r/EF>A
United States
Environmental Protection
Agency
EPA-600A-8I-015
March 1931
Research and
Development
TECHNICAL ASSISTANCE DOCUMENT FOR
THE CALIBRATION AND OPERATION OF
AUTOMATED AMBIENT NON-METHANE ORGANIC
COMPOUND ANALYZERS . >
IEPA
leoo/
U-
81-015
\
US
Prepared for
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
US-
**
»
Prepared by
Environmental Monitoring Systems
Laboratory
Research Triangle Park NC 27711
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring Systems
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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EPA 600/4-81-015
March 1981
TECHNICAL ASSISTANCE DOCUMENT FOR THE
CALIBRATION AND OPERATION OF AUTOMATED
AMBIENT NONMETHANE ORGANIC COMPOUND ANALYZERS
by
Frederick W. Sexton
Raymond M. Michie, Jr.
Environmental Quality Assurance Department
Research Triangle Institute
Research Triangle Park, NC 27709
Frank F. McElroy
Vinson L. Thompson
Methods Standardization Branch
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Contract Nos. 68-02-3222, 68-02-3431
EPA Project Officer: Frank F. McElroy
Quality Assurance Division
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
This document was prepared
in cooperation with
the Research Triangle Institute
Research Triangle Park, NC 27709
U.S. EPA Headquarters Library
1PnnD Ma" code 3201
1200 Pennsylvania Avenue NW
Washi DC 20460
Environmental Monitoring Systems Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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FOREWORD
Measurement and monitoring research efforts are designed to anticipate
potential environmental problems, to support regulatory actions by develop-
ing an in-depth understanding of the nature and processes that impact health
and the ecology, to provide innovative means of monitoring compliance with
regulations, and to evaluate the effectiveness of health and environmental
protection efforts through the monitoring of long-term trends. The
Environmental Monitoring Systems Laboratory, Research Triangle Park, North
Carolina, has responsibility for: assessment of environmental monitoring
technology and systems; implementation of Agency-wide quality assurance
programs for air pollution measurement systems; and supplying technical
support to other groups in the Agency, including the Office of Air, Noise
s.nd Radiation, the Office of Toxic Substances, and the Office of
Enforcement.
Although monitoring of non-methane organic compounds (NMOC) is not
required, per se, by present compliance monitoring regulations, NMOC
monitoring data are vitally important in some areas for planning hydrocarbon
control strategy necessary to achieve the National Ambient Air Quality
Standard for ozone. Prepared at the request of the Office of Air Quality
Planning and Standards (Air, Noise and Radiation), this document provides
technical information and quality assurance procedures which should prove
highly beneficial to control agencies making ambient NMOC measurements with
automated NMOC analyzers.
Thomas R. Hauser, Ph.D.
Director
Environmental Monitoring Systems Laboratory
Research Triangle Park, North Carolina
iii
U.S. EPA Headquarters Library
Mail code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
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iv
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PREFACE
Although this document details problems and difficulties associated
with collecting continuous non-methane organic compounds (NMOC) monitoring
cata, it does so to accent the need for improved quality control and better
use of good laboratory procedures while operating automated NMOC analyzers.
Comments contained herein are not intended to reflect invidiously on the
analyzer manufacturers, authors of instruction manuals, analyzer operators,
or authors of any documentation evaluating NMOC analyzers.
v
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ABSTRACT
This technical assistance document is intended to serve as a supplement
to manufacturers' instruction manuals for automated, ambient, non-methane
organic compound analyzers. It addresses augmented setup, calibration,
operation, and maintenance procedures that have been developed for the
purpose of producing non-methane organic compound data suitable for use in
the Empirical Kinetic Modeling Approach and other dispersion models used to
predict ozone concentrations. The document initially discusses common
aspects of these procedures in general terms for hydrocarbon analyzers as a
whole and then specifically addresses their application to analyzers
manufactured by The Bendix Corporation, Mine Safety Appliances Company, and
Beckman Instruments, Inc. Comments also address analyzers manufacturered by
Byron Instruments, Inc., and Meloy Laboratories, Inc.
vi
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CONTENTS
foreword , ill
Pre face V
Abstract VI
Figures X
Tables xl
Abbreviations and Symbols . XI i
Acknowledgments xii 1
L. INTRODUCTION 1
1.1 Hydrocarbon chemistry and measurement 1
1.2 Continuous and discrete measurements 3
1.3 Purpose 3
:». GENERAL OPERATING PROCEDURES 6
2.1 Introduct ion . . .. 6
2.1.1 Site selection 6
2.1.2 Analyzer environment control 6
2.1.3 Ambient air sampling system 6
2.2 Installation of NMOC Analyzers 7
2.2.1 Unpac king 7
2,2.2 Analyzer instruct ion manual 8
2.2.3 Recordkeeping 8
2.2.4 Setup. 15
2 .3 Operat ion 16
2.3.1 Start-up 16
2.3.2 Periodic calibrations and zero/span 17
checks 17
2.3.3 Operational checks 17
2 .3 .4 Preventive maintenance 17
2 .4 Troubleshooting 18
2,4.1 Flow measurements 18
2.4.2 Leak-checks 19
2.4.3 Sample pump checks 21
3 . CALIBRATION STANDARDS, EQUIPMENT, AND PROCEDURES 22
3.1 Introduction 22
3.2 Zero air standards 23
3 .3 Span gas standards 24
3.4 Effects of moisture 26
3.5 Calibration gas dilution system 26
3 .6 Flow measurements 26
3.7 General multipoint calibration procedure 28
3.8 Level 1 zero and span check 30
3.9 Level 2 zero and span check 31
VII
U.S. EPA Headquarters Library
Wai! COGS 3201
120C Pennsylvania Avenue NW
W&snington DC 20460
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4. AUGMENTED PROCEDURES FOR THE MSA 11-2 CONTINUOUS
NMOC/METHANE MONITOR 32
4.1 Principles of operation 32
4.2 System description 32
4.3 Modifications 35
4.4 Installation 37
4. 5 Operat ion 38
4.5.1 Start-up 38
4.5.2 Periodic calibrations and zero/span checks 38
4.5.3 Operat ional checks 40
4.5.4 Moisture trap check 40
4.5.5 Cutter temperature 40
4.6 Cal ibrat ion 42
4.6.1 Multipoint calibration 42
4.6.2 Level 1 zero/span check 47
4.7 Troubleshooting. 49
4.7.1 Preliminary investigat ions 49
4.7.2 Sample pump system investigation 51
4.7.3 Moisture trap investigation 52
4.7.4 Hydrogen system investigation 52
4.7.5 FID response investigation 53
4.7.6 Sample flow rate investigation 56
4.7.7 Burner air flow rate investigation 56
5. AUGMENTED PROCEDURES FOR THE BENDIX 8201 AND 8202
REACTIVE HYDROCARBON ANALYZER 58
5.1 Principles of operation 58
5.2 System description 58
5.3 Modifications 59
5.4 Installation 61
5 .5 Operat ion 62
5.5.1 Start-up 62
5.5.2 Periodic calibrations and zero/span checks 62
5.5.3 Operat ional checks • 63
5.5.4 Routine chromatograms 63
5 .6 Cal ibrat ion 63
5.6.1 Multipoint calibration 63
5.6.2 Level 1 zero and span check 68
5.7 Troubleshooting 69
5.7.1 Preliminary investigations 69
5.7.2 Chromatogran investigation 70
5.7.3 Sample and back-flush valve leak-check 80
6. AUGMENTED PROCEDURES FOR THE BECKMAN 6800 AIR QUALITY
CHROMATOGRAPH (Cfy, TOC, NMOC) 82
6.1 Principles of operation 82
6 .2 System description 82
6.3 Modifications 84
6.4 Installation 85
6 .5 Operat ion 86
6.5.1 Start-up 86
6.5.2 Periodic calibrations and zero/span checks 88
6.5.3 Operat ional checks 88
vlii
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6.5.4 Routine chromatograms 90
6.6 Calibration 93
6.6.1 Multipoint calibration 93
6.6.2 Level 1 zero and span check 100
6.7 Troubleshooting 100
6.7.1 Preliminary investigations 101
7. COMMENTS ON THE BYRON 233 THC/CH4/CO ANALYZER 102
7.1 Principle of operation 102
7.2 General comments 102
a. GENERAL COMMENT ON THE MELOY HC500-2C FID HYDROCARBON
ANALYZER 104
9. References 105
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FIGURES
Number
Page
1 Leak-check apparatus 20
2 Diagram of a zero air system 24
3 Diagram of a dilution system 27
4 Recommended water trap system 37
5 CH4 channel's response curves - effects of
variations in H2 flow rate 55
6 TOC channel's response curves - effects of
variations in H2 flow rate 55
7 Chromatogram from a. Bendix 8202 analyzer showing
proper analyzer ope rat ion 72
8 Chromatogram from a Bendix 8202 analyzer showing
improper gate timing and baseline shift 72
9 Chromatograms showing analyzer malfunctions 76
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TABLES
Number
Page
3
4
8
10
11
12
13
Summary of problems associated with gathering NMOC
data with automated analyzers 4
Summary of recommendations to reduce the effect of
problems lisced in Table 1 4
Form for recording analyzer information,
10
Typical form for recording routine operational data
from an NMOC analyzer 11
5 Form for recording calibration data 12
6 Form for recording zero and span data 13
7 Form for recording a routine maintenance schedule 14
Listing of methane and propane NBS/SRMs available
in compressed gas cylinders 23
Nominal operating specifications for the MSA 11-2 NMOC
Analyzer
39
Form for recording routine operational data from the MSA
11-2 NMOC analyzer 41
Form for recording routine operational data from the Bendix
8201 or 8202 NMOC analyzer 64
Comparator card 1 (Component card J-10) functions
and potentiometer controls 74
Form for recording routine operational data from the
Beckman 6800 NMOC analyzer
89
Xi
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ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
CRM
DAS
DVM
SKMA
EPA
FID
kPa
LOX
NAAQS
NBS
NMHC
NMOC
psig
ppmC
ppinV
RH
SBFM
SRM
TAD
TNMHC
TOG
URL
url
WTM
SYMBOLS
CH4
C2H4
C3H8
C02
H2
H20
NO 2
03
RCHO
R2CO
SO 2
certified reference material
data acquisition system
digital voltmeter
empirical kinetic modeling approach
U.S. Environmental Protection Agency
flame ionization detector
kilo-Pascals
liquid oxygen
National Ambient Air Quality Standard
National Bureau of Standards
non-methane hydrocarbon
non—methane organic compound
pounds per square inch
parts per million as carbon
parts per million by volume
reactive hydrocarbon
soap bubble flow meter
standard reference material
technical assistance document
total non-methane hydrocarbon
total organic compound
upper range limit, analyzer
upper range limit, recording device
wet test meter
methane
ethylene
propane
benzene
carbon dioxide
hydrogen
water
nitrogen dioxide
ozone
aldehyde
ketone
sulfur dioxide
xii
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ACKNOWLEDGMENTS
The authors of this document gratefully acknowledge the generous assis-
tance of Mr. A. Poli of Mine Safety Appliance Company, Mr. R. Villalobos of
Beckman Instruments, Inc., Mr. G. Funderbunk of the Bendix Corporation, and
Mr. B. Behr of Byron Instruments, Inc., who all provided technical details
and suggestions, many of which would have been unavailable elsewhere.
Also, we acknowledge the invaluable contributions of Dr. C. Eaton, Dr.
J. Sickles, Mr. A. Gaskill, and Ms. S. Powell of the Research Triangle
Institute; Dr. H. Richter, Dr. D. Mage, Dr. B. Dimitriades, and Messrs. L.
?urdue, G. Ortmon, and W. Lonneman of EPA; and others who technically
reviewed the manuscript and helped make the preparation and distribution of
:his document possible.
xiii
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SECTION 1
INTRODUCTION
1.1 HYDROCARBON CHEMISTRY AND MEASUREMENT
Organic compounds containing only the elements carbon and hydrogen are
called hydrocarbons. These elements can be formed into open chain aliphatic
molecules (alkanes, alkenes, alkynes) or closed ring molecules (alicycli.cs,
aromatics). Hydrocarbon compounds are frequently classified as paraffins,
olefins, or aromatics. Paraffins are aliphatic compounds like propane
(C3Hg) which contain no unsaturated (multiple bonded) sites. Olefins
are also aliphatic compounds, but contain one or more multiple bonds, as in
ethylene (0284). Aromatics are unsaturated ring-like structures in which
the benzene ring (CgHg) is the parent structure.
Methane (Cfy) is the simplest and most abundant hydrocarbon in the
ambient air, and at common ambient concentrations it is not harmful to human
health. Attention is directed primarily at the non-methane hydrocarbon
compounds because these compounds are involved in photo-chemical chain
reactions, resulting in an accumulation of photo-chemical oxidants in the
atmosphere. Methane is not sufficiently reactive to participate appreciably
in these photo-chemical reactions and can therefore be subtracted from the
total hydrocarbon concentration to obtain a more accurate measure of
reactive hydrocarbon concentrations. (A detailed discussion of the
hydrocarbon/oxidant relationship is provided in references 1 and 2.)
The concentration resulting from the subtraction of the methane
concentration from total hydrocarbon concentration has been referred to in
the past as reactive hydrocarbon (RH), non-methane hydrocarbon (NMHC), and
total non-methane hydrocarbon (TNMHC). A more precise reference is
non-methane organic compounds (NMOC) because it includes oxygenated organics
such as aldehydes (RCHO) and ketones (R2CO) that also contribute to the
buildup of photochemical oxidants. In addition, the flame ionization
detector (FID) used to measure these compounds exhibits some sensitivity to
oxygenated compounds. Therefore, the designation NMOC is recommended when
referring to organic compounds detectable by flame ionization that
contribute to the buildup of photochemical oxidants.
Concentrations of gaseous hydrocarbons have historically been reported
in various units such as parts per million as carbon (ppmC), micrograms per
cubic meter (Ug/m^) as methane, parts per million by volume as methane
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(ppmV as CH^), and others. To eliminate Che confusion of using several
units, and to normalize the response of the FID to different organics,
hydrocarbon concentrations should be reported as ppmC. This unit is
obtained by multiplying the ppmV concentration of the hydrocarbon compound
by the number of carbon atoms in that compound. For example, 3.0 ppraV of
propane (C^Hg) is equal to 9.0 ppmC.
A National Ambient Air Quality Standard (NAAQS) for hydrocarbons
corrected for methane was promulgated by the Environmental Protection
Agency in 1971 (3). This NAAQS was unique among the standards promulgated
at that time because it was not based upon direct harmful effects to human
health or welfare caused by NMOC. Rather, the standard was based upon the
role NMOC plays as a precursor to the formation of photochemical oxidants
such as ozone. The standard was intended to serve as a guide for attaining
the ozone NAAQS (through control of NMOC emissions) and not as a standard
for compliance. More recently, photochemical models have been developed
which more accurately describe the relationship between NMOC concentrations
and subsequent peak ozone levels. Consequently, the original NAAQS for NMOC
is no longer used.
Historically, ambient hydrocarbon concentrations have been measured by
an FID. In the continuous (automated) NMOC analyzer, the sample is injected
into a stream of hydrogen gas or zero air, and directed to a burner where
combustion occurs. The resulting ionization of the hydrocarbons in the
sample creates an electric current roughly proportional to the carbon
concentration of the sample. The FID is used because it responds to a wide
range of hydrocarbon compounds; is relatively insensitive to non-
hydrocarbons; has a wide, linear dynamic range; and is suitable for
continuous field operations.
Although the detector responds linearly to varying concentrations of
individual hydrocarbons, it does not respond uniformly from one hydrocarbon
species to another. For example, the response of a methane-calibrated FID
to a sample of 9.0 ppmC of methane would be 9.0 ppmC, whereas its response
to a sample of 9.0 ppmC of propane may be only approximately 6.3 ppmC. This
non-uniform per carbon response characteristic is apparently related to the
presence of the oxygen in the sample air. The FID's response to different
compounds is much more uniform when the compounds are separated from the air
sample by a chromatographic column, and are injected into the FIB via an
inert carrier gas.
In continuous NMOC analyzers, which have no columns to separate the
hydrocarbons from the air, or in GC analyzers which use an air carrier, this
non-uniform response to different organic compounds is a problem when
attempts are made to measure the concentrations of unknown organic
compounds. One method to help compensate for this effect is the judicious
choice of the compound used for calibration. Accordingly, propane is
recommended for the calibration of automated NMOC analyzers. Section 3.1
discusses this recommendation in more detail. Further information is also
contained in reference 4.
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:. .2 CONTINUOUS AND DISCRETE MEASUREMENTS
Current analytical methods for obtaining NMOC measurements of ambient
air can be classified as either discrete or continuous. Discrete (manual)
analytical methods use a gas chromatograph with flame ionization detection
(GC-FID) to quantify organic species in the sample. Because such systems
.ire not easily transported, ambient samples are collected in inert bags or
in stainless steel canisters, and are then transported to the chromatograph.
The sophisticated nature of the GC system permits quantification of many
individual organic compounds in the sample. The concentrations of each
organic species can be summed under the categories of paraffins less
uethane, olefins, and aromatics. The total of these three categories, plus
,iny unidentified organics, is the NMOC concentration. Further guidance on
"sum of species" analysis is given in reference 5.
Continuous methods use automated analyzers with FIDs to provide NMOC
concentrations that are generally reported as hourly averages. Such
.inalyzers use either gas chromatographic columns to separate methane from
i:he more complex organics, or catalytic oxidation to oxidize all organics
except methane. The result is that methane and total organic compounds
CTOC) are quantified by the FID separately. Subtracting methane from TOC
(TOC - CH4) gives the NMOC concentration.
Automated NMOC analyzers suffer from a number of inherent technical
problems that limit the quality of data they provide. Several
evaluations (6,7,8) of NMOC analyzers present a clearer assessment of these
problems, and recommend potential solutions. Table 1 summarizes the
problems and Table 2 summarizes the recommendations.
During the summer and fall of 1979, an evaluation (9) of NMOC analyzers
<*as conducted to further study the quantitative effects of the problems with
continuous NMOC monitoring. This evaluation pointed out that careful
attention to set-up, calibration, operation, and maintenance enabled a group
of commercial NMOC analyzers to produce measurements above about 0.5 ppmC
which could be used in photochemical oxidation models.
L.3 PURPOSE
The purpose of this document is to supplement the instruction manuals
of continuous monitoring, ambient level, NMOC analyzers. The document should
3e used in conjunction with the manufacturer's instruction manual so that
careful attention is directed to critical procedures throughout set-up,
calibration, operation, and maintenance of the NMOC analyzer. Most of the
procedures recommended here were developed and evaluated during the 1979
itfMOC analyzer evaluation (9). The document initially addresses these
procedures in general terms for "conventional" NMOC analyzers as a whole and
:hen specifically addresses their application to the following analyzers:
MSA 11-2, Bendix 8201 and 8202, and the Beckman 6800. Comments are also
made on the Byron 233 and the Meloy 500-2C. Note that the TAD is limited to
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TABLE 1. SUMMARY OF PROBLEMS ASSOCIATED WITH GATHERING
NMOC DATA WITH AUTOMATED ANALYZERS
1. Contaminants may be present in compressed gas cylinders containing calibration gases.
2. Compressed gas cylinders of calibration gases sometimes contain the standard in a nitrogen or argon back-
ground. When no oxygen is btended with these gases, FID sensitivity is altered.
3. The assay of calibration gases contained in compressed gas cylinders (as received from the supplier) is
sometimes incorrect.
4. There are wide differences in the per-carbon response to different NMOC species.
5. FID analyzers require hydrogen, which presents a potential operational hazard.
6. The NMOC concentration is obtained by subtraction of two relatively large and nearly equal numbers
(TOC-CH4 = NMOC) and thus is subject to large, relative errors.
7. NMOC analyzers may exhibit excessive zero and span drift during unattended operation.
8. The complex design of some NMOC analyzers creates unique problems that are generally not experienced in
other pollutant analyzers. Meticulous setup, calibration, and operation procedures (which are analyzer-
specific) are difficult to understand and follow.
TABLE 2. SUMMARY OF RECOMMENDATIONS TO REDUCE THE EFFECT OF
PROBLEMS LISTED IN TABLE 1
1. Calibration gases should be checked to determine the concentration of contaminants.
2. Calibration concentrations should be obtained by dynamic dilution of a pollutant standard with zero grade
air containing oxygen. The dilution ratio should be sufficiently high (~ 100:1) to ensure the calibration
sample contains 20.9 ± 0.3 % oxygen.
3. All calibration standards contained in compressed gas cylinders should be traceable to Standard Reference
Materials from the National Bureau of Standards.
4. The NMOC response should be calibrated to a propane standard.
5. The operator should use documented procedures for hydrogen safety.
6. Alt channels should be properly calibrated.
7. The FIDs should be operated in accordance with instructions supplied by the manufacturer and this
document.
8. The training of qualified operators should be augmented with a Technical Assistance Document, which
details calibration and operation procedures for NMOC analyzers.
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those "conventional" analyzers which measure TOG and CH& separately and
derive the NMOC reading by subtraction. No effort has been made to address
other types of NMOC anlyzers, such as direct-reading chromatographs.
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SECTION 2
GENERAL OPERATING PROCEDURES
2.1 INTRODUCTION
The complex operation of NMOC analyzers necessitates the need for close
attention to maintenance schedules and calibration procedures in order to
obtain data suitable for photochemical modeling. Three separate
studies (6,7,8) have documented these needs, as well as the need for less
complex procedures to verify analyzer operations. The procedures discussed
in this document have been selected to address these needs and to direct
attention to the importance of rigid quality control procedures.
This section is intentionally general so procedures pertinent to NMOC
analyzers as a whole can be collectively addressed. More specific
information is contained within the individual analyzer sections located in
the latter half of this document. DO NOT OVERLOOK THIS GENERAL PROCEDURES
SECTION. Many suggestions detailed here must be incorporated into the
monitoring program to obtain suitable NMOC data. These suggestions are not
detailed in the specific analyzer sections.
2.1.1 Site Selection
Proper selection of the monitoring site has been carefully detailed in
references 4, 10, and 11.
2.1.2 Analyzer Environment Control
Control of the station environment surrounding the NMOC analyzer is
recommended. In a recent evaluation of NMOC analyzers (9), controllers
failed (for several days) to maintain the temperature in the monitoring
station within the specified range. The temperature hovered at 38* C
(100* F) and resulted in poor analyzer stability, excessive noise, and
erratic responses from many of the analyzers. To reduce these potential
problems, the temperature range for operating NMOC analyzers should be
controlled between 20 and 30° C (68 and 86° F), the temperature range in
which equivalency testing of other automated methods is currently conducted.
When ambient temperatures exceed about 29* C (85* F) in areas of high
humidity, the sample manifold should be monitored for moisture buildup.
Analyzers without moisture drop-out traps may be damaged by moisture;
therefore, increase the station temperature to within 5 to 7° C (9 and 13*
F) of ambient temperature if excessive moisture accumulates in the station
manifold.
