator does not feel qualified to make this
determination, the VOC emission measurement  contact for the agency can be consulted.

       Brief Description of Analytical  Procedures (including calibration) - The analytical
equipment (e.g., the detector and column), analytical conditions (e.g., oven temperatures,
isothermal analysis, program temperature ramping analysis, gases, and fuels), calibration
procedures, and calibration materials should be  described. The report cannot simply
state that Method  18 allows at least five approaches for preparing the calibration gases.

       Analytical Deviations from Standard Method - See the discussion above on
sampling procedure deviations.

8.2.5   Compliance Report Appendices

       As previously noted, the test coordinator may find it more productive to review
appendix material  first  The essential  elements of the appendices are discussed below.

       Complete Results with Example Calculations - Example calculations should be
provided in the report showing the individual equations and input data.  These
calculations should be checked, with special attention given to all assumed values or
factors used to determine emissions presented in the test report (e.g., molecular weight,
moisture content, and correction factors).  The testing firm should include raw data,
equations, and calculations for all measurement  and calibration procedures in the report.

       Raw Field Data - Check the field data for completeness. It is a good policy for
the test coordinator to sign all completed  field data forms while in the field.  This
practice discourages the alteration of raw  data by the testing firm.
8-6

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       Laboratory Reports, Signed Chain-of-Custody Sheets - Acceptable audit sample
results ensure that the proper detector was used and that the calibration gases were
prepared correctly.  When acceptable audit sample results are obtained, errors in
compliance sample results are generally biased positive to positive interferences.

       The test coordinator should refer to the appropriate chapter in this manual (e.g.,
Chapter 4 for Method 18) to determine exact procedures for validating the analytical
results for a specific method. Although it is the responsibility of the analyst to identify
and eliminate interferences, the test coordinator may wish to compare the retention
times, peak resolution, and peak shapes for the calibration standards, audit samples, and
field samples.

       When performance audit samples are not used in the test program, the test
coordinator will need to conduct a evaluation of the calibration standards used. When
no audit samples are analyzed,  all test results are based on the value assigned to the
calibration standards. Therefore, it is critical that the calibration standards are assigned
the correct values.

       Calibration Procedures and Results - Calibration results are used to calculate
emission concentrations and mass emission results. Complete documentation of
sampling equipment and analytical instrumentation calibration, including complete
presentation of results and calculations should be included in the compliance  test report.
All calculated values must be within round off error of the true value.

       Raw Process and Control Equipment Data (signed  by plant representative) - The
test coordinator and facility representative should sign process and control equipment
data sheets.

      Test Logs, Project Participants and Titles, and Related Correspondence - Self-
explanatory.
                                                                                8-7

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       Cover
       1.     Plant name and location
       2.     Emission source sampled
       3.     Dates of testing
       4.     Testing company name and address

       Certification
       1.     Certification by team leader
       2.     Certification by reviewer (Professional Engineer preferred)

       Introduction
       1.     Test purpose
       2.     Test location, type of process and control equipment
       3.     Any source identification numbers, if applicable
       4.     Test dates
       5.     Pollutants tested
       6.     Name of plant representative
       7.     Other important background information

       Summary of Results
       1.     Emission(s) results and performance audit results
       2.     Process and control equipment data, related to determination of
             compliance
       3.     Allowable emissions
       4.     Discussion of errors, both real and apparent

       Facility Operations
       1.     Description of the process and control equipment
       2.     Process and control equipment flow diagrams
       3.     Process parameter, material, and product results, with example calculations
       4.     Describe portions of process operation tested
       5.     Representativeness of process parameters, raw materials, and products
       6.     Describe portions of control equipment operation tested
       7.     Representativeness of control equipment parameters, and collected
             materials

       Sampling and Analytical Procedures
       1.     Sampling port location(s) and dimensions of cross-section
       2.     Sampling point description, including labeling system
       3.     Brief description of sampling procedures, including equipment and diagram
             of sampling train

                   Figure 8.1. VOC compliance test report format
8-8
                                                                                          I

-------
4.    Description of sampling procedures (planned and accidental) that deviated
      from standard method
5.    Brief description of analytical procedures, including calibration
6.    Description of analytical procedures (planned and accidental) that deviated
      from standard method

Appendices
1.    Complete results with example calculations
2.    Raw field data (original, not computer printouts)
3.    Laboratory report, with signed chain-of-custody forms
4.    Calibration procedures and results
5.    Raw process and control equipment data, signed by plant representative
6.    Test log
7.    Project participants and titles
8.    Related correspondence
                        Figure 8.1.  (Concluded)

                                                                         8-9

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                            APPENDIX A
      ORGANIC COMPOUND DDENTDFICAT1ON AND QUANTIFICATION

A.1   Organic Compound Identification by Retention Time
A2   Adequate Peak Resolution
A3   Proper Response Factors

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A.1    ORGANIC COMPOUND IDENTIFICATION BY RETENTION TIME

       For Method 18, the organic compounds to be measured must be known prior to
the test. To identify and quantify the major components of the organic compounds
known to exist in the sample, the retention time of each component is matched with the
retention times of known compounds (standard reference materials or calibration
standards) under identical conditions. Separation of organic compounds is performed
with gas chromatographic columns, referred to as GC analysis.  The retention time is the
time between sample injection into the gas chromatograph (GC) until the organic
compound reaches the detector. If conditions are maintained constant, the retention
time for each compound will be constant as well, and will serve as the identifying
parameter for each peak.  Care must be taken to assure that two compounds do not
share the same retention time. The retention time shall be within 0.5 seconds or 1
percent of the retention time of the known compound's (calibration standard) retention
time (whichever is greater) to be considered acceptable.  The retention time will vary
with (1) type of column or column material, (2) length of column, (3) temperature of
column, (4) organic compound and several other factors (e.g., other organics present).
The exact seconds or minutes of the retention time do not matter, although the longer
the retention time is,  the longer the analysis time will be.

      The major problem with the use of retention time in identifying organic
compounds is that other organic compounds could share the same retention time.
Compound identification is often achieved by using two GC columns with greatly
different packing materials which have differing physical properties used for separation.
If the proper retention time for a given organic compound is obtained for both columns,
then the analyst would assume that the compound has been identified. A listing of
organic compounds and their retention times, with respect to certain analytical
conditions, is presented in Section 3.16 of the QA Handbook, Volume III titled, "Kovats
Retention Indices." The Kovats Retention Indices are generally used to help the analyst
select the proper column for separating the organic compounds known to be present in
the sample. When the analyst only uses a single column at a set condition, there will
always be some doubt as to whether other organic compounds have the same retention
time and are being reported as the compound of interest It is not uncommon to have as
many as three compounds share the same retention time.

      It is the responsibility of the analyst to ensure that the proper column has been
selected. When additional compounds share the same retention time, the reported value
will be higher than the true value.

      To select the correct GC column or establish appropriate GC conditions, the
analyst must identify approximate concentrations of organic emission components.  With
this information, the analyst can prepare or purchase commercially available standard
mixtures to calibrate the GC under physical conditions identical to those that will be
used for the samples.  The analyst must also have presurvey information  concerning


                                                                           A-l

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interferences arising from other compounds present in the sample matrix and indicating
whether there is need for sample dilution to avoid detector saturation, gas stream
filtration to eliminate paniculate matter, and/or prevention of sample loss by moisture
condensation in the sampling apparatus.

       Most analysts today use an integrator to determine retention times and sample
peak areas. The integrator will print out the retention time for all peaks and the
integrated area of all peaks. The observer should confirm that the peaks match within
the specified time of 0.5 seconds or 1 percent of the retention time, whichever is greater.
The first peak on the printout immediately after injection of the sample is typically not
an organic compound from the source. It is usually the air peak or solvent peak and is
not counted.

A3    ADEQUATE PEAK RESOLUTION

       To obtain proper quantitative values, sample peaks (organic compounds as they
reach the analyzer) must be properly separated. As previously mentioned, compounds
must be separated to enable the detector to analyze only the compound of interest.  The
analyst will perform initial tests using the calibration standards to determine the
optimum GC conditions for minimizing analysis time while still maintaining sufficient
resolution.  Sufficient resolution shall be determined following the procedure  described
by Knoll or in EPA Method 625 where the baseline to valley height  (V) between two
adjacent peaks must be less than 25 percent of the sum of the two peak heights
(P1+P2). The equation is shown in Figure A.1. Both methods for determining peak
resolution give about the same results. EPA Method 625 is easier to calculate and
understand.

       Most integrators will show where they are starting and stopping the peak area
integration by  placing tick marks on the integrator printout.  It is important that the
integrator is set properly to determine the proper area  The observer may wish to check
where  the start and stop marks are placed.

A3    PROPER RESPONSE FACTORS

       Understanding the use of the response factor is important because (1) different
detectors can have a different response factor for the same compound, (2) each detector
can have a different response factor for different compounds, and (3) the same detector
can give a different response factor for the same compound at different conditions.  The
response factor for each compound on any detector can be determined by dividing the
area units from the integrator printout from the standard by the concentration of the
standard (area units/ppm of standard). This is done for all concentrations of  the
standard used to calibrate the detector.  A best fit line, which is not forced through zero,
is typically calculated for these different response factors.  This line is then used to
calculate the ppm from each sample's peak area based on the number of area Figure
A-2

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 A.1.  Adequate -peak resolution, units (area units of sample divided by response factor
 which is area units per ppm). Today's integrators often make this calculation for the
 analyst.

 A3.1  Different Response .Factors for Different Detectors

        It is important to note that different detectors are more or less sensitive to
 different types of organic compounds.  For example, the most commonly used detector,
. the -flame ionization detector, has the highest response factor for organic compounds that
 :are straight chain molecules and  contain only carbon and hydrogen.  The flame
 ionization detector's response factor for compounds that contain chlorine or oxygen is
 reduced. Therefore, if it is calibrated with a compound that contains only carbon and
 hydrogen like methane, propane, or butane, its measured  values for chlorinated or
.oxygenated .compounds would be low.

        The electron -capture detector has the highest response for chlorinated
 .compounds. Its response to methane, propane, and butane would be lower than if  they
 were chlorinated. .Selection of a  detector with a high response for the compound(s)
 being measured is desirable, but is not critical unless the organic compound will not be
 adequately measured by the detector.

. A32 .Different Response Factors for Different Compounds

       After a suitable  detector has been selected, the observer should be aware, as
 -mentioned above, that the same detector may have a different response factor for each
 compound analyzed. Therefore, a corresponding calibration gas must be used for each
 compound. If the test is conducted for four compounds, the method may require that
 four different calibration gases be used.

       Method 25A is designed to measure emissions consisting of organic compounds
 with only carbon and hydrogen and therefore requires instrument calibration with
 propane. Method 25 A can provide accurate measurement of organic compounds
.xontaiBmg elements other than carbon and hydrogen if the detector is calibrated with a
..-mixture  of .organic gases that closely represents gases in the stack.  Response factors are
 published for measurement of different organic compounds on each detector. These may
 :not be accurate, but they are a good indication of the variation in response.  For the
 .flame ionization detector, most compounds will give at least a SO percent response when
 compared to methane; propane, and butane.

       Method-25 was developed to eliminate the reduced response factor problem when
"the organic compounds are unknown. When the organic compounds in the sample  are
 unknown (like after an incineration process), proper calibration gases cannot be selected.
             this problem, Method 25 converts all the elements that give reduced
 Tesponse factors and analyzes the compound as methane in terms of carbon. The results

                                                                              A-3

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                                                                              CM
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                                                                                             I
A-4

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are then reported as parts per million as carbon.   Unfortunately, the true molecular
weights of the compounds are lost and a true concentration or mass emission rate .cannot
be calculated.

       Although it may not always be desirable, there are cases when the use of a
surrogate calibration compound has been allowed. For example, if the regulations
require that all compounds be analyzed, the use of a calibration standard (specific
organic compound can be selected by the tester) for unknown compounds that consists of
less than 20 percent of the total area of all peaks (total response) for all compounds in
the sample would produce only a small error in the total emissions measured.

       A surrogate calibration gas may also be allowed when (1) appropriate calibration
gases are not available, or (2) calibrating with multiple gases in the field is anticipated to
be too inconvenient. The agency may allow the tester to use a single calibration gas
(as a surrogate standard) and correct the measured values based on the response factors
obtained in the laboratory.

A*33  Different Response Factors for the Same Compound

       Manufacturers of GC detectors have published response factors of the organic
compounds for their detector. These values should serve as estimates.  The  exact
response factor will vary with sample composition and conditions of the detector. The
response factor should be similar from day-to-day on a laboratory instrument analyzing
the same compound and  composition of gas under the same conditions. However, the
repeatability of response  factors is not sufficient to eliminate the requirement for
calibration.  It is important to conduct single point response factor checks every couple
of hours or when the environment or sample conditions change significantly.
                                                                              A-5

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                             APPENDIX B
                   VOC OBSERVATION PROCEDURES

B.I  Agency Use of Screening Measurement Methods During Compliance Test
B.2  On-site Observation Procedures Coupled with the Use of Agency Screening
     Methods ~

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B.1   AGENCY USE OF SCREENING MEASUREMENT METHODS DURING
      COMPLIANCE TEST

      As previously stated, most organic gases are invisible.  Therefore, it can be
beneficial for the agency to conduct independent testing to determine the emission levels
and other key parameters. The agency's portable organic analyzer (EPA Method 21
instrumentation) can be extremely useful. The discussion below provides a example of
how these instruments can be used.

      A printing or coating bed operation with a carbon adsorber as the control
equipment is to be tested.  The same principles apply to other types of processes and
control equipment The procedures are as follows:

      1.     Determine which organic compounds are used in the process.
      2.     Obtain the proper calibration gases or determine the correct response
             factor (see Chapter 5) and use a common calibration gas (e.g., methane).
             The analytical instrument must accurately measure low concentrations of
             volatile organic compound emissions (i.e., 0 to 100 ppm or 0 to 500 ppm).
             The observer may determine the organic materials process during the
             pretest survey.  An instrument recorder or other device which provides
             continuous recording of the emission data is highly recommended.  An  .
             external pump may also be required.
      3.     Prepare  instruments and calibration gas(es)  for the pretest (presite) survey.
             Often pretest surveys are conducted before compliance testing. Typically
             the testing firm representative performs the pretest survey.  Agency
             personnel should participate if the compliance test is expected to be
             unusual or difficult.
      4.     During the pretest survey, use the portable VOC analyzer to determine the
             concentration levels at the edge of any hoods, points of possible fugitive
             leaks, at the inlet sampling location, and at the outlet sampling location. If
             problems exist, such as poor hood capture efficiency or fugitive leaks, the
             facility should be informed and the problems corrected prior to the
             compliance test  The facility should also be informed that inspectors will
             use the same procedures and instrumentation during future inspections to
             determine if the problems still exist
      5.     During the compliance test, the same problem areas should be checked for
            -fugitive emissions, and concentrations around the edge of the hood should
             be determined.  Once the  observer is satisfied that all problems have been
             corrected, Ihe test program may start  If only one VOC analyzer is
             available to the observer, it should be used at the outlet sampling location.
             The emissions to the atmosphere should be determined before the first
             run, during the first run, between the first and second runs, during the
             second run, between the second and third runs, and during the third run.
             When two analyzers are available, periodic checks for fugitive emissions


                                                                              B-l

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 B.2
      should be made before, during, and between runs.  Determining the
      emissions before and between runs will prevent the facility from conducting
      testing during portions of the process and control equipment operations
      that have reduced emissions. If emissions increase between the runs, then
      the observer may have to double the testing tune and require testing to be
      conducted on a continuous basis.  The second run starts immediately after
      the first run is completed.  If temperature sensors or other screening
      instruments are used, it is best to have a primary standard (i.e., ASTM
      mercury-in-glass thermometer) available to  check the measured results.

