vvEPA
United States Office of Air Quality EPA-451/R-93-008
Environmental Protection Planning and Standards May 1993
Agency Research Triangle Park, NC 27711
Air/Superfund
AIR/SUPERFUND
NATIONAL TECHNICAL GUIDANCE
STUDY SERIES
COMPILATION OF INFORMATION ON
REAL-TIME AIR MONITORING FOR
USE AT SUPERFUND SITES
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AIR/SUPERFUND NATIONAL TECHNICAL
GUIDANCE STUDY SERIES
Report ASF-28
COMPILATION OF INFORMATION ON
REAL-TIME AIR MONITORS
FOR USE AT SUPERFUND SITES
Prepared for:
U.S. EPA, Region VI
Air Enforcement Branch
1445 Ross Avenue
Dallas, Texas 75202-2733
April 1993
U S Environmental Protection Agency
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SUPERFUND ABBREVIATIONS AND ACRONYMS
AAL Ambient air level
AAM Ambient air monitoring
APA Air pathway assessment (or analysis)
ARARs Applicable Relevant and Appropriate Requirements
CAA Clean Air Act
CAAA Clean Air Act Amendments
CERCLA Comprehensive Environmental Response, Compensation and Liability Act
DOAS Differential Optical Absorption Spectroscopy
DQO Data quality objective
BCD Electron Capture Detector
EPA Environmental Protection Agency
ER Emergency removal
FID Flame lonization Detector
FS Feasibility study
FTIR Fourier Transform Infrared
GFC Gas filter correlation
GC Gas chromatograph
HAP Hazardous air pollutant
HRS Hazard ranking system
HSL Hazardous Substances List
IH Industrial hygiene
LEL Lower Explosive Limit
MEI Maximum exposed individual
met Meteorological
MS Mass Spectroscopy
NAAQS National Ambient Air Quality Standards
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NESHAPS National Emissions Standards for Hazardous Air Pollutants
NDIR Nondispersive Infrared
NIOSH National Institute for Occupational Safety and Health
NPL National Priorities List
NRT Near Real-Time
NSPS New Source Performance Standards
NTGS National technical guidance study
NWS National Weather Service
O&M Operation and maintenance
OAQPS Office of Air Quality Planning and Standards
OEL Occupational exposure limit
OPM Open path monitor
OSC On-Scene Coordinator
OSHA Occupational Safety and Health Administration
OSWER Office of Solid Waste and Emergency Removal
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PA Preliminary assessment
PCBs Polychlorinated biphenyls
PEL Permissible exposure limit
PID Photoionization Detector
PM Paniculate matter
PMj0 Paniculate matter of less than 10 microns in diameter
PNAs Polynuclear aromatic compounds
ppb Parts per billion
ppbv Parts per billion on a volume basis
PPE Personal protective equipment
PPM Parts per million
PSD Prevention of significant deterioration
PUF Polyurethane foam
QA Quality assurance
QC Quality control
RA Remedial action
RAGS Risk Assessment Guidance for Superfund
RCRA Resource Conservation and Recovery Act
RD Remedial design
RfC Reference concentration
RfD Reference dose
RI Remedial investigation
RI/FS Remedial investigation/feasibility study
ROD Record of Decision
RPM Remedial Project Manager
RT Real-Time
SACM Superfund accelerated cleanup model
SARA Superfund Amendments and Reauthorization Act
SCBA Self-contained breathing apparatus
SI Site inspection
SITE Superfund Innovative Technology Evaluation
STEL Short term exposure limit
SVOC Semi-volatile organic compound
TBC To be considered
TCD Thermal Conductivity Detector
THC Total hydrocarbons
TLV Threshold limit value
TLV-C Threshold limit value - ceiling
TLV-STEL Threshold limit value - short-term exposure limit
TLV-TWA Threshold limit value - time-weighted average
TNMHC Total non-methane hydrocarbons
TO Toxic organic
TRI Toxic chemical Release Inventory
TSDF Transfer, storage, and disposal facilities
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TSP Total suspended particulates
TWA Time-weighted average
TWA-REL Time-weighted average - recommended exposure limit
TWA-STEL Time-weighted average - short-term exposure limit
UV Ultraviolet
UV-DOAS Ultraviolet - Differential Optical Absorbance Spectrometer
VOC Volatile organic compound
IV
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TABLE OF CONTENTS
1.0 INTRODUCTION 1-1
1.1 Background 1-1
1.2 Objectives and Scope 1-2
1.3 Overview of Air Monitoring at Superfund Sites 1-3
2.0 DETECTION METHODOLOGIES 2-1
2.1 Electrochemical Systems 2-1
2.2 Total Hydrocarbon Systems 2-4
2.3 Colorimetric Systems 2-8
2.4 Spectrophotometric Systems 2-10
2.5 GC Systems - GC/MS Systems 2-12
2.6 Participate Matter Monitors 2-14
3.0 SUMMARY OF PUBLISHED ANALYZER PERFORMANCE
EVALUATIONS 3-1
3.1 Electrochemical Systems 3-1
3.2 Total Hydrocarbon Systems 3-1
3.3 Colorimetric Systems 3-5
3.4 Spectrophotometric Systems 3-6
3.5 Gas Chromatograph and GC/MS Systems 3-9
3.6 Participate Matter Monitors 3-10
3.7 Summary of Instrument Comparison Studies 3-12
4.0 SELECTION GUIDE 4-1
4.1 Determining the Appropriate Measurement Technology 4-1
4.2 Selecting an Analyzer 4-1
4.3 Vendor-Supplied Information for Specific Real-Time Instruments . . 4-6
5.0 REFERENCES 5-1
APPENDIX A: MANUFACTURER ADDRESSES AND PHONE NUMBERS
APPENDIX B: SURVEY FORM AND DEFINITION OF TERMS
APPENDIX C: CALCULATION OF RESPONSE FACTORS FOR MIXTURES OF
COMPOUNDS
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ACKNOWLEDGMENT
This document was prepared for the U.S. Environmental Protection Agency
(EPA) under EPA Contract No. 68-DO-0125, Work Assignment 11-77. The project was
managed by Mr. Mark Hansen of EPA's Air Enforcement Branch in Dallas, Texas.
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SECTION 1
INTRODUCTION
This report summarizes the results of a U.S. Environmental Protection Agency
(EPA)-sponsored study to compile and evaluate information on commercially-available real-
time air monitoring equipment for use at Superfund sites. In this document, real-time (RT)
and near real-time (NRT) monitors are broadly defined as those instruments or methods that
provide information either instantaneously or within a relatively short time period (i.e., <30
minutes). This section contains background information related to the study, identifies the
objectives and scope of the study, and presents an overview of air monitoring at Superfund
sites.
1.1 BACKGROUND
The Office of Air Quality Planning and Standards (OAQPS) directs a national
Air/Superfund Coordination Program to assist EPA Headquarters and the Regional Superfund
Offices evaluate Superfund sites and determine appropriate remedial actions to mitigate then-
air impacts. Each Regional Air Program Office has an Air/Superfund Coordinator who
coordinates activities at the Regional level. OAQPS has a number of responsibilities related
to the Air/Superfund program, including preparation of national technical guidance study
(NTGS) documents.
Air sampling for volatile and semi-volatile organic compounds (VOCs) and for
paniculate matter (PM) is a fundamental part of remedial actions at most Superfund sites. A
number of real-time air sampling methods are currently available, including portable gas
chromatographs (GCs), mass spectrometry detectors (MSDs), flame ionization detectors
(FIDs), photoionization detectors (PIDs), colorimetric detection systems, and opacity
monitors. The methods vary in their principles of operation and in the types of compounds
to which they apply. Information about the availability and capabilities of various real-time
air sampling methods is needed to ensure that air emissions are adequately characterized
during Superfund site cleanups.
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1.2 OBJECTIVES AND SCOPE
The objectives of this study were to:
1) Review the available literature on real-time (RT) air monitoring;
2) Compile a comprehensive list of real-time and near real-time (NRT) air
sampling techniques, equipment, and vendors;
3) Contact vendors and users to collect information on the technical
specifications of their applicable instruments; and
4) Prepare a guidance document that summarizes the results of the study.
The available literature was reviewed to identify the most current methods for
real-time or near real-time measurement of ambient air concentrations of toxic pollutants
commonly found at Superfund sites. The measurement technologies considered included:
• Automated gas chromatographs;
• Flame ionization detectors (e.g., OVAs);
• Photoionization detectors (e.g., HNus;
• Colorimetric detector tubes (e.g., Draeger tubes);
• Portable GC/mass spectrometers;
• Optical remote sensors; and
• Opacity-based paniculate matter monitors.
The general approach used was to conduct a telephone survey of instrument
vendors to collect the necessary information. Vendors of instrumentation were identified
from vendor lists, their participation at trade shows, and from advertisements.
This document offers technical guidance for use by a diverse audience that
includes EPA Air and Superfund Regional and Headquarters staff, state Air and Superfund
staff, federal and state remedial and removal contractors, and potentially responsible parties.
This manual is written to serve the needs of individuals with various levels of scientific
training and experience in selecting and using real-tune air monitors employed in support of
air pathway assessments (APA). Since, assumptions and judgments are required to develop
air monitoring approaches, individuals involved hi this activity need a strong technical
background in air emissions measurements, instrumentation, monitor ing, and risk assessment.
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Remedial project managers (RPMs), on-scene coordinators (OSCs), and regional air program
staff, supported by the technical expertise of their contractors, can use the information in this
report when selecting monitoring equipment.
The selection of ah" monitoring equipment cannot be reduced to simple
"cookbook" procedures. There is always a potential need for professional judgment and
flexibility when developing compliance monitoring programs for specific Superfund sites.
The information set forth in this manual is intended solely for technical guidance. This
information is not intended, nor can it be relied upon, to create rights substantive or
procedural, enforceable by any party hi litigation with the United States.
1.3 OVERVIEW OF AIR MONITORING AT SUPERFUND SITES
EPA under the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) and the Superfund Amendments and Reauthorization Act (SARA),
is required to develop and implement measures to clean up hazardous or uncontrolled waste
sites. The Superfund process consists of three phases: pre-remedial, remedial, and post-
remedial. The cleanup of a contaminated site under the Superfund program proceeds via a
series of actions (see Figure 1-1) designed to remove or stabilize the contaminated material in
a controlled way. Activities related to an air pathway assessment for a Superfund site may
be necessary during the Site Inspection (SI), the Remedial Investigation (RI), the Feasibility
Study (FS), the Remedial Design (RD), the Remedial Action (RA) and the Post Remediation
(often called Operation and Maintenance (O&M)). Typical ambient air monitoring (AAM)
activities associated with each action are summarized in Table 1-1. An overview of air
monitoring at Superfund sites that is adapted from a recent EPA publication1 is given below.
The overall goal of an air pathway assessment is to evaluate a given site's
actual or potential effects on air quality. Typically, the specific goal of any associated air
monitoring work is to evaluate the exposure of on-site workers or the off-site populace and
surrounding environment to air pollutants. The ah- monitoring issues related to these goals
are discussed below, followed by a discussion of general air monitoring issues.
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Site Discovery
Preliminary Assessment
Site Inspection
Ranking
National Priorities List
Remedial Investigation/
Feasibility Study
Record of Decision
Remedial Design
Remedial Action
Operation and Maintenance
Pre-Remediation
Emergency Removal
Remediation
Post Remediation
Figure 1-1. Phases of the Superfund Process.