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Power supplied to the analyzer should be between 105 and 125 volts at
60 Hz. The normal voltage range supplied to the analyzer, as well as the
presence of power surges, can be determined by periodically monitoring the
voltage supplied to the analyzer with a voltmeter. Typically, voltage
monitoring should be performed when the site is initially set up and at the
beginning of heating and cooling seasons. Elaborate systems to stabilize
the electrical supply and continually record its voltage are expensive and
may be unnecessary if preliminary voltmeter results indicate the voltage
range is within specifications during periods of sudden high power demand.
Another factor affecting the analyzer's environment is dust.
Collection of dust on electrical components can cause shorts to occur in
electrical circuits; therefore, gently blow dust off electrical components
every six months, or more frequently if necessary. Use a dry gas such as
nitrogen or compressed air.
2.1.3 Ambient Air Sampling System
A conventional, ambient air sampling system is detailed in section
2.0.2 of EPA's QA Handbook (10); therefore, only brief comments are made
here.
1. Accumulation of dirt and moisture in the sample manifold will lead
to poor analyzer performance. Regularly clean the manifold when
particulate or high moisture buildup is detected, and position air
conditioning vents away from the manifold.
2. To ensure that the manifold blower is operating, strips of paper
can be suspended in front of the blower's exhaust. The motion of
the paper strips provides a visual check that the blower is
operational. The blower should provide a sample flow of between
85 and 140 L/min (3 and 5 ft3/min) through the system.
3. Ensure that the sample ports on the manifold are pointed towards
the ceiling to reduce the potential for moisture accumulation in
the analyzer's sample line.
4. Periodically inspect the manifold for cracks or leaks and replace
as necessary to prevent sample air contamination by room air.
2.2 INSTALLATION OF NMOC ANALYZERS
NOTE: THE ANALYZER'S INSTRUCTION MANUAL AND THIS TAD
SHOULD BE READ PRIOR TO SUPPLYING POWER TO THE ANALYZER.
2.2.1 Unpacking
Owners of new (and used) NMOC analyzers can avoid extended downtime by
applying a few common sense procedures during unpacking. Upon receiving an
analyzer, ensure that the instruction manual and Manufacturer's Final Data
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Sheet are included. If they are not included, immediately notify the
Manufacturer. Then carefully inspect the shipping container and note the
presence and location of any damage. Remove the analyzer from the box (but
do not apply power to the analyzer) and determine if the exterior of the
analyzer is damaged in the same general area as the shipping container.
Thoroughly inspect the exterior of the analyzer for scratched surfaces, bent
or broken knobs, cracked rotameters, and cracked meter covers. Inspect the
Interior for electronic cards which may have come unseated. Continue
Inspection for broken cards, loose components, loose connections, or other
items which appear abnormal.
If the analyzer is obviously damaged, a shipping claim should immedi-
ately be prepared and directed to both the shipper and the manufacturer. If
analyzer damage is not obvious but the shipping container shows damage,
schedule ample time during start-up for a thorough equipment evaluation.
Leak checks and other evaluations discussed later should be performed on
analyzers suspected of having been damaged during shipping. The
complexities of the NMOC analyzer necessitate proper performance of all
components to insure correct operation.
2.2.2 Analyzer Instruction Manual
A complex analyzer obviously will require a thorough and sometimes
complex instruction manual to describe its maintenance and operational
procedures. An approach to aid the operator in understanding the
instruction manual and recalling analyzer operations follows.
1. Read the instruction manual briefly and become familiar with the
analyzer and the manual. Highlight all references to maintenance
procedures and schedules, routine operational recordings (such as
normal pressure gauge readings or rotameter readings), safety
notes, and actions which can invalidate the analyzer warranty.
2. Several days later, reread the manual and fill in highlighted data
on appropriate forms. (Examples of forms are given in section
2.2.3J
3. Summarize power-up and power-down operations and calibration pro-
cedures on a step-by-step basis. A brief summary which should be
prominently displayed in the analyzer area can be obtained from
the manual and/or this TAD. Some instruction manuals contain
condensed start-up sheets that will serve this purpose if a clear
understanding of the analyzer operation has first been obtained.
2.2.3 Recordkeeping
To aid in the operation of an NMOC analyzer, records and documents
should be organized and kept close at hand. Maintaining awareness of
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operating parameters and maintenance schedules is important to the contin-
uing, accurate operation of an NMOC analyzer. Detailed descriptions of
recordkeeping for air monitoring programs are contained in section 2.0.3 of
the EPA QA Handbook (10).
An analyzer logbook is a typical recordkeeping system. The logbook
contains important records which enable the operator to recognize patterns
in the analyzer's behavior and anticipate potential difficulties. Such a
logbook can be contained in a ring binder and should be located at the
monitoring site near the analyzer. Typical sections which should be
contained in the logbook follow.
1. Instruction manual. Punch the manual (or a copy of it) to fit the
rings and secure it into the binder.
2. Analyzer information. Identify the manufacturer, the analyzer's
name and model number, pollutant monitored, serial number, date
purchased and cost, salesperson's name and phone number, service-
person's name and phone number, and recorder make, model and
serial number (Table 3).
3. Routine check sheet. During routine checks, record operational
information (Table 4).
4. Calibration data - Identify the analyzer make, model and serial
number; name of operator and date of calibration; pollutant
concentration, analyzer responses, and the resulting calibration
curve (Table 5).
5. Zero and span data. Identify the analyzer make, model and serial
number, the date, zero response, span response, span concentra-
tion, slope and intercept (Table 6).
6. Maintenance. Identify the analyzer make, model and serial
number, the maintenance required, when it is required, and when it
is performed (Table 7).
7. Comments. Record all comments relating to the analyzer, such as
manufacturer communications, analyzer malfunctions, etc. Record
the analyzer make, model and serial number at the top of eacj^ page
and date each comment. The first page should be the Manufac-
turer's Final Data Sheet.
-------
TABLE 3. FORM FOR RECORDING ANALYZER INFORMATION
Manufacturer
Model
Pollutant
Serial Number
Date Purchased
Cost $.
Salesperson's Name
Saleperson's Address
Salesperson's Phone No. .
Serviceperson's Name
Serviceperson's Address .
Serviceperson's Phone No..
Recorder Make
Recorder Model
Recorder S/N
Instrument Output
10
-------
TABLE 4. TYPICAL FORM FOR RECORDING ROUTINE OPERATIONAL DATA
FROM AN NMOC ANALYZER
1'
*
>
i
1
!
1
l
x"
4
1
I
1
1
i
*
S
1
|
i
g
I
5
8
|
S*
I
n
f
g
s
5*
I
\J
li\
l
!
I
1
1
1
|
5"
8
S
5
§
i
5'
8
II
g
g
1
11
-------
TABLE 5. FORM FOR RECORDING CALIBRATION DATA
ANALYZER MAKE AND MODEL
CODE NUMBER
PC LLUTANT
DATE OF CALIBRATION
DERIVED CURVES
SERIAL NUMBER
RANGE, ppmC
OPERATOR
Concentration, ppmC
Unadjusted Data
Analyzer Response—DAS Voltage
NMOC
CHy
TOC
Adjusted Data
12
-------
TABLE 6. FORM FOR RECORDING ZERO AND SPAN DATA
ANALYZER MAKE AND MODEL
POLLUT
Data
ANT RANGE, ppmft
Zaro
Response
Span
Rasoonsa
. Span
Concentration
Slopa
Intareapt
13
-------
TABLE 7. FORM FOR RECORDING A ROUTINE
MAINTENANCE SCHEDULE
ANALYZER MAKE AND MODEL:
SERIAL NUMBER: _
Function
Frequency
Date Performed
14
-------
2.2.4 Setup
After generally understanding how the analyzer works, the operator is
prepared to follow the manufacturer's instructions for setting up the unit.
During the setup of any analyzer which uses hydrogen gas, carry out a leak
check of the hydrogen flow system. (See section 2.4.2 for details in
leak-checking flow systemsJ
The hydrogen (H2) gas for the FID requires extreme caution during
handling due to its highly flammable nature. Colorless and odorless H2
gas leaking into an unventilated area is very dangerous and is potentially
explosive. The following precautions summarize safety considerations when
using high pressure H2 cylinders. Additional information on H2 cylinder
safety, as well as safety when using electrolytic hydrogen generators, is
contained in reference 13.
1. Store H2 cylinders in a secured, well ventilated, non-flammable
area, preferably outdoors and out of direct sunlight. Secure the
cylinder to a wall prior to installing the pressure regulator. Do
not store H2 cylinders beside cylinders containing corrosive or
highly oxidizing materials.
2. The H*2 regulator should be dedicated to H2 gas only. The
output stage should contain a pressure relief valve. A flow
restrictor must be connected to the exit of the regulator to limit
gas flow in the event of a break in the H2 tubing. If the
output pressure of a new cylinder is less than the typical charge
pressure (~ 2200 psig) , leak-check the cylinder valve while at
full clockwise and full counter-clockwise position.
3. Use only clean or new 3 mm (1/8 in) diameter stainless steel
tubing to supply H2 to the analyzer. Thoroughly leak-check the
hydrogen line by pressurizing the line up to the analyzer. Turn
off the H2 cylinder valve and observe the outlet pressure.
There should be no decay in pressure after 30 minutes. If there
is a leak, pressurize the line and search for the leak using a
liquid leak detector.
4. When ordering hydrogen cylinders, specify TOC concentration to be
less than 0.1 ppmC.
5. A particulate filter (in a metal holder) can be located on the
outlet of the regulator to ensure that no particulates enter the
analyzer, and subsequently, the FID. Carefully leak-check each
filter holder after the filter is changed.
15
-------
After Che hydrogen system is determined to be safe, recorder and gas
connect ions can be made to the analyzer. A terminal strip for connecting
recorder leads is usually located on the back of the analyzer. Follow
instruction manual directions for identifying each channel and the voltage
outputs from each. Care should be exercised by using signal cable that
contains no splices and is as short as possible. Follow the recorder
manufacturer's suggested procedures in installing the recorder. Signal
cable should be connected to recorders and analyzers with approved
connectors that are either soldered or crimped to the signal cable. Do not
wap bare cable around a connector.
Gas connections can now be made to the inlets located on the rear of
Che analyzer. All sample gas tubing should be composed of Teflon® and be
connected to the analyzer and sample manifold with either stainless steel,
Teflon®, or all glass connectors. Ensure that the tubing has not been
previously used. Specific size tubing is addressed in the analyzer sections
of this document. An all-Teflon® particulate filter, with a pore size of 5
microns or less, should be installed in the sample line. The sample line
should be as short as possible, not exceeding 3m (10 ft.).
2.3 OPERATION
2.3.1 Start-up
REMINDER: SECTION 2 IS INTENTIONALLY GENERAL. MORE
SPECIFIC INFORMATION IS CONTAINED IN THE ANALYZER
SECTIONS TO AID THE OPERATOR DURING START-UP.
By this time, the operator should have a basic understanding of the
•analyzer's operation, should be assured that the hydrogen flow system does
not contain leaks, and should have a set of summary sheets which will aid in
operating the analyzer. It is important to achieve these goals prior to
starting up the analyzer because the complexity of the system may disguise
malfunctions and lead the operator toward improper repairs or unsafe
conditions.
After initial settings and adjustments are complete, supply power to
the analyzer, allow the support gases to flow into the unit, and attempt to
ignite the burners. Do not be concerned with flameouts during the first 15
minutes of operation. If after this period flameouts continue, allow the
flame to extinguish. Allow the analyzer to warm up for twenty-four hours to
ansure that heated elements are up to operating conditions and attempt
ignition if the burner(s) is not already operating. If ignition
difficulties persist, consult troubleshooting. While the analyzer is
stabilizing, sec up the recorder(s) as per the manufacturer's suggestions.
Perform maintenance on the recorder to verify operation and ensure that the
recorders will not be responsible for faulty data.
16
-------
If the analyzer is new, the flow rates and pressure gauges should have
already been correctly adjusted by the manufacturer. Do not adjust pressure
gauges or flow controls if minor discrepancies exist between your readings
and the Manufacturer's Final Data Sheet. Major discrepancies, such as no
gas flow into the FID, should obviously be investigated. If the analyzer is
not new, adjustments should be made to bring the flow rates and gauge
settings into the ranges recommended in each analyzer section of this
document or the instruction manual.
2.3.2 Periodic Calibrations And Zero/Span Checks
An initial multipoint calibration is recommended to establish the cali-
bration curve and determine response linearity. Periodic zero and span
checks are thereafter necessary to update the curve, with less frequent
multipoint calibrations to verify response linearity. The frequency of zero
and span checks and multipoint calibrations should be based on the
analyzer's performance. Analyzer performance should be monitored using a
control chart which documents analyzer response to standards, thus allowing
calculation of response variation to standards. Section 2.0.9 of reference
10 contains additional information on calibration of automated analyzers.
Appendix H of reference 14 discusses application of the control chart.
Although these discussions are directed to analyzers that monitor ambient
air for criteria pollutants, application of this strategy to NMOC anlayzers
is recommended. Further details on calibrations are contained in section 3
and within each specific analyzer section.
2.3.3 Operational Checks
After the NMOC analyzer is calibrated and on-line, routine checks of
operational parameters are recommended. These checks are part of the
quality control program and include recording pressure gauge, rotameter, and
pyrometer readings. The gauge and meter readings should be recorded
immediately following a multipoint calibration and should be designated as
the reference readings. Readings taken during subsequent checks should be
compared to the reference readings to determine if operational parameters
have shifted. (These data can be recorded on routine check sheets similar
to Table 4. Specific forms for other analyzers are included in each
analyzer section of this document.) The sensitive nature of NMOC analyzers
requires investigations of any substantial drift in operational parameters.
Assistance in such investigations is given in the troubleshooting sections
of the instruction manual and this document.
2.3.4 Preventive Maintenance
The complex pneumatic systems and controls contained within NMOC analy-
zers necessitate thorough maintenance procedures and schedules. Adherence
to the manufacturer's maintenance schedules is required to obtain reliable
monitoring data. The importance of maintenance performed by experienced
17
-------
personnel cannot be overemphasized. The manufacturer's instruction
manual. details procedures and schedules. Comments on areas of primary
importance follow,
1. It is strongly recommended that maintenance of NMOC analyzers be
performed by a competent, qualified person. This person should
"specialize" in NMOC analyzer operation, maintenance, and repair
and should be prepared to devote a substantial portion of time to
such matters.
2. The hydrogen flow systems should be leak-checked during start-up
and at least once every 180 days of operation. (A leak-check
procedure is discussed in section 2.4.2.)
3. The analyzer's sample pump should be evaluated every 180 days of
operation to ensure that it has the capacity to maintain necessary
flows and pressures. (Sample pump evaluation is discussed in
section 2.4.3.)
4. Check for loose or dusty electronic cards every 30 days of
operation.
5. Check the particulate filter in the sample line at least every
month and replace when it becomes visibly soiled.
6. Evaluate chromatograms weekly. Analyzers that contain chromato-
graphic columns are usually designed to output chromatograms. A
chromatogram is a valuable troubleshooting tool because it is a
"fingerprint" of the analyzer's operation. A chroraatogram should
be obtained while the analyzer is sampling the methane and propane
standards, so gate timing and sensitivity can be evaluated and
compared to previous chromatograms. These evaluations can
indicate a forthcoming malfunction. (The specific analyzer
sections contain additional information on chromatograms.)
2.4 TROUBLESHOOTING
2.4.1 Flow Measurements
The sensitivity of NMOC analyzers requires proper flow rates throughout
the analyzer. If pressure gauge readings of flow systems begin to decay,
calibration curves begin to drift in one direction, or balance procedures
cannot be performed, flow systems may be developing leaks or obstructions.
When any of these potential problems cannot be corrected by adjusting
pressure gauges to reference readings obtained during the last multipoint
calibration, flow rates throughout the analyzer should be measured and
compared to flow rates obtained during the last multipoint calibration. To
18
-------
enable comparison, all flow rates must be corrected to standard temperature
and pressure (25* and 760 mm Hg). Details on flow rate corrections are
contained in section 2.1.2 of reference 10.
2.4.2 Leak-checks
If measurements indicate reduced flow rates, a leak or obstruction may
be present in the flow system. This section discusses a leak-check
procedure and identifies apparatus that can aid in verifying or locating a
leak. The test apparatus addressed can be fabricated from materials readily
available to most monitoring programs; however, it may not be as sensitive
as a leak-check device produced by the analyzer manufacturer.
CAUTION: INDISCRIMINATE APPLICATION OF LEAK DETECTOR
SOLUTIONS CAN BE HARMFUL TO ELECTRONIC COMPONENTS.
SINCE LOW FLOW RATES IN NMOC ANALYZERS REDUCE THE EFFEC-
TIVENESS OF SUCH SOLUTIONS, THE USE OF LEAK DETECTOR
SOLUTIONS IS RECOMMENDED ONLY UNDER SPECIAL CIRCUMSTANCES,
AS DETAILED LATER IN THIS SECTION.
1. Locate all gauges and flow systems on the instruction manual's
flow chart and highlight each system with different colors. (Red
for H2» green for carrier, etc.)
2. Construct a leak-check apparatus as shown in Figure 1 using a
pressure source (compressed air or nitrogen containing < 0.1 pptnC
TOC), pressure regulator, toggle valve, a 340 kPa (50 psig)
pressure gauge graduated in 7 kPa (1 psig) increments, flexible
tubing, and an exit cap.
3. Leak-check the apparatus by applying pressure, closing the toggle
valve, disconnecting the pressure source, and observing the
pressure gauge reading for 30 minutes. If there is no decay in
the pressure reading, the apparatus contains no leaks. If a leak
develops, locate it with a liquid leak detector and repair it.
Recheck for leaks.
4. Connect the leak-check apparatus to the inlet of the analyzer's
flow system to be leak-checked (either a span gas inlet, carrier
gas inlet, support air inlet, hydrogen gas inlet, or sample
inlet). Ensure that the sample pump is not in the system to be
checked. If it is, bypass it with tubing.
5. Cap the exit(s) of the system to be leak-checked. Most systems
exit into the FID; therefore, locate the flow system's last
fitting from the FID and connect the exit cap. AVOID TOUCHING THE
THREADS OF THE FID AND FITTING.
19
-------
Pressure Regulator
Pressure Gauge
Flexible
Tubing
Exit Cap
Toggle Valve
Pressure
Source
Figure 1. Leak-check apparatus.
Apply a pressure level to the flow system which will not exceed
maximum allowable pressures in the analyzer and close the toggle
valve on the apparatus. The instruction manual or pressure gauge
in-line will indicate maximum allowable pressures.
Monitor the pressure gauge located on the apparatus. If after 30
minutes there is no decrease in the pressure reading, the flow
system contains no leaks. If pressure decrease occurs, relocate
the apparatus and pressurize one-half of the analyzer's flow
system. Continue moving the apparatus until a general area of the
flow system containing the leak is identified. Carefully apply
the leak detector solution to the fittings and tubing if
necessary. Foaming or bubbles indicate the location of the leak.
Inspect the fitting or valve and replace or repair as necessary.
After repairing the leak, recheck the entire system to verify
that all fittings or valves are functioning properly with no
leaks.
20
-------
2.4.3 Sample Pump Checks
Once every 180 days of operation, determine if the sample pump can
supply the necessary head pressure recommended in the manufacturer's
instruction manual. Perform the check by connecting a high pressure gauge
to the outlet of the pump and capping the exit from the gauge. Start the
pump and record maximum pressure output. A noticeable decrease in head
pressure from the last sample pump check may indicate that the pump needs
service.
21
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SECTION 3
CALIBRATION STANDARDS, EQUIPMENT, AND PROCEDURES
3.1 INTRODUCTION
As noted in other sections of this TAD, the response of an FID analyzer
may vary considerably from one organic compound to another. Thus, the
choice of the calibration species has a direct bearing on resulting
analyzer calibration. Historically, continuous ambient NMOC analyzers have
been calibrated largely with methane-in-air standards. Methane was used
primarily because it is chemically simple (C=l, and ppmC = ppmV), it is
readily available, .and it can be used to calibrate both CH^ and TOC
measurement channels (from which NMOC measurements are derived by
subtraction) .-
But propane-in-air standards have also been used to calibrate automated
NMOC analyzers because (the contention is) propane allows a more accurate
measurement of the NMOC concentration in ambient air. This contention is
supported by the following facts and reasons:
1. Propane is more representative (than methane) of the hydrocarbon
mix used to calibrate hydrocarbon analyzers that collected the
data base from which the EKMA model was developed.
2. In a recent study (9), automated NMOC analyzers measured
individual NMOC compounds commonly found in ambient air. Response
to propane was found to be approximately equal to the average
response to all compounds measured. Response to methane was found
to be 20 Co 30% greater than the average response to all compounds
measured.
3. In a recent study (9), analysis of ambient air by automated NMOC
analyzers calibrated to propane produced responses that agreed
quite well with sum-of-species GC-FID results. Agreement between
these methods was also quite good when sampling synthetic organic
mixtures.
4. Direct reading, automated NMOC analyzers (that do not produce
CH^ or TOC output) are generally calibrated to propane
standards (they obviously would not respond to methane standards).
22
-------
For these reasons, EPA recommends chat continuous NMOC data, obtained
for use in dispersion models for predicting ozone concentrations, should be
referenced to propane standards. CE^ and TOO responses should be balanced
and referenced to methane standards. Discussions on calibrations and
standards are contained in this section.
3.2 ZERO AIR STANDARDS
The first step in calibrating an NMOC analyzer is to obtain the
response to a hydrocarbon-free matrix. Ideally, this matrix should
approximate "clean" ambient air; that is, air containing only nitrogen,
oxygen, carbon dioxide, and water vapor. Since the analyzer's response to
this matrix is its baseline or "zero" response, the matrix is frequently
referred to as "zero air".
Zero air is actually not totally free of all organic (or other)
compounds, but is usually considered adequate if the TOG concentration is
less than 0.1 ppmC. It is important that zero air contain ambient
quantities of oxygen, but carbon dioxide and water vapor may also be
present. The effects of oxygen content variations have been studied (9) and
determined to have a significant effect on FID response. Moisture and
carbon dioxide effects on FID response are not as well understood; therefore,
the recommended zero air standard should contain 20.9 _+ 0.3% oxygen in a
nitrogen balance with TOG concentration <0.1 ppmC.
The recommended method for preparing zero air is by scrubbing and
oxidizing unwanted compounds from ambient air. Such cleanup systems are
usually large and contained in the laboratory but may also be small and
contained in the analyzer itself. Zero air is also available from specialty
gas manufacturers who compress the air and store it in cylinders; however,
this source of zero air is not recommended due to possible variable oxygen
concentrations, economic considerations, and frequent bottle changes.