ON-SITE OBSERVATION PROCEDURES COUPLED WITH THE USE OF
AGENCY SCREENING METHODS
       It can be beneficial for the agency to conduct independent screening
 measurements during the compliance test. An approach to conducting independent
 screening measurements during the compliance test is presented below. VOC screening
 instruments (EPA Method 21) can be used for either spot checks or equipped with
f pumps and continuous recorders to provide continuous emissions measurements.  The
 discussions of on-site observation presented in Chapter 3 will still apply.  The concerns
 about safety are even more critical when the agency is conducting their own screening
 measurements. The observer will be in closer contact with the VOC's thereby increasing
 the health and explosion risk. All instruments and methods of using these instrument
 must be intrinsically safe. For using these portable instruments, the EPA manual EPA-
 340/1-86-015, "Portable Instruments User's Manual for Monitoring VOC Sources*
 should be read.

 B.2.1  First Sampling Run

       The observer's emission results should be compared with the testing firm's
 emission results.  On-site analysis by the test  team does  not diminish the need for the
 agency to conduct independent on-site measurements; it improves the chances of
 eliminating errors and obtaining a valid test.  If only one agency observer is present, the
 schedule below will make the most effective use of observation time.  These procedures
 are provided for less experienced observers to help establish a routine for on-site
 observations.  More experienced observers'will follow their established routine.

       For the first test run,  after determining that the facility operations are as specified
 in the protocol, the observer should go to the sampling location to observe  the test team
 as they record the initial data. If a post test leak check is required, the initial sampling
 system leak check need not be observed.  When the observer is satisfied with the
 sampling train preparation, he should allow the testing to begin.  The agency's analyzer
 (VOC screening method) should also be started.  The observer should observe the test
 team's sampling procedures for the first 15 minutes of sampling.  When satisfied with the
 test team performance and the agency's emissions results, the observer will  note the
 B-2

-------
average emissions for the last 10-minute period and then conduct a check on the facility
operations.

      If the process and control equipment are operating satisfactorily and the data are
being recorded as specified, the time of the process and control equipment observation is
noted and the observer returns to the sampling site.  The observer should determine the
emissions during the time that the facility operations were being verified by die observer
(assuming that a pump and recorder are on the analyzer) or take 10 minutes of emission
readings if the analyzer does not have a pump and recorder and must be operated
manually. If the observer is satisfied with the emission results, the analyzer probe should
be removed from the stack and audit gas should be drawn through the probe and
analyzer. The value for the audit sample should be recorded and the appropriate
calculation made to determine the relative accuracy. If any inajor problems exist with
the analyzer, they should be corrected.

     - The observer should observe the completion of the test team's sampling,
particularly the final readings and the final leak check. He should then observe
transport of the samples and sample recovery. If the test team's analysis is to be
conducted on-site, the analysis should be closely observed during the audit gas cylinder
analysis and the analysis of the first test run sample(s). The tester's analyst should be
required to conduct all necessary calculations to determine the field results in terms of
units of allowable emissions standard (e.g., ppmv on a dry, standard condition basis for
the specified organic compound). All procedures and calculations should be validated by
the observer.

      If the agency's organic analyzer is equipped for continuous analysis, it should
continue to run and record the emissions between completion of the  first run and start of
the second run. If the emissions increase significantly during this period, the process and
control equipment parameters should be checked to detennine the reason for the
increase. As previously stated, many VOC process and control equipment operations can
be altered to provide short term emission reductions.  If the observer feels that.this has
happened, it may be necessary to require an  additional sampling ran (total  of four runs),
informing the source that the emissions will not be allowed to increase between sampling
runs.  Another option is to double the sampling time and require that subsequent run to
be started immediately after the prior run.

BJL2  Second Sampling Run

      If the observer is satisfied with all sampling procedures during the first test run,
he should spend most of the second run observing process operations with intermediate
checks on the emission levels.  During the second run, the observer should record the
emissions during two 10-minute periods, conduct one check with the audit gas, and
monitor the facility operations between emission readings.  Ideally, .the emissions will be
recorded continuously, so the observer can correlate the emission levels with facility
operations.


                                                                              B-3

-------
       The observer should observe the test team recording final data of the second test
 run, final leak check, transport of the sampling train to the cleanup area, and recovery of
 the second run samples. The observer should determine what his emphasis will be for
 the third run by considering the facility operations, emission levels measured by the test
 firm, agency measured emissions, and observation of the sampling procedures. If the
 analysis is conducted on-site, these results will also be taken into account  The
 observer's analyzer should continue to monitor the emissions between the second and   .
 third run to ensure that they do not increase between runs. ..

 B.2 J  Third Sampling Run

       The observer should use available information to determine which procedures
 need the most attention for the third run by assessing the observations of the facility
 operations, measured emissions (if applicable), and observation of sampling procedures.
 If the analysis is being conducted on-site, these results must also be taken into account.
 All these elements should be used to determine which procedures may have the greatest
 degree of error. The observer should then focus on these procedures. A check of
 facility operations, sampling procedures, sample recovery, and sample analysis (if
 applicable) should be included in the observation procedures of the third run.
B-4

-------
                   APPENDIX C
     METHOD 18 OBSERVATION PROCEDURES

C.1  Selection of Proper Sampling and Analytical Technique
C.2  Observation of On-site Testing
C3  Preparation of Calibration Standards
C.4  Auditing Procedures
C5  References

-------

-------
 C.1    SELECTION OF PROPER SAMPLING AND ANALYTICAL TECHNIQUE FOR
       METHOD 18

       Because of the number of different combinations of sampling, sample preparation,
 calibration procedures, GC columns packing material and operating procedures, and GC
 detectors covered under this method, a set of tables has been developed to assist the
 tester in selecting (and the observer in evaluating) an acceptable sampling and analytical
 technique.  The compounds listed in these tables were selected based on their current
 status as either presently regulated or being evaluated for future regulations .by. the EPA
 and state and local agencies.  The selected organic compounds for Method 18 presented
 in Table C-l provide the user with: (1) the International Union of Pure and Applied
 Chemistry (IUPAC) name, any synonyms, the chemical formula, the Chemical Abstracts
 Service (CAS) number; (2) method, classification  and corresponding references for more
 information; and (3) information on whether EPA currently has an audit cylinder for this
 compound.

       For a given compound, the sampling or analytical techniques described in Tables
 C-2, C-3, and C4 are classified into one of five categories as follows:

       1.    Reference. This is a method promulgated by EPA as the compliance test
            method for one or more EPA emission regulations.
       2.    Tentative.  This is  a method where EPA method development is completed
            and documented, but the method has not been promulgated.
  	3.    ^Development This is a method currently under development by EPA
       4.    Other.  A method  developed and documented by an organization other
            than EPA
       5.    None. This is a sampling or analytical technique that has not been
            developed or validated but based on experience with similar situations, this
            may work.

       Table C-2 shows.all the sampling techniques  allowed for Method 18: (1) direct
 interface, (2) .Tedlar bag, and (3) adsorption tube sampling. For each compound, each
.of the allowed sampling techniques is rated either:  (1) recommended, (2) acceptable, (3)
 not recommended or (4) unknown.  A particular sampling technique is rated first based
 on current EPA methodology. "Where EPA methodology does not exist, methodology
 provided by organizations other than the EPA is used for rating. As an example on how
 to use Table C-2, the rating for benzene is R-2 for Tedlar bags and A-15,16 with carbon
 disulfide for adsorbent tubes. This means that for sampling, a Tedlar bag is
 recommended as a sampling technique and Reference 2 (Appendix C.5) provides further
.description, while charcoal tubes using carbon disulfide as the desorption liquid are
 acceptable  and Reference 15,and 16 (Appendix C5) provide further description.

      •Before a final sampling technique is selected, the observer and source tester will
;need to consider the general strengths and weaknesses of each technique  in addition to


                                                                            C-l

-------
       TABLE CL STATUS OF SELECTED ORGANIC COMPOUNDS
        FOR METHOD 18 SAMPLING AND ANALYSIS TECHNIQUES
Chemical Abstracts Mam
Synonyms
Formula
CAS Mo.
Method
Class
EPA Audit
Cylinder(ppn)*
                                 Alcohols
Hethenol •
Ethanol . '
Isopropyl Alcohol
n-Propyl Alcohol
n*8utyl Alcohol
Methyl Alcohol
Ethyl Alcohol
2-Propanol
1-Prcpanol
1-Iutanol
CU.O
C.H.O
CAO
CAO
C.*J3
(67-56-1)
(64-17-5)
(67-63-0)
(71-23-8)
(71-36-3)
0-6
0-7 -
0-7
0-8
0-8
30-80
No
No
No
No
                                 Alkanes
Cyclohexane
Hexane
•i
C.MU
C,HM
(110-S2-7)
(110-54-3)
0-9
0-9
80-200
20-90,1000-3000
Alkenes
Ethylene
Propylene '
Ethene
?ropeoe
c^J,
V.
(74-SS-1)
(115-07-1)
•N
N
5-20,300-700
5-20,300-700
Dienes
1 ,3-3utadiene
Hexaeh 1 orocyc I opentadi ene ,
Butadiene
P erch 1 orocyc I opentadi ene
C,H.
c,ct.
(106-99-0)
(T7-47-4)'
0-10
0-11
5-60
NO
                                Aromatic
Benzene
Hesftylene
Ethylbenzene
Cunene .
Xylene (m-,o-,p-)
Toluene
Styrene
2-Maphthylamine
Benzol
1 ,3,5-Trinethylbenzene

1 -Methylethylbenzene
Dimethyl benzene
Methylberuene
Ethenylbenzene
2-Naphthytenamine
C.H.
tyi»
c^,.
CJa
C.H,.
C,H,
CA
c,A«
(71-43-2)
(108-67-8)
(100-41-4)
(98-82-8)
(1330-20-7)
(108-38-3)
(100-42-5)
(91-59-8)
T-12
N
0-13
0-13
0-13
0-9,13
0-13
0-14
5-20,60-400
No
No
No
5-20,300-700
5-20,100-700
No
No
                                Ketones
Acetone
Methyl Ethyl Cetone
Methyl isobutyl Ketone
2-Propanone
2-Butanone
4-Kethy I -2-pentanone
C^(.0
w
C.HB0
(67-64-1)
(78-93-3)
(108-10-1)
0-15
0-16
0-15
No
• 30-80
5-20
                                Epoxides
Ethylene Oxfde
Propylene Oxide
Epoxy Ethane
1,2-Epoxy Propane
«y«.o
W.O
(75-21 -8)
(75-56-9)
0-17
0-18
5-20
5-20,75-200
                                Sutfides
bisC2-Chlopoethyl) Sulffde
Mustard Gas
C.H.CI.S  (505-60-2)  N
                                        No
C-2

-------
                                      TABLE C-l.  (Concluded)
Chemical Abstracts Name
Synonyms
Fermi la
Halogenated
Ethyl idene Chloride
Ethylene Oibromtde
Ethylene Oichloride
Propylene Bichloride
1,1,1 -Trichloroethane
Bromodich lorcmethane
Ch lorodibromomethane
Chloroform
Carbon Tetrachloride
D i ch I orodi f I uoremethane
Methyl Bromide .
Methyl Chloride
Methylene Chloride
Tetraeh I oroethyl ene
. Brcmoform
Trichloroethylene
Trichlorotrifluoroethane
Vinylidene Chloride
Ethyl Chloride
Chlorobenzene
Vinyl Chloride
1 ,2-Oibromo-3-ehloropropane
.1,1-Oichloroethane
1,2*0ibranoethane
1 , 2-0 i ch I oroethane
,£-uicnioraprupene
Nethylchlwofani
Tr ieh loraaethane
Freon 12
Bromome thane
Chloronethane
Dichlorcmethane
Perch loroethyl ene
Tribromomathane
Trichloroethene .
Freon 113
Chloreethane
Monoch I or obenzene
Chi oroethyl ene
DBCP
CJJ.CI,
CXBrCl,
CH3r,Cl
OfCl,
cci.
CHfl '-
c,cV
CHBr,
C.HCI,
C,H,Cl*
C,H*Cl
as NO.
Method
Class
EPA Audit
Cylinder(ppm)*

*
(106-93-4)
(107-06-2)
(78-87-5)
(71-55-6)
(75-27-4)
(124-48-1)
(56-23-5)
(75-71-8)
<75-fl9-2)
(75-25-2)
(79-01-4)
(76-13-1)
<75-3S-<>
(75-08-3)
(75-01-4)
(96-12-8)
0-19
0-20
T-21
0-22
T-21
N
N
T-23
T-23
0-24
0-25
0-26
T-27
-T-21 '
0-19
T-21
0-28
0-29
tr-T9
ft-30
0-37
5-20,50-300
5-20,100-600
3-20,300-700
5-20
No
No
5-20,300-700
5-20
No
No
Mo
1-20
i>"-20 ,300-700
No
S-20, 100-600
5-20
5-20,100-600
No
5-20
5-30
No
Method Classification Code
  R a Reference -   EPA promulgated method.
  T B Tentative -   EPA UKthod development complete; EPA reference available.
  0 " Development
  0 * Other -
  N * None -
EPA method currently utder development.
Method development completed by organizations other, than EPA; reference available.
No reference available; reeoonendation based on experience.
     The codes in the method classification coluan describe the current status of a sampling and analysis
method for each selected coopound.  For example, the method classification code for benzene is: T-12.
This means the current method for benzene is a tentative EPA method with development complete and the   •
reference for the method is citation number 12 in Appendix (j.5
The availability af EPA  audit cylinders is shorn fn this column where:

   (   ) 3 Audit cylinders  for this particular compound are available fran EPA in the concentration ranges
           indicated (Reference 4}.