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1.3.1 Evaluate Exposure of On-Site Workers
4
On-site workers at Superfund sites may be exposed to significant amounts of
air pollutants in the course of performing their jobs. Any source of emissions; at a site will
result in an emissions plume. Fugitive air emission releases at Superfund sites usually occur
at ground level and are not thermally buoyant; therefore, the maximum ambient air
concentrations for such sources occur immediately downwind of the source and at ground
level. Point sources such as air strippers can have relatively short stacks and non-buoyant
plumes; the maximum ambient air concentrations of pollutants released from such sources
often can occur within the site boundaries. Often, it is necessary for on-site workers to
operate equipment or otherwise work hi contact with such emission plumes. As a
consequence, on-site workers must undergo training to recognize and respond to such
potentially adverse exposures as part of their Occupational Safety and Health Administration
(OSHA) mandated safety training.
On-site personnel may work close to emission sources and they tend to not
remain at a fixed location. These factors make it very difficult to accurately predict worker
exposure using a modeling approach. Instead, monitoring is usually performed to determine
worker exposure. This monitoring may entail the use of both portable monitoring
instruments (e.g., hand-held analyzers) to provide immediate feedback on surrogate
indicators such as total hydrocarbons and industrial hygiene (IH) sampling to provide
information on exposure to specific compounds. The IH sampling involves placing
dosimeters or low-volume sampling pumps with sorbent tubes, filters, etc., on the workers
and measuring the average concentration of selected contaminants in the breathing zone over
a given tune period (e.g., an 8- to 10-hour worker shift). The IH sampling yields more
detailed information than portable monitoring instruments, but data turnaround time usually is
at least 24 hours. For IH sampling, the measured values can be compared with occupational
exposure limits to determine whether worker exposure is within safe levels. In general,
short-term acute exposure is more of a concern for on-site workers than is long-term chronic
exposure. A series of action levels is often established that relate the level of required
personal protective equipment (PPE) to specific ambient air concentrations. For example,
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workers may be required to put on respirators if the total hydrocarbon (THC) concentration
in the breathing zone at the work area exceeds some level for a specified period of time
(e.g., if the THC concentration exceeds 10 ppmv for 1 minute).
In many cases, the site health and safety plan requires a conservative (i.e.,
restrictive) approach. At the start of the project, on-site workers are required to wear
adequate PPE to safely work under assumed worst-case levels of emissions. The PPE
requirements are gradually reduced if the air monitoring data collected in and near the work
zones indicate that no problems have been encountered, i.e., that no action levels have been
exceeded. The larger the database of on-site ambient air monitoring data, the greater
confidence there is in extrapolating these data forward in time.
1.3.2 Evaluate Exposure of Off-Site Connnumty/Environment
A major concern at Superfund sites is the potential exposure to pollutants via
the air pathway of residents and workers in the areas surrounding the site. The degree of
concern varies from site to site, as discussed below, depending on the nature of the
contamination, the proposed remedy, and the proximity of the off-site populace (receptors).
The exposure of off-site receptors typically is evaluated at several steps of the Superfund
process and both modeling and monitoring approaches may be employed as part of the
exposure assessment.
The evaluation of human exposure (due to inhalation) using a monitoring
approach generally involves measuring the concentrations of target analytes at the fenceline
of the site for ground-level emission sources and at the areas of maximum estimated ground-
level impacts for elevated emission sources (e.g., thermal treatment unit smokestacks).
Additional ambient air monitoring (AAM) may take place at selected receptor locations in the
surrounding community (e.g., at nearby schools) or on site, if there is public access. Data
are collected at locations both upwind and downwind of the site. The data are compared
with action levels to determine if there is cause for concern at downwind locations. The
difference in the concentrations measured downwind and upwind of the site yields an
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adjusted concentration considered to represent the contribution of the site emissions to the
local air quality.
An evaluation of off-site exposure generally requires that monitoring be
performed whenever significant air emissions may be released from the site. At sites with
the potential for adverse air impacts, this is often addressed by performing a short baseline
study before starting remediation followed by continuous monitoring whenever there is active
remediation at the site.
Usually, a fixed network of point samplers is located around the perimeter of
the site, samples are collected continuously during on-site activities, and all samples are
analyzed. Additional samplers may be located near the working areas. The number of
sampling locations will depend on the size of the site, among other factors. For large sites
surrounded by nearby residences, a twelve-station network can be used to provide nearly
complete coverage of the fenceline (i.e., a station every 30 degrees). In some cases, only
samples from stations located directly upwind or downwind of the site for a given sampling
period will be analyzed; samples collected at locations perpendicular to the emission plume(s)
are not analyzed to save tune and money. Alternatively, a smaller number of AAM stations
may be used and moved from day to day according to predicted wind patterns. If the
meteorological predictions are wrong, however, the monitoring stations may not be in the
emission plume as needed.
1.3.3 General Air Monitoring Issues
Typical APA activities at Superfund sites can be divided into the following
four categories:
1. Screening evaluation of site emissions and impacts on air quality under
baseline or undisturbed conditions;
2. Refined evaluation of site emissions and their effect on air quality
under baseline or undisturbed conditions;
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3. Refined evaluation of emissions and their effect on air quality from
pilot-scale remediation activities; and
4. Refined evaluation of the effects on air quality of full-scale remediation
activities.
Other APA activities may be appropriate for specific site applications. Screening studies are
performed to better define the nature and extent of a problem (i.e., to limit the number of
questions to be considered for a site), while refined studies are performed to find definitive
answers to one or more air-related questions. Although screening studies are less time- and
resource-intensive than refined studies, they do not necessarily use different monitoring
methods or approaches. Screening studies should not be thought of as being necessarily
inexpensive, "quick-and-dirty" or qualitative in nature. Since screening studies have more
associated uncertainty than refined studies do, their experimental design should be more
conservative. For example, if only a few days of monitoring data are to be collected, it
should be collected during periods of worst-case conditions.
Superfund sites often contain a complex mixture of chemical contaminants.
The potential adverse health effects vary from compound to compound, and the health-based
action levels of compounds with relatively similar structures and physical properties may
vary by orders of magnitude. For example, 1,2-dichloroethane is considered to be a much
more potent carcinogen than 1,1-dichloroethane, and benzene is considered to pose a much
more significant risk than equal amounts of toluene or xylenes. Therefore, the most
significant compounds at the site from a health risk standpoint may not necessarily be those
compounds present in the highest concentrations in the soil or water at the site.
The compounds addressed hi the air monitoring program will typically be a
subset of the contaminants present at the site, since it is often prohibitively expensive to
generate data for all contaminants present. Risk assessments for the air pathway usually
indicate that relatively few compounds account for the great majority of the risk. The
compounds to be monitored are those present at the site in significant quantities that have
high toxicity or degree of hazard and are capable of being released to the atmosphere.
Therefore, the air monitoring at the site typically will focus on those compounds thought to
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pose the most significant risk, rather than include an evaluation of every possible compound
found at the site. The selected analytes are usually referred to as target compounds or
compounds of potential concern. Compounds of frequent concern at Superfund sites include:
1. Volatile organic compounds (VOCs), especially benzene and
chlorinated solvents such as vinyl chloride, methylene chloride,
chloroform, etc.;
2. Semi-volatile organic compounds (SVOCs), such as poly chlorinated
biphenyls (PCBs), polynuclear aromatic compounds (PNAs), and
pesticides;
3. Semi-volatile inorganic elements or compounds such as mercury; and
4. Nonvolatile compounds, such as asbestos and cyanide salts; and heavy
metals, such as lead, chromium, cadmium, zinc, beryllium, copper,
and arsenic.
Semi-volatile and nonvolatile compounds may be transported as windblown particulate matter
(PM). Of course, not every compound listed above is present in significant quantities at
every Superfund site.
The proposed remedy will greatly influence the potential emissions from a site.
In general, in-situ remediation methods result in lower levels of air emissions than ex-situ
methods. Any activity that moves or disturbs the waste present at the site can potentially
release emissions of VOCs and PM. Public concern historically has focused on point sources
of air emissions such as incinerator stacks, but fugitive sources of emissions such as
materials handling operations may actually result in greater air emissions at many sites.
The appropriate monitoring methods used to check compliance with established
action levels will vary from target compound to target compound and from site to site.
Compliance monitoring for long-term action levels tends to involve the continuous collection
of tune-integrated samples at fixed locations, while compliance monitoring for short-term
action levels tends to involve the periodic collection of nearly instantaneous samples at
various locations of interest. The purpose of long-term monitoring is to document actual
exposure rather than to provide feedback to on-site operations. The purpose of short-term
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monitoring is to provide information for on-site decision makers to help them select operating
rates and decide whether emission control measures are needed.
In general, compliance with long-term action levels is based on daily samples
collected at each location within an AAM network. Broad-based collection methods such as
evacuated canisters, or sorbent tubes (Tenax, charcoal) are usually selected for VOCs so that
all the target analytes can be measured using only one or two sampling and analysis
approaches. Alternatively, dedicated gas chromatographs (GCs) used as point samplers or
open path monitors (OPMs) may be used hi some cases to provide real-time data and to
minimize total analytical costs. Standard methods developed by EPA are available for
particulate matter of less than 10 microns in diameter (PM10), metals, and some SVOCs.
The selection of monitoring methods to document compliance with short-term
action levels often is more difficult than selection of methods for long-term action levels.
Dedicated GC, GC/MS, or 0PM systems are the only option for the cost-effective
continuous or semi-continuous monitoring of most individual volatile organic compounds.
These methods require a relatively large capital investment and they may not be a viable
option for certain compounds or mixtures of compounds. Several methods are commonly
used for periodic compliance monitoring for short-term action levels. Fixed or portable
broad-band analyzers for total hydrocarbons (THC) or total non-methane hydrocarbons
(TNMHC) can be used if it is assumed that the instrument response (or some fixed fraction
thereof) is wholly due to the most hazardous compound present. Colorimetric tubes that are
compound-specific are available for many compounds, though usually only for relatively high
concentration ranges (e.g., ppm levels). Short-term monitoring for SVOCs and metals
cannot be performed directly. Instead, portable particulate matter monitors can be used to
measure total suspended particulate (TSP). An action level can be established if the average
fraction of SVOCs or metals associated with the TSP is assumed.
The need to evaluate compliance with short-term action levels requires a
timely turnaround of data. The most critical need for timely information is to compare AAM
data with short-term action levels during remediation. As previously discussed, the most
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common solution is to use broad-band THC or TNMHC analyzers or colorimetric tubes. At
sites where the concentrations of specific analytes must be measured, dedicated GCs or
GC/MS instruments used as point samplers have until recently been the only realistic option.
They can provide updated values every 30 minutes or so. The main drawbacks to using of
these instruments as short-term monitors have been the cost of the equipment (e.g., $30,000
per station), the complexity of installing and controlling the monitoring network, maintenance
requirements, and the labor required for data reduction and data management.
A promising monitoring approach for Superfund remedial actions is the use of
open path monitors2. OPMs are spectroscopic instruments configured to monitor the open air
over extended paths of hundreds of meters or more. They rely on the interaction of light
with matter to obtain information about that matter. The potential advantages of OPMs
compared with more conventional air monitoring approaches include: 1) there is rapid,
essentially real-tune data analysis; 2) no sample collection is required hi the normal sense of
the term; 3) no additional analytical costs are associated with each additional sampling
episode; and 4) data are path-weighted concentrations rather than concentrations for specific
sampling points. The first advantage implies that information is available to site decision
makers within minutes and short-term fluctuations La ambient concentrations can be detected.
The last advantage listed implies that it is less likely that an emission plume will evade the
monitoring network and that source terms can be directly determined. Data management
software is available for handling the very large quantities of data generated. The main
disadvantages of OPMs at this tune are the lack of standard operating procedures, the lack of
qualified equipment operators, the lack of standardized procedures for dealing with spectral
interferences, the lack of reference spectra for some compounds of interest, and detection
limits that, for some compounds (e.g., benzene), are higher than those of conventional
methods.