A typical cleanup system recommended for producing zero air for NMOC
analyzers is shown in Figure 2. Ambient air should be drawn from the
outside of the building and filtered before being compressed. Use of
outside air is more likely to provide true ambient concentrations of oxygen
and nitrogen in the zero air matrix. The dryer removes moisture before the
air enters the scrubber unit. As the air passes through the scrubber unit,
compounds such as nitrogen dioxide (N02), sulfur dioxide (802), ozone
(03), etc., are removed. The air then enters the heated catalytic
oxidizer where organics and carbon monoxide (CO) are converted into carbon
dioxide (۩2) and water (1^0). Since many laboratories prepare zero
air, different detailed designs are acceptable if the resulting product is
determined to be within the specifications previously mentioned. (Note:
All pressure regulators should be LOX cleaned and contain non-permeable,
metal diaphragms. Do not use a heat less air dryer in the zero air system
because it will alter oxygen levels in the sample.)
23
-------
Ambient
Air In
, n
U
i
Panic
Filter
ulate
Oil- Lass
Compressor
Storage/Ballast
Tank
P
P
-C
ressure
egutator
Scrubber
Unit
To Dilution
"*" System
Figure 2. Diagram of a zero air system.
Cleanup systems contained within NMOC analyzers may use only a heated
catalyst to oxidize organics. Care should be taken to ensure that the
heater and catalyst are properly maintained. This internal system should be
used only for level 2 zero checks (section 3.9) unless it has been verified
against an external cleanup system. Many monitoring sites normally contain
an external zero air system so a common zero matrix can be delivered to all
analyzers at once.
As mentioned before, zero air compressed in cylinders can also be
utilized to zero the analyzer, although this is not recommended. If
compressed gas is used, ensure that it has the correct oxygen content and
that it is delivered to the analyzer's inlet at atmospheric pressure.
Failure to supply a vent between the cylinder and the analyzer will
pressurize the sample system and could result in improper flows or damage to
i.nternal flow controls. (See the discussion on calibration gas dilution
systems in section 3.5.)
3.3 SPAN GAS STANDARDS
As noted earlier, both methane and propane standards are required to
calibrate an automated analyzer that produces CH^, TOC and NMOC outputs.
These standards are available from several commercial manufacturers in
U.S. EPA Headquarters Library
Mai! code 3201
1200 Pennsylvania Avenue NW
24 Washington DC 20460
-------
compressed gas cylinders at a variety of concentrations. Standards must be
traceable to a Standard Reference Material (SRM) from the National Bureau of
Standards (NBS) or to a commercially certified reference material (CRH). The
procedure to certify a cylinder of gas as traceable to an NBS/SRM or CRM can
be performed by the gas manufacturer or the user. (Traceablity protocol is
addressed in reference 15 or in section 2.0.7 of reference 10.) Table 8
lists several concentrations of methane and propane SRM's that are available
from NBS; however, only one SRM is required for traceability purposes.
Reference 16 addresses NBS/SRM's; consult gas manufacturers about the
availability of CRM's. Methane and propane standards can be combined in a
single cylinder with an ambient air balance. Such a gas cylinder containing
both standards may be used for spot checks between calibrations, but will not
permit the CH4 and TOC channels to be balanced.
Inconsistent results from NMOC analyzers have been partly attributed to
contaminated calibration standards. For this reason, the methane and propane
standards should not only be referenced to an NBS/SRM or CRM every three to
six months, but they should also be analyzed yearly to ensure that the
concentrations of organic contaminants remain less than 0.1 ppmC. For
example, the methane standard should contain less than 0.1 ppmC NMOC, and the
propane standard should contain less than 0.1 ppmC organics other than
propane. Both standards must contain ambient levels of oxygen in a nitrogen
background if no ambient level diluent air is to be blended with the
standards.
TABLE 8. LISTING OF METHANE AND PROPANE NBS/SRMs AVAILABLE
IN COMPRESSED GAS CYLINDERS
SRM
1658A
1659A
1660A
GAS
CH4/Air
CH4/Air
CH4/C3H8/Air
ppmV
0.951
9.43
4.10 (CH4),
0.976 (C3Hg)
ppmC
0.951
9.43
4.10 (CH4),
2.928 (C3Hg)
1665
1666
1667
1668
1669
C3Hg/Air
C3H8/Air
C3H8/Air
C3H8/Air
C3H8/Air
3
10
50
100
500
9
30
150
300
1500
25
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3.4 EFFECTS OF MOISTURE
The effects of moisture on automated NMOC analyzers is not well known.
Elecommendations are therefore not available. Preliminary investigations
indicate that analyzers addressed in this document will not be affected by
moisture if the precautions in each analyzer section are followed.
3.5 CALIBRATION GAS DILUTION SYSTEM
There are basically two methods to deliver calibration standards to
automated analyzers in the field: by dynamic dilution of a single high
concentration standard with zero air, and by using compressed gas cylinders
containing calibration concentrations. The dynamic dilution approach is
recommended for calibrating automated NMOC analyzers because this approach
offers greater stability of the high concentration standard in a cylinder,
greater control of oxygen content in the sample, greater ease in delivering a
variety of accurate calibration standards, and a lower cost to produce
different concentration levels. However, accurate flow measurements are
required.
A dynamic dilution system, as shown in Figure 3, can be used to dilute a
high concentration standard with zero air. This system requires flow
controllers or needle valves to control diluent and pollutant flows; a flow
meter to measure the flow rates; stainless steel, Teflon*, or glass tubing to
direct the flows; a glass mixing flask to blend the two flows; and a glass
nanifold or tee for sampling the standards. The manifold must be vented to
t:he atmosphere to prevent pressure buildup in the sample line connected to
t:he analyzer's SAMPLE port (not CALIBRATE port)! To prevent contamination of
line calibration standard by the room atmosphere, all unused sample ports on
i:he manifold must be sealed, and the flow to the manifold must be 20 to 50%
greater than the analyzer's sample demand. To maintain oxygen at 20.9 +
0.3%, the diluent to pollutant flow rate ratio should be greater than 100:1.
Care must be taken to ensure that the system contains no leaks that can
introduce error into flow measurements or allow contaminants to enter the
system. Leaks may be detected by applying a low level of pressure to the
system and submerging the glassware and tubing in a bath, or by using a
liquid leak detector on the fittings. Care must also be taken to ensure that
i:he system is clean and maintained to prevent contamination. Use only new
Cubing and glassware to construct a dilution system.
3.6 FLOW MEASUREMENTS
Preparing a known pollutant concentration by dynamic dilution requires
accurate measurement of both pollutant and diluent flow rates. Flow rates
must be corrected to standard temperature and pressure (25*C and 760 mm Hg)
unless two measurements taken with the same flowmeter are to be ratioed. For
26
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Figure 3. Diagram of a dilution system.
corrections, atmospheric pressure and temperature in the flow measurement
area must also be measured. The flow measurement device must be traceable to
an NBS standard. Two devices commonly used to measure flows in the field are
soap bubble flowaeters (SBFM) and wet test meters (WTM). Details on
calibrating flow measurement devices are given in section 2.1.2 of reference
10. Comments concerning areas of specific concern follow.
1. When using an SBFM, select a bubble tower that will permit a flow
measurement for at least 15 seconds. That is, use a 10-cm-*
tower for flow rates less than 40 cm^/min, use a lOO-cnP tower
for flow rates between 40 and 400 cm^/min and use a 1000-cnH
tower for flow rates between 400 and 4000 cm^/min.
2. During SBFM measurements, allow only one bubble to traverse the
column while measuring the time interval. The entire calibrated
portion of the column should be used during the measurement. If
the bubble bursts before it traverses the column, check to see if
the column is clean (clean regularly with hot, soapy water and
rinse well) and is not in hot or cold drafts. A standard soap
solution designed^ for flow measurements can reduce the difficulties
with bubble flows.
27
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3. Wet test meters should generally be used within a flow range of
1/3 to 3 neter revolutions per minute. A one liter per revolution
WIM, for example, should be used within the range of 1/3 to 3
liters per minute. WTM's are available in many different
capacities, covering a wide range of applicable flows.
4. WTM calibration factors vary with the flow rate through the meter.
When WTM's are used to measure dynamic flows (rather than
incremental volumes), the ideal calibration (capable of 1%
accuracy) should relate measured flow rate to actual flow rate
(both adjusted to some common set of reference conditions).
However, if meters using factors are operated within the range of
1/3 to 3 revolutions per minute, an accuracy of 2 to 3% can be ex-
pected.
5. Flows through WTM's should be measured by complete meter
revolutions only. Additionally, the number of timed, complete
revolutions should be chosen so the timed interval is not less
than 20 seconds.
3.7 GENERAL MULTIPOINT CALIBRATION PROCEDURE
The actual procedure by which an NMOC analyzer calibration is
referenced to propane varies, depending on the design of the analyzer, and
specifically, the number and type of output channels, the number of zero and
:jpan controls available, and whether the TOC-CH^ subtraction is
implemented on signals before or after they are processed by the span
control circuits.
The following generalized procedure illustrates the normal sequence of
steps that are recommended for calibrating an NMOC analyzer. This general
procedure must be individually adapted to the particular design of each NMOC
analyzer. For example, in its normal configuration, the MSA Model 11-2
analyzer has no TOC output channel. Therefore the internal TOC reading
necessary to obtain the NMOC reading must be balanced to the CH^ channel
to provide a zero NMOC reading when sampling methane. More explicit
information on the exact calibration procedure for each analyzer is con-
tained in the analyzer-specific sections of the TAD and in the operation
aanual for each analyzer.
1. Sample zero air and adjust all channels to read 0.0 ppmC.
2. Sample a concentration of the methane standard equivalent to about
85% of full scale. Adjust the span controls of both the CH4 and
the TOC channels' outputs. Make sure the TOC response equals the
CH4 response so that subtraction of the CH4 response from Che
TOC response will yield an NMOC response of 0.0 ppmC. (This
balance may be accomplished in certain models by adjusting the
28
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hydrogen or sample flow rate to the FID. Analyzers without a TOC
output must be balanced to ensure that the NMOC reads 0.0 ppmC.)
If substantial adjustments are necessary, resample zero air and
adjust the zero responses as necessary, then repeat the balance.
Sample at least two additional concentrations of the methane
standard approximately equally spaced over the scale range.
Record the Clfy and TOC responses. Least squares regression of
the analyzer responses (dependent variable, Y) against the cali-
bration concentration (independent variable, X) should result in a
correlation coefficient of 0.9996 or better if the channel is
linear.
Sample a concentration of the propane standard equivalent to about
85% of full scale. The CH^ channel's response should equal
zero. Analyzers with an independent NMOC channel span pot may be
adjusted as necessary to make the NMOC channel's response equal to
the propane concentration. Do not adjust the TOC channel's
response. If substantial adjustments are necessary, resample the
zero standard and the methane standard as before.
5. Sample at least two additional concentrations of the propane
standard approximately equally spaced over the scale range, and
record the NMOC response. Least squares regression, as before,
should result in a correlation coefficient of 0.9996 or better if
each channel is linear.
NOTE: WHEN THE NMOC CHANNEL IS CALIBRATED WITH PROPANE, THE SUM OF THE CH4
AND NMOC CONCENTRATIONS MEASURED WILL NOT EQUAL THE MEASURED TOC CONCEN-
TRATION BECAUSE OF /THE DIFFERENCE IN FID RESPONSE BETWEEN METHANE AND
PROPANE.
After linearity is established, generate the regression equations that
define the curves for each channel and post the calibration curve, date, and
channel identification on the appropriate recorder. All calibration data and
curves can be entered on a form similar to Table 5 and filed in the cali-
bration section of the analyzer's log book. See section 2.0.9.1.2 of
reference 10 for more detail on calibration theory.
For analyzers which have no direct NMOC output, calculate NMOC response
using the following equation:
NMOC
response
f TOC response
to sample
TOC response
to zero
TOC slope to methane
CH4 response CH4 response
to sample to zero ) TOC slope to methane
CH4 slope to methane
TOC slope to propane
29
-------
An example calculation using actual calibration curves and ambient data
responses from an NMOC analyzer follows.
Methane calibration curves
CH4 response « 9.658X + 0.2256
TOC response * 9.731X - 0.0359
Propane calibration curves
TOC response - 6.536X •*• 0.111
Analyzer responses to ambient air following calibration
CH4 channel * 22.1% Chart
TOC channel « 41.92 Chart
Applying the data to the NMOC equation:
NMOC
response
41.9 + .0359 22.1 - .2256
9.731
9.658
9.731
6.536
3.04 ppmC
(2)
3.8 LEVEL 1 ZERO AND SPAN CHECK
The purpose of the level 1 zero and span check (see section 2.0.9 of
reference 10) is to periodically correct the most recent calibration curve
for zero and span drift. Once linearity is established in a multipoint
calibration, the calibration needs to be checked with only two points;
usually at zero and 85% full scale. The standards and the procedure used
iuring the multipoint calibration should be used, except that during the
level 1 check, only one upscale concentration is necessary.
All NMOC measurements obtained from the analyzer should be converted to
ppmC via the most recent calibration curve or zero and span check.
Accordingly, adjustments to the zero and span pots need be made only if
considerable drift has occurred. (See section 2.0.9.1.3 of reference 10 for
details on drift.) For example, Phase II of the EPA's Equivalency
Designation Program specifies that zero adjustments of analyzers are needed
if the zero response drifts more than _+ 3% of full scale from the intercept
of the most recent multipoint calibration curve. Span adjustments are to be
aade only if the slope of the new calibration curve drifts approximately
nore than +7% from the slope of the most recent multipoint curve.
To calculate zero drift on an NMOC analyzer operating in the 0 to 10
ppmC range, subtract the level 1 zero response from the intercept of the
nost recent multipoint curve. (Response and intercept must be in the same
anits.) The difference is the zero drift, which should be greater than
«-0.3 ppmC, or +3.0% full scale, to warrant a zero pot adjustment.
30
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To calculate span drift, first determine the slope of the Level 1
calibration curve using the equation:
Slope of level 1
calibration curve
Level I span response - Level 1 zero response
Level 1 span concentration
(3)
(Be sure to report response and concentration in units identical to those
used in the multipoint calibration curve.) Calculate span drift using the
equation:
% span drift *
Slope of level 1
calibration curve
Slope of multipoint
calibration curve
Slope of multipoint calibration curve
X 100 <4)
The drift should be greater than about +7% to warrant a span pot adjustment,
(See section 2.0.9.1.3 of reference 10 for more details.)
NOTE: BEFORE POTENTIOMETERS ARE ADJUSTED, CHECK ALL OPERATIONAL PARAMETER
READINGS AND ADJUST THOSE THAT HAVE DRIFTED FROM READINGS TAKEN AFTER THE
LAST MULTIPOINT CALIBRATION. NMOC ANALYZERS ARE VERY SENSITIVE TO CHANGES
IN OPERATIONAL PARAMETERS (FLOW RATES, ETC).
3.9 LEVEL 2 ZERO AND SPAN CHECK
A level 2 zero and span check may be used between the regular level 1
zero and span checks as an unofficial test of analyzer response. This level
2 check may use non-traceable or uncertified standards which may enter the
analyzer at a point other than the normal sample inlet (e.g., span inlet).
No adjustments are made to the analyzer based on a level 2 check, which is
primarily a check of repeatability and operation rather than of absolute
response. If used, the level 2 check should be carried out immediately
following a regular level 1 check or multipoint calibration to obtain
reference readings. At subsequent checks, if the readings have changed
appreciably, then a level 1 zero and span check or a multipoint calibration
should be carried out to determine if the analyzer requires adjustment.
(See section 2.0.9.1.3 of reference 10 for more details.)
31
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SECTION 4
AUGMENTED PROCEDURES FOR THE MSA 11-2
CONTINUOUS NMOC/METHANE MONITOR
NOTE - READING SECTIONS 1, 2 AND 3 BEFORE SECTION 4 IS
STRONGLY RECOMMENDED. INFORMATION WHICH IS CRITICAL TO
THE UNDERSTANDING AND SUBSEQUENT ACCURATE OPERATION OF
THIS ANALYZER IS DETAILED IN THOSE SECTIONS AND WILL NOT
BE REPEATED HERE.
4.1 PRINCIPLES OF OPERATION
The MSA 11-2 continuously splits an ambient sample into two aliquots
for passage into separate FIDs. One aliquot is directed to FID #1 where TOC
concentration is measured, and the second aliquot is directed through a
heated cutter (Hopcalite® is used to oxidize all hydrocarbons other than
methane to C02 and H20) prior to entering FID #2, where the methane
concentration is measured. The CH4 response is then electronically
subtracted from the TOC response to produce the NMOC response. The NMOC and
CH4 responses are then directed to the recorder outputs.
4.2 SYSTEM DESCRIPTION
A description of the analyzer with photographs is given in the analy-
zer's instruction manual. To avoid redundancy, this text will not address
location of components, but rather, emphasize precautions when using
critical components.
4.2.1 Flame lonization Detectors
The analyzer contains two FIDs that enable monitoring NMOC and CH4
concentrations simultaneously. The response from the two FIDs mugt be
balanced to a methane-in-air standard.
4.2.2 Hydrogen Pressure Gauges
The flow of hydrogen fuel to each FID is controlled by a separate pres-
sure regulator, gauge, and restrictor. Increasing the pressure reading on
32
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Che hydrogen gauge will increase the flow of hydrogen to the burner and
affect the sensitivity of that FID.
4.2.3 ^gnitor Switches (Flame-out Indicators)
Two push button controls located on the front panel'control the flow of
hydrogen to each FID. When the button is depressed, hydrogen will flow to
the FID then ignite. When the FID ignites, the light in the button will
turn off. During subsequent flameouts, a solenoid will shut off hydrogen
flow and the light in the button will turn on. The flameout indicator is
controlled by a thermistor located above the flame in the FID. If the
sensitivity of the thermistor is not properly adjusted, the light in the
button may not show true flame status (i.e., the indicator may be off while
the flame is out). Adjustments can be made on the Dual Flame-Out Card to
correct this condition. If the status of the flame is in doubt, observe
analyzer response first to zero air and then to a sample known to contain
methane. If the Clfy channel's responses are the same to both samples, the
CH4 channel's flame is out. If the response varies, the flame is burning.
Check the NMOC channel's flame status with zero air and a sample known to
contain NMOCs (propane).
4.2.4 Air Pressure Gauge
Burner airflow rate, condensate trap vent flow rate, sample vent flow
rate, and sample flow rate to the FID are all related to the air pressure
gauge reading on the front panel. Variations in this reading indicate a
potential malfunction which requires troubleshooting (section 4.7.1.).
4.2.5 Back—Pressure Regulator
Located in the oven are two non-adjustable back-pressure regulators
(one in older models) that control sample flows to the FIDs by controlling
the pressure applied to the two sample capillaries. The pressure gauges
connected to these regulators and the flow rates that vent from the
regulators should be checked regularly because variations in these
parameters indicate a potential malfunction that requires troubleshooting
(section 4.7.1) .
4.2.6 Heated Oven
The FID burners, associated electronics, and pneumatics are contained
in a heated oven maintained at 50 to 55" C. Small fluctuations in the room
temperature therefore do not affect these critical components. Opening the
oven door will obviously cause a loss of heat that may affect the analyzer
response; therefore, it is good practice to perform measurements and adjust-
ments on equipment located inside the oven several hours prior to a multi-
33
-------
point calibration or level 1 zero and span check. If opening the oven door
is necessary, close it as soon as possible to minimize the thermal upset.
4.2.7 Oxidizer
The oxidizer contains palladium and Hopcalite® heated to between 340 to
350" C. At this temperature, all hydrocarbons and carbon monoxide are
removed, leaving a source of hydrocarbon-free air. This air is primarily
used for burner air in the FIDs but can also be tapped and delivered to the
FXDs as a zero air standard.
The use of oxidizer air as a zero air standard is not recommended dur-
ing multipoint calibrations or level 1 zero and span checks if an external
zero air source is used to dilute the span gas standard. Oxidizer air can
3e used in level 2 zero and span checks.
i.2.8 Cutter
The cutter contains MSA brand Hopcalite® that is heated to between 240
and 260" C. At this temperature, all hydrocarbons except methane are
oxidized, allowing CH^ to pass to FID #2. Use only MSA brand Hopcalite®
if the catalyst ever requires replacement. Other catalysts may not perform
properly at the temperature attainable by the cutter. (See section 4.7.1.8
for adjustments.)
4.2.9 Sample Filter/Moisture Trap
Compression of sample air by the analyzer pump almost always results in
moisture condensation in the compressed sample air. It is imperative that
none of this liquid water be allowed to pass into the analyzer. Liquid
water entering the analyzer may damage the cutter or oxidizer, may result in
clogged capillaries or orifices, and may damage other flow control
components.
On the rear of older analyzers is a single Balston condensate trap for
removing water from the sampler. This water removal system should be up-
graded because it is susceptible to malfunction. Analyzers with this system
may have been damaged by water during previous operation and should there-
fore be carefully inspected for damage in the cutter, oxidizer, FID, and
connecting tubing.
On the rear of new analyzers is a water removal system consisting of
two Balston filters and accessories. This system provides much greater
protection against water entry into the analyzer and is discussed in detail
in section 4.3.2.
34
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4.3 MODIFICATIONS
4.3.1 Introduction
The original MSA 11-2 T/HC/Methane monitor was manufactured during the
early 1970s to analyze ambient air continuously for Clfy, TOG, and NMOC
concentrations. Modifications to the original design have occurred over the
years, and an updated model called the MSA 11-2 Continuous NMOC/Methane
Monitor is now available. The principles of operation and detection have
not changed from the earlier model, but the following modifications have
been made:
1. A more powerful sample pump manufactured by Air Dimensions Incorporated
has replaced the smaller Thomas pump.
2. The pump is no longer mounted on the analyzer chassis.
3. A 10-micron Hoke particulate filter has been added to the exit of the
oxidizer.
4. The moisture drop-out trap has been modified.
5. An activated charcoal filter has been added to the inlet of the
cutter.
6. Electronic balance adjustments have been added to enable balancing the
responses from the FIDs more closely.
7. The range change card has been modified to allow for ranges of 10 or 20
ppmC full scale.
8. The oxidizer volume has been increased.
9. The cutter has been moved from the interior of the oven to the rear of
the analyzer chassis.
10. A back-pressure regulator and gauge have been added to the TOC sample
line.
11. A modification has been made to the zero pot to enable zero offset to
observe negative zero drift.
Modifications 1 through 6 should be made to older model 11-2 analyzers
to obtain adequate NMOC data. The remaining modifications are less critical
and may not be needed. The manufacturer suggests employing a factory-
trained serviceperson to update the unit if the operator is not very
familiar with this work.
35
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4.3.2 Moisture Trap
It is imperative that no liquid water be allowed to enter the analyzer.
For maximum protection against liquid water, using a trap system as shown in
Figure 4 is strongly recommended. The filter (5 micron) removes par-
ticulates from the sample air and helps to avoid clogging of subsequent flow
control components. The first condensate trap, consisting of a collection
bowl, Balston filter, and drain valve, collects most of the liquid water.
The valve is normally closed, but is manually opened to drain the water
before the trap fills and water is drawn over to the second trap. In
draining this trap, a small amount of liquid water should be left in the
trap to humidify dry calibration gases during calibration or zero/span
checks. Under conditions of high anbient humidity, the trap may fill in
only a day or two and must be watched closely and drained frequently. More
convenient operation can be obtained by replacing this first Balston trap
with an automatic trap such as the Wilkerson M20-02-000 or equivalent. The
Wilkerson trap has a built-in float valve that drains the trap automatically
as needed, but always retains some liquid water in the trap.