     No  * Audit cylinders  for this particular compound are not avallable frca EPA. The source tester must
           obtain audit  gas cylinders from comercial gas vendors certified fey-irmependcnt-anaiysi* to be
           within 5 percent of the concentration claimed by the vendor.
                                                                                                    C-3

-------
   TABLE C-2. METHOD 18 SAMPLING TECHNIQUES FOR SELECTED
   ;,.;.-!; "A        VOLATILE ORGANIC COMPOUNDS
Selected
Conpcu^ds
Direct
Interface
Tedlar
SaS*
•;- Adso,-bent Tubes and Desorption Liquid
Charcoal*
Other «•
' Desbrption Liquid"**.
                           Alcohols' *
Hethanol "•'
Eshanol * ,
Isopropyl Alcohol
n-?ropyl Alcohol
n-3utyl Alcohol
T
T
T
T
T .
N
N
M
N
M
»
T-7 ' •
T-7 '
T-8
T-8 ' '
A-6; Silica tel
.
-
-
•
'Distilled Water
IX 2-Butanol in CS2
1X 2>3utanol fn CS2
Carbon Disulfide
Carbon Disulfide
                           Alkanes
Cyclohexane < .
Hexane -
T
T
,*.
ethyl ene '
Propylene
T
T

1 ,3-3utadiene , ,
Hexachlorocyclopentadiene
T
T
U
U
T-9
T-9 ' '
- •
Carton Bisulfide
Carbon Bisulfide
Atkenes
N
U
U
U
U
U
" ' ' U
U
Oieoes . ...
A-10
U
' A-41
N " ' " "
U
A- 11; Porapak"*
'•' ' Carbon Disulfide
""" Hexane
Aromatic • . '
Benzene
Nesitylene
Erhy I benzene
Cunene
Xylen* (m-,o-,p->
Toluene
Styrene < • •
e-Kapthylamine
T
T '
T
T
T
T
T
T
, • .
Acetone
Methyl Ethyl ICetone
Methyl Isobutyl ICetone
T
T
T
.-. •
Ethylene Oxide
Propylene Oxide
T
T

bisCZ-Chloroethyl) Sulfide
T
R-t2
U
U
U
U
U
U
U
T-9, 13
U- '
T-13
T-13
T-13
T-9, 13
T-13 '
T-U
-
Carbon Bisulfide
0
Carbon Disulfide
. , Carbon Disulfide
Carbon Oisulfide
Carbon Oisulfide
.Carbon Disulfide
Carbon Disulfide
Ketones-
K
N
M
T-1S
M
T-15
A- 16; Ambersoro
Carbon Disulfide
Carbon Oisulfide
Carbon Disulfide
Epoxides
A
U
T-17
T-18
.
99:1 Benzene:CS2
Carbon Disulfide
Sulfides
U
U
U
U
C-4

-------
                                        Table  C-2. (Concluded)
Selected
Compounds
Street
Interface
Tedlar .
Bag*
Adsorbent Tubes and Desorptioo
Charcoal*-
Other **
Desorptioo
Liquid
liquid***
                                                  Halogenated
Ethyl idem Chloride
Ethylene Dibronide
Ethylene Diehloride
Propylene Dichleride
1,1, 1 -Tr ichloroethano
Bromodichloroaethane
Oi I orodi brojBcmethane
Chloroform
Carbon Tetraehloride
D i ch I orodi f I uoronethane
-. Methyl Bromide
Methyl Chloride
Methylene Chloride
Tetrachloroethylene ' '
Sromoform
Trichloroethylene
Tr i ch lorotri f luoroethene
Vinyl idene Chloride
Ethyl Chloride
Chlorobenzene
Vinyl Chloride
1,2-Dibromo-3-chlor9propar>e
T
T
T
T
T
T
T
T
T
T
T
T
T
• T
T
T
T
T
T
T
T
T
U , .1- T-19
K-31
R-21-
U
R-21 '
U
U
R-23
R-23
U
U ,
U
R-27
R-21 .
U
R-21
R-21
U
U
U
R-30
U
T-20
T-19
T-22
T-19
U
U
T-19
T-19
. T-24
T-E5
T-26
T-32
T-33.
T-19
T-34
T-35
T-28
- T-29
T-19
T-36
T-37 .
.
-
*
-
.
-
•
-
-
•
-
-
.
*
.
*
•
.
-
-
»
•
Carbcti Disulfi'd*
99:1 8trtnr*;HsOH
Caracn Bisulfide
15X Acetone in CycJ-ohexane
Carocrt Risulficte
U
U
Cartoon Oisulfide
Carbon oisytftde
Hethyl«f« Chloride
Carixn Oisulfide
Watlranol
CarDon DiauLtioe
Cartefi 3 i su I f i d»
Carbon DisulHde
Carbon O'stjlHde
Carson Oisulfide
Career; Bisulfide
Cartoon Oisulfide
Carbon Disulfiae
Carbon O'sulfide
Carbon OisulfiAj
Rating Code
 ft > Reconmnded.
 A a Acceptable.
                      Based  on actual source tests experience (sampling and analysis) this method is
                      valid  and is the method of choice among Method 18 users.

                      Based  on actual source tests or similar source test experience (sanpling and
                      analysis),  this method is valid.  The tester must  evaluate for specific test.

                      Method has  no documented experience,  but in theory could be valid.

                 ided. Based  on actual source tests or similar source test experience and/or theory, this
                      method is invalid.

 U  » unknown.         Method has  no documented experience  and the theoretical aspects of saivling by this
                      method are  inconclusive.  The tester must demonstrate that this samp I ing- method is
                      valid.                       -                                          •    •    -

     The rating codes for stapling are based on the extent  of method validation,  for example, the rating
code for benzene  is: T; 8-12; A-9,13.  This  means that  direct interface is theoretically possible for
benzene, but no documented experience has been found; Tedlar  bags are the recommended sanptinq mthod for
benzene  by the tentative EPA method referenced in citation  12 in  AppendixC.5; and sampling with
charcoal adsorption tubes is acceptable following the two methods referenced in citations 9 and 13 in
Appendix  .5.

  * - If eondensibles exist, use the procedure described in Section 3.16.4 of the EPA Quality Assurance Handbook
      Volume HI.

 ** * Solid sorbents ether than charcoal recommended.

*** » The  recommended desorption  solution is given in this column.  Analyst should consult the appro-
      priate'reference for details.
                                                                                                      C-5

-------
TABUE C-3. GC DETECTORS FOR SELECTED VOLATILE ORGANIC
                COMPOUNDS BY METHOD 18
Selected Conpoirris
Cas Chromatograph Detector *
FID
ECO
PIB
1 EUCD
Alcohols
Hethanol
Ethsnol
Isopropyl Alcohol
n-Propyl Alcohol
n-autyl Alcohol
R-4,6
R-7
8-7
R-8
R*8 >
X
N
N
N
N
T-38
T-38
T-38
T-38
T-38
N
H
N
N
N
Alkane*
Cyclohexane
Hexane
R-4,9'
R-4,9
N
K
T-38
T-38
M
N
Alkenes
Ethytem
Propylene
A-4
A-4
K
M
T-38
T-38
. H
N
Dfenes
1,3-8utadiene
Hexachloroeyclopentadiene
R-4,10,ii
«-11
H
T
T-38
U ,-
H
T
                              Aromatic
Benzene
Mesitylene
Ethylbenzene
Cumene
Xylene 
Toluene
Styrene
2-Napthylanine
R-4,12
T
R-13
R-13
R-4,13
«-4,9,13
R-13
R-14
N
N
M
M
N
N
N
N
T-38
T-38
T-38
T-38
T-38
T-38
T-38
U
M
N
N
H
M
II
N
K
                              Ketones
                              Epoxides
                              Sul fides
   bis(2-Chloroethyl> Sulfide  j    U
Acetone
Methyl Ethyl Ketone
Methyl Isobutyl Ketone
R-1S
R-4.16
R-*,t5
N
a
K
T-38
T-38
T-38
N
H
K
Ethytene Oxide
Propylene Oxide
R-4,17
R-4,18
N
N
T-38
T-38
M
H
 C-6

-------
                             TABLE C-3.  (Concluded)
Selected Casiwunds
Gas Chromtograph Detector •
FID
.EO | P10
ELO
                                  Halogenated
Ethyl idem Chloride
ithylene Dibremide
Ethylene Oiehloride
Propylene DicMoride
1 , 1 , l-Tricfilaroethane
Bronodidi l-orsnethene
Ch t or od i browmethane
CMorofoni
Carbon Tetrschloride
Otchlorodifluoremethane
Methyl Broaride
Methyl Chloride
Methylene Oloride
Tetrachloroethylene
Bromofora
Trichloroethylem
T r i eh 1 orotri f I uoroethane
Vinyl idem Chloride
Ethyl Chloride
Chlorocenzene
Vinyl Chloride
1 , 2-0 i broMo-3-ch I oropr opane
R-19
A-4
R-4,21
A-4
8-4,21
U
U
. R-4,23
R-4,23
R-24
a-25
R-26
R-4, 27,32
R-4.21
R-19
R-4,2t
R-4,21
R-4,28
R-29
R-4,19
»-4,30
U
• T
R-20
T
T
r
T
T
• • T ' '
T
T ' '
T
T
T •
T
- T
T
' T
••• T '
T
T
T *
R-37
U
U
T-38
T-38
U
U
U
T-38
T.-38
H-38
T-38
T-38
T-38
T-38
T-38
T-38
H-38
T-38
T-38
T-38
T-38
U -
T
T
T
R-22
T
T
T
A-23
A-23
T
T
T
T
T
T
T
T
T
T
T
T
T
      Code
    ft ec UMIIIGI HJed*
A * Acceptable.
    Theoretical.
                        Based  on actual source test experiences (sanpling and analysis)
                        this method is valid and is the method of choice aocng Method  18
                        users.

                        Based  on actual source tests or similar source test experience
                        (sampling and analysis), this aethod  is valid. The tester oust
                        evaluate for specific test.

                        Method has no documented experience,  but in theory could be  .
                        valid.

4   N * Mot Recomended.  Based  on actual source tests or similar source test experience
                        and/or theory, this wtftod is invalid.

   U * unknown.         Method has no doeunented experience and the theoretical aspects
                        are not  conclusive.  The tester oust  demonstrate that this
                        detection nthod is valid.

       The rating codes for GC  detectors are based on the detector specified in the method
  that is referenced.  For example, the rating code for benzene is:  8-4,12; M; T-38; N.
JThis means that the F!0 is recanaended for detection of benzene by both references 4 and
  12 cited in Appendix £.5; the SO and the ELO are not receamended for benzene; and
  detection of benzene tnth a P1D  is theoretically possible based on the ioniration
  potential found in reference 33.
 i.
  *  The following abbreviations are used for the gas diromatography detectors:
  FID  3 Flaw !cnization Detector
  ELO a Electraconductivity Detector
            (Hall Detector)
                                                        ED  * Electron Capture Detector
                                                        PID  3 Photoionization Detector
                                                        (with lamps up to 11.7 electron
                                                         volts)
                                                                                                    C-7

-------
|V
Is--:
      TABLE C-4. RECOMMENDED CALIBRATION TECHNIQUES FOR SELECTED
                VOLATILE ORGANIC COMPOUNDS BY METHOD 18
Selected Compounds
Nethods for Direct Interface
and Tedlar Bag Sanples
Gas
Cylinders
Gas
Injection
into
Tedlar Bag
Liquid
Injection
into
Tedlsr Bag
Methods for Adsorption
Tube Sanples
Prepare
Standard in
Oesorption
Liquid
Prepare
Standard
on Tube
and Desarb
                                   Alcohols
                                  Aromatics
                                   Cetones
Nethanol
ithanol
Isopropyl Alcohol
n-Propyl Alcohol
n-Butyl Alcohol
T-4
U
U
U
U
H
N
N
N
N
U
V
U
U
U
»~6
8-7
8-7
8-8
8-8
T
T
T
T
T
Alkanes

Cyctohexane
Hexane

Ethylene
Propylene

1,3-3utadiene
Nexach lorocyclopentadiene
T-4
T-4
H
N
Alkenes
T-4
T-4
U
U
U
U

N
N
8-9
R-9

U
U
T
T

U
U
bienes
A-10
U
R-10
N
N
U
8-41
8-11
U
T
Benzene
Mesitylene
Ethyl benzene
Cunene
Xyler* (m-,o-,p->
Toluene
Styrene
2-Kapthylanrine
B-12CSRK 1806)
U
U
U
T-4
T-4
U
U
X
H
N
N
K
N
M
U
A- 12
U
U
U
U
U
U
U
8-9,13
U
8-13
8-13
8-13
8-9,13
8-13
8-14
T
U
T
T
T
T
T
T
Acetone "
Kethyl Ethyl Ketone
Methyl Isobutyl Ketone
U
T-4
T-4

Ethylene Oxide
Propylene Oxide

bis(2-Chloro«thyl} Sulfide
T-4
T-4

U
N
N
N-
Epoxides
U
U
Sulfides
U
U
U
U

N
N

U
8-15
8-16
8-15
T
T
T

8-17
8-18

U
T
T

U
           C-8

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                                      TABLE CM.  (Concluded)
Selected Compounds
Methods or Direct Interface
and T dlar Bag Samples
Gas
Cylinders
Gas
Injection
into
Tedlar Bag
Liquid
Injection
into
Tedlar Sag
Methods for Adsorption
Tube Saacles
Prepare
Standard in
Desorption
Liquid
Prepare
Standard
on Tube
and Desorb
                                           Halogenated
Ethyl idene Chloride
Ethylene Oi bromide
Ethytene Oichloride
Prepylene Oicftloride
1,1,1-Trichloroethane
Bromodichlorooethane
CJUorosibrcHioptethene
Chloroform
Carbon Tetrachloride
D ich lorodi f Igorcmethane
Methyl Bromide
Methyl Chloride
Methytene Chloride
T et r ach I or oethy I ene
Bremoform
Trichloroethylene
Triehlorotriftuoroe thane
Vinyl idene Chloride
Ethyl Chloride
Cilorobenzene
Vinyl Chloride
1 , 2-Oibrofflo-3-chloropropane
U
T-4
R-21
T-4
R-21
U
U
R-23
R-23
U
U
U
R-21
R-2KSRM 1809}
U
R-21
R-21
T-*
U
T-4
R-30
U
N
H
• M
N
N
U
U
M
N
U
U
U
N
H
• H
N
M
N
N
N
.A-30
H
U
N-31
A-21
U
A-21
U
U
A-23
A-23
M
N
M
A-21
A-21
U
A-21
A-21
U
U
U
N
U
R-19
R-20
R-19
R-22
R-19
U
U
R-19
R-19
8-24
R-25
R-26
R-32
R-33
R-19
R-34
R-35
R-28
U-29
R-19
R-36
R-37
T
T
T
T
T
U
U
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Rating Code
 M m Reconiiiended.
 A s Acceptable.
     Theoretical.
                        Based on  actual source test experience  (sampling and analysis} this method
                        is valid  and is the method of choice among Method  18 users.
                        Based on  actual source tests or similar source test experience ling and
                        analysis},  this method is valid.  The tester must  evaluate for specific
                        test.                •   .                                           •
                        Method has  no documented sampling and analysis experience, but in theory
                        could be  valid.
    N * Mot Recommended. Based on  actual source tests or similar source test experience  and/or
                        theory, this method is invalid.
    U « Unknown.        Method has  no docunented experience  and the theoretical aspects are not
                        conclusive.  The tester must demonstrate that this calibration Method is
                        valid.

      The rating codes for calibration procedures are based on procedures specified in applicable sampling and/or
 ... analytical methods.   For exaople, the rating code for benzene  is:  R-12CSXM 1806); N;  A-12; R-9,13; T.  This
  neans that for beniene, the reeonaended calibration procedure  for direct interface  and Tedlar bag  samples
  involves the use  of gas cylinders with the procedures described  in citation 12 in AppendixC.5 and Standard
  Reference Material 1806 (available from the National Bureau  of  Standards, Gaithersburg,  MO); calibration
  standards for benzene prepared by  gas injection into Tedlar  bags  is not recommended; calibration standards
  prepared by liquid injection into Tedlar begs Is acceptable following the procedures described in citation 12
  in Appendix  .5; preparation of  calibration.standards in desorption liquid is the reccBBaended procedure for the
.„.adsorption tube methods described in citations 9 and 13 in Appendix  .5;  preparation of calibration standards
  on adsorption tubes followed by desorption is theoretically valid  for use with adsorption tube samples.
                                                                                                     C-9

-------
 the guidance provided in Table C-2.  The strengths and weaknesses for the allowed
 sampling techniques are as follows:

 Direct Interface or Dilution Interface
 Strengths:

       1.
       3.
Tedlar Bag

Strengths:

      1.

      2.
      3.

      4  —

Weaknesses:

      1.

      2.

      3.
 Samples are collected in a manner that retain the same compounds and
 concentrations as the stack emissions.
 No loss or alteration in compounds due to sampling since a sample
 collection media (bag or adsorbent) is not used.
 Method of choice for steady state sources when duct temperature is below
 100°C and organic concentrations are suitable for the GC detector.
Weaknesses:

       1.
       2.

       3.
       4.
GC must be located at the sampling site.
GC cannot be operated at a sampling site if the presence of the H2
flame will be hazardous.
Cannot sample proportionally or obtain a time integrated sample.
Results represent only grab samples and should not be used for non
steady state processes.
Samples are collected in a manner that retains the same compounds and
concentrations as the stack emissions.
Samples may be returned to the laboratory for GC analysis.
Multiple analyses, if necessary, may be performed on each collected
sample.
Samples can be collected proportionally.
Unless protected, Tedlar bags are awkward and bulky for shipping back
to the laboratory. Caution must be taken to prevent bag leaks.
Stability of compound(s) of interest in Tedlar bags must be known and
sample storage time is generally less than 24 hours.
Polar compounds should not be collected due to bag absorption.  Direct
interface or dilution interface is the method of choice for polar compounds.
C-10

-------
Adsorbent Tubes

Strengths:

      1.    Samples collected are compact and easy to return to the laboratory for
            analysis.
      2.    Samples may be returned to the laboratory for GC analysis.
      3.    Sample storage time generally can be extended to a week by keeping
            samples at O°C.