The issue of detection limits is often a concern during selection of a
monitoring device. Compliance monitoring for action levels generally requires that the
detection limit of the sampling and analytical approach be lower than the action level
concentration. The emissions from the site must be distinguished from the sample-to-sample
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variability that is always present. Therefore, the precision of the measurement method is
critical, but of course the precision of analytical methods tends to deteriorate as the detection
limit is approached. There often is a trade-off between analytical data turnaround time and
detection limit. Measurement methods that provide rapid data turnaround often are screening
methods that provide rapid feedback for parts-per-million (ppm) concentration levels rather
than for parts-per-billion (ppb) or lower concentration levels. The data accuracy and
precision of such screening methods also tend to be less desirable that those of non-screening
methods. For example, portable THC analyzers can exhibit a large daily zero and upscale
drift, especially if they are exposed to very high concentration levels or if the internal
batteries are allowed to fully discharge. As previously mentioned, dedicated GC, GC/MS,
or OPM systems may be the best options to meet data turnaround and detection limit
requirements for sites where potential adverse air impacts are a major concern.
The uncertainty of the AAM data also is an issue. The accuracy of the
monitoring data must be adequate to determine whether action levels are being exceeded.
The precision of the AAM data must be adequate to determine differences from ambient or
upwind concentrations of the compounds of interest. If action levels are selected that are at
or near detection limits, the accuracy and precision of the analytical data usually will not be
as good as they would be for measurements of higher concentrations.
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SECTION 2
DETECTION METHODOLOGIES
The air monitoring instruments surveyed for this document can be separated
into six categories according to their detection methodology or intended analyte. The six
categories are:
1. Electrochemical Systems;
2. Total Hydrocarbon Systems;
3. Colorimetric Systems;
4. Spectrophotometric Systems;
5. GC and GC/MS Systems; and
6 Paniculate Monitors.
This section briefly describes each category of instruments and its relative
advantages and limitations with respect to Superfund monitoring applications. Table 2-1 lists
typical parameters for each system. Information for individual instruments within each
category are given in Section 4.
2.1 ELECTROCHEMICAL SYSTEMS
A wide selection of electrochemical systems are available for the measurement
of toxic gases. These systems are commonly used in industrial hygiene applications because
of their small size, simple operation, and low cost. Electrochemical sensors are designed to
be compound specific; they respond to only one compound (i.e., oxygen, carbon monoxide,
hydrogen sulfide, hydrogen chloride, sulfur dioxide, etc.) rather than a broad family of
compounds.
The electrochemical sensor is a simple device consisting basically of a fuel cell
with an anode, cathode, and electrolyte. As a specific pollutant diffuses into the cell, it
becomes consumed in a chemical reaction. As this occurs, an ion current is generated
proportional to the rate of pollutant consumption. This current flow is amplified and
displayed by the instrument as a measure of concentration.
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Electrochemical sensor systems are popular choices for air monitoring of
specific toxic compounds. They are reasonably accurate (up to ±2% of full scale) in the
ppm to percent concentration range and relatively inexpensive. Although they are
lightweight, they are durable and shock resistant. The electrochemical cell requires little
power (many instruments are powered from disposable alkaline batteries). Detection
capability is usually in the parts per million (ppm) range.
Because of their specificity, electrochemical sensors are not particularly useful
when the pollutant is unidentified or there are several contaminants of interest. The list of
pollutants to which electrochemical sensors respond is somewhat limited and does not include
many toxic organic compounds that may be encountered at Superfund sites. These sensors
are subject to interference problems that may produce false negative or false positive
readings. A final drawback is their life expectancy - the fuel cell (much like the power of a
battery) is consumed during the detecting of gases and the longer the duration of the
exposure, the sooner the sensor must be replaced. Typical sensor life expectancy varies
between six months to two years.
2.2 TOTAL HYDROCARBON SYSTEMS
Total hydrocarbon monitors are capable of detecting a wide range of
hydrocarbons and other VOCs. The most popular total VOC measurement systems are those
that use flame ionization detectors (FID) and photoionization detectors (PID). Thermal
detection monitors and solid state detectors are also available.
2.2.1 FID Monitors
The flame ionization detector uses a hydrogen flame burning in air. When a
sample of gas containing hydrocarbons passes through the flame, it is ionized in the flame.
A small ion current begins to flow. This current flow is amplified by the instrument and
displayed on the instrument meter as a measure of the hydrocarbon (VOC) concentration in
the sample.
2-4
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Flame ionization is a method that has been widely applied in commercial
instrumentation. The flame ionization detector is available hi portable, battery-powered
instrumentation as well as hi AC-powered stationary systems. FIDs offer a wide linear
dynamic range and a response that extends up to 1 percent (10,000 ppm). Since they
respond well to most organic compounds, they are particularly well suited to most
monitoring applications associated with Superfund remediation efforts. The response tune of
these instruments usually is only a few seconds.
The response of the flame ionization detector to particular hydrocarbon
compounds varies from compound to compound (e.g., 25 to 150%, as methane). Therefore,
when used to measure specific hydrocarbon compounds, an FID instrument response factor
must be generated to relate measurement responses to the instrument's calibration curve
(methane, hexane, benzene, or propane gas is typically used for calibration). FID detectors
are somewhat sensitive to water vapor and their response is diminished by compounds
containing electronegative atoms such as oxygen, sulfur, and chlorine. Stationary FID
systems require a separate hydrogen source to fuel the FID hydrogen flame. Compressed
zero-grade air or nitrogen may also be required. These gases are usually provided in
compressed gas cylinders although in some applications hydrogen and zero air generators
may be used.
2.2.2 PIP Monitors
Photoionization detectors use ultraviolet (UV) light to ionize gas-phase
molecules in the air sample. The sensor consists of a sealed UV light source that emits
photons which are sufficiently energetic to ionize many organic species without ionizing the
major components of the air such as oxygen, nitrogen, carbon monoxide, carbon dioxide,
methane, or water vapor. The resulting ion current is amplified by the instrument and
applied to a meter movement or digital readout.
PID instruments are well suited for field use. Powered by rechargeable
batteries, they generally weigh less and are simpler to operate than comparable FID
2-5
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instrumentation. Since UV light is used to ionize the sample, supply gases are not necessary.
PIDs respond well to most aromatic molecules such as benzene, toluene, and xylene as well
as to many aliphatic molecules such as hexane.
PID analyzers do not respond to methane; they are also relatively insensitive to
some chlorinated compounds such as trichloroethane. The upper measurement range of the
photoionization detector is typically much less than a flame ionization detector (2000 ppm vs.
10,000 ppm). Depending on the manufacturer, high humidity can cause erratic readings.
2.2.3 Thermal Detection Systems
The use of thermal properties of gases to determine concentration is one of the
earliest methods of process analytical instrumentation. Several types of thermal detection
systems are available. Systems based upon thermal conductivity or thermal combustion are
among the more common.
A thermal conductivity detector (TCD) uses the specific heat of conductance of
the sample gas hi order to determine its concentration. The sample gas is passed over a hot
filament. The thermal conductivity of the gas sample causes the filament temperature to
change. As the filament's temperature changes, so too does its electrical resistance. This
change in resistance is then used as the instrument's output signal.
A heat of combustion system measures the amount of heat given off when a
combustible gas is burned. The sensor typically consists of two alumina beads each
surrounding a platinum wire which is heated to a temperature of approximately 450°C. One
of the alumina beads is passivated so that it will not react with combustible gases. The other
bead is catalyzed so that the combustible gas ignites upon contact. The heat from the
combustion increases the electrical resistance of the filament. This in turn changes the output
of a Wheatstone bridge circuit which is used as the sensor signal.
2-6
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These analyzers tend to be simple in design and operation. Since they were
developed to detect the presence of explosive or combustible gases in the air, they find
frequent use in applications demanding the quick determination of gas flammability. Their
lightweight and battery-powered operation make them well suited to field applications. Since
most thermal detection systems are designed to monitor explosive or flammable atmospheres,
instrument readouts are typically calibrated on a 0 to 100% LEL (Lower Explosive Limit)
scale.
Users of thermal detection analyzers must be aware of interfering gases and
vapors that could create major aberrations hi instrument response. These instruments
respond typically only to high contaminant concentrations (the LEL of even the most
explosive gas is approximately 10,000 ppm). Therefore, they are not suitable for detection
of the low concentrations of contaminants usually encountered in evaluating potential health
risks. Analyzer stability can be adversely affected by inadequate temperature control. These
systems are generally nonspecific. Because they measure the thermal characteristics of the
total sample, they are unable to distinguish between the components producing the
measurement.
2.2.4 Solid State Sensors
This is a relatively new technology that shows promise for real-tune
monitoring applications. Solid state or semiconductor sensors have a resistance in ambient
air that is affected by the absorption of oxygen on the semiconductor surface. Oxygen
molecules alter the semiconductor's electrical resistance by capturing electrons on the
semiconductor's surface thereby increasing its resistance. The sensor's surface can be
altered so that the sensor's resistance changes when specific gases displace the absorbed
oxygen. The sensor can be designed so that it is unaffected by gases other than those
selected for monitoring.
Solid state sensors offer the advantage of reduced costs and small physical
size. Because they can be designed to respond to specific gases, they are particularly useful
2-7
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in monitoring for leaks or releases of known compounds. Common applications include
toxic gas monitors, automotive emission control systems and refrigerant leak detectors.
These sensors are relatively inaccurate (±5%) and tend to be designed for
very specific monitoring applications. They would be of limited use, for instance, in
monitoring situations where the composition of a pollutant gas or vapor is unknown.
2.3 COLORIMETRIC SYSTEMS
Portable colorimetric devices offer a unique approach to the detection of toxic
compounds. There are basically three types of colorimetric devices: Solid, Paper Tape
Samplers, and Liquid.
Solid: This type of colorimetric device, commonly called a detector tube, uses
a small glass tube filled with porous solid granules. The granules are treated with a reagent
that reacts with a specific gas contaminant hi such a way as to produce a distinct color
change. Typically used in conjunction with a hand sampling pump, a precise volume of
sample is drawn into the tube over 1 to 3 minutes. Within a minute, a color change begins
at the air inlet end of the tube. The length of the color change, read against a standard scale
marked hi ppm, is proportional to the air concentration. For long term sampling
applications, a battery or AC-powered pump may be used may be used in conjunction with
the detector tube.
Paper Tape Samplers: In these devices, a chemically treated paper tape is
drawn at a constant rate over the sampling orifice. A known volume of air is drawn through
the reagent-treated paper by a self-contained pump. The reagent reacts with the vapor and
produces a stain on the paper medium. A beam of light is reflected off the exposed portion
of the tape and the intensity continually measured as a function of the pollutant concentration.
Liquid: A known volume of sample is drawn by a self-contained pump
through a sample cell containing a liquid reagent. The reagent reacts with the vapor to
2-8
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produce a color change. A beam of light is shone through the sample cell as well as through
a clear reference cell. The difference hi light transmission through the two cells is converted
electronically into a measurement of sample concentration.
The solid type of colorimetric system, i.e., detector tubes, have numerous
advantages. These devices are small, light, hand operated, safe hi all atmospheres, and
provide an immediate readout. Many tubes are available hi several concentration ranges.
Detection is fairly chemical-specific and versatile (tubes are available for over 250
compounds). For small sampling programs, detector tubes provide a low-cost alternative to
other analytical methods. Some tubes have an indefinite shelf life but many deteriorate
within a year or two. Shelf life can be extended by storing tubes hi a refrigerator; however,
the tube must be warmed to ambient temperatures before being used.
While detector tubes are essentially grab sample devices, the paper tape and
liquid colorimetric devices are designed for long term sampling efforts. These devices tend
to be simple to operate, have a low initial cost, and are adaptable to measurement of a broad
range of compounds.