The second water trap consists of a collection bowl, Balston filter,
and a vent controlled by a back-pressure regulator. This trap provides
secondary protection and collects any water carryover from the first trap.
The continuous venc flow prevents any water buildup in this trap, which
should never show more than a partial fogging.
Beyond the second trap is a valve which expands the sample air (by
about 4 psig), thereby lowering its dew point and avoiding any subsequent
condensation. This valve and its connection to the trap should rise
vertically from the trap to discourage water droplets from approaching the
valve. Finally, a section of transparent tubing (a rotameter with no ball
works fine) follows the valve. This tubing provides a. final verification
that no liquid moisture is entering the analyzer. Any sign of condensation
or fogging in this area indicates a malfunction in the trap system. See
section 4.5.4 for procedures to set up and adjust the system and see 4.7 for
troubleshooting procedures.
36
U.S. EPA Heac.•'' :-j^. 3201
1200 "'em-^K ,.-,,- Avenue NW
Wf:S!•;„ gior, DC 20460
-------
Balston or
Wilkerson
Trap
_ »
j
Baiston )
Trap L
To Analyzer
Inspection
Tube
Expansion
Valve
Filter
Pump
Drain Valve
Vent
Back Pressure
Regulator
Figure 4. Recommended water trap system.
4.4 INSTALLATION
The manufacturer's instruction manual addresses procedures to install
the analyzer. Additional comments follow.
1. Before supplying power to the analyzer, ensure that all electronic
component cards are properly seated by attempting to push the
cards snugly into the connectors. Be particularly certain that
the electrometer box located inside the oven is properly seated.
2. Minimize the distance between the analyzer and the sample mani-
fold. Use clean, 3 mm (1/8 in) diameter inert tubing to make the
sample line. The sample line length should not exceed 3 m
(10 ft).
3. Leak-checks should be made on the hydrogen flow system of old and
new analyzers. The leak-check procedure outlined in section 2.4.2
can be used.
37
I
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CAUTION: ONLY EXPERIENCED, QUALIFIED OPERATORS SHOULD
PERFORM THE LEAK-CHECK, AVOID FINGER CONTACT WITH THE
FITTING THREADS DUE TO POSSIBLE TRANSFER OF OILS THAT
WILL TEMPORARILY INCREASE THE BASELINE RESPONSE.
^.5 OPERATION
4.5.1 Start-up
The MSA 11-2 analyzer has two selectable modes of operation. Channel 2
can be operated to output either TOC (non-subtracting) or NMOC (sub-
tracting), depending on the location of a jumper on the electrometer card
(see MSA Instruction Manual). For most NMOC monitoring applications, the
ItfMOC mode is much more advantageous than the TOC mode; therefore, the NMOC
'subtracting) mode is strongly recommended. Calibration and zero and span
procedures in this TAD address only the CH4/NMOC mode of operation. The
iJJMOC mode is selected by placing the jumper in the "S" position.
With the ON/OFF switch in the OFF position, plug the analyzer's power
cord into a power source that has been determined to be stable (see section
1.1.2 for details). Turn the switch to ON, light the FID burners, and moni-
:or oxidizer, cutter, and oven temperatures. If temperatures do not rise,
or if they rise beyond suggested levels, turn the analyzer off and consult
:roubleshooting procedures. If the temperature rises smoothly, allow the
analyzer to warm up for 24 hours before recording the readings from the
pyrometer and pressure gauges. With new analyzers, compare pyrometer and
pressure gauge data to those supplied on the Manufacturer's Final Data
Sheet, If disagreements exist, notify the manufacturer and ascertain if the
difference is significant. If the analyzer has been used before, adjust
flows, temperatures, and pressures to the values used previously. If
previous settings are unknown, select trial settings within the ranges
specified in Table 9. Flow measurement details and other procedures for
setting up or checking out component operation are discussed in this section,
4.5.2 Periodic Calibrations and Zero/Span Checks
An initial multipoint calibration is recommended to verify linearity in
the calibration curve, and periodic level 1 zero and span checks are there-
after necessary to update this curve. The frequency of level 1 zero/span
checks and subsequent multipoint calibrations should be based on the
analyzer's performance. Performance can be monitored through use of a con-
trol chart which documents responses to standards and ultimately enables
calculation of variation in response to standards (drift). (See section
2.0.9 of reference 10 for details on calibration and level 1 and level 2
zero and span checks. See section H of reference 14 for details on control
charts. See section 4.6 of this TAD for specific calibration procedures.)
38
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TABLE 9. NOMINAL OPERATING SPECIFICAT1ONS
FOR THE MSA 11-2 ANALYZER
Parameter
Specifications
Front Panei
H2 pressure reading (per gauge):
Air pressure reading:
Oven temperature:
Oxidizer temperature:
Cutter temperature:
Oven
Back-pressure regulator gauge(s) reading:
Back-pressure regulator vent flow rate:
Sample flow rate to FID No. 1:
Sample flow rate to FID No. 2:
H2 flow rate to FID No. 1:
H2 flow rate to FiD No. 2:
Burner air flow rate to FID No. 1:
Burner air flow rate to FID No. 2:
Back Panel
48 to 62 kPa {7 to 9 psig)
138to152kPa(20to22psig)
50 to 55° C (122 to 131° F)
340 to 350° C (644 to 662° F)
240 to 260° C (464 to 500° F)
17 to 21 kPa (2.5 to 3.0 psig)
500 ± 100cm3/min
12 to 14cm3/min
Equal to sample flow rate to FID No. t
15 to 20 cm3/min
- Equal to H2 flow rate to FID No. 1
200 ± 50 cm3/min
200 ± 50 cm3/min
Moisture trap flow rates:
Set up and adjust as per section 4.5.4.
39
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4.5.3 Operational Checks
The first six parameters listed on Table 9 should be checked at least
once a week and more frequently if necessary. These readings, along with
analyzer responses, zero and span pot settings, and other routine checks
:hat may be necessary can be recorded on Table 10. (Routine monitoring may
tot require that unadjusted responses to standards be recorded; however,
special cases may warrant such data.) If any of these parameters shows
substantial change from the last check, or if drift out of the specified
range has occurred, recheck the analyzer calibration with a level 1 zero and
span check and make the necessary adjustments.
NOTE: FREQUENTLY CHECK THE MOISTURE TRAP FOR PROPER
OPERATION DURING PERIODS OF HIGH RELATIVE HUMIDITY.
4.5.4 Moisture TrapCheck
If the analyzer uses the double-bowl moisture trap previously
described, use the following procedure to adjust vent flow at least once a
week, or more frequently if water removal is inefficient.
I. Adjust the expansion valve to full open.
2. Adjust the back-pressure regulator on the second trap for zero vent
flow.
3. Adjust the air pressure regulator on the front panel of the analyzer
to about 32 psig (220 kPa). If the sample pump cannot produce 32 psig
here, see section 4.7.2.
4. Adjust the back pressure regulator on the second Balston trap to obtain
30 psig (207 kPa) on the front panel gauge.
5. Adjust the expansion valve to obtain 26 psig (179 kPa) on the front
panel gauge.
6. Readjust the front panel pressure to the correct operating pressure,
20-22 psig (139-152 kPa).
4.5.5 Cutter Temperature
The cutter temperature should be checked and adjusted during start-up
and approximately every 6 months of operation thereafter. It should also be
checked and adjusted if: (1) the cutter is replaced, (2) the cutter
temperature changes, (3) the analyzer shows abnormal span drift, or (4) the
CH4 channel responds to non-methane compounds. (See section 4.7.1.8 for
details.)
40
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41
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i.6 CALIBRATION
This section details specific procedures for multipoint calibrations
and zero and span checks of the MSA 11-2. The analyzer's instruction manual
nay contain deviations from these procedures, but the step-by-step proce-
dures that follow are currently recommended by the EPA. These procedures
cover the CHa/NMOC mode of operation only (section 4.5.1)!
4.6.1 Multipoint Calibration
1. If this is an initial calibration, or if the cutter temperature is due
for checking (section 4.5.5), it should be checked and adjusted prior
to the calibration according to the procedure given in section 4.7.1.8.
2. To conserve calibration gas during calibration, shut off the vent flow
from the moisture drop-out trap located on the back of the analyzer.
Quickly check the back-pressure regulator gauges located inside the
oven before and after vent flow is shut off. If the pressure reading
varies before and after shutting off the moisture trap vent, trouble-
shoot the back-pressure regulators located in the oven.
3. Place the range selector switch in the range most frequently used
during anbienC monitoring.
4. Disconnect the analyzer's sample line from the ambient manifold and
reconnect it to the calibration system's manifold. Cap the port on the
ambient manifold and any open ports on the calibration system's sample
manifold.
5. Supply an atmosphere of the zero standard to the manifold at a flow
rate that is 20 to 50% greater than the analyzer's sample flow demand.
DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. The test atmosphere
must contain an ambient level of oxygen and must not contain more than
0.1 ppmC TOC. See section 3.2 for details.
6. Adjust the analyzer's zero controls for both channels to the desired
baseline responses. A 5% of full scale positive offset on the
recording device is recommended to observe any negative drift. Use
either the analyzer's zero pots or the recorder's controls to obtain
the offset. Ensure that the responses from both channels are equal
before recording the responses on forms similar to Tables 5 and 10.
7. Supply an atmosphere of methane standard to the calibration manifold at
a flow rate that is 20 to 50% greater than the analyzer's sample flow
demand. The methane concentration should be between 70 and 90% full
scale.
8. Adjust span pot #2 (which controls CH4 response from FID #2) to
provide the analyzer response calculated as follows:
42
-------
Response
'Sample concentrat ion
I URL
X url + Zero offset
(5)
where
Response • Response of the recording device measuring the
analyzer output in recording device units.
Sample concentration = Concentration of the calibration standard
delivered to the analyzer in ppmC.
URL * The upper range limit of the analyzer in ppmC.
url ™ The upper range limit of the recording device in recording device
units .
Zero offset
The amount the recording device response is set above the
zero baseline while the analyzer is measuring the zero
calibration standard (in recording device units).
NOTE: The response, url, and zero offset must be in identical units.
For example, if a strip chart recorder is the recording device, units
will be % Chart and the url may equal 100% chart. If a digital
voltmeter (DVM) is the recording device, units may be millivolts or
volts and the url may be, for example, 1000 mV. If a data acquisition
system (DAS) is the recording device, units may be ppraC and the url
will equal 10 ppmC. If the front panel meter on the analyzer is the
recording device, units will be ppmC and the url may be either 10 or 20
ppmC.
For example,
methane span concentration
8.0 ppmC,
analyzer range being monitored * 10 ppmC
recorder range being used = 100% chart
recorder offset « 5% chart
Response
8_.Q ppmC
10 ppmC
X 100%)
+ 5% - 85% chart
(6)
Therefore, the analyzer's span potentiometer should be adjusted until
the analyzer output is equal to 85% chart on the recorder while
sampling the 8.0 ppmC methane standard.
43
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If step 8 results in a span pot setting greater than 300, decrease
pressure to H2 gauge #2 until the Clfy response has increased to a
point where the span pot can be reduced to about 250. If the span pot
setting is less than 200, increase pressure to H2 gauge #2 until the
CH4 response has decreased to a point where the span pot can be
increased to about 250. DO NOT EXCEED 9.0 psig H2-
NOTE: IF THE FID RESPONSE INCREASES WHEN INCREASING
HYDROGEN PRESSURE, THE BURNER IS OPERATING ON THE WRONG
SIDE OF ITS PEAK RESPONSE CURVE. CONTINUE INCREASING
HYDROGEN PRESSURE UNTIL RESPONSE STARTS TO DECREASE AND
THE CORRECT SPAN POT SETTING IS OBTAINED.
(SEE SECTION 4.7.5 IF THE PROPER RESPONSE IS UNOBTAIN-
ABLE OR IF DIFFICULTIES DEVELOP.)
10, Set span pot #1 NMOC to the same dial setting (not response) as span
pot #2.
11. Repeat steps 5, 6, 7, 8, 9, and 10 if span pot adjustments were
necessary or if hydrogen pressure gauge #2 was adjusted.
12. Continue sampling the methane standard. For the FIDs to be balanced,
the NMOC response must be within +1.0% of the zero response obtained in
step 6. If the FIDs are balanced, go to step 14.
13. Balance detectors: If the FIDs are not balanced:
(a) Check that both span pots are dialed to the same setting.
(b) Locate the range change board (inside the electrometer assembly
located in the oven) and rotate the balance controls of channels 1
and 2 (accessible through holes in the electrometer cover) to their
maximum clockwise position. Make adjustments quickly to minimize
heat loss!
NOTE: ONLY THE 1980 11-2 MODELS HAVE ELECTROMETER
BALANCE CONTROLS. USERS OF THE OLDER MODEL MUST
UPDATE THEIR ANALYZER TO INCLUDE THIS MODIFICATION.
-------
14.
(c) Record both hydrogen pressure gauge readings. Adjust hydrogen
pressure gauge #1 until the NMOC response to the methane standard
equals the earlier NMOC response to the zero standard (step 6).
Do not adjust the hydrogen pressure outside the 34-62 kPa (5 to
9 psig) range. Increase hydrogen pressure to decrease NMOC
response, or vice versa. See the note in step 9.
(d) If balance is achieved, repeat steps 5 through 13.
fe) If balance is not achieved by step c, adjust the NMOC hydrogen
pressure (gauge #1} or both hydrogen pressures, if necessary, to
get as close to balance (NMOC response within +_ 1% of NMOC zero
response) as possible. Do not exceed the 34-62 kPa (5-9 psig)
hydrogen pressure range. Then, using the balance controls on the
range change board located inside the electrometer (accessible
through holes in the electrometer cover), rotate the channel #2
balance control counter-clockwise to increase the NMOC response,
or rotate the channel #1 balance control counter-clock wise to
decrease the NMOC response. Repeat steps 5 through 12. If
balance cannot be achieved, see section 5.7.5.
After the FIDs are balanced, record responses on Tables 5 and 10.
Determine the CIfy channel's response to two or more additional con-
centrations of the methane standard that are spaced approximately
equally over the analyzer range. (The NMOC channel's response should
remain equal to the earlier response to zero standard.) Record the
CH4 and NMOC channel's responses (from the recording device) on
Table 5. Using a calculator, perform a least squares linear regression
of the CH4 channel responses (to methane and zero standards) and the
corresponding calibration concentrations. The calibration concentra-
tions should be in units of ppmC and should be entered into the cal-
culator as the independent variable X. The CH^ channel's response
should be in units of the recording device and should be entered as the
dependent variable Y. A correlation coefficient (r) of 0.9996 or
better verifies that the CH^ response is linear. (If the response is
not linear, plot the data and determine if an error has been made in
data entry or in determination of calibration concentration.) Obtain
the slope and intercept of the regression and record the equation in
the following form:
CH
;, Response * CH, Slope x Methane concentration + CH, Intercept (7)
45
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where
CH4 Response = Analyzer's CH4 channel reading in recording device
units (see note following step 8).
CH4 Slope * Regression slope in recording device units per ppmC.
Methane concentration » Calibrated methane concentration in ppmC.
Intercept = Regression intercept in recording device units.
Post the CH^ channel's multipoint calibration curve equation on the
analyzer's recording device and also on Tables 5 and 10.
15. Supply an atmosphere of propane standard to the calibration manifold at
a flow rate that is 20 to 50% greater than the analyzer's sample flow
demand. The propane concentration should be between 70 and 90% of full
scale.
16. Adjust span pot #1 (which controls NMOC response from FID #1) to pro-
vide the desired analyzer response. Equation 5 in step 8 can be used
here.
17. If an adjustment is made in step 16, recheck the NMOC channel's
response to the zero standard and adjust zero pot #1 if necessary.
Record the stable zero responses from the NMOC and CH^ channels.
Sample the propane standard, and again record the stable responses to
propane. (Cfy response should be equal to the earlier response to
zero air.)
18. Determine the NMOC channel's response to two or more additional concen-
trations of the propane standard that are spaced approximately equally
over the analyzer range. (The CH^ channel's response should remain
equal to the earlier response to zero standard.) Record the NMOC and
CH4 channel's responses (from the recording device) on Table 5.
Using a calculator, perform a least squares linear regression of the
NMOC channel's response (to propane and zero standards) and the
corresponding propane calibration concentrations. The calibration con-
centrations should be in units of ppmC and should be entered into the
calculator as the independent variable X. The NMOC channel's response
should be in units of the recording device and entered as the dependent
variable Y. A correlation coefficient (r) of 0.9996 or better verifies
that the NMOC response is linear. (If the response is not linear, plot
the data and determine if an error has been made in data entry or in
determination of calibration concentration.) Obtain the slope and
intercept of the regression and record the equation in the following
form:
46
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NMOC Response * NMOC Slope x NMOC Concentration •*• NMOC Intercept (8)
where
NMOC Response * Analyzer's NMOC channel reading in recording device
units (see note following step 8).
NMOC Slope * Regression slope in recording device units per ppmC.
NMOC Concentration » Calibrated NMOC concentration in ppmC.
NMOC Intercept » Regression intercept in recording device units.
Post the NMOC channel's multipoint calibration curve equation on the
analyzer's recording device and on Tables 5 and 10. Record all zero
and span pot readings in Table 10.
19. Disconnect the analyzer's sample line from the calibration system's
manifold and reconnect it to the ambient manifold.
20. Follow the procedure in section 4.5.4 to reset the moisture trap vent
flow rate.
21. Record readings from the first seven analyzer parameters listed in
Table 10. These readings will now be the reference readings until
another multipoint calibration is performed. Be certain that the
station logbook, strip charts, etc., are properly annotated, dated, and
initialed.
22. If level 2 zero and span checks are to be used, carry out such a check
now to establish reference zero and span readings for subsequent com-
parison. (See section 2.0.9.1.3 of reference 10 for definitions and
additional information on level 1 and 2 zero and span checks.)
4.6.2 Level 1 Zero/Span Check
The following level 1 zero/span check (2-point calibration) is similar
to a multipoint calibration except only the zero air standard and one up-
scale standard are used. These responses are then used to calculate the new
calibration curve which is used to correct subsequent monitoring, data until
another level 1 zero/span check or multipoint calibration is performed. As
part of an overall quality assurance program, the operator may want to
record unadjusted responses to standards before making any changes to opera-
tional parameters or zero and span potentiometers.
1. Disconnect the analyzer's sample line from the ambient manifold and
reconnect it to the calibration system's output sampling manifold. Cap
the sample port on the ambient manifold and any open ports on the cali-
bration system's sample manifold.
47
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2. To conserve calibration gas during calibration, shut off the vent flow
from the moisture trap located on the back of the analyzer. Quickly
check the back-pressure regulator gauges located inside the oven
immediately before and after the moisture trap vent is shut off. If
the pressure reading varies before and after shutting off the moisture
trap vent, troubleshoot the back-pressure regulators located in the
oven.
3. Supply an atmosphere of the zero standard to the calibration manifold
at a flow rate of 20 to 50% greater than the analyzer's sample flow
demand. DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET.
4. After obtaining a stable zero reading, determine if zero drift is
greater than about _+ 3,0% (see section 3.8 for zero drift calculation).
If necessary, adjust the analyzer's zero pots to obtain the correct
responses. Record the zero responses on forms similar to Tables
6 and 10.
5. Supply an atmosphere of methane standard to the calibration manifold at
a rate 20 to 50% greater than the analyzer's sample flow demand. The
methane concentration should be between 70 and 90% full scale.
6. After obtaining a stable Clfy reading, use the span drift equation
from section 3.8 (Equation 4) to calculate the amount of span drift on
the CH^ channel. If the drift is greater than about _+_ 7.0%, perform
steps 8 through 21 in the multipoint calibration procedure in section
4.6.1. (Linearity assessment is not necessary in steps 14 and 18.)
7. If span drift is within specifications, check to see that the NMOC
channel's response is within _+_ 1.0% of the NMOC channel's earlier
response when sampling the zero standard. If so, the FIDs are
balanced. If the FIDs are not balanced, perform steps 8 through 21 in
the multipoint calibration procedure, section 4.6.1. (Linearity
assessment is not necessary in steps 14 and 18.)
8. If the span drift is less than about +_ 7.0% and the FIDs are balanced,
record the response and determine the slope and intercept of the Cfy
channel's level 1 calibration curve. Post the level 1 calibration
curve equation on the analyzer's recording device and on Tables 6 and
10.
9. Supply an atmosphere of propane standard to the calibration manifold at
a rate 20 to 50% greater than the analyzer's sample flow demand. The
propane concentration should be between 70 and 90% of full scale.
10. After obtaining a stable span reading, use the span drift equation from
section 3.8 (Equation 4) to calculate the amount of span drift on the
48
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NMOC channel. If Che drift is greater than about _+ 7.0%, adjust span
pot #1 to provide the proper analyzer response. (Use Equation 5 in
step 8, section 4.6.1, to calculate response.)
11. Record the responses and determine the slope and intercept of the NMOC
channel's level 1 calibration curve. Post the NMOC channel's level 1
calibration curve equation on the analyzer's recording device and in
Tables 6 and 10. Record all zero and span pot readings on Table 10.
12. Reconnect the sample line to the ambient manifold.
13. Reopen the moisture trap vent and adjust vent flow according to the
procedure given in section 4.5.4.
14. If level 2 zero and span checks are to be used, carry out such a check
now to establish reference zero and span readings for subsequent com-
parison.
4.7 TROUBLESHOOTING
The manufacturer's instruction manual covers this subject under the
same heading. Additional comments follow.
4.7.1 Preliminary Investigations
Operational problems such as slow response to standards (response time
greater than 10 seconds), inability to balance FID responses, long stabili-
zation periods (greater than 5 minutes), frequent flame-outs, or low sensi-
tivity indicate the potential need for in-depth troubleshooting. Prior to
undertaking in-depth troubleshooting, a preliminary investigation is recom-
mended to rule out variations in operational parameters.
1. Check that all pressure gauges on the analyzer are set to the specifi-
cations stated on the Manufacturer's Final Data Sheet (or to the speci-
fications stated in Table 9 if a manufacturer's data sheet is not
available). If the analyzer has been operating properly for several
months, ensure that the pressure gauges are set to the readings
recorded during the most recent multipoint calibration when the FIDs
were balanced.
2. Inspect the hydrogen source and hydrogen filters (located outside the
analyzer) for proper operation. If neither hydrogen pressure gauge on
the analyzer can be adjusted to its proper setting, see section 4.7.4.
3. Inspect the sample filter and replace it if dirty. Replace the sample
line leading to the analyzer if particulate buildup-is noticeable.
49
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Perform the moisture trap setup procedure outlined in section 4.5.4.
If the sample pump cannot produce 32 psig head pressure during the pro-
cedure, see section 4.7.2.
Determine if the sample vent flow rates through the back-pressure regu-
lators (located in the oven) are within specifications.