Weaknesses:

      1.    Quantitative recovery of organic compounds from the adsorbent material
            must be known.
      2.    Breakthrough sample gas volume for organic compounds for the adsorbent
            material must be known.
      3.    Any effect of moisture (in the stack gas) on the adsorbent material
            collection capacity must be known.  Moisture in the sample above
            2 to 3 percent may severely reduce the adsorptive capacity.
      4.    Generally, samples are collected at a constant rate.
                                                                    VJL
      Table C-3 shows the GC detectors commonly used with  Method  18. For each
compound, each GC detector is rated as: (1) recommended,  (2) acceptable, (3) not
recommended, or (4) unknown. A particular GC detector is rated first based on current
EPA methodology. Where EPA methodology does not exist, methodology provided by
organizations other than the EPA is used for rating. As an example on how to use
Table C-3, the rating for benzene is R-2 for FID. This means FDD is recommended as
the GC detector and  References 4 and 12 (Appendix C.5) provide further description.

      Table C-4 shows the GC calibration preference for each compound based on the
technique used for sampling.  Where appropriate, the source of calibration standards is
also shown.  For each compound, the calibration technique shown is rated either:
(1) recommended, (2) acceptable, (3) not recommended, or (4) unknown. A particular
calibration technique is rated first based on current EPA methodology.  Where EPA
methodology does not exist, methodology provided by organizations other than the EPA
is used for rating.  As an example on how to use Table C-4, the rating for benzene is.
R-12 (SRM 1806) for gas cylinders. This means gas cylinders assayed and certified
against a National Institute of Standards (NIST) gaseous Standard Reference Material
(SRM) using EPA Traceability Protocol No.  1 (Reference 4) are recommended as the
calibration standard.  Reference 12 provides  further description on the source of the
calibration standard.  NIST SRM  1806 would be used to assay and certify the calibration
standard.
                                                                            C-ll

-------
       For those compounds not listed in the tables, a general approach of classifying
 compounds and then selecting the method typically used for that classification is
 provided (Figure C.1, page C-13). The first classification in this general approach is
 sample concentration.  Method 18 can generally be used for samples having a
 concentration of greater than approximately one part per million by volume.  For
 samples in the part per billion volatile organic compounds range, typically the volatile
 organic sampling train is used.  For samples in the pan per billion semivolatile
 compounds, generally the modified method 5 sample train is used.  The discussions on
 the volatile organic sampling train (VOST) and modified method 5 (MM5) trains is
 beyond the scope of this manual but can be found in the Solid Waste Sampling Handbook
 SW-896. Method 18 can be used for most gaseous organic compounds with a
 concentration greater than 1 ppm.

       The second classification of compounds depends on stack temperature and
 moisture content. In general, higher stack temperatures are obtained through direct
 combustion which means higher moisture. The temperature/moisture are classified as
 low temperature and moisture, medium temperature and moisture, and high moisture
 and temperature.
                     t

       The first temperature/moisture classification is low moisture and temperature.
 Low moisture is defined as less than 1 percent.  The second temperature/moisture
 category is medium temperature and moisture (3 to 10 percent). The significance of
 3 percent to 10 percent moisture is:

       1.     If the  container sample is  allowed to sit at room temperature moisture will
             condense.
       2.     At between 3 to 10 percent moisture, techniques of heating the containers
             can be used to keep the water in a vapor form.

       The final temperature/moisture category is for moisture content greater than
 10 percent.  This moisture  content renders most of the heating techniques impractical
 because the moisture is more easily condensed and therefore eliminates most of the
 standard sampling analytical techniques.

      After the sampling conditions have been selected according to temperature and
 moisture, the next classification deals with the polarity of the organic compound. Polar
 compounds are generally those compounds that mix with water, such as alcohols, and act
 as water since water is a polar compound. Silica is a good sorbent for both water and
 alcohols. The nonpolar compounds, such as  the chlorinated organics, typically do not
mix with water and can therefore be easily purged out of water.

      For nOnpolar compounds at low levels or ambient temperatures and moisture
 content all the collection techniques would work which include: Tedlar bags, adsorption
tubes, and direct and dilution interface.  Charcoal  as we know is the most widely used
sorbent for nonpolar compounds.
C-12

-------
   LU
UJ LU O

i^£
  LU
35

°l*z
5CH-.5
3 o o j=
s°K"5
— "^ ••• «


 T
                                   u_

                                   QC
                                   UJ
a.


O
         c



         O
         Q.
                          
-------
       For collection of polar compounds at ambient temperatures and moistures (Figure
 C.1, page C-13), all sampling techniques with the exception of Tedlar bags work.  Bags
 tend to adsorb polar compounds.  Silica is the sorbent most commonly used for polar
 compounds.  Direct and dilution interface will work for all cases of polar and nonpolar
 compounds in steady state emissions and where the compounds can be separated quickly.

       Sampling under medium temperature and moisture conditions (Figure C.1, page
 C-13) is the same as under low temperature and moisture condition with the exception
 that containers must be heated to prevent moisture and organic condensation.
 Therefore, nonpolar compound sampling would include heated container, adsorption
 tube, direct and  dilution interface methods.  The polar compounds would best utilize
 adsorption tube, direct and dilution interface techniques.

       It should  be noted that the adsorption tubes must be kept cool and that sorbent
 collection, efficiency may be severely affected by water. One approach when moisture  is
 present is to sacrifice the first adsorption tube  for collection of water and then have a
 third collection tube as the backup tube.

       The high  temperature/high moisture conditions (Figure C.I, page C-13)
 necessitate direct and dilution interface sampling or the recently EPA developed
 adsorption tube sampling technique for nonpolar compounds such  as chlorinated organics
 that are not soluble in water. This technique will not work for compounds that are
 soluble in water.
                                                        s
 C2    OBSERVATION OF ON-SITE TESTING

       The test coordinator should use the techniques and tables provided above in
 Appendix C.1 to ensure that  the sampling and  analytical techniques selected by the tester
 are acceptable. Because of the complexity involved in sampling organic compounds from
 the variety of potential source types, only the more common problems are addressed for
 each sampling method. The  observer should have the tester conduct the recommended
 quality assurance/control  checks and procedures provided in this Chapter to assess the
 suitability:of the  sampling technique.

      Specific sampling system descriptions and observers checklists  are provided below.
The procedures are presented by sampling techniques as shown. The observer can
therefore read only the material of interest.
Chapter

4.53
   A
   B
   C
Sampling Approaches

Evacuated Container Sampling
Sampling System Preparation
Proportional Sampling
Indirect Pumping Bag Sampling
Page

  4-5
  4-6
  4-6
  4-7
C-14

-------
 Chapter           Sampling Approaches                                      Page

    D              Sample Recovery and Transport to Laboratory                 4-9
    £              Common Problems                                          4*9
    F              Stability Check                                             4-9
    G              Retention Check                                           4-9

 Appendix          Sampling Approaches                                      Page
 -
 C.2.1.             Evacuated Container Sampling (Heated and Unheated)        C-15
    H              Direct Pumping Bag Sampling                 .              C-22
    I              Explosion Risk Area Bag Sampling                          C-23
    J              Prefilled Bag Sampling                                     C-23
 C2.2              Direct Interface Sampling                                  C-27
 C.2.3              Dilution Interface Sampling                                 C-30
 C.2.4              Adsorption Tube Sampling                                  C-32

 G2.1  Evacuated Container Sampling (Heated and Unheated)

       In this sampling technique, sample bags are filled by evacuating the rigid air-tight
 containers that hold them. The suitability of the bags for sampling should have been
 confirmed by permeation and retention checks using the specific organic compounds of
 interest during the presurvey operations. The permeation and retention checks must be
 performed on the field samples to ensure that the container sampling technique is
 acceptable.                                                         ~-

       The means of transporting the bags to the  laboratory for analysis within the
 specified time should also have been  determined. Delays in shipping and/or analysis can
 result in significant changes in concentration for many compounds.  EPA has conducted
 several field evaluations of Method 18 bag sampling techniques on a variety of organic
 compounds.  In the EPA Field validation reports  the specified time between sample
: collection and analysis is shown.  The permeation and retention checks are not required
 by Method 18 but are highly recommended for compounds and  source categories  that
 have not been validated by EPA.

       On-site sampling includes the following steps:

       1.    Conducting preliminary measurements and setup.
       2.    Preparation and setup of sampling system.
       3.    Preparation of the probe.
       4.    Connection of electrical service and leak  check of sampling system.
       5.    Insertion of probe into duct and sealing of port.
       6.    Purging of sampling system.
       7.    Proportional sampling.

                                                                             C-15

-------
       8.     Recording data.
       9.     Recovering sample and transportation to laboratory.

       The "On-site Checklist" (Figure C.2, page C-17) includes checks for each of the
 following procedures and should be completed by the observer.

 To assist the observer in noting the most critical items to observe, the key points are
 printed in bold lettering.

       Method 18 requires that samples be collected proportionally, meaning that the
 sampling rate must be kept proportional to the stack gas velocity at the sampling point
 during the sampling period.  If the process has a steady state flow (constant), then the
 flow rate "does not have to be varied during sampling. The average velocity head (phot
 reading) and range of fluctuation is determined and then utilized to establish the proper
 flow rate-settings during sampling.  If it is found that the process is not steady state, then
 the velocity head must be monitored during sampling to maintain a constant proportion
 between the sample flow rate and the flow rate in the duct.

       A total sampling time greater than or equal to the minimum total sampling time
 specified in the applicable emission standard must be selected. The number of minutes
 between readings while sampling should be an integer. It is desirable for the time
 between readings to be such that the flow rate does not change more than 20 percent
 during, this period.
                                                        s
       If it was determined from the literature or the preliminary survey laboratory work
 that the sampling system must  be heated during sample collection and analysis, the
 observer must ensure that the sample system does not go below the specified
 temperature. The average stack temperature is used as the reference temperature for
 the initial heating of the system and should be determined.  Then, the stack temperature
 at the sampling point is measured and recorded during sampling to  adjust the heating
 system just above the stack temperature or the dew point.  In addition, the use of a
 heated sampling system typically requires that  the analysis be conducted on-site since it is
 not practical to maintain the sample bag at elevated temperatures for long periods of
 time.

      A.     Sampling System Preparation - See Chapter 4.5

      B.     Proportional Sampling - See Chapter 4.5

      C.     Indirect Pump Bag Sampling - See Chapter 4.5

      D.     Sample Recovery and Transport  to Laboratory - See Chapter 4.5

      £.     Common Problems - See Chapter 4.5
C-16

-------
 EQUIPMENT SETUP

 Flue Gas Flowrate	constant,	variable
.Sampling rate	constant,	proportional
 Sample tune	required,	actual
 Time per point	minutes,  probe heat required _ yes	no

 DIRECT OR DILUTION BAG SAMPLING

 Apparatus

 Pitot tube: Type S	  Other	, Properly attached  	
 Pressure gauge: Manometer	 Other	, Sensitivity	
 Probe liner: Borosilicate ,	Stainless steel	Teflon	
   Clean  	, Probe heater (if applicable) on 	  Glass wool filter
   (if applicable) in place  	Stainless steel or Teflon unions used
   to connect to sample line
 Sample line: Teflon	, Cleaned 	, Heated (if applicable) 	
 Bag: Tedlar	  Other	, Blank checked  	, Leak checked 	
   Reactivity check	,  Retention check	
 Flowmeter: Proper range	, Heated (if applicable)	, Calibrated ^	
 Pump: Teflon coated diaphragm	, Positive displacement pump       >  .
   Evacuated canister	, Personnel pump	
 Heated box with temperature control system: Maintained at proper temperature	
 Charcoal adsorption tube to adsorb organic vapors: Sufficient capacity  :   •_-
 Dilution equipment: N2 gas	, Hydrocarbon-free air	, Cleaned and
   dried ambient air	, Dry gas meter	
 Barometer: Mercury	, Aneroid	, Other	
 Stack and ambient temperature: Thermometer	, Thermocouple	,
   Calibrated _	:

 Procedures

 Recent calibration (if applicable): Pitot tube	, Flowmeter	,
   Positive displacement pump*	, Dry gas meter*	, Thermometer	,
   Thermocouple	, Barometer	
 Sampling technique: Indirect bag	, Direct bag	, Explosion risk bag	,
   Dilution bag	, Heated syringe	, Adsorption tube	,
   Proportional rate	, Constant rate	, Direct interface	,
   Dilution interface	
 Filter end of probe and pitot tube placed at centroid of duct (or no closer than 1 meter
   to stack wall) and sample purged through the probe and sample lines*

          Figure C.2. On-site measurements checklist.
                                                                            C-17

-------
Vacuum line attached to sample bag and system evacuated until the flowmeter
   indicates no flow (leakless)*	
Heated box (if applicable) same temperature as duct*	
Velocity pressure recorded and sample flow set	
Proportional rate sampling maintained during run*	
Stack temperature, barometric pressure, ambient temperature, velocity pressure
   at regular intervals, sampling flow rate at regular intervals, and initial and
   final sampling times recorded*	
At conclusion of run, pump shut off, sample line and vacuum line disconnected
   and valve on bag closed	
Heated box (if applicable) maintained at same temperature as duct until analysis
   conducted	
No condensation visible in bag*	
Sample bag and its container protected from the sunlight	
Audit gases collected in bags using sampling system*
Explosive area bag sampling: (with following exceptions same as above)	
Pump is replaced with an evacuated canister or sufficient additional line is added
   between the sample bag container and the pump to remove the pump from the
   explosive area	           .     .
Audit gases collected in bags using sampling system*	
Prefilled bag: Proportional rate	Constant rate	
Dilution factor determined to prevent condensation*	
Proper amount of inert gas metered into bag through a properly calibrated dry gas
   meter*	
Filter end of probe (if applicable) and pilot tube placed at centroid of duct (or
   no closer than 1 meter to stack wall) and sample purged through the heated probe,
   heated sample line, and heated flowmeter or positive displacement pump*	
Leak checked  and partially filled bag attached to sample line	
Stack temperature, barometric  pressure, ambient temperature, velocity pressure at
   regular intervals, sampling rate at regular intervals, and initial and final
   sampling times recorded*	
Probe, sample line, and properly calibrated flowmeter or positive displacement pump
   maintained at the stack temperature*	
Sampling iconducted at the predetermined rate, proportionally or constant for entire
   run*	
No condensation visible in probe, sample lines, or bag*	
At conclusion  of run, pump shut off, sample line disconnected and valve on bag
   dosed	
Sample bag and  its container protected from sunlight	
Audit gases collected in bags using dilution system*	
                             Figure C.2.  (Continued)
C-18

-------
Sample Recovery and Analysis

(As described in "Post sampling operations checklist," Figure CIO, page C-37)

DIRECT AND DILUTION INTERFACE

Apparatus

Probe: Stainless steel	, Glass	, Teflon	, Heated system (if
   applicable)	, Checked	
Heated sample line: Checked*	
Thermocouple readout devise for stack and sample line: Checked*	
Heated gas sample valve: Checked*	
Leakless Teflon-coated diaphragm pump: Checked*	
Flowmeter: Suitable range	
Charcoal adsorber to adsorb organic vapors	
Gas chromatograph and  calibration standards (as shown in "Post sampling operations
   checklist," Figure C.10)*	

For dilution interface sampling only:
Dilution pump: Positive displacement pump or calibrated flowmeter with Teflon-
   coated diaphragm pump checked*	
Valves: Two three-way attached to dilution system	
Flowmeters: Two to measure dilution gas, checked*   -"
Heated box: Capable of maintaining 120°C and contains three pumps, three-way
   valves, and connections, checked*	
Diluent gas and regulators: N2 gas	, Hydrocarbon-free air	,  Cleaned air _,
   Checked 	

Procedures

All gas chromatograph procedures shown in "Post sampling operations checklist"
   (Figure CIO)
Recent calibration: Thermocouples	, Flowmeter	, Dilution system
   (for dilution system only)*	
Filter end of heated probe placed at centroid of duct (or no closer than 1 meter to
   stack wall), probe and sample line heat  turned on and maintained at a temperature of
   0°C to 3°C above the source temperature while  purging stack gas	
Gas chromatograph calibrated while sample line purged*	
After calibration, performance audit conducted and acceptable*	
Sample line attached to GC and sample analyzed after thorough flushing*	


                             Figure C2. (Continued)

                                                                           C-19

-------
With probe removed from stack for 5 min, ambient air or cleaned air analysis is
   less than 5% of the emission results*    '	
Probe placed back in duct and duplicate analysis of next calibration conducted
   until acceptable agreement obtained*	
All samples, calibration mixtures, and audits are analyzed at the same pressure
   through the sample loop*	

Sample Analysis

(As shown in "Post sampling operations checklist," Figure C.10.)