Because many toxic gases have similar chemical properties and react with the
same reagents, colorimetric devices are subject to considerable interferences. The flow rates
of those systems using built-in pumps must be checked regularly since airborne dusts and lint
will quickly clog the orifices of these instruments causing low flow rates and inaccurate
measurements. Measurement accuracy varies considerably (5 to 25%) between
manufacturers and types of compounds being measured. Detector tubes from different
manufacturers are not interchangeable. The colorimetric reaction is temperature sensitive to
some extent and inaccurate readings may result during temperature extremes. The shelf life
of the reagents used to promote the colorimetric change is a critical consideration.
Typically, reagents are good for 1 to 2 years if manufacturer's recommendations are
observed.
2-9
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It is a common assumption, often supported by vendors, that no special
training is required to obtain reliable measurement data with detector tubes. It has been
repeatedly demonstrated that serious errors hi sampler operation, hi selection of sampling
locations and tunes, and hi the interpretation of results occur when detector tubes are used by
untrained operators.
2.4 SPECTROPHOTOMETRIC SYSTEMS
This category encompasses a broad range of popular analyzer systems that
determine airborne pollutant concentrations by measuring their absorption of radiant energy.
In the majority of instrument applications, radiant energy from the ultraviolet, visible, or
infrared regions of the electromagnetic spectrum is used. Spectrophotometric systems most
applicable to Superfund air monitoring applications include Nondispersive infrared (NDIR)
analyzers and Optical Remote Systems.
2.4.1 NDIR Analyzers
The most commonly used NDIR analyzers for continuous air monitoring
applications are single component analyzers using a double-beam and gas selective Luft
detectors filled with the gas to be analyzed. These analyzers are capable of analyzing many
gases and vapors, inorganic and organic. An infrared source inside the instrument emits
infrared light over a broad frequency range. Various gases and vapor absorb infrared energy
at specific frequencies. This fact, together with the use of selected filters determines the
instrument's response to a specific chemical or gas.
NDIR analyzers are highly selective - they are capable of measuring a single
component in a complex mixture of gases and vapors. They have a broad measurement
range (they can measure toxic gas concentrations from the low-ppm to high percentage range)
and respond to hundreds of compounds (typical applications include chlorofluorocarbons,
methane, CO, CO2, SO2, and solvents).
2-10
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Despite advantages in high selectivity, sensitivity, and accuracy, NDIR
analyzers are subject to interferences - other environmental gases may absorb the same
frequency of infrared radiation as the gas being measured. These instruments are often
temperature and noise sensitive and usually need to be protected from external shock and
vibration.
2.4.2 Optical Remote Sensor Systems
Measuring ambient air pollutants with optical remote sensor systems provides
an alternative approach to the traditional methods of assessing pollutant concentrations.
Instead of measuring single components at a number of discrete points above and downwind
of the source, remote sensing provides the concentrations of multiple components along a
path that can be up to several hundreds of meters in length. The path-averaged concentration
can be compared to pre-set action levels. These measurements also can be combined with
on-site meteorological data to produce emission rate estimates from many types of area
sources in near-real tune. These rates can then be used with an atmospheric dispersion
model to predict downwind ambient concentrations. Typical applications of optical remote
systems include perimeter monitoring, early emission warning systems, and emission
monitoring at landfills and surface impoundments.
Optical remote systems can be grouped into two classes: narrow-band sensors -
monochromatic laser sensors (long path absorption) and differential absorption lidar (laser
infrared radar) and broadband sensors - Fourier transform spectrometers, UV spectrometers,
and correlation radiometers. The distances/areas covered by these sensors vary, and are
dependent upon their spectral regions.
Recent advances in optical remote sensing include Differential Optical
Absorption Spectroscopy (DOAS) and infrared photoacoustic absorption sensors. A DOAS
system can measure up to twenty components in a beam of light that may be up to two miles
long. Measurements are based on optical absorption spectroscopy using absorption in the
ultraviolet to near infrared range. Infrared photoacoustic absorption sensors operate by
2-11
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measuring small acoustic energy changes. A light is shone through the sample gas stream.
Measurement is then made of the acoustic field generated when excited molecules collide,
transferring the absorbed energy to heat and thereby to pressure variations hi the gas at the
modulation frequency. Detailed information on the applicability of these systems for
Superfund sites has recently been published.2
The advantages of optical remote systems are impressive. They are capable of
measuring many components at one tune. Open path methods have much lower detection
limits (<0.1 ppm) than traditional real-tune monitors. When combined with on-site
meteorological data, they make it possible to determine the types and rates or quantities of
volatile organic compounds and toxics being emitted from a point source. They are able to
provide path-averaging concentration data and offer near real-tune measurement capability.
Optical Remote Systems almost always have a higher capital cost than
comparable traditional measurement systems. They require staff with specialized expertise to
install and operate these systems. Although easier to calibrate than conventional systems,
data verification is often perceived to be a problem. Optical systems must sometimes be
customized to a given environment to avoid interferences caused by compounds that have the
same or similar optical absorption properties.
2.5 GC SYSTEMS - GC/MS SYSTEMS
Gas chromatography (GC) is widely used in air monitoring applications
because of its ability to separate the components of a complex pollutant gas mixture so that
each component can be identified and measured. Components are characterized by then-
retention tunes - the time it takes for a compound to pass through the GC column to the
detector. Factors affecting retention time include the column temperature, the carrier gas
flow rate, the column packing material, polarity effects and the different solubilities of the
various components. Gas chromatographs can be equipped with a variety of detectors
including flame ionization (FID), photoionization (PID), thermal conductivity (TCD), flame
photometric (FPD), and electron capture (BCD).
2-12
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Mass spectrometry (MS) can be combined with gas chromatography for
improved identification of chromatographic fractions and peaks.
2.5.1 GC Systems
GC systems can provide both qualitative and quantitative characterization of a
multicomponent sample. Qualitative interpretation of a chromatogram peak involves deter-
mining the time it takes for the peak to elute from the column (i.e., retention time) and com-
paring this tune to the reference data. Peaks can be quantified by comparing them with
standard chromatograms to determine a ratio of peak area to the known concentration. A
number of different detectors can be used with GC systems.
Continuous GCs are common in many air monitoring applications. A
continuous GC can be connected to as many as 30 sample points, each located as far as 1000
feet away, by means of heated sample lines. Using an automated multiport valve system, the
continuous GC sequentially samples and analyzes each sample point.
Non-continuous, portable GCs designed particularly for field use have become
more sophisticated in the past two to three years and now offer improved detection levels.
This, comb hied with the advantages of their portability and simpler design and operation,
make them an attractive option for volatile organics or toxic gas sampling and analysis
applications.
Gas chromatographs offer excellent qualitative and quantitative characterization
of ambient air quality. Because gas chromatographs separate sample constituents, users can
analyze most gases and vapors with few problems from interferents.
Gas chromatographs are complex, expensive systems. The selection of proper
columns and detectors, the generation of calibration curves, and overall chromatograph
operation involves a high degree of complexity requiring experienced and skilled operators
with strong backgrounds in analytical chemistry. While general instrument performance is
2-13
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excellent, a gas chromatograph's response will vary depending upon the type of analysis
being performed.
2.5.2 GC/MS Systems
Mass Spectrometry (MS) can be combined with gas chromatography for
unproved identification of chromatographic fractions and peaks. In its simplest form the
mass spectrometer is a vacuum device hi which ions are created from the sample gas, then
separated by mass and detected. lonization of the sample gas is achieved by collision of
rapidly moving electrons with molecules of the air sample as it enters the instrument. The
resulting ions are removed as quickly as they are formed by means of electrostatic fields, and
accelerated and focused into an ion beam. The beam is transmitted to the resolving portion
of the analyzer.
Widely used as an analytical tool for the process industries, mass spectrometry
combined with gas chromatography is finding increasing applications hi the area of air
monitoring. Capable of single or multi-stream analysis, GC/MS systems add greater
specificity to the analysis of multicomponent gas streams than can be provided by gas
chromatography alone.
These systems, due to their complexity, require expensive and elaborate
equipment together with a high degree of operator training and skill. Because they require
environmentally controlled shelters with regulated sources of power and support gases, air
pollutant monitoring applications are typically restricted to large air monitoring networks.
2.6 PARTICULATE MONITORS
During hazardous waste cleanup activities, a large variety of solid or liquid
particulates (aerosols) may be released into the ambient air. This can include contaminated
and non-contaminated soil particles, heavy metal particulates, pesticide dusts, and droplets of
organic or inorganic liquids. Effective manual methods have long existed for sampling these
2-14
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materials. Timer-controlled high volume samplers have been used traditionally hi numerous
ah* monitoring applications for measurement of both total suspended participates (TSP) as
well as particulates less than 10 microns hi diameter (PM10). Both methods require
subsequent analysis of collection filters, a process that can take, at the very least, 24 hours.
Direct reading instruments able to continuously monitor and display ambient ah" paniculate
counts, have been available for several years and are increasing hi use. They fall into two
classes: optical devices and radiometric devices.
Optical Devices: Optical-based particulate monitors include Transmissometers
and Light Scattering devices. In its most basic form, a transmissometer consists of a light
source and a detector. By comparing obstruction of a light beam by particulate matter hi the
sample gas to an unobstructed light path, the transmissometer provides a measurement of
particulate concentration expressed hi units of optical density or opacity. Light scattering
devices employ a photocell to detect the light scattered by particulates. The number of
electronic pulses generated by the photocell is related to the number of particles counted hi
the sample.
Radiometric Devices: Radiometric measurement of particulates is
accomplished by a radiation attenuation technique. Low-energy beta radiation is normally
used hi these applications. In the typical beta-gauge, a filter tape is slowly moved past a
radioactive beta source. The sample is drawn into the sample inlet of the instrument where
it passes through a tape filter mechanism. The radiometric attenuation of the filter is
measured before collection hi the clean state and then after collection hi the dirty state.
These two readings are processed by the instrument so that a measurement of the mass of the
collected particulate can be obtained.
Automated particulate monitors are able to provide real or near-real tune data
on ambient air particulate concentrations. They are particularly valuable, therefore, hi
emergency-monitoring networks where hourly data updates are required. These systems
require less of an operator's tune than the traditional high-volume sampler. Data are
automatically digitized for easy transfer to a computer-based data acquisition system.
2-15
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Automated particulate monitors are more expensive than customary participate
sampling methodologies and because of then- increased complexity, they require greater
technical skills from the operators responsible for maintaining them. Since they must be
installed in an environmentally controlled shelter, they are less adaptable to small or short-
term monitoring programs.
2-16
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SECTION 3
SUMMARY OF PUBLISHED ANALYZER PERFORMANCE EVALUATIONS
This section presents results of selected laboratory and field evaluations of
real-time analyzers. As in the previous sections, the discussion is organized by detection
methodology. Efforts were made to obtain reviews of instruments or groups of instruments
that are widely-used and have operational characteristics typical of their category. The final
subsection contains a summary of a study that compared the performace of several methods.
3.1 ELECTROCHEMICAL SYSTEMS
TG-KA: The TG-KA series, manufactured by CEA Instruments, Inc., is a
typical example of an ambient air monitor utilizing an electrochemical sensor for detection of
gaseous pollutants. This instrument has a digital readout calibrated in units of ppm. It is
powered by rechargeable nickel-cadmium batteries and weighs only 0.7 pounds. Since its
upper range is 20 ppm its use is restricted to low concentration applications. The gases
detected by this instrument include: ammonia, arsine, bromine, chlorine, diborane, hydrogen
sulfide, hydrogen chloride, hydrogen cyanide, hydrogen fluoride, hydrogen, ozone,
phosgene, phosphine, and silane.