(a) Open the door and connect tubing to a back-pressure regulator
vent.
(b) Run the tubing outside the oven and tape the door closed. Do not
crimp the tubing.
(c) Connect a flow meter to the tubing and measure the flow rate. The
rate should be approximately 500 cm^/min.
(d) If the flow rate from either vent differs by more than 5% from the
flow rate measured during the most recent period of normal opera-
tion, see section 4.7.2.
Measure the sample flow rates into the FIDs.
(a) Disconnect a sample line from the base of the FID.
(b) Connect an adapter to the nut of the sample line.
(c) Connect tubing to the adapter, run the tubing out of the oven, and
tape the oven door closed. Do not crimp the tubing.
(d) Connect a flow meter to the tubing and measure the flow rate. The
rate should be between 10 and 15 cm^/min.
(e) If either sample flow rate differs by more than 5% from the flow
rate measured during the most recent period of normal operation,
see section 4.7.6.
Measure the burner air flow rates into the FIDs.
(a) Disconnect a burner air line from the side of the FID.
(b) Connect an adapter to the nut on the burner air line.
(c) Connect tubing to the adapter, run the tubing out of the oven, and
tape the oven door closed. Do not crimp the tubing.
(d) Connect a flow meter to the tubing.
(e) Measure :he flow rate. The rate should be approximately
200 + 50 cra3/min.
50
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(f) If etcher burner air flow rate differs by more than 5% from the
flow rate measured during the most recent period of normal
operation, see section 4.7.7.
8. Perform the cutter temperature adjustment procedure.
(a) Locate the "cutter temperature card" in the top of the
analyzer. (See instruction manual for location and detailed
photograph of the card.)
(b) Sample a methane standard until a stable methane response is
obtained.
(c) Slowly increase cutter temperature (wait 30 minutes after each
adjustment) until a decrease in methane response is noticed.
(d) Allow the response to stablize (1 hour) and record the temperature
as TI .
(e) Slowly reduce the cutter temperature and observe the increasing
methane response.
(f) When methane response cannot be increased by a further cutter
temperature decrease, allow the response and temperature to
stabilize and record the temperature as T£.
(g) The difference between T2 and Tj should be at least 7* C
(10* F). If not, decrease T2 until the difference is obtained.
No change in methane response should occur.
4.7.2 Sample Pump System Investigation
The sample pump supplies the sample, burner air, moisture trap vent,
and sample vent to specific areas in the analyzer. Deterioration of the
pump, blockages in flow systems, or leaks in flow systems can alter the flow
rate of one or more of these critical flows. If preliminary investigations
identify a significant change in the sample vent flow rate (flow rate
differs by more than 5% from the flow rate measured during the most recent
period of normal operation), or the proper AIR pressure reading cannot be
obtained or the sample pump cannot produce at least 32 psig during the
moisture trap setup, carry out the following investigation.
1. Inspect the sample filter and intake to the pump for obstructions.
(a) Clean or replace as necessary.
2. Inspect the tubing between the pump outlet and AIR pressure gauge for
an obvious leak (hissing will be detected).
(a) Repair or replace the leaky element.
51
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3. If adjustments were made in steps 1 or 2 , remeasure the sample
vent flow rate (4.7.1.5). If flow rates are not within 400 to
600 cra
(a) Adjust the flow control valve located inside the analyzer (see
flow diagran in the instruction manual!"!
(b) If the flows cannot be properly adjusted, ensure that the sample
pump is functional before replacing the back-pressure regulator.
4. Perform the moisture trap set up procedure (4.5.4).
(a) If the pump pressure cannot produce 32 psig, clean or replace the
pump diaphragm.
4.7,3 Moisture Trap Investigation
If the second moisture trap begins accumulating water, immediately
investigate the system.
1. Ensure that the first moisture trap is neither flooded nor installed in
reverse. (Observe the arrows located on the top of the trap for flow
direction. )
2. Perform the setup procedure outlined in section 4.5.4.
3. Perform troubleshooting steps in section 4.7.2.
4.7.4 Hydrogen System Investigation
If the hydrogen pressure gauge readings begin to drift, investigate the
system.
1. Ensure that the hydrogen source is not depleted and that no leaks or
obstructions exist in the tubing delivering the gas to the analyzer.
2. Measure the hydrogen flow rate to the FID.
(a) Disconnect a hydrogen line from the side of the distribution
manifold.
(b) Connect an adapter to the fitting located on the side of the dis-
tribution manifold.
(c) Connect tubing to the adapter, run the tubing out of the oven, and
tape the oven door closed. Do not crimp the tubing.
(d) Connect a flow meter to the tubing.
(e) Depress the ignitor button on the front panel to allow hydrogen
gas to flow through the flow meter.
U.S. EPA Headquarters Library
Mai! code 3201
1200 Penn?y>vani& Avenue NW
52 Washington DC 20460
-------
(f) Measure the flow rate. The rate should be approximately
15 to 20 cm3/min.
(g) If the flow rate differs by more than 5% from the flow rate
measured during the most recent period of normal operation, see
step 3 below.
3. Inspect the hydrogen restrictors in the fittings connected to the dis-
tribution manifold for debris and clean or replace as necessary.
(Clean or replace both fittings if one needs cleaning or replacing.)
(a) Remove the hydrogen line fitting from the exit side of the distri-
bution block.
(b) Soak the fittings in a solvent (methyl alcohol) for several hours
(ultrasonic bath can hasten the cleaning).
(c) Connect a clean air pressure line to the outlet of the fitting and
force air through the fitting (in reverse) while the fitting is
submerged in solvent.
(d) After unrestricted flow is obtained through the fitting, remove
the fitting from the solvent and continue to pass air through it
until all solvent is evaporated.
(e) Install the cleaned restrictor and measure the hydrogen flow.
4. Determine if any other part of the hydrogen flow system contains
obstructions. If so, replace or attempt to clean by reverse flushing
with methyl alcohol.
5. Leak test the hydrogen flow system and determine if a leak is present.
(Use the procedure detailed in section 2.4.2.)
6. Check the hydrogen gauge for possible malfunctions.
4.7.5 FID Response Investigation
If the FID response increases with increasing hydrogen pressure, or the
FIDs cannot be balanced, or the factory-specified pressure or flow settings
do not produce satisfactory analyzer operation, and no flow abnormalities
exist, new settings must be established. The complex interrelationship
between hydrogen pressure, hydrogen flow, and FID response for the two
burners makes this difficult to do by trial and error. A better approach is
to determine the complete pressure-flow and flow-response relationships for
each FID over a wide range, and then use these relationships to pick a
viable operating point.
53
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1. Measure hydrogen flow races into the FIDs at several different hydrogen
pressure settings. Cover the 5 to 9 psig range of the gauges and plot
flow rates against pressure gauge readings.
2. Measure both sample flow rates into the FIDs.
3. Reset the moisture trap vent flow to ensure that it is properly
adjusted (see 4.5.4).
4. Place the jumper on the electrometer card in the N (non-subtract ing)
position to permit recording of the TOG and Cfy. responses. Adjust
the two electrometer balance controls to their maximum clockwise
position and the two span controls to their maximum position. Allow
the analyzer to re-establish thermal equilibrium.
5. Disconnect the analyzer's sample line from the ambient manifold and
reconnect it to the calibration system's manifold.
6. Supply an atmosphere of methane standard to the calibration manifold at
a rate 20 to 50% greater than the analyzer's sample flow demand.
The methane concentration should be between 70 and 90% full scale.
7. Reduce hydrogen pressure on gauges #1 and #2 until each gauge reads 5.0
psig (35 kPa) . (If a flame-out occurs, increase H2 pressure to the
point where the flame can be sustained.) Record the hydrogen gauge
readings, along with the corresponding response (H2 #1 controls TOG
response and H2 #2 controls CH4 response).
8. Increase both hydrogen pressure gauge readings in intervals of 0.5 to
1.0 psi. Record stable responses from both channels to each hydrogen
pressure reading. Continue increasing hydrogen pressure up to 9.0 psig
(62 kPa). Operating the burners at high hydrogen flow rates for
extended periods may be detrimental to the burner components; there-
fore, return hydrogen pressure to 7.0 psig after obtaining the last
response.
9. Repeat step 8 while sampling the zero air standard.
10. Using the hydrogen pressure-flow relationship from step 1, calculate
the hydrogen to sample flow rate ratios for each hydrogen setting.
Plot the hydrogen to sample flow rate ratios on the abscissa, and the
corresponding analyzer responses to methane and zero on the ordinate
for each FID. NOTE: Analyzer response to methane should be the net
response. Net response is the actual methane response less the zero
response at each hydrogen pressure setting. See Figures 5 and 6.
54
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NET RESPONSE
1.0 1.2 1.4 1.S 1.8
H. TO SAMPLE FLOW RATE RATIO
Figure 5. CH4 channel's response curves—effects of variations
in H2 flow rate. Sample flow rate @ 10.2 cm3/min,
net response » response to constant methane concen-
tration less response to zero air.
100 -
80 •
80 .
70 •
60 •
SO .
40 •
30 •
20 •
10 •
0 .
NET RESPONSE
ZERO RESPONSE
1.0
1.2
1.4
1.8
1.8
2.0
H2 TO SAMPLE FLOW RATE RATIO
Figure
6. TOO channel's response curves—effects of variations
in H2 flow rate. Sample flow rate @ 10.2 cm^/min,
net response = response to constant methane concen-
tration less response to zero air.
55
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11. If either response curve contains a peak, adjust the hydrogen pressures
to selected values which produce approximately equal CH4 and TOC
responses. Preferably, the resulting hydrogen setting should be near
or somewhat to the right of the peak response hydrogen setting.
12. If the response curves from step 10 do not contain a peak, or if the
peak is contained on a broad plateau, adjust the hydrogen pressures to
selected values which produce approximately equal CH^ and TOC
responses, preferably at hydrogen to sample ratios of about 1.0 to 1.4.
13. Reconnect the sample line to the ambient manifold and place the jumper
on the electrometer card in the S (subtracting) position to permit
recording of NMOC and CH^ responses.
14. Recheck analyzer operation to see if proper balance and calibration can
now be achieved. If not, pick new operating points from the response
curves, adjust parameters, and recheck analyzer operation.
4.7.6 Sample Flow Rate Investigation
If either sample flow rate to the FID (4.7.1.6) differs by more than 5%
from the flow rate measured during the most recent period of normal opera-
tion and the sample pump system has been eliminated as the problem (section
4.7.21, carry out the following investigation.
1. Ensure that both sample capillaries produce the same flow when con-
nected to the same outlet of the distribution manifold. If flows are
not within +_ 0.2 cm^/min of each other, clean both in an ultrasonic
bath of methyl alcohol, and then recheck flow rates. If differences
still exist, order new, matched capillaries from the manufacturer.
2. Determine if any other part of the sample flow system contains obstruc-
tions. (Measure flow rates from both sample ports of the distribution
manifold. They should be equal. If not, measure the flow rate entering
and exiting the cutter. If these flow rates are not equal, the cutter
is clogged. Replace the cutter and check flow rates.)
Leak test the sample flow system.
section 2.4.2.)
(Use the procedure detailed in
4.7.7 Burner Air Flow Rate Investigation
If either burner air flow rate to the FID (4.7.1.7) differs by more
than 5% from the flow rate measured during the most recent period of normal
operation, and if the sample pump system has been eliminated as the problem
(4.7.2), carry out the following investigation.
56
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Inspect the burner air restrictors in the distribution manifold for
debris and clean or replace as necessary. (If one needs cleaning or
replacing, clean or replace both restrictors.)
(a) Remove the burner air line from the exit side of the distribution
block.
(b) Soak the fittings in a solvent (methyl alcohol) for several hours
(an ultrasonic bath can hasten the cleaning).
(c) Connect a clean air pressure line to the outlet of the fitting and
force air through the fitting (in reverse) while the fitting is
submerged in solvent.
(d) After free flow is obtained through the restrictor, remove the
fitting from the solvent and continue to pass air through it until
all solvent has evaporated.
(e) Install the cleaned restrictor and measure the burner air flow as
before.
Determine if any other part of the burner air flow system contains
obstructions. If so, replace or attempt to clean by reverse flushing
with methyl alcohol. (If any obstruction is located in the oxidizer,
replace or repack the unit.)
Leak test the burner air system and determine if a leak is present.
(Use the procedure detailed in section 2.4.2.)
57
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SECTION 5
AUGMENTED PROCEDURES FOR THE BENDIX 8201
AND 8202 REACTIVE HYDROCARBON ANALYZER
NOTE: READING SECTIONS, 1, 2, AND 3 BEFORE SECTION 5 IS STRONGLY
RECOMMENDED. INFORMATION WHICH IS CRITICAL TO THE UNDERSTANDING
AND SUBSEQUENT ACCURATE OPERATION OF THIS ANALYZER IS DETAILED IN
THOSE SECTIONS AND WILL NOT BE REPEATED HERE.
The manufacturer has prepared a relatively detailed instruction manual which
can guide users during installation and operation of the model 8201 and 8202
inalyzers. The thoroughness of the manual will therefore allow this
section to be brief. As stated in the introduction, the purpose of this TAD
Is to supplement the analyzer's instruction manual by augmenting critical
installation and operation procedures.
5.1 PRINCIPLES OF OPERATION
The analyzer's instruction manual contains a discussion on this subject in
;he "Introduction". In the discussion the term "mechanical separating
device" is used in place of chromatographic column; and the "detector" cell
is a hydrogen flame ionization detector (FID). Both analyzer models have
essentially the same design, so a brief summary of their operation follows.
Ihe analyzers contain one FID and one sample loop. At the start of the 200
second cycle, sample is directed from the sample loop into the mechanical
separating device. The methane component of the sample emerges first and is
injected into the FID for measurement. As the separating device is back-
flushed, another sample from the sample loop is directed straight to the FID
for measurement of TOC. Internal subtraction of the CH4 and TOC measure-
ments results in the NMOC reading.
5.2 SYSTEM DESCRIPTION
A detailed description of the analyzer is given in the analyzer's
instruction manual. This TAD will therefore not address location of com-
ponents, but will emphasize the uses and precautions of those which are
critical.
58
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5.2.1 Flame lonization Detector
The analyzer contains one FID. The separate responses of the Clfy. and
TOC channels must be balanced to a methane-in*air standard.
5.2.2 Hydrogen Pressure Gauge
The flow of hydrogen fuel to the FID is controlled by a pressure regu-
lator, gauge, and restrictor. Increasing the pressure reading on the
hydrogen gauge will increase the flow of hydrogen to the burner and affect
the sensitivity of the FID.
5.2.3 Flameout Indicator
If a condition exists which causes the hydrogen flame in the FID to
extinguish, the analyzer will either automatically attempt reignition or
will shut off flow of hydrogen to the FID. The action is determined by the
position of toggle switch S7 located on the front panel. In the event of a
flame-out, the flame-out indicator will illuminate. If the status of the
flame is in doubt, observe analyzer response first to zero air and then to a
sample known to contain hydrocarbon. If the TOC channel's responses are the
same to both samples, the flame is out.
5.2.4 Sample/Back-Flush Valves
The 0-rings of these two valves are susceptible to wear and thus
leakage. Replace 0-rings in both valves every 6 months, or sooner if leaks
develop. The 8202 manual contains details on specific leak-check proce-
dures . A procedure for leak-checking these valves, and the sample flow
system, is detailed in section 5.7.3 of this TAD.
5.2.5 Columns
To prevent column contamination, the columns should be capped whenever
they are removed from the analyzer or whenever the analyzer is powered-down
for an extended period of time.
5.3 MODIFICATIONS
The model 8201 analyzer has been slightly modified to produce the model
8202. The principle of operation and detection is unchanged. Differences
between the two models follow.
5.3.1 Relocation of Timer
The MANUAL CYCLE POSITION TIMER and the CH4, THC and ZERO FUNCTION
LIGHTS have been moved from inside the 8201 analyzer to the front panel of
the 8202.
59
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5.3.2 Instruction Manual
The analyzer instruction manual has been rewritten.
5.3.3 Calibration Procedure
The calibration procedure for the 8202 calls for a zero air standard
and three methane/ethane in air span standards. (See section 5.6 for the
EPA recommended calibration procedure.) The sequence of events during cali-
bration, zero/span checks, and electronic timing has been changed.
5.3,4 "C ali forn i a" Mod i fie at ion
At monitoring sites where significant concentrations of "heavy" hydro-
carbons exist, a problem may arise with the Bendix analyzer which causes the
TOC reading to be too low. The cause of the low TOC reading is that during
the TOC measurement, the methane and heavy hydrocarbons may separate due to
the chromatographic action of the surfaces of the lines and components with
which the sample comes in contact. This causes the normal TOC peak on the
FID to separate into 2 distinct peaks, one for methane and light compounds
and the other for the heavier compounds. The height of these separate peaks
is less than the height of a single combined peak. Since the analyzer
detects only peak height and not peak area, the resulting TOC reading is
reduced by the separation.
This TOC peak separation may be worse with some analyzers than with
others. A test for the effect is to run a chromatogram (see section 5.7.2)
using a mixture of methane and a heavier compound such as ra-xylene. If
separation is occurring, it will show up as a separation of the TOC peak
into separate peaks in the chromatogram.
A modification to the analyzer to reduce the effect of this TOC separa-
tion has been developed by Bendix for certain California monitoring
agencies. The modification may become standard for new model 8202 analy-
zers, and Bendix will likely offer a kit to modify existing instruments.
The modification consists of a new chromatographic column, a new capillary,
and some plumbing changes. It also includes a change in the operation of
the analyzer such that the TOC reading is obtained first and the CH^
reading last. This means that the valve and gate timing must be changed.
For analyzers incorporating this modification, appropriate changes must be
made to the instructions in section 5.7.2. Consult the Bendix Corporation
for further details on this modification.
60
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5.4 INSTALLATION
The analyzer's instruction manual contains a discussion on the subject
under the same heading. Additional comments follow.
5.4.1 General Comments
1. Before supplying power to the analyzer, ensure that all electronic
cards are properly seated by attempting to push the cards snugly into
the connectors .
2. Minimize the distance between the analyzer and the sample manifold.
Use clean, 3 mm (1/8 in) diameter inert tubing to make the sample line.
The sample line length should not exceed 3 m (10 ft).
3. Leak-checks should be made on the hydrogen flow system of old and new
analyzers. See the instruction manual for details or use the procedure
in section 2.4.2 of the TAD.
CAUTION: ONLY EXPERIENCED, QUALIFIED OPERATORS SHOULD
PERFORM THE LEAK CHECK. AVOID FINGER CONTACT WITH THE
FITTING THREADS DUE TO POSSIBLE TRANSFER OF OILS THAT WILL
TEMPORARILY INCREASE THE BASELINE RESPONSE.
4. Hydrogen gas, burner air, and carrier air should not contain TOC con-
taminant concentrations that can not be "bucked-out" by the auto zero.
(Perform a level 1 zero and span check after replacing any of these
support gases.)
5. If zero air is used to dilute span gases, it must not contain more than
0.1 ppmC TOC concentration.
6. Connect a recorder to the NMOC output located in the rear panel of the
analyzer. If desired, recorders can also be connected to the analy-
zer's TOC and CH4 outputs. A temporary, multiple speed recorder
capable of operating at ~16 in per hour is necessary for recording
chromatograms from the analyzer's front panel jack.
7. Do not connect calibration gas to the CALIBRATE port.
8. The needle valves located inside the analyzer (NDLV 1) and oven (NDLV 2
and 3) can be accessed through small holes drilled through the analyzer
cover and oven. Knobs on the valves can be removed, leaving the stem
to be adjusted by a long screwdriver. This modification enables flow
rate adjustments without removing the analyzer cover and oven top,
which eliminates heat loss and subsequent flow rate instabilitly during
adjustments.
61
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"'.4.2 Sample Pump Installation
The instruction manual specifies installing the sample pump outlet to
t.he SAMPLE port on the rear of the analyzer. In this configuration, the
iiample passes through the pump before analysis by the analyzer. However, a
very simple modification allows the pump to draw the sample through the
isample loop in the analyzer such that the sample does not pass through the
pump first. The modification consists of connecting the inlet of the sample
pump to the CALIBRATE port of the analyzer and turning the front panel
selector switch to the calibrate position. This switch must be left in the
CALIBRATE position during normal operation. Sample air will thus be drawn
Into the SAMPLE VENT port and out the CALIBRATE port to the pump. In this
mode, the flow is adjusted with the sample needle valve (006718-2), as the
back pressure regulator on the rear panel will have no effect.
J.5 OPERATION
5.5.1 Start-Up
The analyzer's instruction manual covers this discussion under "Opera-
:ion". Additional comments follow.
1. After supplying power and support gases to the analyzer, allow the
analyzer to operate for several hours to enable temperatures and flow
rates to stabilize; then measure flow rates. Use good laboratory pro-
cedures in measuring flow rates. (See section 3.6 in this TAD for
guidance during flow measurements.)
2. The model 8201 instruction manual specifies normal settings or ranges
for most of the operational parameters. If a Manufacturer's Final Data
Sheet (Bendix's Factory Test Data Sheet) is not available with the
analyzer, set the parameters as specified in the instruction manual, or
to previously used values.
5.5.2 Periodic Calibrations and Zero/Span Checks
An initial multipoint calibration is recommended to verify linearity in
the calibration curve. Periodic level 1 zero and span checks are thereafter
necessary to update the calibration curve. The frequency of level 1 zero
and span checks and subsequent multipoint calibrations should be based on
the analyzer's performance. Performance can be monitored through the use of
a control chart which documents responses to standards and ultimately
enables calculation of variation in response to standards (drift). (See
section 2.0.9 of reference 10 for details on calibrations and level 1 and
level 2 zero and span checks. See section H of reference 14 for details on
control charts. See section 5.6 of this TAD for calibration procedures.)
62
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5.5.3 Operational Checks
The analyzer's operational parameters should be checked at least once a
week, or more frequently if necessary. Parameters that should be routinely
checked and recorded on Table 11 are pressure gauge readings, analyzer
responses, and other routine checks that may be necessary. (Routine
monitoring may not require that unadjusted responses to standards be
recorded; however, special cases may warrent such data.) If any of these
parameters shows substantial change from the last check, recheck the
analyzer calibration with a level 1 zero and span check and make the
necessary adjustments.
5.5.4 Routine Chromatograms
A chromatogram (Bendix uses the term "spectrum") should be evaluated
during start-up and on a weekly basis thereafter to determine if analyzer
parameters have shifted outside the limits of proper operation. Critical
parameters, such as gate timing, FID sensitivity, and flow rates can be
investigated through careful evaluation of the chromatogram. See section
5.7.2 for procedures to obtain a chromatogram, methods to evaluate the
chromatogram, and adjustments to correct improper analyzer operation.
5.6 CALIBRATION
This section details specific procedures for multipoint calibrations
and zero and span checks of the Bendix 8201 and 8202. The analyzer's
instruction manual may contain deviations from these procedures, but the
step-by-step procedures that follow are currently recommended by the EPA.