If a dilution system is used, check the following:
With the sample probe, sample line, and dilution box heating systems on, probe and
   source: thermocouple inserted into stack and all heating systems adjusted to a
   temperature of 0°C to 3°C above the stack temperature	
Hie dilution system's dilution factor is verified with a high concentration gas of
   known concentration (within 10%)	
The gas chromatograph operation verified by diverting a low concentration gas into
   sample loop	
The same dilution setting used throughout the run	
The analysis criteria is the same shown as for the direct interface  and in the
   "Post sampling operations checklist," (Figure C.10.)

ADSORPTION TUBES
Apparatus

Probe: Stainless steel
Glass
Teflon
Heated
   system and filter (if applicable)
Silica gel tube or extra adsorption tube used prior to adsorption tube when
   moisture content is greater than 3 percent	
Leakless sample pump calibrated with limiting (sonic) orifice or flowmeter.
Rotameter to detect changes in flow	
Adsorption tube: Charcoal (800/200 mg), Silica gel (1040/260 mg)	
Stopwatch to accurately measure sample time	
                             Figure C.2. (Continued)
C-20

-------
  Procedures

  Recent calibration of pump and flowmeter with bubble meter	
  Extreme care is taken to ensure that no sample is lost in the probe or sample line
     prior to the adsorption tube	
- Pretest leak check is acceptable (no flow indicated on meter)	
  Total sample time, sample flow rate, barometric pressure, and ambient temperature
     recorded	
  Total sample volume commensurate with expected concentration and recommended
     sample loading factors	•
  Silica gel tube or extra adsorption tube used prior to adsorption tube when
     moisture content is greater than 3 percent    •	
•' Post-test leak check and volume rate meter check is acceptable (no flow indicated on
     meter, post-test calculated flow rate within 5 percent of pretest flow rate)

  Sample Analysis

  (As shown in the "Post sampling operations checklist," Figure CIO, page C-37.)


  •Most significant items/parameters to be checked.
                               Figure C.2.  (Concluded)

                                                                              C-21

-------
   F.  Stability Check - See Chapter 4.5

   G.  Retention Check - See Chapter 4.5

   H.  Direct Pump Bag Sampling - Direct pump sampling is conducted in a manner
       similar to evacuated container sampling, with the exception that the needle valve
       and the pump are located between the probe and sample bag and the sample
       exposed surfaces of both must be constructed of stainless steel, Teflon or other
       material not affected by the stack gas (Figure CJ, page C-23), Due to the
       additional likelihood that sample may be lost in the needle valve and pump, it is
       recommended that the probe, sample line, needle valve, and pump be heated. If
       it has or can be shown that this not a concern, then the heating may be
       eliminated. All precautions, procedures, data forms and criteria can be applied.
       Ensure that the system has been adequately purged before attaching the bag and
       sampling.

   I.  Explosion Risk Area Bag Sampling - Explosion risk area bag sampling is also
       similar to evacuated container sampling. The major difference is that no electri-
       cal components can be used in the explosion risk area. The first option of the
       tester is to locate the electrical equipment (e.g.,  the pump) outside the explosion
       risk area and run a long flexible line to the container.  If that option is not
       possible, an evacuated steel container may be used as shown in Figure C.4, page
       C-24.  This option may involve a potential spark hazard and must be checked
       through the plant safety officer. It is unlikely that electrical heating of the system
       will likely be allowed. If an evacuated steel container is used, the leak check can
       be conducted outside the explosion risk area and the probe can be purged with a
       hand squeeze pump. The tester may wish to consider an alternative method of
       sampling such as adsorption tubes and an intrinsically safe personnel sampling
       pump or the syringe method. The primary concern must be safety in an explosion
       risk area and all operations must be outlined in writing and cleared through the
       Plant Safety Officer. The same criteria as described above for suitability of the
       bag will apply and must be met.

   J.  Prefilled Bag Sampling - The prefilled bag sampling technique is similar to the
       heated direct pump sampling method.  The major difference is that the sample
       bag is prefilled with a known volume of nitrogen, hydrocarbon-free air, or
       cleaned, dried ambient air prior to sampling and the volume of gas sampled must
       be accurately determined (Figure G3, page C-23).  When using a flowmeter  or
       metering pump, the maximum dilution that should be attempted  is 10 to 1.
       Alternatively, a heated, gas tight syringe may be  used to collect the source and
       inject it into the sample bag. A heated, gas tight syringe can be used for dilutions
       of 5 to 1 when the dilution is performed in the syringe and 50 to  1 when
       performed in the bag. The use of a heated, gas tight syringe should follow the
       procedures shown below. Both techniques should be verified in the laboratory
C-22

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    using higher concentrations of calibration gases and must be within 10 percent of
    the calculated value.  The technique is verified in the field by diluting the audit
    gases in the same manner as the stack gases (see Chapter 4.7 for auditing
    procedures).

Following are the recommended steps to conduct prefilled bag sampling:

1.  Hie sampling should be conducted proportionally as described above in
    Appendix G2.1. Calculation of the average sampling rate versus the average AP
    will be the same with the exception that the volume of the prefilled inert gas must
    be taken into account.
2.  The suitability of the prefilled bag sampling technique should have been checked
    in the laboratory. This would include calculating the dilution factor required to
    obtain an acceptable sample concentration.  The dilution factor must be properly
    calculated since the concentration of the sample will be corrected for the inert gas
    volume.
3.  In the laboratory area, fill the sample bag (previously leak checked) with the
    calculated volume of inert gas.  Because of the potential for leaks, bags should be
    filled the same day they are used. The inert gas volume must be determined with
    a calibrated dry gas meter or mass flowmeter.  The bag should be sealed and
    taken to the sampling site.
4.  At the sampling site, the sampling system is leak checked without the sampling
    bag attached.  Turn on the heating system and heat the system to the stack
    temperature. Connect a U-tube H2O manometer or equivalent to the inlet of the
    probe. After the system comes  to the desired temperature,  turn on the pump and
    pull a vacuum of about 10 in. of H2O. Turn off the needle valve and shut off the
    pump. If there is no noticeable leak within 30 seconds, then the system is leak
    free.  The heating and leak check are again important.
5.  Place the probe in the stack at the sampling point (centroid or no less than 1
    meter from the wall)  and seal the port so there will be  no in-leakage of ambient
    air.  Turn on the pump and purge the system for 10 minutes. While the system is
    purging, determine and set the proper flow rate based on the AP.
6.  Turn off the pump and attach the sample bag.  Compare  the heating system.
7.  The sampling will be  conducted proportionally. The stack temperature and
    heating system temperature should be monitored and recorded.  Record the data
    on the sampling data form.
8.  At the conclusion of the run, turn off the pump and remove the probe from the
    duct. Remove the bag and seal it.
9.  Conduct a final leak check. The system should pass the leak check; if it does not
    pass, repeat the run.
                                                                          C-25

-------
   K. Heated Syringe Sampling - The heated syringe technique can be used with the
       prior approval of the Administrator. This technique should only be used when
       other techniques are impractical.  The heated syringe technique requires on-site
       analysis with three syringes collected and analyzed for each run.  The require-
       ments for the use of the syringes are the same as for the bag with regard to the
       reaction of the gases with time and.the retention of the gases in the syringe.

   Following are the procedures recommended for the syringe sampling technique:

   1.  If heating is required, then the syringe must be encased in material that has a
       high density to maintain the proper temperature. Alternatively, an external
       heating system can be used that keeps the syringe at the proper temperature until
       just before use and to which the syringe can be immediately returned. The
       syringe must be properly heated.  A check can be made on the heating system by
       filling the syringe with inert gas after the sample injection, reheating it and then
       mject the inert gas.  If the system give a concentration of 10 percent or more of
       the original sample concentration, then the sampling system is unacceptable.
   2.  The access port should be extremely small to prevent in-leakage of ambient air.
       The port may be covered with Teflon or other nonreactive material that will allow
       the syringe to penetrate the material for sampling.
   3.  For the direct injection  method (no dilution), place the syringe needle into the
       stack and fill and discharge the full volume that will be sampled three times.
       Then, draw the emission sample into the syringe, immediately seal the syringe and
       return to the heating system, if applicable. The  second and third syringes are
       sampled at equal time intervals spanning the required sample (run) time.  The
       syringe samples must not be taken one immediately after another.
   4.  For the diluted syringe method, the inert gas is introduced into the syringe three
       times and discharged. Following this, the proper volume of inert gas is pulled
       into the syringe. The syringe is then placed into the duct and the proper volume
       of stack gas is added. Immediately remove the syringe needle from the duct, seal
       the syringe, and return to the heating system, if applicable.  If a dilution approach
       is :iised it  should be checked as shown in Item 1 and the dilution factor should be
       checked using calibration gases.
   5.  Foi>the bag diluted syringe method, the bag should be prefilled with the proper
       volume of inert gas.  The sampling is conducted as described above and the
       sample injected into  the bag through a septum.
   6.  Record the data on a field sampling data form.
   7.  Since the method requires that a proportional  sample collected, the velocity head
       (AP) should be recorded at about the same time that each sample is collected.
       The concentrations can then be mathematically corrected to provide an integrated
       value.  If the process is a constant source operation (less than 10 percent change
       in flow over the sampling period), it is not necessary to correct the measured
       values.
C-26

-------
C22 Direct Interface Sampling - The direct interface procedure can be used provided
that the moisture content of the stack gas does not interfere with the analysis procedure,
the physical requirements of the equipment can be met at the site, and the source gas
concentration is low enough that detector saturation is not a problem. Adhere to all
safety requirements when using this method.  Because of the amount of time the GC
takes to resolve the organic compounds prior to their analysis, the GC can only typically
make three analyses in a one-hour period. Therefore, the number of injections hi the
direct interface method is greatly limited by the resolution time.  At least three injections
must be conducted per sample run.

   Following are the procedures recommended for extracting a sample from the stack,
transporting the sample through a heated sample line, and introducing it to the heated
sample loop and the GC. The analysis of the sample is described in Appendix G3.

   1. Assemble the system as shown Figure C.5, making all connections tight.
   2. Turn on the sampling system heaters.  Set the heaters to maintain the stack
      temperature as indicated by the stack thermocouple. If this temperature is above
      the safe operating temperature of the Teflon components, adjust the heating
      system to maintain a temperature  adequate to prevent condensation of water and
      organic compounds.
   3. Turn on the sampling pumps and set the flow rate at the proper setting. Typically
      11/min is used. The sample rate may vary for the type of system  used. The
      system may use either an internal pump or external pump.
   4. After the system reaches the same temperature as the stack,  connect a U-tube
      H2O manometer or equivalent to the inlet of the probe. Pull a vacuum of about
      10 in. of H2O,  and shut off the needle valve and then the pump.  The vacuum
      should remain stable for 30 seconds. If the system leaks,  repair and:then recheck
      the system.
   5. Calibrate the system  as described in Appendix C.3. Repeat'until duplicate
      analyses are within 5 percent of their mean value (Appendix C.3). The calibration
      of the system is critical.
   6. Conduct the analyses of the two audit samples as described in Chapter 4.8.  The
      results must agree within 10 percent of the true value (or greater, if specified on
      the cylinder). If the results do not agree, repair the system and repeat the
      analyses until agreement is met or until approval is given by the representative of
      the Administrator. The performance audit is critical.
   7. After the audit has been successfully completed, place the inlet of the probe at
      the centroid of the duct, or at a point no closer to the walls than 1 meter, and
      draw stack gas into the probe, heated line, and sample loop.  Purge the  system for
      a least 10 minutes.
   8. Record the field sampling data on a form such as the form shown in Figure C.6.
   9. 'Conduct the analysis  of the sample as described in Appendix C3.  Record the
      data on the applicable data form.  Ensure that the probe and sample lines are
      maintained at 0°C to 3°C above the stack temperature (or a temperature which


                                                                             C-27

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 10.
 prevents condensation).  The sample lines must be properly heated and
 equilibrated. A good check on the system is to pull the sample probe out of the
 stack at the conclusion of a sample run.  The system should return to less than
 about 5 percent of the sample concentration within about 5 minutes.

 Conduct the post-test calibration as described in Appendix C3. System
 calibrations are critical.
 C2.3  Dilution Interface Sampling - Source samples that contain a high concentration of
 organic materials may require dilution prior to analysis to prevent saturating the GC
 detector.  The apparatus required for this direct interface procedure is basically the same
 as described above, except a dilution system is added between the heated sample line
 and the gas sampling valve.  The apparatus is arranged so that either a 10:1 or 100:1
 dilution of the source gas can be directed to the chromatograph.

   Following are the procedures recommended for extracting a sample from the stack,
 diluting the gas to the proper level, transporting the sample through a heated sample
 line, and introducing it to the heated sample loop and the GC. The analysis of the
 sample is described in Appendix C.3.
   1.
   3.
   4.
C-30
Assemble the apparatus by connecting the heated box, as shown in Figure C.7,
between the heated sample line from the probe and the gas sampling valve on the
chromatograph.  Vent the source gas from the gas sampling valve directly to the
charcoal filter, eliminating the pump and rotameter.  ,--'
Measure the  stack temperature, and adjust all heating units to a temperature 0°C
to 3°C above this temperature.  If the temperature is above the  safe operating
temperature of the Teflon components, adjust the heating to maintain a
temperature high enough to prevent condensation of water and  organic com-
pounds.  Heating is typically more critical for stacks that require dilution. The
check of removing the probe from the stack as recommended above should be
demonstrated.
After the heaters have come to the proper temperature, connect a U-tube H2O
manometer or equivalent to the inlet of the probe.  Turn on the pump and pull a
vacuum of about  10 in. of H2O. Shut off the needle valve and then turn off the
pump. The vacuum reading should remain stable for 30 seconds.  If a leak is
present, repair and then recheck the system.
Verify operation of the dilution system by introducing a calibration gas at the inlet
of the probe. The diluted calibration gas should be within 10 percent of the
calculated value.  If the results for the diluted calibration gas are not within
10 percent of the expected values, determine whether the GC and/or the dilution
system is in error. If the analyses are not within acceptable limits because of the
dilution system, correct it to provide the proper dilution factors. Make this
correction by diluting a high concentration standard gas mixture to adjust the
dilution ratio as required.  The dilution factor must be correct to obtain the true
value.  A dilution system can give proper results, but it can also provide very
poor results when improperly conducted.