3.2 TOTAL HYDROCARBON SYSTEMS
3.2.1 FED Systems
The Foxboro OVA 108: The OVA 108 is a example of a widely used, portable
FID analyzer specifically designed for field applications. The OVA 108 is certified
intrinsically safe (Class I, Division 1, Groups A-D). It has an logarithmic readout with an
upper range of 10,000 ppm and a resolution of 0.5 ppm at the lower end of its scale.
3-1
-------
The instrument consists of an instrument case and a sample probe connected to
the case by a 3 foot flexible sample umbilical. The instrument case contains a sample pump
(approximately 2 liters/minute), the FID assembly, an electronics module, a rechargeable
battery pack, and a small hydrogen fuel cylinder. The meter readout is part of the sample
probe. Operational controls are all located on the inside face plate of the instrument case.
During use, the instrument case is supported by a shoulder strap while the probe is held in
hand.
Several instrument problems have been documented.3 Instrument sensitivity
can be affected by high humidity. High humidity apparently also contributes to pump and
pre-amplifier failures. The instrument battery life suffers during cold weather causing
flame-out and/or ignition problems as well as reduced sensitivity. Problems with instrument
drift were also reported.
Several studies have been performed to examine the response factor of the
instrument to various compounds. Radian measured the response of the OVA Model 108 and
the TLV Sniffer to 168 organic compounds in an EPA-sponsored study.4 The concentration
range examined was typically from 50 ppm to 10,000 ppm. Response factors were
determined for each compound (RF = actual concentration/instrument response) based on
calibration of the instruments with methane. The response factors were found to vary with
concentration. Response factors varied from less than 0.65 to greater than 25 for both
instruments.
A follow-up study looked at the response factor for the same two FIDs for
nine binary chemical combinations5. The response factor for the mixture was found to fall
between the responses of the two individual compounds at the total concentration of the
mixture. Synergistic effects appeared to be weak. Weighted average models were found to
provide the best fit for the data. The authors recommend the use of either an arithmetic or
logarithmic scale model. A procedure for calculating an overall response factor for gas
mixture is given in Appendix C.
3-2
-------
Numerous additional FID response factors have been published.6'7-8-9 The
actual response of a given FID, however, may be unique to the FID model or example being
tested. At a minimum, instrument users should obtain response factors for the compounds of
interest from the manufacturer of the real-time monitor.
Byron 301: The Byron 301 is an example of a fixed (non-portable), FID-
based total hydrocarbon analyzer. The Byron 301 hydrocarbon analyzer requires an air-
conditioned, weatherproof, equipment enclosure with regulated 120 VAC power. Cylinders
containing fuel gas, span and calibration gases must also be supplied. The 301 employs a
short GC column and a flame ionization detector to analyze methane and non-methane
hydrocarbons. The instrument operates on a 3 minute cycle and is able to perform 20
analyses/hour. Instrument ranges are 0 to 2, 5, 10, 20, 50, or 100 ppm. A skilled operator
is required for instrument setup and operation.
In one application, five Byron 301s were used in a real-time air monitoring
network to measure fence-line air quality during a refinery dismantlement.10 The purpose of
the system was to ensure that emissions did not migrate beyond the site borders. This was
accomplished by shutting down work activities whenever downwind fenceline nonmethane
concentrations exceeded upwind concentrations by more than 1 ppm.
The Byron 301 instruments operated successfully throughout the project
although a few problems were encountered. A nearby radio station induced enough radio
frequency interference to cause the analyzer's zero and span calibration controls to activate
randomly. This problem was never completely solved although it was mitigated by the
installation of RF line filters. Eventually manual calibration procedures had to be used in
place of automatic calibration.
The 1 ppm action level had to eventually be replaced by a 5 ppm action level
since instrument drift alone was causing alarms to be sounded - even when no work was
being performed.
3-3
-------
Beckman Model 400A: The Beckman 400A, like the Bryron 301, is an FID-
based, continuous total hydrocarbon analyzer. This instrument is accurate, easy to operate,
and reliable. It responds well to a wide range of compounds and compound classes. Similar
to the Byron 301, the Beckman is relatively large and is not readily portable. Support gases
are required for analyzer operation. If long sampling lines are used, provisions must be
made to control temperature changes, water condensation and paniculate matter.
3.2.2 PIP Systems
HNU PI-101: The HNU PI-101 is a typical example of a PID-based portable
hydrocarbon analyzer. The PI-101 is designed for work in Class I, Division 2 areas. The
PI-101 consists of a sample case with a sample probe. The sample probe, connected to the
instrument by a flexible wire cable, contains the UV lamp, the detection chamber, a small
fan for sample draw, and a pre-amplifier assembly. Zero and span controls, and the
instrument display meter are located on the instrument pack. The meter is a linear analog
display with three ranges (0 to 20, 0 to 200, and 0 to 2000 ppm). Instrument resolution is
0.2 ppm on the 0-20 ppm range.
One study reported frequent complaints about the short lifetime of the HNU
PI-101's photoionization lamps.3 No environmental problems with temperature or humidity
were reported.
Another study reported the accuracy of the PI-101 to be 96 percent at the 5
ppm concentration level while instrument results were reproducible to ±1 percent."
Limitations were cited regarding the instrument's ability to monitor specific gases and
vapors. It did not detect hydrogen, cyanide, or methane gases, for example. It was felt that
this characteristic could be an advantage, however, when investigating municipal/industrial
landfill sites where the disproportionate concentrations of methane can totally hide the
presence of other more toxic vapors when a flame ionization detector is used. The same
study found the PI-101's performance to deteriorate rapidly due to poor weather conditions
(particularly increases in humidity).
3-4
-------
3.2.3 Thermal Detection Systems
TLV Sniffer: Bacharach Inc. manufactures several lines of portable analyzers.
Among these is the popular TLV Sniffer. The TLV Sniffer's detector is a heat of
combustion system. The sample gas is exposed to two resisitive elements - one is coated
with a platinum catalyst, the other is inert. The two elements act as arms of a Wheatstone
bridge so that a current imbalance produces a bridge signal proportional to the gas
concentration.
The TLV Sniffer has 3 ranges, 0 to 100, 0 to 1000, and 0 to 10,000 ppm. It
is typically calibrated to hexane. Instrument resolution is 2 ppm on the 0 to 100 range. The
instrument consists of two units: the instrument pack contains a sample pump (1750
mL/min), battery pack, analog display meter, detector module, and electronics board; the
probe is a short aluminum tube with a filter assembly.
The TLV Sniffer has been criticized in one study for being unstable in
conditions of high humidity or temperature extremes.3 The response time of the instrument
was also criticized as being slow and the location of the zero adjust knob was considered to
be a poor design since it was easily bumped during field use, causing the calibration to be
offset.
3.3 COLORIMETRIC SYSTEMS
Detector tubes manufactured by National Draeger, Inc., Matheson Gas
Products, and Bendix/GASTEC were evaluated in one study with respect to their application
in air monitoring programs." The usefulness of detector tubes was found to be limited by:
• Their low accuracy (approximately ±25%);
• The tendency for leaks to occur during the sampling operation; and
• The need to read color charts or scales to determine pollutant
concentrations.
3-5
-------
The study concluded that detector tubes were more suitable to industrial
workplace applications than hazardous material sites. Interferences from other gases often
present at hazardous incident sites would, it was felt, tend to affect detector tube readings,
resulting in higher concentrations being reported than were actually present.
Despite these limitations, it was recognized that detector tubes are easy to use,
inexpensive, and capable of producing qualititive and semi-quantitative data. In this respect,
they offer an inexpensive, easily implemented supplement to more sensitive instrumental
analyses.
3.4 SPECTROPHOTOMETRIC SYSTEMS
3.4.1 Nondispersive Infrared Systems
Foxboro Miran: Two evaluations of the Foxboro Miran IB were reviewed.
The Miran is a popular IR analyzer designed for portable monitoring applications. It
contains a preprogrammed library of approximately 115 chemicals with additional capacity
for 10 to 15 user-generated calibration listings. The Miran is housed in a fairly large
instrument case containing the detector cell, pump, batteries, and electronics. It is a
relatively heavy instrument - 28 pounds. Sample is drawn through a flexible sample probe.
One report found the Miran to be difficult to use due to interferences at the
wavelength being used3. A second report, which discussed use of the Miran for
measurement of formaldehyde emissions in foam-insulated housing, confirmed this finding.12
In this second study, measurements by a Miran 1A were compared to NIOSH (National
Institute for Occupational Safety and Health) Method P&CAM 125, the traditional method
for determining formaldehyde concentrations. This study found no correlation between the
NIOSH method and the Miran measurements. Because the Miran at times indicated
unusually high formaldehyde concentrations, it was determined that unidentified interferents
were biasing the IR analyzer's measurements. The Miran was consequently not used for the
remainder of the study.
3-6
-------
3.4.2 Optical Remote Systems
A recent study2 comparing conventional point monitoring to open path
monitoring drew the following conclusions:
• Conventional systems are currently able to achieve lower detection
limits;
• Open path systems are able to report exceedences of short-term action
levels in a matter of minutes; conventional systems require several
hours;
• Conventional systems more accurately identify the presence of
compounds near the detection limit, however open path systems do a
better job identifying compounds when concentrations levels rise;
• Conventional systems are well documented and accepted; open path
systems are not well understood and have little document support; and,
• Conventional systems do not function well in areas where the sampler
can not be placed on the ground; open path systems are sensitive to
line-of-sight obstructions.
Nicolet Model 749 & Opsis Model AR500: A technology demonstration test of
two open path systems was conducted in March - April 1991 at a petrochemical plant in the
Houston, Texas area13. A Nicolet FTIR model 749 interferometer and a Opsis model AR500
UV system, were installed along the fence line separating the plant and an adjacent
residential area. Both systems performed well throughout the test period and produced
reliable data. For the UV system, two minor adjustments of the optics were required. The
IR system required virtually no alignment after the initial installation.
An existing monitoring station was located adjacent to the FTIR system. This
station was equipped with an automated canister sampler which collected 24-hour average air
samples every 4 days and point measurement instrumentation for O3, NO2, and SO2. Direct
comparisons of point source measurements with open path measurements were therefore
possible. Measurements by the UV system were compared with the point source SO2 and O3
3-7
-------
analyzers. Measurements by the FTTR system were compared with the canister sampling
system, and measurements of the two open path systems were compared with each other.
The study describes one 24-hour period of comparative SO2 sampling by the
open path and point source systems. During this period, SC>2 data from both systems
indicated rapid variations in ambient SO2 concentrations. Agreement between the two
systems in reported SQj concentrations was remarkably close. Similarly close agreement and
tracking was seen between measurements by the UV system and the point source Os analyzer
over another 24-hour period.
The dominant compounds detected by the FTIR system are volatile organics.
Point source detectors were not available for individual organic compounds, so comparisons
were made with the 24-hour average values provided by the canisters at the air monitoring
station. The canister samples, once collected, were analyzed off site using a gas
chrornatograph/multiple detector (GC/MD). Comparison of the FTIR data for pfopylene
were compared with GC/MD results for four days. The data indicate similar trends in
concentration and no particular data bias from either instrument.
A comparison of both open path systems was made during one time period for
ambient SO2 concentrations. In this case, excellent agreement was seen between the two
systems throughout the time period.
In another study, an FTIR was used at a Superfund site during pilot-scale
excavation and dewatering operations to monitor emissions of benzene, toluene,
ethylbenzene, and xylenes (BTEX).14 During periods of active remediation, no target
compounds were detected by the FTIR. The system was able, however, to detect emissions
of methane, total straight-chain alkanes and total branched-chain alkanes. Four additional
case studies of the use of FTIR and/or UV-DOAS at Superfund sites may be found in
Reference 2.