5.6.1 Multipoint Calibration
1. Disconnect the analyzer's sample line from the ambient sample manifold
and reconnect it to the calibration system's manifold. Cap the port on
the ambient manifold, and on any open ports on the calibration system's
manifold.
2. Place the analyzer's range selector switch in the desired concentration
range. (Calibrate the analyzer on the range normally used during
ambient sampling.) Ensure that the TIMER and VALVE toggle switches are
in the AUTO position.
3. Supply an atmosphere of methane-in-air to the calibration manifold at a
flow rate that is 20 to 50% greater than the analyzer's sample flow
demand. DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET.
4. Run a chromatogram (at least once a week) and evaluate it for proper
analyzer operation (gate timing, flow rates, etc; see section 5.7.2 for
63
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TABLE 11. FORM FOR RECORDING ROUTINE OPERATIONAL DATA FROM THE
BENDIX 8201 OR 8202 NMOC ANALYZER
jl
]
i
1
s"
•
1
I
I
1
i
s
i
i
i
i
i
t
**
!
si
i
1
5
I
|
5*
2
ll\
I
4
1
!
1
i
I
5'
I
i
5
1
1
5
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S*
8
1
.
64
-------
procedures).
calibration.
Allow the analyzer to stabilize before continuing
Supply an atmosphere of the zero standard to the sample manifold at a
flow rate 20 to 50% greater than the analyzer's sample flow demand. DO
NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. The test atmosphere must
contain an ambient level of oxygen and must not contain more than 0.1
ppmC TOC. (See section 3.2 for details.)
NOTE: THE ANALYZER'S AUTO ZERO WILL CORRECT FOR MINOR
CONTAMINATION IN THE HYDROGEN, BURNER AIR, AND CARRIER AIR,
BUT WILL NOT CORRECT FOR ZERO GAS CONTAMINATION.
DISCREPANCY BETWEEN THE AUTO-ZERO LEVEL AND THE ZERO-AIR
RESPONSE MAY INDICATE CONTAMINATED ZERO AIR.
Adjust the TOC zero pot, 0*4 zero pot, and the NMOC zero pot to
obtain the desired baseline. (A 5% full scale offset is recommended to
observe negative drift.) The THC, CH4, NMOC sequence must be
followed if subsequent adjustments are necessary. Ensure that readings
from all channels are equal before recording them on Tables 5 and 11.
Supply an atmosphere of the methane standard to the sample manifold at
a flow rate 20 to 50% greater than the analyzer's sample flow demand,
DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. Methane concentration
should be between 70 and 90% full scale.
Adjust the front panel CH4 and TOC span pots to provide the analyzer
response calculated as follows:
Response «
Sample concentration
„ , ....
X url + zero offset
(9)
where
Response = Response of the recording device measuring the analyzer
output in recording device units .
Sample Concentration * Concentration of the calibration standard
delivered to the analyzer in ppmC.
URL * The upper range limit of the analyzer in ppmC.
url * The upper range limit of the recording device in recording device
units .
65
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Zero offset = The amount the recording device response is set above
the zero baseline while the analyzer is measuring the
zero calibration standard (in recording device units).
NOTE: The response, url, and zero offset must be in identical units.
For example, if a strip chart recorder is the recording device, units
will be in percentages of chart and the url may equal 100% chart. If a
digital volt meter (DVM) is the recording device, units may be in
millivolts or volts and the url may be, for example, 1000 mV. If a Data
Acquisition System (DAS) is the recording device, units may be in ppmC
and the url will equal 10 ppmC. If the front panel meter on the
analyzer is the recording device, units will be in ppmC and the url may
be 10 ppmC.
Record the stable responses on Tables 5 and 11,
If either span pot is adjusted, recheck the zero and then the methane
responses (Steps 5 through 9). Ensure that all channels' responses to
the zero standard are within +_ 1.0% of zero, that the CH4 and THC
responses to the methane standard are within _+ 1.0% of the actual con-
centration, and that the NMOC response to the methane standard is
within + 1.0% of the NMOC response to the zero standard.
10. Determine the CH4 and TOC channels' responses to two or more addi-
tional concentrations of the methane standard that are approximately
equally spaced over the analyzer range. (The NMOC channel's response
should remain equal to the earlier zero standard response.) Record the
CH4 and TOC channels' responses (from the recording device) on Table
11. Using a calculator, perform a least squares linear regression of
the CH4 channel responses (to methane and zero standards) and the
corresponding calibration concentrations. The calibration
concentrations should be in units of ppmC and should be entered into
the calculator as the independant variable X. The CH4 channel's
responses should be in units of the recording device and should be
entered as the dependent variable Y. A correlation coefficient (r) of
0.9996 or better verifies the CH4 response as linear. (If the
response is not linear, plot the data and determine if an error has
been made in data entry or in determination of a calibration concen-
tration.) Obtain the slope and intercept of the regression and record
the equation in the following form:
CH, Response
CH. Slope X Methane Concentration + CH, Intercept
(10)
66
U.S. EPA Headquarters Library
Me;- code 3201
1200 Pern?*. v--n,?. Avenue NW
Wasningzon DC 20460
-------
where
CH4 Response
Analyzer's CH4 channel reading in recording device
units (see note following step 8).
CH4 Slope » Regression slope in recording device units per ppmC.
Methane Concentration * Calibrated methane concentration in ppmC.
CH^ Intercept « Regression intercept in recording device units.
Post the CH4 channel's calibration curve equation on the analyzer's
recording device and also on Tables 5 and 11. Also, using the above
equation and the TOG responses, determine the TOC calibration curve and
post it accordingly.
11. Supply an atmosphere of the propane standard to the sample manifold at
a flow rate 20 to 502 greater than the analyzer's sample flow demand.
DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. Propane concentration
should be between 70 and 90% full scale.
12. Adjust only the NMOC span pot to provide the analyzer response cal-
culated from equation in 9 step 8. If the NMOC span pot is adjusted,
recheck the NMOC response to the zero standard and adjust the zero pot
if necessary. Recheck the NMOC response to the propane standard.
Record the stable responses on Tables 5 and 11.
13. Determine the NMOC channel's response to two or more additional concen-
trations of the propane standard that are spaced approximately equally
over the analyzer range. The CH4 channel's response should remain
equal to the earlier response to zero standard. Record the stable
responses (from the recording device) on Table 5. Using a calculator,
perform a least squares linear regression of the NMOC channel's
response (to propane and zero standards) and the corresponding propane
calibration concentrations. The calibration concentrations should be
in units of ppmC and should be entered into the calculator as the
independent variable X. The channel's response should be in units of
the recording device and should be entered as the dependent variable Y.
A correlation coefficient (r) of 0.9996 or better verifies that the
response is linear, (if the response is not linear, plot the data and
determine if an error has been made in data entry or in determination
of calibration concentration.) Obtain the slope and intercept of the
regression and record the equation in the following form:
NMOC Response = NMOC Slope X NMOC Concentration +• NMOC Intercept (11)
67
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where
NMOC Response
Analyzer's NMOC channel's reading in recording device
units (see note following step 8).
NMOC Slope = Regression slope in recording device units per ppmC.
NMOC Concentration a Calibrated NMOC concentration in ppmC.
NMOC Intercept » Regression intercept in recording device units.
Post the NMOC channel's multipoint calibration curve equation on the
analyzer's recording device and on Tables 5 and 11.
14. Record all operational parameter readings. These readings will now
become the reference readings until another multipoint calibration is
performed. Be certain that the station logbook, strip charts, etc.,
are properly annotated, dated, and initialed.
15. If level 2 zero and span checks are to be used, carry out such a check
now to establish reference zero and span readings for subsequent com-
parison. (See section 2.0.9.1.3 of reference 10 for definitions and
additional information for level 1 and 2 zero and span checks.)
5.6.2 Level 1 Zero and Span Check
The following level 1 zero/span procedure (2-point calibration) is
similar to a multipoint calibration except that only the zero air standard
and one upscale standard are used. These responses are then used to cal-
culate the new calibration curves, which are used to correct subsequent
monitoring data until another level 1 zero/span check or multipoint calibra-
tion is performed.
1. Follow the procedures in section 5.6.1, modified as follows.
(a) Record responses on Tables 6 and 11.
(b) After step 5, determine the zero drift in the CH4, TOG, and NMOC
channels (see section 3.8).
If drift exceeds about _+ 3%, perform step 6 and make the adjust-
ments. If drift is less than about _+_ 3%, skip step 6.
(c) After step 7, determine the span drift in the CH4 and TOG
channels (see Equation 4 in section 3.8). If drift exceeds about
+ 7%, make the adjustments in steps 8 and 9.
68
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(d) Omit step 11, but determine the slope and intercept of the CH4
and TOG channel's level 1 calibration curve.
Post the level 1 calibration curves on Tables 6 and 11 and on the
analyzer's recording device.
(e) After step II, determine the span drift in the NMOC channel (see
Equation 4 in section 3.8). If drift exceeds about + 7%, make the
adjustment in step 12.
(f) Omit step 13, but determine the slope and intercept of the NMOC
channel's level 1 calibration curve. Post the level 1 calibration
curve on Tables 6 and 11 and on the analyzer's recording device.
5.7 TROUBLESHOOTING
The manufacturer's instruction manual covers this subject under the
same heading. Additional comments follow.
5.7.1 Preliminary Investigations
Operational problems, such as slow response to standards, inability to
balance the TOG and CH4 channels' responses, long stabilization periods,
frequent flame-outs, or low sensitivity indicate the potential need for
in-depth troubleshooting. Prior to undertaking in-depth troubleshooting
procedures, a preliminary investigation is recommended to rule out varia-
tions in operational parameters.
1. Ensure that all pressure gauges on the analyzer are set to the specifi-
cations stated on the Manufacturer's Final Data Sheet. (If a manu-
facturer's data sheet is not available, use the instruction manual's
settings.) If the analyzer has been operating properly for several
months, ensure that pressure gauges are set to the readings recorded
during the most recent multipoint calibration when analyzer operation
was satisfactory.
2. Inspect the hydrogen source and hydrogen filters (located outside the
analyzer) for proper operation.
3. Inspect the sample filter and replace if dirty. Replace the sample
line leading- to the analyzer if particulate buildup is noticeable.
4. Run a chromatogram as explained in section 5.7.2. If the chromatogram
has changed since the last multipoint calibration, measure all flow
rates in the analyzer and adjust to the proper specifications. Signi-
ficant changes in flow may indicate a leak or an obstruction. If flow
rates are within specifications, the gate timing may need adjustment.
69
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5.7.2 Chromat og r am Inve s tig at io n
5.7.2.1 Procedures for Obtaining a Chromatogram—
NOTE: IF YOUR ANALYZER INCORPORATES THE "CALIFORNIA"
MODIFICATION, SEE SECTION 5.3.4.
1. Allow the analyzer to sample an atmosphere containing a tnethane-in-air
standard. Ensure that the atmosphere contains ambient levels of
oxygen and that it is delivered at atmospheric pressure to the SAMPLE
inlet of the analyzer (section 3.5).
2. Place the METER selector switch on the front panel to the ELECTROMETER
position.
3. Connect a strip chart recorder to the analyzer's front panel. Select a
fast chart speed that will allow easy identification of time on the
strip chart.
4. Allow the analyzer to operate for about 10 minutes. Identify the
repetitive measurement cycles which last 200 seconds. Each cycle
should contain an automatic zero, CH^ peak, automatic zero, and TOC
peak. The strip chart recording of the cycle is a chromatogram. (See
Figure 7 for a chromatogram depicting proper analyzer operation.)
5. Place the METER selector switch to the TIMER POSITION.
6. Advance the strip chart to a point where the pen can rest on a timing
line of the chart. Stop the chart advance motor.
7. Observe the FRONT PANEL METER. Immediately after the meter indicates
completion of a 200-second cycle (the needle will pass full scale then
drop to zero), simultaneously place the METER selector to ELECTROMETER
and engage the strip chart advance motor.
8. Observe the CH^, TOC, and zero function lights. When the ZERO light
illuminates, flick the chart recorder pen to mark the chart. When the
light goes off, flick the pen again.
9. When the CH4 light illuminates, flick the pen, and repeat when the
light goes off.
10. Perform similar actions when the auto zero and THC lights illuminate
and go off.
70
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11. Remove Che chart, measure the number of seconds from the start of the
measurement cycle to each flick, and record the times on the chart.
12. For increased accuracy, repeat steps 6 through 11 several times and
average the ON/OFF times for each gate. Also for increased accuracy,
the same procedure can be repeated with a stopwatch instead of a strip
chart. With the METER in the TIMER position, begin the watch when the
cycle begins and call out times to an assistant when the function
lights illuminate and go off. A digital watch with split time
functions would be very helpful in performing this procedure.
5.7.2.2 Chromatogram Evaluation—
Chromatograms depicting proper and improper analyzer operation are
shown in Figures 7 and 8. The Chromatogram depicting proper operation shows
auto zero gates ON and OFF just prior to the Cfy and TOC peaks, the peak
gates ON just prior to elution of the peak, and the peak gates OFF just
after the response returns to the baseline.
Gate timing is critical because when a peak gate is ON, the signal from
the FID is collected until the gate goes off. This signal is referenced to
the auto zero signal and is eventually directed out the back panel to the
recorder. If gate ON/OFF activity occurs during peak emergence, as in
Figure 8, some of the peak may be missed. This results in an incorrect
analyzer response for the component measured. A procedure to correct
improper timing is discussed in 5.7.2.3, below.
Another characteristic of proper operation is a stable baseline
response. The auto zero response prior to the CH^ peak must be equal to
the auto zero response prior to the TOC peak. In Figure 7, the responses
during auto zeros remain the same, whereas in Figure 8, the responses during
auto zeros are different. Variable baselines can be caused by differences
in carrier flow rates when passing through the analytical column and when
bypassing this column. The variable carrier flow rate will alter the
hydrogen-to-carrier ratio, and thus alter the sensitivity of the FID. To
prevent a change in sensitivity, the carrier flow rate bypassing the column
during the TOC measurement must be balanced to the carrier flow rate passing
through the column during the CH4 measurement. A procedure to correct
improper carrier flow rates is discussed in 5.7.2.3, below.
5.7.2.3 Adjustments to Correct Improper Baseline Shift on Gate Timing—
If evaluation of a Chromatogram indicates improper carrier flow rates
(discussed in 5.7.2.2) perform the following steps:
1. Place the front panel VALVE 1 and 2 switches in the OFF position and
activate the AUTO H2 SHUT OFF.
71
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End m*Mur«m«it cyd« 9 200 MC
- TOC «•«<>«« 147 we
Auto ztro off
9113MC ,
•TOC gat* one 119 Me
Auto zero on 9 106 sec
' TOC Peak
*. CH4 gitt off © 46 MC
Auto zero off
,CH4P«ak
' CH4 git* on 9 25 MC
Auto zero on 9 16 MC
Begin meaiurament cycle
Figure 7. Chromatogram from a Bendix 8202 analyzer
showing proper analyzer operation.
•TOC fmk
TOC 9*U on ifttr ittit of p«k
Improper
bcMlinc
riirft
CH4 gM* off bwfor* end of p«k
CH4Ptik
Figure 8. Chromatogram from a Bendix 8202 analyzer showing
improper gate timing and baseline shift.
72
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2. Connect a flow measuring device to the FID VENT on the back panel and
measure the flow rate. Record this as the column flow rate. (The
manufacturer may call this the "total column flow rate".)
3. Adjust the AIR CARRIER pressure regulator to obtain the column flow
rate recorded on the Manufacturer's Final Data Sheet.
4. Connect a rotameter or mass flow meter to the FID VENT (if not already
connected) and record the flow rate reading.
5. Place the VALVE 2 switch in the ON position and adjust the restrictor
on Valve 2 (located inside the analyzer oven off port 4) to obtain the
same flow rate as in step 4. The carrier flow bypassing the column
should now be equal to the carrier flow through the column.
6. Activate the AUTO IGNITION switch, place both VALVE 1 and 2 switches in
the AUTO position, and obtain a chromatogram.
7. If auto zero responses are not equal, adjust the restrictor on Valve 2
until auto zero responses are equal.
8. Activate the AUTO H2 SHUT OFF and place VALVE 1 in the OFF position
and VALVE 2 in the ON position. Measure the FID VENT flow rate. If
this column bypass flow rate is not within + 1% of the column flow rate
obtained in step 3, troubleshoot the flow systems for leaks,
obstructions, and column contamination.
If evaluation of a chromatogram indicated improper gate timing
(discussed in 5.7.2.2), perform the following steps:
1. Operators of the 8201 model should refer to section 5.4.4 TIMING
TROUBLESHOOTING in their instruction manual and Figure 7-16 COMPARATOR
CARD SCHEMATIC DIAGRAM. Operators of the 8202 model should refer to
section 5.5 CARD ADJUSTMENTS in their instruction manual and Figures
5-7, 5-8 and 5-9. Actions recommended in the instruction manual may be
necessary if the following steps are unsuccessful in correcting
improper gate timing.
2. Convert the ON/OFF times (obtained in the TAD section 5.7.2.1) for each
improperly timed gate from seconds to timer-dial settings. The
timer-dial (part #R-60) is a 10-turn, 200-second potentiometer that
facilitates checking or setting the analyzer's gates. The timer-dial
is mounted inside the 8201 analyzer beside the oven and is labeled
TIMER POSITION. On the 8202 model, the timer-dial is mounted on the
front panel and is labeled MANUAL CYCLE POSITION TIMER. For this
discussion, the R-60 dial will be referred to in both models as the
timer-dial.
73
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In Figure 8, the improperly timed City gate goes off at X seconds. To
convert seconds to timer-dial units, use the following equation:
Y a or
* X 1000 timer-dial units
200 sec
y timer-dial units
(12)
Verify that the City gate indicator goes off at y timer-dial units.
Place Valves 1 and 2 in the OFF position and the TIMER toggle switch in
MANUAL. Increasing the timer-dial to past y units should cause the
City gate indicator to go off.
The correct gate OFF time for the City peak should be several seconds
after the peak returns to the baseline. Estimate the number of seconds
that should be added to X to produce the correct OFF time. Convert
this corrected time from seconds to timer-dial units and rotate the
timer-dial to the corrected units. The City gate indicator should be
off.
Locate Comparator Card #1 (component card J-10) inside the analyzer and
rotate pot R-76 until the City gate indicator just comes on. Check
gate operation by rotating the time dial through y units.
Reset the analyzer controls to obtain a chromatogram and verify that
the City off gate is properly adjusted.
After the operator is confident performing timing adjustments, the
verifying chromatogram need not be obtained until all timing adjust-
ments are completed. For example, to correct the TOC ON gate problem
in Figure 8, the Auto Zero ON and OFF gates may need to be adjusted to
allow sufficient time for TOC gate adjustment. Follow the sequence of
events discussed in steps 2 through 5, with modifications to fit the
specific timing adjustment. Table 12 lists the specific potentiometers
that will alter the different functions.
TABLE 12. COMPARATOR* CARD 1 (COMPONENT CARD J-10)
FUNCTIONS AND POTENTIOMETER CONTROLS
Function
CH4 gate OFF
TOC gate ON
TOC gate OFF
CH4 Auto Zero ON
CH4 Auto Zero OFF
TOC Auto Zero ON
TOC Auto Zero OFF
Potentiometer Number
R-68
R.76
H-54
R-64
fl-40
R-52
R-29
R-38
'Comparator card 2 (component card J-11) is identical to card 1 (J-10) but control* valve 1 and 2
ON/OFF timing and the actual timer cycle. Sea illustrations of these cardi in the instruction
manual for details.
74
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5,7.2.4 Chromatograms Showing Analyzer Malfunctions—
The following section identifies specific chromatogram patterns, shown
in Figure 9, that indicate analyzer malfunctions. The information is
reproduced from the Bendix 8202 Reactive Hydrocarbon Analyzer Operation and
Service Manual. Permission for reproduction was granted by the Bendix
Corporation, Environmental and Process Instruments Division, Lewisburg, West
Virginia 24901.
A. SYMPTOM: Constant basline drift in one direction, then starts in other
direction.
PROBABLE CAUSE
Column has stopped bleeding and has
started to clean.
Dirty carrier or dryer. Dirty dryer
on H2 and/or air on FID.
Dirty FID cell.
REMEDIAL ACTION
Allow time for column to
complete its cleanup.
Change carrier bottle and/or
dryers.
Clean FID cell.
B. SYMPTOM: Blip in baseline that varies with flow rate. The higher the
flow, the larger the blip.
PROBABLE CAUSE
Dust in the FID cell.
Condensate in cell vent.
Varying pressure on FID vent
SYMPTOM: No peaks.
PROBABLE CAUSE
Electrometer off.
No carrier gas flow.
No flame.
REMEDIAL ACTION
Clean the cell.
Clean the vent.
Check for partial blockage.
Also, room pressure may be
changing due to doors or
windows being opened.
REMEDIAL ACTION
Check jet potential voltage.
Turn power ON.
Check carrier gas supply and
carrier shut-off switch.
Check H2 and air flows and
light flame.
75
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B
SYMPTOM
Constant baseline drift in
one direction, then startJ
in othar direction.
SYMPTOM
Blip in baseline that varies
with flow rate. The higher
the flow the larger the blip.
SYMPTOM
No peeks
t_
SYMPTOM
Little or very poor
sensitivity (normal
elution time).
H
1 SYMPTOM
Poor sensitivity (longer
elution time).
SYMPTOM
Baseline irregular
I SYMPTOM
Baseline appears as a
sinewave type trace.
SYMPTOM
Stepping baseline
SYMPTOM
Negative peaks
[SYMPTOM
SYMPTOM
Irregular or noisy
baseline
Distorted peaks
SYMPTOM
Constant baseline
drift in one
direction
Figure 9. Chromatograms showing analyzer malfunctions.
76
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Defective recorder.
Leak at column connections.
Recorder not connected correctly.
No voltage applied to detector
cell on ionization detector.
Cable disconnected from FID.
Column temperature too low to elute
peaks.
Refer to recorder manual for
troubleshooting procedure.
Tighten connections.
Refer to schematic of
recorder hookup. Be sure no
jumpers are grounding signal
Check electrometer voltage
output. Refer to
electrometer schematic.
Connect the cable.
Raise column temperature to
proper level.
SYMPTOM: Little or very poor sensitivity (elution time normal).
PROBABLE CAUSE REMEDIAL ACTION
Incorrect sample size.
Electrometer OFF (FID).
No sample flow.
Clean sample chamber.
Turn electrometer ON.
Check pump operation and
STANDARD SAMPLE solenoid
(SOLV 3) valve operation.
E. SYMPTOM: Poor sensitivity (longer elution time).
PROBABLE CAUSE
Analyzer temperature too low.
Carrier flow too low.
Leak downstream of injection valve.
SYMPTOM: Baseline irregular.
PROBABLE CAUSE
Column bleeding.
REMEDIAL ACTION
Check and reset to correct
temperature.
Increase flow rate.
Locate and repair leak.
REMEDIAL ACTION
Replace defective column
with a properly conditioned
column.
77
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G.