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    5.  Verify the GC operation using a low concentration standard by diverting the gas
       into the sample loop and bypassing the dilution system. If these analyses are not
       within acceptable limits, correct the  GC by recalibration, etc. The test
       coordinator should verify these calculations.
    6.  Conduct the analyses of the two audit samples  as described in Appendix G3 using
       either the dilution system or directly connect the gas sampling valve as required.
       The results must agree within 10 percent of the true value or greater value if
       specified on the cylinder. If the results do not  agree, repair the system and repeat
       the analyses until agreement is met or until  approval is given by the
       representative of the Administrator.  The performance audit is critical and should
       go through the dilution system when possible.
    7.  After the dilution system and GC operations are properly verified and the audit
       successfully completed, place the probe at the centroid of the duct or at a point
       no closer to the walls than 1 meter, and purge the sampling system for at least 10
       minutes at the proper flow rate.  Conduct the analysis of the sample as described
       in-Appendix C.3.  Record the field and analytical data  on the applicable data
       forms. Ensure that the probe, dilution system,  and sample lines are maintained at
       0°C to 3°C above the stack temperature (or  a temperature which prevents
       condensation).
   8.  Conduct the post-test calibration and verification of the dilution system as
       described in Appendix C.3.  Check the calibration calculations.

   If the dilution system is used for bag sampling, the  procedures for verifying operation
of the dilution system will be the same as shown above.  The diluted calibration gas will
be collected in a bag and then verified.  Also  the audit samples will be collected in a bag
and analyzed. Acceptable results must be obtained for the audit samples prior to
analysis of the field samples.

G2.4  Adsorption Tube Sampling - Adsorption tube sampling can be used for those
organics specified in  Table C-2, page C-4, and for other compounds as specified in the
National Institute of Occupational Safety and  Health (NIOSH) methods. The selection
and use of adsorption tubes must be validated in the laboratory or through the use of the
literature.- This check will include selecting the proper adsorption material, and then
checking the capacity, breakthrough volume, adsorption efficiency, and desorption
efficiency.  The adsorption efficiency can be greatly affected by the presence of water
vapor and other organics in, and temperature of, the stack gas.  If sampling is
conducted for more than one organic compound, the adsorption and desorption effic-
iency checks must consider each.  Because changes in process and control equipment
conditions  can greatly affect all of the parameters stated above, it is recommended as  a
standard operating procedure that more than one adsorption tube be used.  The first
tube is analyzed as described in Appendix C3. If no problems are found, then the
second tube can be discarded.  If problems with the first tube's adsorption efficiency are
discovered, then the primary section of the second tube can still be analyzed and the
results included with  those of the primary portion of the first tube.
   Following are the  recommended procedures for  adsorption tube sampling:
C-32

-------
                                   .;-
1.  The sampling system is assembled as shown in Figure C.8, page C-34. The
    adsorption tube(s) must be maintained in a vertical direction for sampling.  This
    is done to prevent channeling of the gases along the side of a tube.  It is
    recommended that the sampling probe be eliminated when possible.  If a sample
    probe is used, it should be cleaned prior to its initial use with the extraction
    solvent.  Teflon tubing should be used for the probe and sample line.
2.  Just prior to sampling, break off the ends of the adsorption tubes to provide  an
    opening at least one-half of the internal  diameter. Audit samples must be
    collected on the adsorption tubes during the test program as described in
    Chapter 4.8.  Since on-site analysis is typically not conducted when using
    adsorption tubes, it is recommended that two samples be collected from each of
    the two audit  cylinders. This allows the  tester a second chance to obtain the
    proper value for each audit cylinder.
3.  Prior to sampling and the collection of the audit samples, the sampling system
    must be leak checked by connecting a U-tube H2O manometer or equivalent to
    the inlet of the sample probe or adsorption tube. Turn the pump on and pull a
    vacuum of about  10  in. of H2O.  Shut off the needle valve and then turn off the
    pump. The vacuum must remain stable  for 30 seconds. If a leak is present,
    repair and recheck the system.  The leak check must be passed.
4.  If the flow rate in the duct varies by more than 10 percent during the sampling
    period, the sample should be collected proportionally.  The proportional sampling
    procedures will be the same as described for the bag sampling.  The only
    difference is that instead of using the volume of the bag as  the limiting factor to
    determine the average sampling rate, the breakthrough volume is the limiting
    factor.   If the source is a constant rate source (less than a 10 percent change in
    flow rate for the sampling period), the samples can be collected at a  constant rate.
5.  Prepare  the field blank just prior to sampling. The field blank will be handled in
    be same manner as the field samples and should be from the same lot as  the
    other adsorption tubes. Blank correction can be allowed.
6.  The flow rate  meter must have been calibrated in the laboratory prior to the field
    trip.  The volume of sample collected must be accurately known for adsorption
    tube sampling. The calibration data should be checked.
7.  The sample run time must be equal to or greater than that specified by the
    applicable regulation.  During each sample run, the data should be recorded  on
    the sample data form as shown  in Figure C.9, page C-35.
8.  At the conclusion of each run, conduct another leak  check as described above.  If
    the system does not pass the leak check, the run should be rejected, the leak
    located and repaired, and another run conducted.
                                                                          C-33

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   9.  After completing a successful leak check, remove the adsorption tube from the
       holder and seal both ends with plastic caps. The tubes should be packed lightly
       with padding to minimize the chance of breakage. If the samples are to be held
       for an extended period of time, they should be kept cool to reduce the amount of
       migration of the  organic from the primary section to the secondary section.
       Note: Pack the tubes separately from bulk samples to avoid possible
       contamination.
   10. It is recommended, that at the conclusion of the test, the sample probe (if used)
       be rinsed into a 20-ml glass scintillation vial with about 5 to 10 ml of the
       desorption solvent. This sample will be analyzed as  a check on the loss of the
       organic in the probe during sampling.  If more than 10 percent of the total
       sample collected in the adsorption tubes is present in the probe, the samples
       should be rejected or the sample catch adjusted to account for the loss.
       Alternatively, the probe can be rinsed after each run and the rinse added to  the
       desorption solvent prior to analysis.
   11. At the conclusion of the test program, check all samples to ensure that they are
       uniquely identified and check all data sheets to ensure that all data has been
       recorded.

O3    VOC SAMPLE ANALYSIS

   Figure CIO, page C-37, post sampling operations checklist can be used as a guide by
the testing firm for sample analysis or by the observer for observation of the sample
analysis.

C3.1  Preparation of Calibration Standards

   Calibration standards are to be prepared prior to sample analysis following the
procedures described below.  Refer to Table C-4, page C-8, for recommendations on the
procedures suitable for selected compounds.  Note that there are two basic types of
standards, gaseous or liquid; the type prepared depends on the type of sample collected.
Gaseous calibration standards will be needed prior to the analysis of preliminary survey
samples collected in glass flasks or bags, and final samples collected in bags or by direct
and dilution interface sampling. There are three techniques for preparing gaseous stan-
dards, depending on availability and the chemical characteristics of the standard
compound(s); gas cylinder standards may also be used directly, if the proper
concentration ranges are available. Liquid calibration standards are required for the
analysis of adsorption tube samples from the preliminary survey and/or the final
sampling, as well as to determine the desorption efficiency;  there are two techniques for
preparing liquid calibration standards.  The concentrations of the calibration standards
should bracket the expected concentrations of the target compound(s) at the source
being tested.  Specific procedures for preparing and analyzing each  type of standard are
described below.
C-36

-------
Date	Plant Name
Sampling Location	
Checks for Analysis of All Calibration Standards

A minimum of three concentration levels used for each target compound?
	Yes	No  (The concentration used should bracket the expected concentrations
of the actual field samples.)
Proper GC conditions established prior to standard analysis?	Yes	No
   (For initial conditions use analytical conditions found to be  acceptable during
   preliminary survey sample analysis.)
Individual peak areas for consecutive injections within 5 percent of their mean for each
   target compound?	Yes	No
   (Repeat analysis of standards until 5 percent criteria is met.)
Second analysis of standards after sample analysis completed?	Yes	No
Peak areas for repeat analysis of each standard within 5 percent of their mean peak
   area?	Yes	No
   (If no, then report sample results compared to both standard curves.)
Checks for Calibrations using Commercial Cylinder Gases

Vendor concentration verified by direct analysis?	Yes	No
Sample loop purged for 30 seconds at 100 ml/min prior to injection of calibration
   standards?      Yes     No
Checks for Preparation and Use of Calibration Standards Prepared by Dilution

Dilution system flowmeters calibrated?	Yes	No
   (Calibrate following procedure described in Appendix C3.)
Sample loop purged for 30 seconds at 100 ml/min prior to injection of calibration
   standards?	Yes	No
Dilution ratio for dilution system verified?	Yes	No
   (Analysis of low concentration cylinder gas after establishing calibration curve
   recommended to verify dilution procedure, but not required since audit sample will
   also verify dilution ratio.)
                  Figure C.10.  Post sampling operations checklist.
                                                                            C-37

-------
Checks for Preparation and Use of Calibration Standards by Direct Injection of
Gaseous Compounds or Liquid Injection

Tedlar bag used to contain prepared standard leak and contamination free?
   Yes	No	
Dry gas meter used to fill bag calibrated?	Yes	No
   (Calibrate meter following procedure described in Appendix C3)
Organic standard material used for injection 99.9 percent pure?	Yes	No
   (If no, then determine purity and use to correct calculated calibration standard con-
   centration.)
Prepared standard allowed to equilibrate prior to injection?	Yes	No
   (Massage bag by alternately depressing opposite ends 50  times.)
Sample loop purged for 30 seconds at 100 ml/min prior to injection of calibration
   standards?      Yes      No       >
Development of Relative Response Factors and Retention Times

Suitable target organic or surrogate compound selected?	Yes	No
   (Select compound that is stable, easy to prepare in the field, and has a retention time
   similar to the target organic compounds.)
Relative response factors and retention times verified in the laboratory prior to actual
   field use?	Yes	No
   (If no, verify following the procedure described in Appendix C.3.)
^
Checks for Preparation, Use, and Determination of Desorption Efficiency for Adsorption
Tube Standards

Organic standard material used for injection 99.9 percent pure?	Yes	No
   (If no, then determine purity and use to correct calculated calibration standard con-
   centration.)
Correct adsorbent material and desorption solvent selected?	Yes	No
   (Refer to Table C-2 for proper adsorbent material and desorption solvent.)
Desorption efficiency determined for adsorbent to be used for field sampling?
       Yes     No
                             Figure C.10.  (Continued)
C-38

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Checks for All GC Analysis of Field Samples

deck type of carrier gas used:  Helium	Nitrogen	Other	
Carrier gas flow rate and pressure set correctly?  	Yes	No
   (Carrier gas flow rate and pressure set according to conditions developed during
   presurvey sample analysis and within limitations of the GC as specified by GC
   manufacturer.)
Oxygen and hydrogen flow rate and pressure for FID correct?	Yes	No
   (Oxygen and hydrogen gas  flow rate and pressure for FID set according to conditions
   developed during presurvey sample analysis and within limitations of the GC as
   specified by GC manufacturer.)
Individual peak areas for consecutive injections within 5 percent of their mean for each
   target compound?	Yes	No
   (Repeat analysis of standards until 5 percent criteria is met)
Audit sample analyzed and results within 10 percent of actual value?	Yes	No
   (If no, recalibrate GC and/or reanalyze audit sample.)
Checks Type of Standard Used for Tedlar Bag Sample Analysis

Gas cylinders	dilution of gas cylinders	direct gas injection
   direct liquid injection	and/or relative response factors and retention .times
Checks For GC Analysis Of Tedlar Bag Samples

Sample loop purged for 30 sec. at 100 ml/min prior to injection of calibration
   standards?	Yes	No

Stability of gas sample in Tedlar bag determined?	 Yes	No
   (Determine stability by conducting a second analysis after the first at a time period
   equal to the time between collection :and the first analysis.  The change in
   concentration between the first and  second analysis should be less than 10 percent.)
Retention of target compounds in Tedlar bag determined?	Yes	No
                             Figure CIO. (Continued)
                                                                            C-39

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 Check GC Interface Technique Used

 Direct Interface      10:1 Dilution Interface
100:1 Dilution Interface
Checks For Suitability of GC Interface Technique

Analytical interference due to moisture content of source gas?	Yes	No
   (Moisture in the source gas must not interfere with analysis in regard to peak
   resolution according to EPA Method 625 criterion where the baseline-to-valley height
   between adjacent peaks is less than 25 percent of the sum of the two adjacent peaks.)

Physical-requirements for equipment met on-site? 	Yes	No
   (The physical requirements for the equipment include sheltered environment, "clean",
   uninterrupted power source suited for equipment, and adherence to safety aspects
   related to explosion risk areas.)

Source gas concentration below level of GC detector saturation?	Yes	No
   (Concentrations delivered to the detector can be reduced by using smaller gas sample
   loops and/or dilution interface.)

Sampling systems purged with 7 changes of system volume prior to sample
   analysis?	Yes	No
Check Type(s) of Standards Used for Interface Techniques

Gas Cylinders	Dilution of Gas Cylinders	Direct Gas Injection
   Direct Liquid Injection	and/or Relative Response Factors and
   Retention Times
Checks For Dilution Interface Analytical Apparatus

Dilution rate verified (within 10 percent) by introducing high concentration gas  through
   dilution system and analyzing diluted gas?	Yes	No
   (If dilution rate not verified, then first check calibration of GC by reanalyzing a
   calibration standard and then adjust dilution system to give desired ratio.)

Sampling systems purged with 7 changes of system volume prior to sample analysis?
       Yes      No
                             Figure CIO. (Continued.)
C-40

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Check Type of Standard Used for Adsorption Tube Analysis

Prepared directly in Desorption Solvent	and/or Prepared on adsorbent and
   desorbed	

Checks for GC Analysis of Adsorption Tube Samples

Desorption procedure used identical to procedure used to determine the
   desorption efficiency?	Yes	No

Collection efficiency determined for adsorption tubes used for actual field sampling?
   	Yes	No
   (If no, then determine collection efficiency following the procedures described in
   Appendix G3.)

Check Type of Standard Used for Analysis of Heated Syringe Samples

Gas Cylinders	Dilution of Gas Cylinders	Direct Gas Injection	
   Direct Liquid Injection	and/or Relative Response Factors and
   Retention Times
                            Figure CIO.  (Concluded)
                                                                          C41

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If"
       For each target compound, a minimum of three different standard concentrations
 are required to calibrate the GC. An exception to this requirement involves developing
 relative response factors for each compound to be tested as compared to a  single organic
 compound. Once in the field, the GC is calibrated for all target compounds using the
 single organic. Hie validity of this procedure must be first be proven in the laboratory
 prior to the test. To save time, multiple component standards can be prepared and ana-
 lyzed provided the elution order of the components is  known.

       It is recommended that the linearity of the calibration curve be checked
 comparing the actual concentration of the calibration  standards to the concentration of
 the standards calculated using the standard peak areas and the linear regression equa-
 tion.  The recommended criteria for linearity is for the calculated concentration for each
 standard be within 7 percent of the actual concentration.

       After establishing the GC calibration curve, an  analysis of the audit cylinder is
 performed as described in Chapter 4.7. For an instrument drift  check, a second analysis
 of the calibration standards and generation of a second calibration curve is  required
 following sample analysis. The area values for the first and second analyses of each
 standard must be within 5 percent of their average.  If this criterion cannot  be met, then
 the sample values obtained using the first and second calibration curves should be
 averaged. In addition, if reporting such average values for the samples is warranted, an
 additional analysis of the audit cylinder should be performed. The average  of the audit
 values obtained using the two calibration curves should be reported.