3-8
-------
3.5 GAS CHROMATOGRAPH AND GC/MS SYSTEMS
Foxboro Model 128: The Foxboro Model 128 Organic Vapor Analyzer
incorporates all the features of the OVA 108 (a total organic analyzer) with an externally
mounted GC column that enables separation of organic compounds under ambient
temperature conditions. The instrument can be used in either of two modes: the total organic
mode or the GC mode. In the GC mode a 250 microliter sample is introduced into the unit
via the sample probe and a manual valve. A portable strip chart recorder is used to print out
compound peaks as they elute from the column.
An evaluation of instrument precision determined 5 percent variation in
reproducibility of peak heights, 1 to 3 percent variation in reproducibility of peak retention
times, and 5 to 10 percent variation in reproducibility of relative retention times11. The
detection limit of the unit was found to be 0.2 ppm. Reported instrument limitations
included an inability to detect inorganic compounds and sensitivity to ambient air temperature
fluctuations.
HNU, AID, Photovac, and Xon Tech Portable GCs: A 1987 survey of leak-
detection devices included descriptions of four portable gas chromatographs manufactured by
AID Inc., HNU, Photovac Inc., and Xon Tech that required no external support equipment
such as compressed gas cylinders, AC power, integrator, etc.15 These instruments are
battery powered and contain an on-board cylinder for storage of hydrogen fuel. Sample
collection is typically accomplished with gas-tight syringes, sorbent cartridges, evacuated
canisters, or polymer gas bags. These GC's do not contain an extractive pump for con-
tinuous sample monitoring. This study found these analyzers, as a group, to be free from
interference problems. It was mentioned that experienced operators are required. The only
maintenance problems reported were keeping the sampling column clean.
Shimadzu Mini-2 GC: The Shimadzu Mini-2 GC is a portable process GC
equipped with a flame ionization detector. The analyzer can also support an electron capture
detector (ECD). The Mini-2 GC is able to analyze a wide range of hydrocarbon compounds
3-9
-------
ranging from light gases to heavier hydrocarbons. Compressed gases are required to support
the flame. Since oxygenated compounds tend to be retained on the GC column, accuracy for
these compounds may be low. The basic instrument is operated isothermally, however
temperature ramping is possible with an optional temperature controller.
The Mini-2 GC, like all analyzers in this class, requires a trained operator and
a set-up time of at least 24 hours. When operated and calibrated properly, it offers lower
detection limits of about 1 ppm and the ability to analyze and speciate a wide variety of
compounds.
Viking SpectraTrak 600 GC/MS: The Viking GC/MS is believed to be typical
of GC/MS instruments, however, the use of field GC/MS instruments is still very limited.
The Viking instrument was used at a Superfund site during pilot-scale excavation and
dewatering operations.14 Grab samples of exit gas from flux chambers were collected in
Tedlar bags and analyzed on-site using the GC/MS. No problems were encountered.
Detection limits of 10 ppbv were achieved for the BTEX compounds. Run times were
approximately 30 minutes and final data was available within a day. The same instrument
was also used during the same time-frame to analyze extracts from soil and sludge samples.
3.6 PARTICULATE MONITORS
MIE RAM-1: The MIE RAM-1 is a typical example of an optical-based, real-
time particulate monitor. The RAM-1 is a portable, self-contained aerosol monitor. The
measurement principle of the instrument is based on the detection of scattered light in the
near-infrared region of the electromagnetic spectrum. This instrument is designed to detect
all dust particles with diameters of less than 0.1 micrometers to 20 micrometers.
An evaluative study of the RAM-1, conducted in Japan, compared it with the
standard methodology which used a low-volume air sampler (LVS) with a standard elutriator
and a filter (an elutriator separates a suspension of a finely divided solid into parts according
3-10
-------
to their weight by a process of washing, decantation, and settling).16 The results obtained
with the RAM-1 proved to be quite consistent with standard methodology.
Two tests were conducted in the study. In the first test, two, identical RAM-
Is were used to make comparison measurements in a dust chamber and in typical workplace
environments. The results indicated a smaller scatter between the two RAM-Is than that
measured by other instruments such as a digital dust counter and a piezobalance monitor. A
second test compared paniculate measurements between a LVS equipped with a Teflon-
bounded glass fiber filter and the RAM-1. The testing was conducted with four different
dust atmospheres. The results demonstrated good agreement between the RAM-1 and the
manual method for all test dusts. This study concluded that the RAM-1 saved time when
sampling dusts in the workplace and furthermore produced results that compared favorably
with the standard methodology.
Wedding PM10 Beta Gauge; The PM10 Beta Gauge provides real-time
measurements of suspended paniculate matter with aerodynamic diameters of 10 microns or
less. The sampler provides flow rate and mass concentration outputs and is equipped with a
critical flow orifice to control volumetric flow. Digital outputs and control circuitry enable
data downloading to a computer-based data acquisition system.
A recent study reports performance test results and operating characteristics of
the Wedding & Accociates PMjo Beta Gauge Automated Particle Sample.17 Three (3) Beta
Gauge samplers and three (3) PM10 Reference Method High Volume samplers were deployed
at test sites with their inlet openings at the same heights. A total of fifteen (15) days of
particulate data were collected at each site. Hourly Beta Gauge data were averaged over
each 24 hour period to provide a direct comparison with the 24-hour sample data collected
by the Reference Method. Filters from the high volume samplers were weighed on an
analytical balance checked against a set of NIST-traceable weights. Agreement between the
two systems was very good. The resulting regression lines of each system had slopes within
1.2 percent of unity and intercepts < 1.5 ug/m3. Values of the coefficient of determination
3-11
-------
(R2) were in excess of 0.99 (i.e., only 1 percent of the variation between the two methods
can not be attributed to variations in the reference method itself).
3.7 SUMMARY OF INSTRUMENT COMPARISON STUDIES
A laboratory-scale study of selected monitoring techniques was performed to
determine the suitability of the techniques for measuring ppm-level concentrations of
mixtures of polar solvents.18 Among the methods tested were:
• OVA Model 108;
• HNU Model 101A;
• Beckman Model 400A (EPA Method 25A), and
• Byron Model 301.
Six replicate tests were performed for each of the test methods at each of four
test atmospheres (a total of 24 test runs for each test method). The data were used to
calculate the accuracy and precision of each method. The test results are summarized in
Table 3-1. The test results are shown graphically in Figures 3-1 and 3-2 for medium- and
high-level solvent mixtures at high humidity. Tests at 18 to 27 percent relative humidity had
similar results. The figures also include results for sampling and analytical methods that are
not real-time methods.
3-12
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SECTION 4
SELECTION GUIDE
If air monitoring is necessary during a Superfund remediation effort, then the
purpose, type, and scope of the monitoring program should be well defined so that ap-
propriate instrumentation can be selected. Selection of appropriate instrumentation can be
broken into two steps: 1) determine the appropriate measurement technology; and then 2)
determine the appropriate analyzer.
4.1 DETERMINING THE APPROPRIATE MEASUREMENT
TECHNOLOGY
The flowchart in Figure 4-1 identifies the basic steps to be followed in
determining an appropriate measurement technology. Table 4-1 is a summary of the
responses of different measurement systems to some common air monitoring pollutant
categories and should also be consulted at this stage.
4.2 SELECTING AN ANALYZER
The flowchart ends by referring the reader to the analyzer tables in the
following subsection for selection of a specific analyzer. In addition, Section 2 above
discusses the various detection methodologies and their relative advantages and limitations.
The analyzer tables in the following subsection provide detailed information about the
specific analyzers surveyed for this report.
Total hydrocarbon analyzers are the most frequently selected class of analyzers
for Superfund air monitoring applications. Table 4-2 lists the total hydrocarbon analyzers
surveyed for this report and indicates whether they are for portable or stationary monitoring
purposes.
4-1
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Table 4-1.
Summary of Applicability of Various Measurement Systems
to Selected Classes of Contaminants
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Measurement System
Electrochemical
Fir?
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Colorimetric
GC-GC/MS
NDIR
Optical Remote Systems
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Single component analysis.
Subject to interferences
Lower response to oxygenated, halogenated,
and nitrogen-containing compounds
Good response to heterocyclics, aromatics,
and aliphatics. Does not respond to methane.
Limited accuracy. Single component analysis.
Multi-component analysis at ppb level.
Can use several types of detectors.
Relatively interference free.
Single component analysis. Not suitable for
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molecules.
Multi-component analysis at ppb level.
Subject to interferences.
•J = Applicable in some cases
•Certain analyzers (e.g., FIDs, PIDs) may be suitable for single specific VOC or SVOC
compounds, but not for mixtures of compounds.
bFK> and PID instruments do not give a true reading of total hydrocarbons. Rather, they are
capable of providing a total instrument response to a broad number of compounds.
4-3
-------
Table 4-2.
Listing of Total Hydrocarbon Analyzers
V'"-- ,-"'>v "''•" MaiHi&dhBBrer "^ >,^4~ \
AIM
Bacharach
CSI
Eagle Monitoring
Eagle Monitoring
Foxboro
Foxboro
GOW-MAC Instrument
GOW-MAC Instrument
HNU Systems
HNU Systems
HNU Systems
HNU Systems
HNU Systems
HNU Systems
Heath Consultants
Heath Consultants
Heath Consultants
International Sensor Technology
MSA
MSA Instrument
MSA Instrument
MSA Instrument
MSA Instrument
MSA Instrument
MSA Instrument
Matheson Gas Products
Matheson Gas Products
Matheson Gas Products
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Model 1200
TLV Sniffer
HC5002C
EM700
EM7000
OVA-88
OVA-108
Model 23-500
23500 TH Analyzer
HNU 201-250
HNU 201
DL-101
IS-101
PI-101
HW-101
DP-IIM
PF-H
DP-m
Remote Link System III
Detector Tubes
Gas Corder - FID
R-Photon PID
Gas Corder - PID
Model 1015A
Model 1015C
Model 1015H
Custom Gas Det.Sys.
Model 805A
Detector Tubes
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FID
FID
FID
FID
FID
FID
FTD
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PID
PID
PID
PID
PID
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FID
FID
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Solid
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PID
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Portable
Stationary
Stationary
Stationary
Portable
Portable
Stationary
Stationary
Stationary
Stationary
Portable
Portable
Portable
Portable
Portable
Portable
Portable
Stationary
Portable
Portable
Portable
Portable
Stationary
Stationary
Stationary
Stationary
Portable
Portable
4-4
-------
Table 4-2.
(Continued)
-*--'><, jVfadsu&ctarcr = ' \
National Draeger
Pace Environmental
Pace Environmental
Pace Environmental
Pace Environmental
Pace Environmental
Photovac
Rosemount Analytical
Rosemount Analytical
Rosemount Analytical
Sensidyne
Sensidyne
Sentex Systems
Thermal Environmental
Thermal Environmental
Thermal Environmental
' ,^8«gx«r
Detector Tubes
JUM- VE7
JUM109A
JUM 3-100
JUM 5-100
JUM 3-300
Microtip
404A
400A
402
Portable FID
Detector Tubes
Scentogun
Model 51
Model 580S
Model 52
% % % .