FID cell contaminated.
Bad electrical ground.
Carrier gas regulation poor,
Defective electrometer.
Unstable oven temperature.
H2 and/or air regulation poor.
SYMPTOM: Baseline appears as a sinewave
PROBABLE CAUSE
Poor temperature control.
Hydrogen flow too high.
Dryers dirty.
Leak at jet.
Low tank pressure on carrier gas—
bottle pressure should be over 10
psig.
Defective carrier gas flow regulator.
Defective H2 and/or air regulators.
Clean the FID cell.
Check the analyzer for
proper grounds.
Check carrier gas flow
control and regulator. Be
sure upstream pressure is
high enough to operate
regulator. Pressure should
be at least 10 psig.
Check electrometer.
Check to see if temperature
controller is operating
properly.
Check flow rates to be sure
of proper flows and regula-
tion.
type trace.
REMEDIAL ACTION
Check the temperature control
for proper operation. Check
seal around door for leaks.
Be sure there is no obstruc-
tion to air flow in the oven.
Lower the hydrogen flow.
Replace the dryers.
Locate and repair leak.
Replace tank.
Replace the flow regulator.
Clean or replace regulator.
78
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H. SYMPTOM: Stepping baseline.
PROBABLE CAUSE
Defective recorder.
I. SYMPTOM: Negative peaks.
PROBABLE CAUSE
Signal reverse circuit energized.
Recorder leads reversed.
J. SYMPTOM: Irregular or noisy baseline
PROBABLE CAUSE
Loose leads.
Bad ground connections.
Carrier gas leak.
Contaminated columns .
Contaminated carrier gas.
Dirty switch or switches.
REMEDIAL ACTION
Refer to the recorder manual.
REMEDIAL ACTION
Refer to Control Module
manual (if applicable).
Reverse the recorder leads on
the rear hookup panel.
REMEDIAL ACTION
Tighten all leads from power
supply to cell.
Tighten all ground
connections to ensure earth
potential.
Locate and repair leak.
Replace or recondition
columns.
Replace carrier gas bottle
and replace dryers and
filters .
Locate the dirty switch and
clean with suitable solvent.
Recorder slidewire dirty.
H2 and/or air flow rates too
high or too low.
Detector insulators dirty.
Contaminated FID cell.
Clean with suitable solvent
Adjust flow rates.
Clean insulators.
Clean FID cell.
-------
Detector coaxial cable defective.
Loose signal leads.
K. SYMPTOM: Distorted peaks.
PROBABLE CAUSE
Flame burning above jet into ignitor
or collector electrode area.
Replace the coaxial cable.
Check all connections to be
sure they are tight.
REMEDIAL ACTION
Hydrogen and air flows too
high. Reduce flows.
L. SYMPTOM: Constant baseline drift.
PROBABLE CAUSE
Column bleed.
•Dirty carrier.
Dirty FID cell.
Defective electrometer.
Detector temperature increasing.
Leak in column tubing.
Column temperature too high for
the column.
5.7.3 Sample and Back-Flush Valve Leak Check
REMEDIAL ACTION
Replace or recondition
columns.
Replace carrier or dryer, and
filters.
Clean FID cell.
Repair or replace electro-
meter .
Allow time for detector tem-
perature to stabilize.
Locate and repair leak.
Lower the column temperature
or choose another type of
column.
1. A pressure test apparatus described in section 2.4.2 can be used. The
analyzer's instruction manual also addresses leak-checks.
2. Select the CALIBRATE position on the front panel toggle switch.
3. Cap the SAMPLE VENT.
4. Pressurize the CALIBRATE inlet port. With VALVE 1 in the ON position,
pressure decay indicates a possible leak in the sample valve at 0-rings
30
-------
to ports 3, 5, 4, and 6. With VALVE 1 in the OFF position, pressure
decay indicates a possible leak in the sample valve at 0-rings to ports
3, 2, I, and 6.
5. Remove the cap and pressure source.
6. Cap the FID vent and the back-flush vent.
7. Pressurize the AIR CARRIER inlet port. When VALVE 2 is in the ON
position (and VALVE 1 is known to be leak proof), pressure decay
indicates a possible leak in the back-flush valve at 0-rings to ports
3, 5, 4, and 6. With VALVE 2 in the OFF position, pressure decay
indicates a possible leak in the back-flush valve at 0-rings to ports
3, 2, 1, and 6.
-------
SECTION 6
AUGMENTED PROCEDURES FOR THE BECKMAN 6800
AIR QUALITY CHROMATOGRAPH (CH4, TOC, NMOC)
NOTE: READING SECTIONS 1, 2, AND 3 BEFORE SECTION 6 IS STRONGLY
RECOMMENDED. INFORMATION WHICH IS CRITICAL TO THE UNDERSTANDING
AND SUBSEQUENT ACCURATE OPERATION OF THIS ANALYZER IS DETAILED IN
THOSE SECTIONS AND WILL NOT BE REPEATED HERE.
The manufacturer has prepared a relatively detailed instruction manual
which can guide users during installation and operation of the model 6800
analyzer. The thoroughness of the manual will therefore allow this section
to be brief. As stated in the introduction, the purpose of this TAD is to
supplement the analyzer's instruction manual by augmenting critical
installation and operation procedures.
6.1 PRINCIPLES OF OPERATION
The analyzer's instruction manual contains a discussion of this subject
under "Instrument Theory". A brief summary of the CH4, TOC, and NMOC
component analysis follows.
A measured amount of sample is injected directly into the FID to
measure TOC concentrations. Following the TOC measurement, a second,
separate sample is injected into a stripper column to separate CH4 and CO
from C02 and heavy organics. A second column then separates CH4 from CO
prior to injection into the FID, where the CH4 concentration is measured.
The CH4 concentration can then be externally subtracted from the TOC con-
centration to obtain a measure of the NMOC concentration. (Modifications
are available to enable internal subtraction of CH4 from TOC to obtain a
direct NMOC output.)
6.2 SYSTEM DESCRIPTION
A detailed description of the analyzer is given in the analzer's
instruction manual. This TAD will therefore not address location of com-
ponents, but will emphasize the uses and precautions of those which are
critical.
82
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6.2.1 Flame lonization Detector
The analyzer contains one FID. Response from the CH^ and TOC
channels must be balanced to a methane-in-air standard. If zero air is
necessary to dilute span gas to the required calibration concentrations, the
CH4 and TOC channels must first be balanced to the zero air standard, and
then to the methane-in-air standard.
6.2.2 Hydrogen Pressure Gauge
The flow of hydrogen fuel to the FID is controlled by a pressure
regulator, gauge, and restrictor. Increasing the pressure reading on the
hydrogen gauge will increase the flow of hydrogen to the FID and affect the
sensitivity of the burner. Ensure that the hydrogen reading does not vary
from day to day. If the reading does vary, measure the flow rate and take
appropriate corrective actions.
CAUTION: ENSURE THAT ALL TUBING CARRYING HYDROGEN GAS IS LEAK
PROOF. SEE INSTRUCTION MANUAL, PAGE 12.
6.2.3 Flame-out Indicator
In the event of a flame-out, the flame-out indicator will illuminate.
If the status of the flame is in doubt, observe analyzer response first to
zero air, and then to a sample known to contain methane. If the TOC
channel's responses are the same to both samples, the flame is out.
6.2.4 Slider Valves
The slider valve is a stainless steel valve which contains a Teflon®
slider. The ON/OFF positions of the slider dictate where sample is
directed. Friction of the slider against the stainless steel causes wear of
both the slider and the steel, ultimately resulting in a leak. Frequent
maintenance of these valves is strongly recommended. The slider should be
replaced every 6 months, or sooner if a leak develops or if the slider
begins to open and close sluggishly. When the slider is replaced, the
stainless steel valve must be lapped to ensure a smooth seat for the slider.
During reassembly, the valve connectors must be tightened uniformly and only
to the point where no sample leakage occurs. Use of a vacuum applied to a
valve port is recommended to aid in determining when the valve is leak-
proof and thus sufficiently secure.
6.2.5 Columns
To prevent column contamination, all columns should be capped whenever
they are removed from the analyzer or whenever the analyzer is powered-down
83
-------
for an extended period of time. Failure to do so will allow the molecular
sieve to absorb C(>2. Subsequent operation results in CO2 outgassing
which will show up as a noisy, erratic baseline response.
6.3 MODIFICATIONS
The model 6800 analyzer has been slightly modified over the years. The
principles of operation and detection have not changed, but the following
modifications have been adopted.
6.3.1 Stripper Column
CO
To improve stability of the molecular sieve column (which separates
from CH^), the stripper column that preceeds the molecular sieve column
has been modified. The original packing material, Poropak, appeared to
break down and allow passage of volatile fragments to the sieve column,
resulting in deactivation. To correct this, a combination column containing
silica gel and an inert Teflon® support/partition liquid has replaced the
Poropak column.
6.3.2 Hydrogen Pressure Regulator
To eliminate diffusion of atmospheric water vapor into the hydrogen
carrier stream, the original permeable diaphragm located in the hydrogen
carrier gas regulator has been replaced with a stainless steel diaphram.
Also, the body of the regulator has been changed to brass.
6.3.3 Scrubber
The scrubber. (683526) upstream of the molecular sieve column is not
necessary and has been removed. Subsequent resizing of the capillary to
adjust pressures and flows must be performed when the scrubber is removed.
6.3.4 Sample Pump
In the normal configuration of the sample pump, the sample passes
through the pump before analysis by the analyzer. However, a very simple
modification allows the pump to draw the sample through the sample loops in
the analyzer such that the sample does not pass through the pump first. The
modification consists of disconnecting the pump from its normal connection
to the 3-way solenoid valve, and reconnecting it in series with the line
going from Valve B to the SAMPLE VENT. The pump inlet is connected to port
6 of Valve B, and the outlet is connected to the SAMPLE VENT. The bypass is
removed from the pump, and a needle valve, installed between the pump inlet
and Valve B, is used to control the flow rate. The sample inlet for the
analyzer then becomes the port on the 3-way solenoid valve to which the pump
was originally connected.
84
-------
6.3.5 Pressure Regulator
The service air, air carrier, hydrogen fuel, and burner air pressure
regulators have been replaced by improved regulators (865774).
6.3.6 Catalytic Converter Board
The catalytic converter board installed in analyzers before February
1973 contains a 4.7-ohm resistor (Rl) rated at 2 W. This should be replaced
with a 5-ohm 5-W resistor.
6.3.7 Oxidation Catalyst
The oxidation catalyst, which scrubs air to be used for combustion and
sample carrier, has been replaced. The original nickel oxide catalyst has
been replaced with palladium-on-alumina.
6.4 INSTALLATION
The analyzer's instruction manual contains a discussion of this subject
under the same heading. Additional comments and a specific start-up proce-
dure follow.
6.4.1 General Comments
1. Before supplying power to the analyzer, ensure that all electronic com-
ponent cards are properly seated by attempting to push the cards snugly
into the connectors.
2. Minimize the distance between the analyzer and the sample manifold.
Use clean 3 mm (1/8-in) diameter inert tubing as the sample line. The
sample line length should not exceed 3 m (10 ft).
3. Leak-checks should be made on the hydrogen, air carrier, and sample
flow systems of old and new analyzers. See sections 3.1.4 through
3.1.6 in the instruction manual for details. A leak-check apparatus is
discussed in section 2.4.2 of this TAD.
CAUTION: ONLY EXPERIENCED, QUALIFIED OPERATORS SHOULD
PERFORM THE LEAK-CHECK. AVOID FINGER CONTACT WITH THE
FITTING THREADS DUE TO POSSIBLE TRANSFER OF OILS THAT WILL
TEMPORARILY INCREASE THE BASELINE RESPONSE.
4. Hydrogen gas, burner air, and carrier air should not contain TOC con-
taminant concentrations that cannot be "bucked-out" by the auto zero.
Perform a level 1 zero and span check after replacing any of these
support gases.
85
-------
5. Zero air used to dilute span gases must trot contain more than 0.1 pptnC
TOG concentration.
6. Connect recorders to the Clfy and TOC outputs (and NMOC output if
available) located on the rear panel connector. Also, a temporary
recorder for the front panel jack (to record chromatograms) is useful.
7. Calibration gases should enter the analyzer through the SAMPLE inlet
port. Do not connect calibration gas to the CALIBRATE port.
-------
5.
(d) Turn on Valve B switch and observe slider movement and illumi-
nation of switch indicator.
(e) Move Manual/Auto switch to Auto, Valves A and B should deactivate
and indicators should go out.
(f) Return valve switches A and B to off position and Manual/Auto
switch to Manual.
Leak-check the air and sample flow systems as described in section
3.1.5 and 3.1.6 of the analyzer's instruction manual.
WARNING: CHECK THE CONDITION OF THE WATER DRAIN TUBING BE-
TWEEN THE FID AND OVEN EXTERIOR FOR HARDENING AND BRITTLENESS.
LEAKS IN THIS DRAIN MAY LEAD TO AN EXPLOSION BY ALLOWING A
BUILDUP OF HYDROGEN IN THE OVEN DURING REPEATED IGNITION
ATTEMPTS.
6. Establish correct gas flows.
(a) Turn off H2 fuel at the pressure control.
(b) Connect a flow meter to the hydrogen carrier and fuel line after
disconnecting from FID. (See Figure 5-9 in the instruction
manual.)
(c) Adjust H2 Carrier pressure control to obtain 25 cm^/rain and
record gauge read ing. A typical reading is between 12 and 20
psig.
(d) Adjust H2 Fuel pressure control to obtain a total flow (carrier
plus fuel! of 30 to 31 cm^/min, and record gauge reading. A
typical gauge reading is between 5 and 11 psig.
(e) Disconnect flow meter and reconnect H2 carrier and fuel line.
(f) Connect a flow meter to the air carrier line after disconnecting
from the FID.
(g) Adjust air carrier pressure control to obtain a carrier
flow of 33 to 35 cm-Vmin and record the gauge reading.
A typical gauge reading is 18-26 psig. Disconnect the
flow meter and reconnect the tubing.
87
-------
7. Ignite detector burner.
(a) Place Flame-Out Override switch to ON.
(b) Place the Manual Range Select switch to _1£ and the Monitor Select
switch to Ampl. Out. Note the meter response while proceeding
with the following steps.
(c) Reduce the Burner Air pressure gauge setting by approximately 50%
and momentarily C3 to 5 seconds) raise the Flame Ignition switch.
The meter response should drive upscale momentarily upon ignition
of the flame, then settle to some upscale level, indicating flame
ignition.
(d) Repeat the above step until flame ignites, and then reset burner
air to recorded setting.
(e) Turn off Flame-Out Override switch.
8. Allow system to stabilize 12 to 24 hours prior to performing any
calibrations.
6.5.2 Periodic CaLibrations and Zero/Span Checks
An initial multipoint calibration is recommended to verify linearity in
the calibration curve. Periodic level 1 zero and span checks are thereafter
necessary to update the calibration curve. The frequency of level 1 zero
and span checks and subsequent multipoint calibrations should be based on
the analyzer's performance. Performance can be monitored through the use of
a control chart which documents responses to standards, and ultimately
enables calculation of variation in response to standards (drift). (See
section 2.0.9 of reference 10 for details on calibrations and level I and
level 2 zero and span checks. See section H of reference 14 for details on
control charts. See section 6.6 of this TAD for specific calibration
procedures.)
6.5.3 Operational Checks
The analyzer's operational parameters should be checked at least once a
week, or more frequently if necessary. Parameters that should be routinely
checked and recorded on Table 13 are pressure gauge readings, analyzer
responses, and other routine checks that may be necessary. (Routine moni-
toring may not require that unadjusted responses to standards be recorded;
however, special cases may warrant such data.) If any of these parameters
shows substantial change from the last check, or if drift out of the speci-
fied range has occurred, recheck the analyzer calibration with a level 1
zero and span check and make necessary corrections.
88
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5.5.4 Routine Chromatograms
A chromatogrant should be evaluated during start-up, and on a weekly
oasis thereafter, to determine if analyzer parameters have shifted outside
the limits of proper operation. Critical parameters, such as gate timing,
FID sensitivity, and flow rates can be investigated through a careful
evaluation of the chrotnatogram. The procedure for obtaining a chromatogram
and setting gate timing follows.
1. Momentarily close RESET switch to place system in reset condition.
2. Set OPERATIONAL STATUS switches as follows,
(a) Move Manual/Auto Switch to Manual.
(b) Move Calibrate/Operate Switch to Operate.
(c) Move Manual ATT/Auto ATT Switch to Manual ATT.
3. Turn off front panel switches designated Valve A, Valve B.
4. Allow the analyzer to sample an atmosphere containing a methane-in-air
standard at about 8 ppmC plus about 10 ppm or higher CO. Ensure that
the atmosphere contains ambient levels of oxygen and that it is
delivered at atmospheric pressure to the SAMPLE inlet of the analyzer
(section 3.5).
5. Move Monitor Select Switch to AmpI. Out.
6. Momentarily close Start switch and turn Manual Range Select switch
to 1.
7. Turn on Auto Zero switch until meter reading drops to zero, then turn
switch off. If zero is not obtained, refer to section 6.5 in the
analyzer's instruction manual.
8. Turn Manual Range Select switch to 100 and Chromatogram Attenuator
switch to 1 for a span gas between 8 and 10 ppm.
9. Turn on chromatograph recorder chart drive. Select a chart speed that
permits adequate peak separation. The minimum chart speed should be
40 on/hr (16 in/hr).
10. One or more manual test Chromatograms, using the recorder connected to
the front panel jack, must now be run to determine TOC peak emergence
time. To inject the sample, turn on the Valve B switch for 25 seconds.
The recorder should register a flat-topped peak. If the peak is off-
scale, turn the chromatogram attenuator switch to the next higher
90
-------
setting, wait at least 30 seconds, then repeat actuation of Valve B
switch. Continue until desired onscale peak is obtained. When onscale
peak height is obtained, note and record settings used on Manual Range
Select and Chromatogram Attenuator switches. Also note the times of
the start and end of the TOG peak.
NOTE: ALLOW AT LEAST 30 SECONDS BETWEEN SUCCESSIVE SAMPLE
INJECTIONS WITH VALVE B TO ENSURE COMPLETE PURGING OF THE
SAMPLE LOOP.
11. A series of two-component manual test chromatograms must now be run to
determine the methane and carbon monoxide peak emergence times and
Valve A actuation time. Both CH£ and CO components must be run, even
through some users may not require the CO measurement output. It has
been determined that column degradation can cause overlapping of the CO
and CH^ components. Therefore, the CO may act as an interferent for
the CH4 measurements. It is not sufficient to remove, turn off, or
deprogram the CO component card to eliminate the interferent response.
(a) In the first trial run, when the recorder pen is on a major time
division on the chart, turn on Valve A. After 75 seconds, turn
off Valve A switch and wait for the methane and carbon monoxide
peaks to register on the recorder chart. If peaks are offscale,
turn the chromatograptn attenuator switch to the next higher
setting and repeat. Note the height of the methane peak.
(b) In the next trial, turn on Valve A for 65 seconds and note the
height of the methane peak on the resulting chromatogram.
(c) Continue trial runs, each time using a shorter energization period
(10-second decrement) for Valve A, until a chromatogran is
obtained showing decreased amplitude for the methane peak. (Be
sure to take into consideration any changes in the setting on the
Crhomatogram Attenuator and Manual Range Select Switches). A
decreased height of methane peak indicates premature de-energi-
zation of Valve A, with a resultant loss of a portion of the
sample. Therefore, the correct energization period for Valve A is
about 6 to 10 seconds longer than that used in the last trial run.
For most instruments, duration of the required energization period
is between 40 and 75 seconds.
91
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(d) When the desired chromatogram is obtained, note and record the
settings used on Manual Range Select and Chromatogram Attenuator
Switches. Also note the start and end times of the CH^ peak.
12. Using the test data obtained in the preceding steps, program the time-
related functions for the Valve Board, auto zero board, and individual
component boards following the procedures given in Section 3.0 of the
analyzer's instruction manual.
NOTE: PRIOR TO REMOVING OR INSTALLING THE BOARDS FOR
PROGRAMMING, TURN OFF THE ELECTRICAL POWER SWITCH LOCATED
ON THE FRONT PANEL. IF THE SWITCH IS NOT PROMPTLY RESTORED
TO THE ON POSITION, THE FAILSAFE FEATURES WILL TURN THE
ANALYZER OFF.
13. Timing Circuit Board for Valves A and B.
(a) Program che Valve B Function, TOC sample injection "on" at 001
second, and "off" at 025 seconds.
(b) Program the Valve A, Sample-Injection/Stripper Function "on" at
030 seconds. The required "off" time is determined from the ener-
gization time determined in step 11 plus 30 seconds. For example,
if the duration of the required energization period for Valve A
has been determined to be 65 seconds, the corresponding "off" time
would be 095 seconds, with respect to time "zero".
14. Component board assigned to TOC.
(a) Program the TOC component gate window to include the full TOC peak
on the TOC test chromatogram. The typical timing is "on" at 006
seconds; "off" at 020 seconds. Leave the window "on" as long as
possible to allow detection of heavy organics.
(b) Set range selector switch S3 for the 10 ppm range position.
92
U.S. EPA Headquarters Library
Mai! code 3201
1200 Pennsyvanie Avenue NW
Washington DC 20460
-------
15. Component board assigned to methane.
(a) Program the "on" and "off times to include the full methane peak
on the methane manual test chromatogram (step 11). Remember to
add 30 seconds to the times determined in step 11.
(b) Set Range Select switch S3 for the 10 ppm range.
16. Auto Zero Board.
(a) Program the first auto-zero "A" to occur 12 to 15 seconds prior to
the emergence of the methane peak on a stable portion of the base-
line. Duration of the auto zero period need only be 4 or 5
seconds. Check the manual test chromatogram (step 11) to verify
flat baseline in the region, to be used for auto zeroing.
(b) Program the second auto-zero "B" near the end of the cycle
(292-298 seconds) where the baseline is flat (preparatory to the
TOC peak on the next cycle). The auto-zero function must not be
programmed to coincide with an elution of a peak.
17. Run additional chromatograms to verify the various time settings, if
necessary.
6.6 CALIBRATION
This section details specific procedures for multipoint calibrations
and zero and span checks of the Beckman 6800. The analyzer's instruction
manual may contain deviations from these procedures, but the step-by-step
procedures that follow are currently recommended by the EPA.
6.6.1 Mult ipoint Galibrat ion
1. Disconnect the analyzer's sample line from the ambient sample manifold
and reconnect it to the calibration system's manifold. Cap the port on
the ambient manifold, and on any open ports on the calibration system's
manifold.
2. Place the analyzer's range selector switch in the desired concentration
range. (Calibrate the analyzer on the range normally used during
ambient sampling.)
3. Supply an atmosphere of methane standard to the calibration manifold at
a flow rate 20 to 50% greater than the analyzer's sample flow demand.
DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET.
93
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Run a chroraatogram (at least once a week) and evaluate it for proper
analyzer operation (gate timing, flow rates, etc.; see section 6.5.3
for procedures). Investigate unusual behavior and consult trouble-
shooting for procedures to correct the problems. Allow the analyzer to
stablize before continuing calibration.