 C3.2  Analysis of Direct Interface Samples

       Prior to analysis of the direct interface sample, the GC should be calibrated using
 a set of gaseous standards prepared by one of the techniques described above and a
 successful analysis of an audit sample should be completed.  If possible, the audit
samples should be introduced directly into the probe.  Otherwise, the audit-samples are
introduced into the sample line immediately following  the probe. The calibration is
done by-disconnecting the sample line coming from the probe, from the  gas sampling
valve sample loop inlet, and connecting the calibration standards to the loop for analysis.
During the analysis of the calibration standards and the audit sample(s), make certain
that the sample loop pressure immediately prior to the injection of the standards is at
the same pressure mat will be used for sample analysis. To analyze the  direct interface
samples after GC calibration, use the following procedures:

       1.  Record the sample identify, detector attenuation factor, chart speed, sample
          loop temperature, column temperature and  identity, and the carrier gas type
          and flow rate on a form.  It is also recommended that the same information
          be recorded directly on the chromatogram.  Record the operating parameters
          for the particular detector being used.
           C-42

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      2.  Examine tbe chromatogram to ensure that adequate resolution is being
          achieved for the major components of the sample. If adequate resolution is
          not being achieved, vary the GC conditions until resolution is achieved, and
          reanalyze the standards to recalibrate the GC at the new conditions.
      3.  Immediately after the first analysis is complete, repeat steps 2 and 3 to begin
          the. analysis of the second sample.
      4.  After conducting the analysis of the first sample with acceptable peak
          resolution,  determine the retention time of the sample components and
          compare them to the retention times for the standard compounds. To quali-
          tatively identify an individual sample component as a target compound, the
          retention time for the component must match, within 0.5 seconds or
          1 percent, whichever is greater, the retention time of the target compound
          determined with the  calibration standards.
      5.  At the completion of the analysis of the second sample,  determine if the area
          counts for the two consecutive injections give area counts within 5 percent of
          their average.  If this criterion cannot be met due to the length of the analysis,
          and the emissions are known to vary because of a cyclic or batch process, men
          the analysis results can still be used with the prior approval of the
          Administrator.  If the sample time is extended and the number of injections
          increased, the agency can accept the  data that does not meet the above
          requirements.
      6.  Analyze a minimum  of three samples collected by direct interface  to consti-
          tute an emissions test. More will be required if the source is variable and the
          10 percent  requirement is not met.
      7.  Immediately following the analysis of the last sample, reanalyze-the cali-
          bration standards, and compare the area values for each standard to the
          corresponding area values from the first calibration analysis.  If the individual
          area values are within 5 percent of their mean value, use the mean values to
          generate a final calibration curve  to determine the sample concentrations. If
          the individual values are not within 5 percent of their mean values, generate
          a calibration curve using the results of the second analysis of the calibration
          standards,  and report the sample  results compared to both standard curves.

C3.3 Analysis of Dilution Interface Samples

          For the analysis of dilution  interface samples, the procedures described for
direct interface sampling shown above, with the addition of a check of the dilution
system.  Prior to any sample analysis, the GC must first be calibrated, followed by the
dilution system check  and an analysis of the audit sample(s).  The audit sample(s) are
introduced preferably  into the inlet to  the dilution system or directly into the gas
                                                                              C-43

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sampling valve. Use the following procedures to conduct the check of the dilution
system:

       1.  Heat the dilution system to the desired temperature (0° to 3°C above the
           source temperature) or, if the dilution system components can not tolerate
           that temperature, to a temperature high enough to prevent condensation.
           Heating is typically very critical; the gases must be kept at or above the stack
           temperature at all points through the system. Many systems have an internal
           pump which is not well heated*  Conduct the check on the system as
           described above by pulling the probe from the stack at the conclusion of the
           first run.
       2.  Adjust the dilution system to achieve the desired dilution rate, and introduce
        ....  a high concentration target gas into the inlet of the dilution system.  After
        :   dilution through the stage(s) to be used for actual samples, the target gas
         ,  should be at a concentration that is within the calibration range.
       3r  Purge the gas sample loop with diluted high concentration target gas at a rate
           of 100 cc/min for 1 minute. Adjust the loop pressure measured by a water
           manometer connected to a tee at the outlet  of the loop, to  the loop pressure
           that was used during calibration and will be  used during sample analysis.  The
           procedure for pressure adjustment for the sample loop will vary with the type
           of dilution system that is used. In general, the loop pressure can be lowered
           by reducing the flow into the loop and raised by restricting the flow from the
           loop.
       4.  After achieving the proper loop pressure, immediately switch the gas sample
           valve to the inject position.
       5.  Note the time of the injection on the strip chart recorder and/or actuate the
           electronic integrator.  Also, record the sample identity, detector attenuation
           factor, chart speed, sample loop temperature, column temperature and identi-
           ty, and the carrier gas type and flow rate on a form.  It is also recommended
           that the  same information be recorded directly on the chromatogram.  Record
           the operating parameters for the particular detector being used.
       6.   Determine the peak area and  retention time for the target compound used for
        :  the dilution check, and calculate the area value using the detector attenuation.
           Compare the retention time to the retention time of the target compound
           calibration standard. The retention times should agree within 0.5 seconds or
        v  1 percent, whichever is greater. If the retention times do not agree, identify
           the problem and repeat the dilution check.
       7.   Calculate the concentration of the dilution check gas (Cd) using the following
           formula.
C-44

-------
                                                                     Equation C-l
          where:

             Y  =  Dilution check target compound peak area, area counts,
             b  =  y-intercept of the calibration curve, area counts,
             S  =  Slope of the calibration curve, area counts/ppm^ and
             d  =  Dilution rate of the dilution system, dimensionless.

          8. If the calculated value for the dilution check gas is not within 10 percent of
             the actual dilution check gas, then determine if the GC or the dilution
             system is in error.  Check the calibration of the GC by analyzing one of the
             calibration samples directly bypassing the dilution system. If the GC is
             properly calibrated, then adjust the dilution system, and repeat the analy-
             sis of the dilution check gas until the calculated results are within 10
             percent  of the actual concentration.

      Once the dilution system and the GC are operating properly, analyze the audit
sample(s).  Upon completion of a successful audit, the system is ready to analyze
samples. To load the sample from the dilution system may not require a pump on the
outlet of the sample loop, but calibration of the GC using standards prepared in Tedlar
bags will require a pump. The system should be configured so that the pump can be
taken off line when it is not needed.

G3.4 Analysis of Adsorption Tube Samples

      Prior to the analysis of adsorption tube samples, the target compounds adsorbed
on the adsorption material must be desorbed.  The procedures for the analysis of the
sample desorption  solutions are the same as those used for the standards. During
sample analysis, the sample collection efficiency must be determined.  Use the following
procedures to determine the collection efficiency:

      1.  Desorb the primary and backup sections of the tubes separately using the
          procedures found to give acceptable (50 percent) desorption efficiency for the
          spiked adsorption material. Use the same final volume of desorption solution
          for the samples as was used for the standard solutions. If more than one
          adsorption  tube was used in series per test run, delay desorbing the additional
          tubes until  the analysis of the primary and backup section of the first tube is
          complete, and the collection efficiency for the first tube determined. Select
          the samples from the sampling run when the flue gas or duct moisture was the
          highest and, if known, when the target compound concentrations were the
          highest and analyze them first.
      2.  Calibrate the GC using standards prepared directly in desorption solvent or

                                                                              C45

-------
          prepared on adsorbent and desorbed.
      3.  Select a suitably sized injection syringe (5 or 10 ul), and flush the syringe with
          acetone (or some other suitable solvent if acetone is a target compound) to
          clean the syringe.
      4.  Flush the syringe with the desorption solution from the tube's backup section
          by withdrawing a syringe full of the solution from the septum vial, and di-
          spensing the solution into a beaker containing charcoal adsorbent
      5.  Refill the syringe with the backup section desorption solution, withdraw the
          syringe from the vial, and wipe the syringe needle with  a laboratory tissue.
      6.  Adjust the syringe volume down to the amount used for injecting standards
          and inject the sample into the GC. Note the time of the injection on the strip
          chart recorder and/or actuate the electronic integrator. Also, record the
          sample identity, detector attenuation factor, chart speed, injection port
        rr temperature, column temperature and identity, and the carrier gas type and
          flow rate on the data form. It is also recommended that the same
        •"• information be recorded directly on the chromatogram. Record the  operating
          parameters for the particular detector being used.
      7.  After the analysis, determine the retention time of the major sample
          components, and compare these retention times to the retention times deter-
          mined for the target compounds during analysis of the standards. To quali-
          tatively identify an individual sample component as a target compound, the
          retention time for the component must match, within 0.5 seconds or
          1 percent, whichever is greater, the retention time of the target compound
          determined with the calibration standards. Determine  the peak area for each
          target compound identified in the sample.
      8.  Repeat the  injection of the first sample until the area counts for each
          identified target compound from two consecutive injections are within
          5 percent of their average.
      9.  Multiply the average area count of the consecutive injections by the  attenu-
          ation factor to get the area  value for that sample.
      10. Next analyze the desorption solution from the primary section of the same
        ~ adsorption tube following steps 4 through 9 above.
      11. For each target compound,  calculate the total weight (W), in ug, present in
        -"each section, taking into account the desorption efficiency using the following
          formula below.
C-46

-------
                         Wf   W^— x —                 Equation C-2
    where:                                           .

             =  Weight of primaiy tube,
             =  Weight of backup tube,
      Y     =  Average value for the target compound in the section (primaiy
                or backup), area counts,
      b      =  y-intercept from the three-point calibration curve for the target
                compound, area counts,
      S      =  Slope from .the three-point calibration curve for the target
                compound, area/ug, and
      DE    =  Desorption efficiency (if standards prepared directly in desorp-
                tion solvent are used for calibration).

12. Determine the percent of the total catch found in the primary section for each
    target compound identified using the following formula.
                          E  =	2—xlOO                   Equation C-3
   where:

      E^    =  Collection efficiency of the primary section for target
                compound x, percent,
             =  Catch of compound x hi the primary section, ug, and
             =  Catch of compound x in the backup section, ug.

   If the collection efficiency for the primary section for each target compound
   identified is &  90 percent, then the collection efficiency for that compound is
   acceptable. If the collection efficiency for all the target compounds identified
   in the sample is acceptable, then the analysis of any additional tubes used in
   series behind the first tube will not be necessary.  Proceed with the analysis of
   the other adsorption tube samples.
13. If the collection efficiency for any identified target compound is not accept-
   able, then analyze the second tube (if used) connected in series and determine
   the collection efficiency for that tube using the  steps described above.  If the
   second tube does not exhibit acceptable collection and a third tube was used,
   analyze the third tube. If acceptable collection efficiency cannot be
   demonstrated for the sampling system, then the emission test using
   adsorption tubes will not be acceptable.

                                                                      C-47

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       14. Immediately following the analysis of the last sample, reanalyze the cali-
          bration standards, and compare the area values for each standard to the
          corresponding area values from the first calibration analysis. If the individual
          area values are within 5 percent of their mean value, use the mean values to ,>
          generate a final calibration curve for determining the sample concentrations.
          If the individual values are not within 5 percent of their mean values,
          generate a calibration curve using the results of the second analysis of the
          calibration standards, and report the sample results compared to  both
          standard curves.

C.4    AUDITING PROCEDURES

       Direct Interface Sampling - Since direct interface sampling involves on-site analys-
is, the performance audit is conducted on-site after the calibration of the GC and prior
to sampling.  The audit gas cylinder is attached to the inlet of the sampling probe. Two
consecutive analyses of the audit gas must be within 5 percent of the average of the two
analyses. The tester/analyst then calculates the results and informs the audit supervisor.
The observer records all information and results on the "Field audit report form" and
then informs the tester/analyst as to the acceptability of the results.

       Dilution Interface Sampling - Since dilution interface sampling involves on-site
analysis, the performance audit is conducted on-site after the calibration of the GC and
prior  to sampling.  If the audit gas cylinder obtained has a concentration near the diluted
sample concentration, the audit gas is introduced directly into the sample port on the
GC.  If the audit gas cylinder obtained has a concentration close to the expected  sample
concentration, then the audit gas is introduced into the dilution system. The observer
may wish to order one  cylinder to assess both the  dilution system and the analytical
system and another cylinder to assess only the analytical system.  Follow the same proce-
dures described above for recording the information and reporting the results.

       Adsorption Tube Sampling - The analysis for adsorption tube sampling is usually
conducted off-site.  Therefore, the audit analysis is conducted off-site.  The recom-
mended procedure is to conduct the audit once prior to the test and again following the
test  Though the audit sample could be analyzed by direct injection, the inclusion of the
chromatogram printout in the  report will prove that the audit results were obtained
through adsorption  tube sampling and a solvent extraction. Alternatively, the audit
samples can be collected on-site or off-site and then analyzed just prior to the analysis  of
the field samples. Since the observer will likely not be present during the analysis, the
results are reported by telephone.

       To collect the audit gas with  the adsorption tube sampling train, connect a sample
T to the line from the audit gas cylinder.  Place the adsorption tube sampling system  on
one leg of the T; connect a rotameter to the other leg. With the sampling system off,
turn on the audit gas flow until the rotameter reads 2 1pm. Turn on the sampling system
and sample the audit gas for the specified run time. Approximately 11pm should be
discharged through  the rotameter.

C-48

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1.     Method 18 - Measurement of Gaseous Organic Compound, Emissions by Gas
      Chromatography. Federal Register. Volume 48, No. 202, October 18,1983,
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2.     Amendments to Method 18.  Federal Register. Volume 49, No. 105, May 30,
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3.     Miscellaneous Clarifications and Addition of Concentration Equations to Method
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4.     Stability of Parts-Per-Million Organic Cylinder Gases and Results of Source Test
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5.     Traceability Protocol for Establishing True Concentration of Gases Used for
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6.     Methanol, Method 2000.  NIOSH Manual of Analytical Methods, Volume 2,
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7.     Alcohols, Method 1400. NIOSH Manual of Analytical Methods, Volume 1, Third
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8.     Alcohols D, Method 1401. NIOSH Manual of Analytical Methods, Volume 1,
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9.     Hydrocarbons, BP 36 - 126T, Method 1500. NIOSH Manual of Analytical
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10.   Development of Methods for Sampling 1,3-Butadiene. Interim Report prepared
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12.   Method 110 - Determination of Benzene from Stationary Sources, Proposed Rule.
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                                                                          C-49

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 13.   Hydrocarbons, Aromatic, Method 1501. NIOSH Manual of Analytical Methods,
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       -.? -
23.   Development of Methods for Sampling Chloroform and Carbon Tetrachloride.
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24.   Dichlorodifluoromethane, Method 111. NIOSH Manual of Analytical  Methods,
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38.   VOC Sampling and  Analysis Workshop. Volume HI. U.S. Environmental
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                                                                         C-51

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 39.    Knoll, J.E., M. A. Smith, and M. R. Midgett. Evaluation of Emission Test
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       Code of Federal Regulations. Title 40. Part 61. Appendix C, July 1, 1987.

 44.    Method 625 - Base/Neutral Acids. Code of Federal Regulation. Title 40. Part
       136. Appendix A, July 1, 1987.

 45.    Cl through C5 Hydrocarbons in the Atmosphere by Gas Chromatography, ASTM
       D 2820-72, Part 23. American Society for Testing and Materials, Philadelphia,
       PA, 23:950-958, 1973.

 46.    Corazon, V. V.  Methodology for Collecting and Analyzing Organic Air
       Pollutants. U.S. Environmental Protection Agency Publication No.  EPA-600/2-
       79-042, February 1979.

 47.    Dravnieks, A., B. K. Krotoszynski, J. Wbitfield, A. O'Donnel, and T. Burgwald.
       Environmental Science and Technology, 5(12): 1200-1222,1971.

 48.    Eggertsen, F. T., and F. M. Nelson.  Gas Chromatographic Analysis of Engine
       Exhaust and Atmosphere. Analytical Chemistry, 30(6): 1040-1043, 1958.