Detector i
Solid
FID
FID
FID
FID
FID
PID
FID
FID
FID
FID
Solid
PID
FID
PID
PID
AjipHcatioo
Portable
Stationary
Stationary
Stationary
Stationary
Stationary
Portable
Stationary
Stationary
Stationary
Portable
Portable
Portable
Stationary
Portable
Stationary
Abbreviations:
CB = Catalytic Bead
EC = Electrochemical
FID = Flame lonization Detector
PID = Photoionization Detector
Plat = Platinum
SS = Solid State
TC = Thermal Conductivity
TD = Tin Dioxide
4-5
-------
4.3 VENDOR SUPPLIED INFORMATION FOR SPECIFIC REAL-TIME
INSTRUMENTS
The results of the survey of real time and near-real time ambient air
analyzers are presented in this section in a series of tables. Definitions of abbreviations
shown in the tables are given in Figure 4-2. Analyzer information is organized within six
categories (Electrochemical Systems, Total Hydrocarbon Systems, Colorimetric Systems,
Spectrophotometric Systems, GC & GC/MS Systems, and Paniculate Systems). Each
category has three tables: Performance Specifications, Operational Parameters, and General
Characteristics. Thus, the information can be found in Tables 4-3 through 4-20.
The instruments within a given category may vary greatly in portability,
specificity, detection limit, cost, etc. The instruments within a given category should not be
assumed to be equivalent. All information contained in the tables was supplied by vendors of
these instruments. The information is believed to be current as of January 1993. Users are
strongly encouraged to verify or confirm this information before purchasing real-time
monitors.
4-6
-------
1/D
1/MO
1/USE
1/WK
1/YR
2-3/WK
A
AC
ACal
Ac
AID
AHc
Anlyz
BU
Bz
C
CB
CC
CO
CH4
CO
CO,
cs
Cat
Cat 6
CF
Cfreq
Chg
a
CIC
Cnscn
Co
Comp
Contact
Crx
ct/min
D
D/A
DC
DL
OS
Detctr
dF
Div
DtS
E
E1-E3
EC
Once per day
Once per month
Once per use
Once per week
Once per year
Two/three times per week
Analog
Alternating Current
Auto-Cal
Active
Argon lonization Detector
Alkaline
Analyzer
Basic Unit
Benzene
Combustibles
Catalytic Bead
Chemical Cassette
Chemical Dependent
Methane
Carbon Monoxide
Carbon Dioxide
Compound Specific
Calibration
Calibration Gas
Cell Filter
Calibration Frequency
Charge Time
Class
Chlorine Compounds
Consummables
Continuous
Compensated
Contact Closure
Chemical Reaction
Count per minute
Digital
Digital/Analog
Direct Current
Data Download
Data Storage
Detector
Degrees Fahrenheit
Division
Detector Specific
Electronic
1 to 3 orders of magnitude
Electrochemical
ECO
ELCO
EO
ER
ERFC
El
F
fbr/cm3
FC
FD
FID
Fix
FP
Frmldhyd
FS
FS/3D
FS/1 2 Hr
FS/D
FS/MO
FTIR
ft3
G
GC
Gal
GFC
GFS
GO
Gel
Grp
H
H2
H,0
H,S
HC
HG
Hex
Hgt
HID
Hmax
Hrs
I
IB
IPA
IR
IS
Intrfmts
L
L/M
Electron Capture Detector
Electolytic Conductivity Detector
Ethylene Oxide
Electric Radiation Field
Electric Radio Field Chamber
Electrical Interference
Field
Fiber/cubic centimeter
Factory calibrated
Faraday Detector
Flame lonization Detector
Fixed
Flame Photometric
Formaldehyde
Full Scale
Full Scale per 3 days
Full Scale per 1 2 hours
Full Scale per day
Full Scale per month
Fourier Transform Infrared Spectroscopy
Cubic feet
Gas
Cas Chromatograph
Lead acid gell cell
Gas Filter Correlation
Gold Film Sensor
Galvanic Oxide
Lead Acid Gel Cell
Group
High
Hydrogen
Water Vapor
Hydrogen Sulfide
Hydrocarbon
Mercury
Hexane
Height
Helium lonization Detector
Maximum Humidity
Hours
Injection
Isobutylene
Infrared Photoacoustic Absorption
Infrared
Intrinsically safe
Interferents
Low
Low to Medium
Figure 4-2. Definition of Abbreviations in Selection Tables
4-7
-------
LEI
LLS
LFB
lb«
Lead
Lit
Lngth
Lnrty
Lumidor
M
M/H
ML
WON
MS
Merc
Mil
Min
Mttpt
Mntc
Mv
mA
mV
mW/cm2
mglm3
N
NA
NC
ND
NDIR
NFS
NiCad
NO
non-CH4
O
0,
OL
OP
OPM
OPT
OT
P
PG
Pv
PID
Part
Pent
Plat
Lower Exploiive Limit
Later fight Mattering
Later fiber detection
Pounds
Lead Acid Battery
Lithium
Length
Linearity
Lumidor Safety Products
Medium
Medium to high
Maintenance Level
Monthly
Mass Spectrometer
Mercury
Million
Minutes
Multipoint
Maintenance
Movable
Milfiamperes
Millivolts Direct Current
Milliwatts per square centimeter
Milligrams per cubic meter
No
Not Applicable
Non-continuous
No Data
Non-dispersive Infrared
No fixed schedule
Nickel Cadmium
Nitrous Oxide
Non-methane
Other
Oxygen
Operator Training Level
Open Path
Opacity-based paniculate monitor
Options
Operating Time
Port
Particle Generator
Passive
Photoionization Detector
Participates
Pentane
Semi-conductor Platinum Filament
Port
ppb
ppm
Pwr
r
RD
RF
RPM
RS
RT
Red
S
SC
SM
SS
SV
Sh
Snsr
T
TC
TD
TECO
TED
THC
Tl
Tmax
Tmin
UD
ug/m3
uM
UV
uW/cm2
V
Var
vdc
VOC
Vol
Wdt
Wk
Wt
Y
Yrs
ZG
%
~
f
Portable
Parts per bOBon
Parts per mjffion
Power
Correlation coefficient
Readout
Reference Filer
Radiation based particulate monitor
Reference Scatter
Response Time
Radiation
Sulfur
Sensor Chamber
Sample Methodology
Solid State
Semi-volatile Organic Compounds
Shelter
Sensor
Toxics
Thermal Conductivity
Tin Dioxide
Thermo Environmental
Thermal Electric Diode Detection
Total Hydrocarbons
Time Integrated
Maximum Temperature
Minimum Temperature
User Dependent
Microgram/cubic meter
Micrometer
Ultraviolet
Microwatts per square centimeter
Volts Direct Cunent
Various
Volts Direct Cunent
Volatile Organic Compounds
Volume
Width
Week
Weight
Yes
Years
Zero Gas
Percent
Approximately
microns
Figure 4-2. (Continued)
4-8
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-------
SECTION 5
REFERENCES
1. Ekiund, B. Procedures for Conducting Air Pathway Analyses for Superfund
Activities, Interim Final Documents: Volume 1 - Overview of Air Pathway
Assessments for Superfund Sites (Revised). EPA-450/l-89-001a, 1993.
2. Draves, J, and Ekiund, B. Applicability of Open Path Monitors for Superfund
Site Clean-Up. EPA-451/R-92-001. U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina. May, 1992.
3. Skelding, T.T. Survey of Portable Analyzers for the Measurement of Gaseous
Fugitive Emissions. U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, 1992.
4. Brown, G.E., D.A. DuBose, W.R. Phillips, and G.E. Harris. Response
Factors of VOC Analyzers Calibrated With Methane for Selected Organic
Chemicals. EPA-600/2-81-002 (NTIS PB81-136194). U.S. EPA/OAQPS,
Research Triangle Park, NC. September 1980.
5. DuBose, D.A., G.E. Brown, and G.E Harris. Response of Portable VOC
Analyzers to Chemical Mixtures. EPA-600/2-81-110. U.S. EPA/OAQPS,
Research Triangle Park, NC. June 1981.
6. Dietz, W.A. Response Factors for Gas Chromatographic Analyses. Journal
of Gas Chrom., Vol. 5, p. 68-71. 1967.
7. The Foxboro Co. Century Organic Vapor Analyzer Response Chart. Personal
communication from Nancy Mendez (Foxboro) to John Randall (Radian).
August 19, 1988.
8. Jorgensen, A.D., K.C. Picel, and V.C. Stamoudis. Prediction of Gas
Chromatography Flame lonization Detector Response Factors from Molecular
Structures. Analytical Chem., Vol. 62, No. 7, p.683-689. April 1, 1990.
9. Yieru, H., O. Qingyu, and Y. Weile. Characteristics of Flame lonization
Detection for the Quantitative Analysis of Comples Organic Mixtures.
Analytical Chem. Vol. 62, No. 18, p2063-2064. September 15, 1990.
10. Yare, B.S. and J.W. Hathorn. "Site-Wide, Real-Time Air Monitoring During
Remediation." In: Hazardous Materials Control. Volume 4, Number 4,
July/August 1991, pp. 33-37.
5-1
-------
11. Montgomery, R.E., Remeta, D.P., and Gruenfeld, M. "Rapid On-Site
Methods of Chemical Analysis." In: Contaminated Land: Reclamation and
Treatment. Smith, M.A., Editor. Plenum Press, New York, New York,
1985, pp. 257-309.
12. Georghiou, P.E., Snow, D., and Williams, D.T. "Formaldehyde Monitoring
in Urea-Formaldehyde Foam-Insulated Houses in St. John's Newfoundland,
Canada: Correlative Field Evaluation of a Real-Tune Infrared
Spectrophotometric Method." In: Environment International, Vol. 9, Number
4, 1983, pp. 279-287.
13. Spellicy, R.L., Crow, W.L., Draves, J.A., Buchholtz, W.F., and Herget,
W.F. "Spectroscopic Remote Sensing: Addressing Requirements of the Clean
Ah- Act." In: Spectroscopy, Volume 6, Number 9, November/December
1991, pp. 24-34.
14. Eklund, B. Estimation of VOC Emissions From Excavation Activities at the
Gulf Coast Vacuum Site - -Summary Report. EPA Contract No. 68-CO-0003,
WA 1-13, Task 7. Report to Ms. Joan Colson, EPA/RREL, Cincinnati, Ohio.
February 27, 1992.
15. Eklund, B. and Crow, W. Survey of Vendors of External Petroleum Leak
Monitoring Devices for Use with Underground Storage Tanks. EPA-600/4-87-
016 (NTIS PB87-212346). U.S. Environmental Protection Agency,
Environmental Monitoring Systems Laboratory, Las Vegas, Nevada. March,
1987.
16. Konishi, Y., Takata, T. and Homma, K. "Evaluation of the Real-Tune
Aerosol Monitor." In: Aerosols in the Mining and Industrial Work
Enviornments, [Paper presented at the International Symposium]. Marple, V.
and Liu, B., Editors. Ann Arbor Sciene Publisher, Ann Arbor, Michigan,
Volume 3, 1983, pp. 797-809.
17. Wedding, J.B. and Weigand, M.A. "An Automatic Particle Sampler with
Beta Gauging." Journal of the Air & Waste Management Association.
Volume 43, No. 4. 1993, pp 475-479.
18. Eklund, B., K. Williams, and V. Lara. Laboratory Evaluation of VOC
Emission Measurement Methods For Paint Spray Booths. Report to
Confidential Client. March 20, 1992.
5-2
-------
APPENDIX A
MANUFACTURERS' ADDRESSES AND TELEPHONE NUMBERS
This section lists the Company Name, Address, and Telephone Number of the
instrument manufacturers contacted for this survey. Inclusion or omission of names in this
list neither implies endorsement or censure of a particular product or manufacturer.
more
Also included in this Appendix is a list of selected companies that rent one or
models of real-time analyzers.
-------
Table A-1. Vendor List
O>M]fc^**AMB ^
ABB Environ Mon. Systems
ABB Process Analytics
AIM USA
Anarad Inc.
Arizona Instrument Corp.
Bacharach Inc.
Biosystems, Inc.