Supply an atmosphere of the zero standard to the sample manifold at a
flow rate 20 to 50% greater than the analyzer's sample flow demand.
DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. The test atmosphere
must contain an ambient level of oxygen and must not contain more than
0.1 ppmC TOC. (See section 3.2 for details.)
NOTE: THE ANALYZER'S AUTO ZERO WILL CORRECT FOR MINOR
CONTAMINATION IN THE HYDROGEN AND BURNER AIR BUT WILL NOT
CORRECT FOR ZERO GAS CONTAMINATION. DISCREPANCY BETWEEN
THE AUTO-ZERO LEVEL AND THE ZERO AIR RESPONSE MAY INDICATE
CONTAMINATED ZERO AIR.
6. Set Operational status switches as follows.
(a) Move Single/Continuous to Cone inuous.
(b) Move Manual/Auto to "Auto.
(c) Move CaUJbirat: e/Operate to Operate.
(d) Move ATT/Auto ATT to Auto ATT.
Momentarily actuate the start switch and allow the analyzer to complete
3 complete cycles in the automatic mode, or to cycle until a stable
response is obtained on the memory recorder outputs for each component.
Record the stable responses on Tables 5 and 13. If the responses are
not within + 1% of each other and zero, ensure that the TOC and Cfy
channel ele~tronics are balanced before investigating contamination in
the cylinder, lines, and regulators. (Be certain all regulators con-
tain metallic diaphragms and are LOX cleaned.)
If the analyzer does not contain an NMOC subtraction card, proceed to
step 8.
-------
7. Zero the NMOC response by the following procedure:
(a) Set operational status switches as follows.
Move Manual/Auto to Manual.
Move Calibrate/Operate to Calibrate.
(b) On the TOC component board, place the OFF/MANUAL/AUTO switch on
MANUAL. Make certain this switch on the CH^ component board is
in either the OFF or AUTO position.
(c) Place the MONITOR SELECT switch at the memory position assigned to
TOC (usually MEMORY 1 position). Adjust CALIBRATE control for a
reading of exactly zero on the front panel meter. Leave the
CALIBRATE control at this setting until the zero procedure is
completed.
(d) On the NMOC subtraction board, remove the pin from the position
marked SAME RANGE or LOWER RANGE, thus removing the CH^ memory
input from the subtraction board. Place the AUTO/MANUAL switch
on MANUAL. Insert the pin into the connection marked READOUT
MEMORY 5 POSITION. (With a five-component analysis system, the
pin may be used only during initial zeroing of the subtraction
circuit. The pin must be removed prior to programming of the
component board assigned to the fifth component.)
(e) Place MONITOR SELECT switch at MEMORY 5 position. Adjust
potentiometer R14 on the subtraction board for a zero reading on
the front panel meter.
(f) Replace pin in the SAME RANGE or LOWER RANGE position.
(g) Repeat step 6 and obtain the stable NMOC response to the zero
standard. Record the response on Tables 5 and 13.
8. Supply an atmosphere of the methane standard to the calibration mani-
fold at a flow rate 20 to 50% greater than the analyzer's sample flow
demand. DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. The methane
concentration should be between 70 and 90% full scale.
9. Set Operational status switches as follows.
(a) Move Single/Continuous to Continuous .
(b) Move Manual/Auto to Auto.
(c) Move Calibrate/Operate to Operate.
(d) Move Manual ATT/Auto ATT to Auto ATT.
95
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LO. Momentarily actuate the start switch and allow chromatograph to com-
plete 3 complete cycles in the automatic mode, or to cycle until a
stable response is obtained on the memory recorder outputs for each
component. If the recorder output is off scale for a given component,
turn the respective potentiometer (R12) two turns counterclockwise to
decrease memory gain and repeat until an onscale response is obtained,
11. Calibrate the
channel as follows.
(a) Momentarily actuate the reset switch.
(b) Set operational status switches as follows.
Move Manual/Auto to Manual .
Move Calibrate/Operate to Calibrate .
Move Manual ATT/ Auto ATT to Auto ATT.
(c) Turn Manual range select to position 1 and the CH^ component
board switch to the manual (center) position.
(d) Adjust the calibrate control to simulate the memory recorder
response of the CH^ component which was obtained with the
methane span gas.
(e) Adjust the CH4 component board potentiometer (R12) to yield the
correct memory recorder response as calculated in the following
equation:
Sample concentration ., . ..,
Response * «-—=== X url + zero offset ,
UKL \
13)
where
Response * Response of the recording device measuring the analyzer
output in recording device units.
Sample Concentration » Concentration of the calibration standard
delivered to the analyzer in ppmC.
URL = The upper range limit of the analyzer in ppmC.
url = The upper range limit of the recording device in recording
device units .
Zero offset = The amount the recording device response is set
above the zero baseline while the analyzer is
measuring the zero calibration standard (in
recording device units).
96
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12.
NOTE; The response, url, and zero offset must be in identical
units. For example, if a strip chart recorder is the recording
device, units will be percentages of chart and the url may equal
1002 chart. If a digital voltmeter (DVM) is the recording device,
units may be millivolts or volts and the url may be, for example,
1000 mV. If a Data Acquisition System (DAS) is the recording
device, units may be ppmC and the url will equal 10 ppmC. If the
front panel meter on the analyzer is the recording device, units
will be ppmC and the url may be 10 ppmC.
(f) Return the CH4 component board switch to the auto position.
Calibrate the TOC component as follows.
(a) Momentarily actuate the reset switch.
(b) Set operational status switches as follows.
Move Manual/Auto to Manual.
(c)
Move C al ibrate/Operate to Calibrate.
Move Manual ATT/Auto "ATT to Auto ATT.
Turn Manual range select to position _1_ and the TOC component
board switch to the manual (center) position.
13.
14.
(d) Adjust the calibrate control to simulate the memory recorder
response of the TOC component which was obtained with the methane
span gas.
(e) Adjust the TOC component board potentiometer (R12) to yield the
correct memory recorder response as calculated in Equation 13.
The CH4 and TOC responses to the methane standard must be within
+1.0% of each other and the actual concentration of the test
atmosphere.
(f) Return the TOC component board switch to the auto position.
Return all switches to the normal automated "run" position. Momentar-
ily actuate the start switch and allow the chromatograph to complete 2
automated cycles to verify that adjustments were correct.
Determine the Qfy and TOC channel's response to two or more addition-
al concentrations of the methane standard, spaced approximately equally
over the analyzer range. (The NMOC channel's response should remain
equal to the earlier response for zero standard.) Record the CH4 and
TOC channel's responses (from the recording device) on Table 5. Using
a calculator, perform a least squares linear regression of the
97
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channel responses (to methane and zero standards) and the corresponding
calibration concentrations. The calibration concentrations should be
in units of ppraC and entered into the calculator as the independent
variable X. The CH4 channel's response should be in units of the
recording device and entered as the dependent variable Y. A
correlation coefficient (r) of 0.9996 or better verifies the CH4
response is linear. (If the response is not linear, plot the data and
determine if an error has been made in data entry or in determination
of calibration concentration.) Obtain the slope and intercept of the
regression and record the equation in the following form:
15,
L6.
CH4 Response « CH4 Slope X Methane Concentration + City Intercept (14)
where
CH4 Response = Analyzer's City channel reading in recording device
units (see note following step 11).
CH4 Slope » Regression slope in recording device units per ppmC.
Methane Concentration = Calibrated methane concentration in ppraC.
CH4 Intercept = Regression intercept in recording device units.
Post the CH4 channel's calibration curve equation on the analyzer's
recording device and also on Tables 5 and 13. Also, using the above
equation and the TOC responses, determine the TOC calibration curve,
and post accordingly.
Supply an atmosphere of the propane standard to the calibration mani-
fold at a flow rate 20 to 50% greater than the analyzer's sample flow
demand. DO NOT PRESSURIZE THE ANALYZER'S SAMPLE INLET. The propane
concentration should be between 70 and 90% full scale.
Set Operational status switches as follows.
(a) Move Single/Continuous to Continuous.
(b) Move Manual/Auto to "Auto.
(c) Move C alib rate/Ope r at e to Operate.
(d) Move Manual ATT/Auto ATT to-Auto ATT.
Momentarily actuate the start switch and allow chromatograph to com-
plete 3 complete cycles in the automatic mode, or to cycle until a
stable response is obtained on the memory recorder outputs for each
component. The TOC response should be about 30% less than the actual
propane concentration, and the City response should be equal to the
earlier zero response. Record the stable responses on Tables 5 and 13.
(If the analyzer contains an NMOC subtraction board, record the stable
NMOC responses and disregard the TOC response.)
98
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17. Determine the TOG channel's response (or Che NMOC channel's response if
the analyzer has the NMOC subtraction board) to two or more additional
concentrations of the propane standard spaced approximately equally
over the analyzer range. Record the stable responses (from the
recording device) on Table 5, Using a calculator, perform a least
squares linear regression of the channel's response (to propane and
zero standards) and the corresponding propane calibration concentra-
tions. The calibration concentrations should be in units of ppraC and
entered into the calculator as the independent^ variable X and the
channel's response should in units of the recording device and entered
as the dependent variable Y. A correlation coefficient (r) of 0.9996
or better verifies that the response is linear. (If the response is
not linear, plot the data and determine if an error has been made in
data entry or in determination of calibration concentration.) Obtain
the slope and intercept of the regression and record the equation in
the following form:
Channel's response
Channel's slope X Propane concentration +
Channel's intercept
(15)
18.
where
Channel's response « Analyzer channel's reading in recording device
units (see note following step 11).
Channel's slope • Regression slope in recording device units per ppmC.
Propane concentration = Calibrated propane concentration in ppmC.
Channel's intercept * Regression intercept in recording device units.
If the analyzer contains an NMOC subtraction board, enter the NMOC
responses in the regression and post the NMOC channel's multipoint
calibration curve equation on the analyzer's recording device and on
Tables 5 and 13. If the analyzer does not contain an NMOC board, enter
the TOC responses in the regression and determine the TOC calibration
curve to propane. Use the slope of this curve and Equation 1 in
section 3.7 to calculate NMOC responses from future TOC and CH^
responses.
Record all operational parameter readings. These readings will now
become the reference readings until another multipoint calibration is
performed. Be certain that the station logbook, strip charts, etc.,
are properly annotated, dated, and initialed.
99
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19. If level 2 zero and span checks are to be used, carry out such a check
now to establish reference zero and span readings for subsequent
comparison. (See section 2.0.9.1.3 of reference 10 for definitions and
additional information in level 1 and 2 zero and span checks.)
5.6.2 Level 1 Zero and Span Check
The following level 1 zero/span procedure (2-point calibration) is
similar to a multipoint calibration except that only the zero air standard
and one upscale standard are used-. These responses are needed to calculate
the new calibration curves, which should be used to correct subsequent moni-
:oring data until another level 1 zero/span check or multipoint calibration
is performed.
1. Follow the procedures in section 6.6,1 modified as follows.
(a) Record responses on Tables 6 and 13.
(b) After step 6, determine the zero drift in the CH^ and TOC chan-
nels (Equation 4, section 3.8). If drift exceeds about + 3X,
determine that the CH^ and TOC channel's electronics have not
drifted (see the instruction manual) and evaluate the zero air
system for possible contamination.
If the analyzer contains an NMOC subtraction board, determine the
zero drift in the NMOC channel after step 6. If drift exceeds
+3%, perform step 7 and make adjustments. If drift is less than
+3%, skip step 7.
(c) After step 10, determine the span drift in the Clfy and TOC chan-
nels (section 3.8). If drift exceeds about + 7%, make the adjust-
ments in steps 11 and 12 and obtain stable responses, as in
step 13.
(d) Omit step 14, but determine the slope and intercept of the CH^
and TOC channel's level 1 calibration curve.
Post the level 1 calibration curve on Tables 6 and 13 and on the
analyzer's recording device.
(e) After step 16, determine the TOC channel's response to propane and
calculate the new TOC slope to propane. If the analyzer contains
an NMOC board, determine the NMOC response to propane and deter-
mine the level 1 calibration curve.
6.7 TROUBLESHOOTING
The manufacturer's instruction manual covers this subject under the
same heading. Additional comments follow.
U.S. EPA Headquarters Library
Mai! code 3201
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6.7.1 Preliminary Investigations
Operational problems such as slow response to standards, inability to
balance channels' responses, long stabilization periods, frequent
flame-outs, or low sensitivity indicate the potential need for in-depth
troubleshooting. Prior to undertaking in-depth troubleshooting procedures,
a preliminary investigation is recommended to rule out variations in opera-
tional parameters.
1. Check that all pressure gauges on the analyzer are set to the specifi-
cations stated on the Manufacturer's Final Data Sheet (or to the speci-
fications stated in section 6.5.1.6 if a manufacturer's data sheet is
not available). If the analyzer has been operating properly for
several months, ensure that pressure gauges are set to the readings
recorded during the most recent multipoint calibration when analyzer
operation was satisfactory.
2. Inspect the hydrogen source and hydrogen filters {located outside of
the analyzer) for proper operation.
3. Inspect the sample filter and replace if dirty. Replace the sample
line leading to the analyzer if particulate buildup is noticeable.
4. Run a chromatogram. If the chromatogram has changed since the last
multipoint calibration, measure all flow rates in the analyzer and
adjust to the proper specifications. Significant changes in flow may
indicate a leak (slider valves may need replacement every 6 months) or
an obstruction. Follow guidelines in the instruction manual.
5. If flow rates are within specifications, the gate timing may need
adjustment (see section 6.5.4).
6. If columns are found to be deactivated, as indicated by the loss of
separation, replace them with new columns rather than trying to
reactivate the used ones.
101
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SECTION 7
COMMENTS ON THE BYRON 233 THC/CIty/CO ANALYZER
The Byron model 233 analyzer was not evaluated in the 1979 NMOC analy-
zer study (9); thus, augmented procedures to supplement the analyzer's
instruction manual are not reported here. Conversations with the
manufacturer have produced comments on general guidance which are reported
here in lieu of augmented procedures. (NOTE: The Byron model 404 was
evaluated in the 1979 study.)
7.1 PRINCIPLE OF OPERATION
The analyzer was designed to fulfill the requirements of the Federal
Reference Method for determination of hydrocarbons corrected for methane
(Appendix E, Part 50, Title 40 of the Code of Federal Regulations). A brief
summary of the Byron 233 operation follows.
A measured amount of sample is injected directly into the FID to
measure TOC concentration. Following the TOC measurement, a second,
separate sample is injected into a stripper column to separate CH^., CO,
and C02 from the heavy organics. A second column then separates CH4
from CO and CC>2 prior to injection into the flame ionization detector
where the CH^ concentration is measured. The City concentration can then
be externally subtracted from the TOC concentration to obtain a measure of
the NMOC concentration.
7.2 GENERAL COMMENTS
1. Support air supplied to the analyzer is used as carrier air, FID
burner air, and valve actuation. This air must not contain more than
0.1 ppraC TOC or more than 0.1 ppm CO + C02-
2. The hydrogen supply must be ultra-high purity or better (contains no
more than 0.1 ppmC TOC).
3. The hydrogen flow system can be leak-checked as follows.
(a) Remove the hydrogen restrictor from the methanizer and cap the
tubing.
(b) Increase the analyzer's hydrogen regulator to the maximum
position.
102
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(c) Supply hydrogen to the analyzer's H2 inlet at 30 psi. Shut off
• the hydrogen supply.
(d) Any decay in the analyzer's hydrogen pressure gauge reading in
30 minutes indicates a leak.
(e) The leak must be located and repaired.
4. Prior to ignition of the hydrogen flame, increase the hydrogen pres-
sure about 3 to 10 psig higher than recommended for normal operation,
After the burner has been lighted for at least 10 minutes, reduce
hydrogen pressure to specifications.
5. Whenever the support air is changed, check the span response.
6. Moisture will deactivate the molecular sieve column. The column
should be reactivated every 6 months.
103
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SECTION 8
GENERAL COMMENT ON THE MELOY HC 500-2C
FID HYDROCARBON ANALYZER
The Meloy HC 500-2C was included in the 1979 hydrocarbon analyzer
evaluation (9). After the study was completed, the manufacturer indicated
the analyzer's detector would be redesigned. This major change in the
analyzer reduces the usefulness of augmented procedures for operating the
ariginal analyzer; therefore, no procedures are reported here.
The manufacturer has been requested to supply information on the modi-
fied analyzer; however, the information was not available in time to be
included in this TAD. Users of this analyzer should consult the manu-
facturer for recommendations.
104
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SECTION 9
REFERENCES
Air Quality Criteria for Ozone and Other Photochemical Oxidants,
Environmental Criteria and Assessment Office, U.S. Environmental
Protection Agency, Research Triangle Park, N.C. 27711, Publication No.
SPA-600/8-78-004, April 1978,
Demerjian, K. L., Kerr, J. A., and Calvert, J. G., The Mechanism of
Photochemical Smog Formation in Advances in Environmental Science and
Technology, Volume 4, p. 1-262, John Wiley and Sons, Inc., New York,
1974.
40 CFR Part 50, National Primary and Secondary Ambient Air Quality
Standards, FR 36 (84):8186, April 30, 1971.
Guidance for Collection of Ambient Non-Methane Organic Compound (NMOC)
Data, for Use in 1982 Ozone SIP Development, and Network Design and
Siting Criteria for the NMOC__and NOV Monitors, Office of Air Quality
Planning and Standards, the U.S. Environmental Protection Agency,
Research Triangle Park, N.C., Publication No. EPA-450/4-80-011, June
1980.
Singh, H. B., Guidance for the Collection and Use _qf^_Ambient
Hydrocarbon Species Data in Development of Ozone Control Strategies,
Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, N.C., Publication No.
EPA-450/4-80-008, April 1980.
Reckner, L. R., Survey of Users of the EPA Reference Method for
Measurement of Non-Methane Hydrocarbons in Ambient Air, U.S.
Environmental Protection Agency, Research Triangle Park, N.C.,
Publication No. EPA-650/4-75-008, December 1974.
Harrison, J. W., et al., Evaluation of the EPA Reference Method for
Measurement of Non-Methane Hydrocarbons, Environmental Monitoring
Systems Laboratory, U.S. Environmental Protection Agency, Research
Triangle Park, N.C., Publication No. EPA-600/4-77-033, June 1977.
McElroy, F. F., Thompson, V. L., Hydrocarbon Measurement Discrepancies
Among Various Analyzers Using Flame-Ionization Detectors, Environmental
105
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Monitoring Support Laboratory, U.S. Environmental Protection Agency,
Research Triangle Park, N. C., Publication No. EPA 600/4-75-010,
September 1975.
9. Sexton, F. W., McElroy, F. F,, Michie, R. M., Jr., Thompson, V. L., A
Comparative Evaluation of Seven Automatic Ambient Non-Methane Organic
Compound Analyzers, Environmental Monitoring Systems Laboratory, U.S.
Environmental Protection Agency, Research Triangle Park, N,C. (Draft
document).
10. Quality Assurance Handbook for Air Pollution Measurement Systems,
Volume II - Ambient Air Specific Methods, U.S. Environmental Protection
Agency, Research Triangle Park, N.C., Publication No. EPA-600/4-77-
027a, Revision 1, July 1, 1979.
11t Site Selection for the Monitoring of Photochemical Air Pollutants, U.S.
Environmental Protection Agency, Publication No. EPA-450/3-78-013,
April 1978.
12. 40 CFR Part 50, Appendix E, Addenda A, Suggested Performance Specifica-
tions for Atmospheric Analyzers for Hydrocarbons Corrected for
Methane.
13. Eaton, W. C., Use of the Flame^Photometric Detector Method for
Measurement of Sulfur Dioxide in Ambient Air - A Technical Assistance
Document, Environmental Monitoring Systems Laboratory, U.S.
Environmental Protection Agency, Research Triangle Park, N.C.,
Publication No. EPA-600/4-78-024, May 1978.
14. Quality Assurance Handbook for Air Pollution Measurement Systems,
Volume I - Principals, U.S. Environmental Protection Agency, Research
Triangle Park, N.C., EPA Publication No. 600/9-76-005, January 1976.
15. Traceability Protocol for Establishing True Concentrations of Gases
Used for Calibrations and Audits of Air Pollution Analyzers (Protocol
No. 2 ), June 1978, Environmental Monitoring and Support Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, N.C.
27711.
16. NBS Special Publication 260, NBS Standard Reference Materials Catalog,
1979-1980 Edition, National Bureau of Standards, Washington, DC 20234.
106
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TECHNICAL REPORT DATA
tPlcase read fuunictions on the reverse before comnltting;
SO.
2.
3. RECIPIENT'S ACCESSIOWNO.
-iTi.S A\C SUBTITLE
TECHNICAL ASSISTANCE DOCUMENT FOR THE CALIBRATION AND
OPERATION OF AUTOMATED AMBIENT NON-METHANE ORGANIC
COMPDUND ANALYZERS
5. REPORT DATE
March, 1931
6. PERFORMING ORGANIZATION CODE
7 ALTHOAtSI
Frederick W. Sexton, Raymond A. Michie, Jr. (RTI)
Frank F. McElroy, Vinson L. Thompson (EPA)
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Quality Assurance Department
Research Triangle Institute
Research Triangle Park, North Carolina 27709
10. PROGRAM ELEMENT NO.
1A9F60E10C
11. CONTRACT/GRANT NO.
Contract Ho. 68-02-3222
Task Directive No. 7
12. SPONSORING AGENCY NAME AND ADDRESS
Quality Assurance Division
Environmental Monitoring Systems Laboratory
Offi;e of Research and Development
U.S. Environmental Protection Agency
yrin TriannTo Daylc Mnr»fi-> f.arnMna 77711
13_T,YPE,OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
IS. SUi'PLEMENTARVNOTiS
Technical Assistance Document
16. ABSTRACT
This technical assistance document is intended to serve as a supplement to manu-
factjrers1 instruction manuals for automated, ambient, non-methane organic compound
analyzers. It addresses augmented set-up, calibration, operation, and maintenance
procedures that have been developed for the purpose of producing non-methane organic
compound data suitable for use in the Empirical Kinetic Modeling Approacn and otner
dispersion models used to predict ozone concentrations. The document initially
discusses common aspects of these procedures in general terms for hydrocarbon analyzers
as a whole and then specifically addresses their application to analyzers manufactured
by Tne Bendix Corporation, Mine Safety Appliances Company, and Beckman Instruments,
Inc., and Meloy Laboratories, Inc.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air pollution
Measurement
Calibration
Air pollution monitoring
Non-methane organic
compound analyzers
NMOC analyzers
FID analyzers
Hydrocat»bon analyzers
Technical assistance
document
6SA
'3. ii
STATEMENT
RELEASE TO PUBLIC
EPA Form 2220-1 (9-73}
19. SECURITY CLASS iTha Report!
UNCLASSIFIED
21. NO. OP PAGES
122
20. SECURITY CLASS I This page >
UNCLASSIFIED
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