 49.    FeairheUer, W. R., P. J. Mara, D. H. Harris, and D. L. Harris. Technical Manual
       for Process Sampling Strategies for Organic Materials, U.S. Environmental
       Protection Agency Publication No. EPA-600/2-76-122, April 1976.

 50.    FR, 39 FR 9319-9323, 1974.

 51.    FR, 39 FR 32857-32860,  1974.

 52.    FR, 41 FR 23069-23072 and 23076-23090, 1976.

53.    FR, 41 FR 46569-46571,  1976.

54.    FR, 42 FR 41771-41776,  1977.

C-52

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                             APPENDIX D
                METHOD 25 OBSERVATION PROCEDURES

D.I  Specifications for Method 25 Sampling Equipment
D.2  Specifications for Method 25 Analytical Equipment
D.3  Method 25 Nomenclature and Equations

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D.I    SPECIFICATIONS FOR METHOD 25 SAMPLING EQUIPMENT

       Heated Probe - Heat-traced and capable of maintaining 269°F ±5°F (129"C
±3°C). An elbow or nozzle is attached to the tip to allow the tip to be turned away
from the direction of flow. The probe exit should be equipped with a T" and
thermocouple well so that the exit temperature can be monitored.

       Filter and Housing - 25 mm glass mat filter with 0.5 micron cut size and a heated
container capable of maintaining the filter temperature at 250°F ±5°F (121°C ±3°C).
Must be equipped with a thermocouple well to monitor the filter temperature during
sampling. The housing should be large enough to keep the sample/purge valve hot
along with the connecting tubing going to the condensate trap.

       Sample/Purge Valve - Three-way valve to allow the stack gas to be sampled
through the condensate trap and sample tank or diverted to a purge pump. The valve
should also have a neutral position to seal the sampling train from either the stack or
purge pump.

       Condensate Trap - 3/8 inch diameter 316 stainless tubing bent to a "U" shape and
packed with quartz wool.

       Metering Valve - Stainless steel fine metering valve for regulating the sample flow
rate through the train.
                                                 X
       On/Off Valve or Sealing Quick Connect - For sealing the train to prevent
ambient air leakage  and for doing leak checks.

       Sample Tank - Rigid vessel at least 4 h'ters in volume with on/off valve or sealing
quick connect. Should be stainless steel or aluminum in construction.

       Purge Pump and Switching Valve - Capable of purging the probe and filter
housing for 10 minutes at 60 to 100 cc/min.

Other equipment needed:

       Mercury Manometer or absolute pressure gauge - Capable of measuring pressure
to the nearest 1 mm Hg in the range of 0 - 900 mm Hg.

       Vacuum Pump - Capable of evacuating a sample tank to within  10 mm Hg of
absolute zero pressure.

      Table D-l is a checklist for sampling equipment specifications and calibration
which may be completed or used as a guide by the observer.  Table D-2 is sampling
operations checklist which may be completed or used as a guide by the observer.

                                                                            D-l

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I?..'
                     TABLE D-l.  METHOD 25 EQUIPMENT CHECKLIST

                    Observer  complete once for each test series.
                    Check if acceptable; "X" if not acceptable.
         Probe
              - Capable of maintaining 269PF ±5°F   	
              - Movable nozzle at tip to turn away from flow
              - Theromcouple well at probe exit   	
              - Last thermocouple calibration date
              - T/C reading i ambient 	
                               Reference temp
      Dev
         Filter
              - Housing capable of keeping filter § 250°F ±5°F   	
              -,.Thermocouple well in filter housing             	
              - Last thermocouple calibration date              	
              - T/C reading 8 ambient  	.   Reference temp      Dev
         Purge Sample valve
              - .Three positions: Sample
                                 Purge
Neutral
              - Located between filter and condensate trap
         Condensate Trap
              - Stainless steel and inconel construction
              - Capable of sealing ends after sampling
              - Quartz wool packing instead of porasil or S/S shot
              - Each has unique identification code  	
         Rotameter
              - Last calibration date  	
              - Gamma  	  gamma between 0.9 and 1.1

         sample Tank
              - Rigid construction
- Greater than or equal to 4.5 liter capacity
- On/off valve or quick connect  	
- JJnique identification code  	
         Purge Pump
              - Capable of purging probe and filter  (60 - 100 cc/min)

         Vacuum Gauge -
              - 0 to 30 in Hg vacuum to  measure sample tank vacuum  _
         Mercury Manometer or Pressure Gauge -
              - 1 mm Hg graduations capable of 0-900 mm Hg absolute

         Sample Train Volume Calibrated  	
         Each Sample Tank Volume Calibrated ± 5 cc.  	
         D-2

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                        TABLE  D-2.   METHOD 25 SAMPLING CHECKLIST

                          Observer  complete for each test run.
                      Check  if Acceptable   "X" if not acceptable.

            Sample Tank Leak Check
                 Pretest Temp (TL)    	 Pressure (PL)  	
                 Post-test Temp (Tf)  	 Pressure (Pf)  	
            Post-test Pressure Adjusted for Temperature Change (Pa)
                 Pa = PL  *  Tf/Ti        P« absolute pressure T« °K or °R
                 pa =	*	/

            Is Pa acceptable (± 5 mm Hg of pretest)

            Sample Train Leak Check
                 Sample Flow Rate (F cc/min)	 Bar. Press  (Pb mm Hg)
                 Leak Check Time (t min) 	   Train's Volume  (Vt cc)

            Allowable Leak Rate
                 delta P= .01 * F * t / Vt
                 delta P - .01 * 	 * 	/ 	  -  	  mm Hg

            Actual delta P  	    Is Actual less than allowable .-?

            Sample point at average stack delta P  	
            System Purge by sample pump with stack gas 10 minutes

            Start of Sampling
            Smooth start concurrent with timer 	.__
            Desired sample flow rate achieved quickly  	
            Flow rate maintained at ± 10% of mean
            Probe exit temperature maintained at 269°F ±5°F
            Filter temperature maintained at 250°F ±5°F  	
            Condensate trap labelled with run # etc. 	
            Sample tank labelled with run #, etc.  	
            Data Sheet Review

                 Company Name	 Source ID
                 Run Number                              Date
                 Condensate Trap ID  	          Sample Tank ID
                 Sample Tank: final press.  	, final temperature	
...cs.               Sample .Tank Pressurization - press. 	  Temperature

            Dry ice available for sample transport to lab
            Chain of custody sheet filled out for condensate trap and sample
            tank'                                                        	
                                                                          D-3

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D2  SPECIFICATIONS FOR METHOD 25 ANALYTICAL EQUIPMENT

      Gas chromatograph - Equipped with a sample switching valve and flame
ionization detector.

      Oxidation Catalyst - Catalytic oxidizer with 19 percent chromia catalyst on
alumina pellets.  Must be able to heat the catalyst to 650°C

      Reduction Catalyst - 100 mesh pure nickel powder mounted in a tube furnace
capable of reaching 400°C.

      Trap Oven - Specifically built to hold one condensate trap. Capable of
maintaining 200°C for the trap burn and 300°C for conditioning traps for reuse after
analysis.'*1

      NDIR analyzer -  0 to 5 percent range for monitoring trap  burn progress.

      Intermediate Collection Vessels (ICVs) - Should be greater in volume than
sample tank.  Should have volume calibrated to ±5 cc.

      Hg manometer - Scaled to 1 mm Hg for reading the tank evacuation and
pressurization parameters of the ICVs.

DJ  METHOD 25 NOMENCLATURE AND EQUATIONS

      The following nomenclature is used in the calculations:

      C   =  TGNMO concentration of the effluent, ppm C equivalent.
      Cc   =  Calculated condensible organic (condensate trap) concentration of the
              effluent, ppm C equivalent.
      C&  =  Calculated condensible organic (condensate trap) blank concentration of
              the sampling equipment, ppm C equivalent.
      C^ -  Measured concentration (NMO  analyzer) for the condensate trap ICV,
        -?•'    ppm CO2.
           =  Measured blank concentration (NMO analyzer)  for the condensate trap
              ICV, ppmCO2.
           =  Calculated noncondensible organic  concentration (sample  tank) of the
              effluent, ppm C equivalent.
           =  Calculated noncondensible organic blank concentration (sample tank) of
              the sampling equipment, ppm C equivalent.
      C,,,,  =  Measured concentration (NMO analyzer) for the sample tank, ppm
              NMO.
      Cto  =  Measured blank concentration (NMO analyzer) for the sample tank, ppm
              NMO.
D-4

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      F    a*  Sampling flow rate, cc/min.
      L    =  Volume of liquid injected, ul.
      M    =  Molecular weight of the liquid injected, g/g-mole.
      m,,   =  TGNMO mass concentration of the effluent, mg C/dsm3.
      N    =  Carbon number of the liquid compound injected (N = 12 for
               decane, N = 6 for hexane).
      Pf    =  Final pressure of the intermediate collection vessel, mm Hg
               absolute.
      Pb    =  Barometric pressure, cm Hg.
      Pd    =  Gas sample tank pressure before sampling, mm Hg absolute.
      Pt    -  Gas sample tank pressure after sampling, but before pressurizing,
               mm Hg absolute.
      Ptf   =  Final gas sample tank pressure after pressurizing, mm Hg absolute.
      Tf    =  Final temperature of intermediate collection vessel, °K.
      Tti    =  Sample tank temperature before sampling, °K.
      T,    =  Sample tank temperature at completion of sampling, °K.
      Ttf   =  Sample tank temperature after pressurizing, °K.
      V    -  Sample tank volume, m3.
      Vt    =  Sample train volume, cc.
      Vv    =  Intermediate collection vessel volume, m3.
      V8    =  Gas volume sampled, dsm3.
      n    =  Number of data points.
      q    =  Total number  of analyzer injections of intermediate collection
               vessel during analysis (where k = injection number, 1... q).
      r     =  Total number  of analyzer injections of sample tank during
               analysis (where j = injection number, 1 ... r).
      Xj    =  Individual measurements.
      x     =  Mean value.
      p    =  Density of liquid injected, g/cc.
      6    =  Leak check period, min.
      AP   =  Allowable pressure change, cm Hg.

      The following are the equations used to calculate the concentration of TGNMO, the
allowable limit for the  pretest  leak check, and to assess the efficiency of the condensate
recovery system.

      Allowable Pressure Change - Calculate the allowable pressure change, in cm Hg, for
the pretest leak check using the following equation.  This value is then compared  to the
actual pressure change, in cm Hg, to determine if the train is suitable for sampling.
                                    = 0.01      i                   Equation D-l
                                                                             D-5

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       Sample Volume - For each test run, calculate the gas volume sampled using the
 following equation.
                         Vg  - 0.3857  V
                                                      •ti
                                                      Lti
           Equation D-2
       Noncondensible Organics Concentration - For each sample tank, determine the
 concentration of nonmethane organics, in ppm C, using Equation D-3.
                              tf
tmj
                         Equation  D-3
                                ti
                                 ti
       Noncondensible Organics Blank Concentration - For blank sample tank, determine
the concentration of nonmethane organics, in ppm C, using Equation D-3 and the values for
Ctob. The blank value may not exceed 5 ppm. If the blank value exceeds 5 ppm C, then
the value of 5 ppm C may be used as the blank value. The calculated blank value is C'b.

       Condensible Organics Concentration - For each condensate trap, determine the
concentration of organics, in ppm C, using Equation D-4.
               Cc = 0.3857
     q
i    z   c
q   v--
                                                  cmk
           Equation  D-4
      Condensible Organics Concentration - For each condensate trap, determine the
concentration of organics, in ppm C, using Equation 6-4 and the values for Cmb. The blank
value, Q.,,,,,, may not exceed 15 ppm.  If the blank value exceeds 15 ppm C, then the value
of 15 ppm C may be used as the blank value.  The calculated blank value is C^,.
D-6

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      TGNMO Concentration - To determine the TGNMO concentration for each test run,
use Equation D-5.


                          C = Ct - CA + Cf ' - C&  - C^             Equation D-5
      TGNMO Mass Concentration - To determine the TGNMO mass concentration as
carbon for each test run, use Equation D-6.


                                  me = 0.4993 C                     Equation D-6
      Percent Recovery - Calculate the percent recovery for the liquid organic injections
used to assess the efficiency of the condensate  recovery and conditioning system using
Equation D-7. The average recovery for triplicate injections should fall within 10 percent
(90 to 110 percent of the injected amount).


                   Percent Recovery  = 1.604 — x — x -* x —      Equation D-7
                                           L    p    T    N
      Relative Standard Deviation - Calculate the relative standard deviation (RSD) for
the percent recoveries for triplicate injections of liquid organics using Equation D-8. The
RSD should be less than 5% for each set of triplicate analyses.
/.
                                                                     Equation D-8
      It is recommended that a computer program or spreadsheet software be used to
handle all calculations.  The output of the computer program provided by the tester in the
emission test report should be in a standardized form containing all of the information listed
in Figure D.I. A copy of the program used for calculations should be included with the test
results.
                                                                             D-7

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                                   TECHNICAL REPORT DATA
                            (Pleat read tmtrucr.ens on the rtvent before completing)
                             2.
                                                          3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
  MANUAL FOR CDDRDINATION OF VOC EMISSIONS TESTING
  USING EPA METHODS 18, 21,  25, AND 25A
                           Final Report:   Sept. 1991
                          E. PERFORMING ORGANIZATION CODE.
7BiiIMBei?eeB, Steve Eckard,  Cheryl Davis-Eckard
                                                          B. PERFORMING ORGANIZATION REPORT NO.
                                                           10. PROGRAM ELEMENT NO.
i. PERFORMING ORGANIZATION NAME AND ADDRESS
Entropy EnvironmentalistB,  Inc.
Research Triangle Park
North  Carolina, 27709
                           IV CONTRACT /GRANT NO.
                           Contract No.  68-02-4462
                           Work Assignment No. 90-117
12. SPONSORING AGENCY NAME AND ADDRESS
Stationary Source Compliance Division
Office of Air Quality Planning and Standards
U.S.  Environmental Protection Agency
Washington,  DC 20460
                                                           13. TYPE OF REPORT AND PERIOD COVERED
                           1*. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
EPA Technical Contact:  Vishnu Katari (703) 308-8717, ITS: 382-8717
16. ABSTRACT
This manual deals with observation of compliance testing for volatile organic
compounds.  A volatile organic compound (VOC) is defined in 40  CFR Subpart A, General
Provisions, 60.2, as any organic compound which participates in atmospheric
photochemical reactions  or which is measured by a reference method,  an equivalent
method,  or an alternative method; or which is determined by procedures specified
under  any subpart.  The  purpose of this report is to provide the observer with
procedures to (1) identify the data necessary to determine compliance,  (2) oversee
the compliance test, and (3)  review the compliance test report  written by the testing
team.  A detailed overview of the methods have been provided for the more experienced
observer.  Chapter 2 of  this  report provides the observer with  procedures and
references for establishing the test objectives.  Chapter 3 discusses the pretest
survey and the procedures for observing the compliance test.  Chapters 4, 5, 6, and 7
present  sampling and analysis observation procedures for Methods IB, 21,  25, and 25A,
respectively.  Chapter 8 presents review procedures for the compliance test report
submitted by the facility.                                                       '  • '
17.
K6Y WORDS AMD DOCUMENT ANALYSIS        	

              |b.lQ6NTIFl6RS/OP6N ENDED TERMS |c.  COSATI Field/Group
                  DESCRIPTORS
is. DISTRIBUTION STATEMENT

RELEASE TO PUBLIC
              IB. SECURITY CLASS (Tliit Reportl
                  UNCLASSIFIED
                                              20. SECURITY CLASS (Tltit pegtl
                                                  UNCLASSIFIED
                                         22. PRIOT
EPA Forai 2220-1 (•,•*. 4.77)  pucvieui KOiTtoM i* o»*eucrc

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w~'""""Quartern Library

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