Bruel & Kjaer
Capital Controls Co. Inc.
CEA Instruments Inc.
Climet Instrument Company
CMS Research Corporation
Dasibi Environmental Corp.
Eagle Monitoring
Environmental Devices
ELIEco-Logic
Extrel Corp.
Foxboro
Gas Tech Inc.
General Microwave Corp.
Gow Mac Instrument Co.
Graseby Anderson
Heath Consultants, Inc.
HNU Systems Inc.
Industrial Scientific
International Sensor Tech.
Lumidor Safety Products
Matheson Gas Products
Mattson Instruments, Inc.
MDA Scientific Inc.
MET One
Metrosonics Inc.
Microsensor Systems
MIDAC Corporation
MIEInc.
Milton Roy
MSA Instrument Division
STREET ADDRESS
155 Route 46 West
2516 Highway 35
12919 SW Freeway #170
Box 3160
Box 1930
625 Alpha Dr.
Five Brookside Road
P.O. Box 23
Box 211
16 Chestnut St. Box 303
P.O. Box 1760
200 Chase Park S., Ste 100
515 West Colorado Street
23 Mauchly, Suite 109A
88 Essex Street
143 Dennis Street
575 Epslon Dr.
600 North Bedford Street
8445 Central Ave.
5500 New Horizons Blvd.
Box 32
4801 Fulton Industrial Blvd
11710 Almeda Genda Road
160 Charlemont St.
1001 Oakdale Road
17771 Fitch St.
11221 Interchange Circle, S
30 Seaview Dr.
1001 Fourier Drive
405 Barclay Blvd.
481 California Avenue
Box 23075
62 Corporate Court
1599 Superior Ave., Ste B3
1 Federal St. #2
1238 W. Grove Ave.
101 Technology Drive
ciT^sT^n^ip;X-:ii;;:
Wayne, NJ 07470
Manasquan, NJ 08736
Stafford, TX 77477
Santa Barbara, CA 93705
Tempe, AZ 85280
Pittsburgh, PA 15238
Middlefield, CT 06455
McKafee, NJ 07428
Colmar.PA 18915
Emerson, NJ 07630
Redlands, CA 92373
Birmingham, AL 35244
Glendale, CA 91201
Irvine, CA 92718
Haverhill,MA 01830
Rockwood, Ontario NOB2KO
Pittsburgh, PA 15238
East Bridgewater, MA 02333
Newark, CA 94560-3431
Amityville, NY 11701
Bound Brook, NJ 08805
Atlanta, GA 30336
Houston, TX 77234
Newton, MA 02161
Oakdale, PA 15071
Irvine, CA 92714
Miramar, FL 33025
Secaucus, NJ 07096
Madison, WI 53717
Lincolnshire, IL 60069
Grants Pass, OR 97526-9918
Rochester, NY 14692
Bowling Green, KY 42103
Costa Mesa, CA 92627-3625
Billerica, MA 01821-9938
Orange, CA 92665
Pittsburgh, PA 15230-0120
f1Mbi$»;|
(201) 890-7170
(908)223-0443
(800) 275-4246
(805) 963-6583
(800) 528-7411
(412) 963-2000
(203) 344-1079
(800) 252-4871
(800) 523-2553
(201) 967-5660
(714) 793-2788
(205) 733-6911
(818) 247-7601
(714) 753-7855
(508) 686-0210
(519) 856-9591
(412) 963-7530
(508) 378-5477
(510) 745-8700
(516) 226-8900
(908) 560-0600
(800) 241-6898
(800) 432-8487
(617) 964-6690
(800) 338-3287
(714) 863-9999
(305) 433-7000
(800) 544-1658
(508) 831-5515
(800) 323-2000
(503) 479-1248
(716) 334-7300
(502) 745-0099
(714) 645-40%
(508) 663-7900
(714) 974-5560
(800) 672-4678
-------
i^tl*;O^PANY:NAME--vV xx.
MTI Analytical Instruments
National Draeger Inc.
Nicolet Instrument Corp.
PPM Enterprises
Pace Environmental Products
Photovac International Inc.
Rosemount Analytical, Inc.
Sensidyne Inc.
Sentex Systems Inc.
SRI Instruments, Inc.
Thermo Environ Instruments
Viking Instruments
Wedding
ir STREET ADDRESS
41762 Christy St.
Box 120
5225 Verona Rd.
11428 B Kingston Pike
1196 Easton Rd.
25B Jefryn Blvd. West
4001 Greenbriar, Ste 150E
16333 Bay Vista Dr.
553 Broad Ave.
6700 Paradise Road, Ste B
8 West Forge Parkway
12007 Sunrise Valley Drive
P.O. Box 1756
CITY/STATE/ZIP ;
Freemont, CA 94538
Pittsburgh, PA 15230
Madison, WI 53713
Knoxvffle, TN 37922
Horsham, PA 19044-1405
Deer Park, NY 11729
Stafford, TX 77477
Clearwater, FL 34620
Ridgefield, NJ 07657
Las Vegas, NV 89119
Franklin, MA 02038-3136
Reston,VA 22091
Ft. Collins, CO 80522
j^lraoNKltf
(510) 490-0900
(412) 787-8383
(800) 356-8088
(615)966-8796
(215) 957-1144
(516) 254-4199
(713) 274-0500
(800) 451-9444
(201) 945-3694
(702) 361-2210
(508) 520-0430
(703) 758-9339
(800) 367-7610
Table A-2. Instrument Rental Company List
COMPANY NAME
CAE Instrument Rental
Hazco
Intek
On-Site Instruments
Response Rentals
STREET ADDRESS
207 Woodwork Lane
2006 Sprinboro West
10410 Rockley Road
689 N. James Road
1460 Ridge Road East
CITY/STATE7ZIP
Palatine, IL 60067
Dayton, OH 45439
Houston, TX 77099
Columbus, OH 43219-1837
Rochester, NY 14621
PHONE
(312) 934-86687(800)553-5511
(800) 332-0435
(713) 498-58557(800) 323-6527
(614) 237-30227(800) 766-7483
(716) 266-39107(800) 242-3910
NOTES: 1. The vendors listed in Table A-l may also offer their monitoring equipment for rent.
2. The listing of instrument rental companies is not all-inclusive.
-------
APPENDIX B
SURVEY FORM AND DEFINITION OF TERMS
A copy of the survey form is provided in this section together with a definition of the
terms used in the survey form. Terms are defined in the order of their appearance in the survey
form. An exception is the intrinisic safety definitions which are listed last.
-------
FORM#
DATE:
PHONE #:
COMPANY:
CONTACT:
INSTRUMENT:
L DETECTION TECHNOLOGY
Electrochemical
Flame lonization
Photoionization
Colorimetric
Nondispersive Infrared
Infrared Photoacoustic Absorption
Ultraviolet
Solid-State
Pulsed Fluorescence
Chemiluminescence
Gas Chromatograph
Thermal Conductivity
Optical Remote Sensor
Opacity-based Paniculate Monitor
Radiation-based Paniculate Monitor
Other.
REVIEWER:
IL DETECTION SPECIFICITY
Volatile Organic Compounds
Semi- Volatile Organic Compounds
Total Hydrocarbons
Particulates
Specific Toxic Compound(s)
Specific Combustible Compoundfs)
Other:
lit ^SAMPLING INTERFEKENTSr-
Water Vapor
Methane
Sulfur Compounds
CO.,
CO
0,
Stray electrical currents
Other:
Tm;*rcW
-------
RADIAN
CORPOflJtTIOM
FORM#
V; OPERATIONAL PARAMETERS j /
DESIGNED FOR
JFIELD..USEJ;
PORTABILITY
POWER
DISPLAY
im-RINSICALLY '
&&& '•
DIMENSIONS •
^ x, ' -S ' >, -' •
"XtKjfaCBCS^ -- ^ i
SAMPLING "...","<- *r -,
MEmODOfcQOY^
; COSTS *
OPERATION &
MA1NTEHANCE
CALIBRATION
HEOABlLTrr/
DATASTORAGE?
Yes No
Portable
120 DC
vac
Digital
A/or Temp:
Movable
Batterv Type:
Analog
Units:
Yes No
Weight:
Active
Continuous
Class:
Length:
Passive
Min Temp:
Max Humidity:
Fixed Needs Shelter?/; Y N
Operating Time:
Logarithmic
Charge Time:
Other
Resolution:
Division:
Widtli:
Injection
Group(s):
Height:
Other
Non-Continuous Time-Integrating
Sample Cell/Sensor Chamber Open path
Basic Unit:
S
Exp&usez
Electronic
Auto-Cal
Options
5:
L
M H
Cal Gas
N/A
ATo. units sold (approx./yr):
Yes No
Maintenance
S/yr:
Maitiienancef \ ; .; :
Frequency:
Consummables
S/yr
L M H
Type of Cal Gas:
No. years available?
COMPUTER DOWNLOAD?
Yes No
••VlJ'>PEREbRMA>FC:E::SPECIFlCATlONS : - "/••• '- "v^^?^/--
ACCURACY
RESPONSE TIME
LINEARITY
ZERO DRIFT
OUTPUT SIGNAL
-------
Detection Technology:
Detection Specificity:
Volatile Organic
Compounds:
Semi-Volatile Organic
Compounds:
Total Hydrocarbons:
Particulates:
Toxics:
Combustibles:
Sampling Interferents:
Range:
Max Temp:
Min Temp:
Portable:
DEFINITION OF TERMS
The technique used to detect and measure the pollutant or parameter.
The compound or group of compounds to which the instrument is designed to respond.
Important members of this category are:
Aromatic hydrocarbons (e.g.: benzene, toluene, xylenes, ethylbenzene, cumene, styrene)
Halogenated hydrocarbons (e.g.: methylfluoride, ethylchloride, propylbromide, n-
butyliodide, methylene chloride, chloroform, carbon
tetrachloride, ethylene chloride)
Aldehydes:
Ketones:
(e.g.: formaldehyde, acetaldehyde, propionaldehyde)
(e.g.: acetone, methyl ethyl ketone, ethyl ketone)
Important members of this category include polynuclear aromatic hydrocarbons with four
or fewer fused rings and their nitro derivatives, chlorobenzenes, chlorotoluenes,
polychlorobiphenyls, organochlorine and organophosphate pesticides and the various
polychlorodizenzo-p-dioxins.
Strictly speaking, this term refers to the group of compounds which are made up of only
carbon and hydrogen atoms. In practice, this term has come to refer to those compounds
which cause a flame ionization detector to give a signal.
Refers to the measurement of suspended particles (i.e. dust) in the air. Typically There are
three categories of participate measurement: 1) mass participate concentration (MFC), 2)
total suspended particulate (TSP), and 3) inhalable particulate: <, 10 micron (PMIO).
Chemical substances that produce a harmful physiological effect at relatively low dosages.
Examples include: aldehydes, ammonia, hydrogen chloride, bromide, fluoride, sulfur
dioxide, nitrogen dioxide, phosgene, chlorine, bromine, fluorine, dimethyl sulfate, ozone,
carbon monoxide, hydrogen cyanide, lead compounds, isopropyl alcohol, ethyl ether,
methyl chloride, acetone, DDT, mercury, chromium, arsenic, carbon tetrachloride,
chloroform, ethylene dibromide, ethylene glycol.
Gases that readily ignite in the presence of a combustion source. Examples include:
acetone, ammonia, butane, chloroform, ethane, ether, ethylene, formaldehyde, gasoline,
hexane, hydrogen, jet fuel, kerosene, natural gas, propane, styrene, toluene, turpentine,
vinyl chloride, xylenes.
Any substance or species which causes a deviation of instrument output from the value
which would result from the presence of only the pollutant of concern.
The lower and upper detectable limits of an analyzer.
The maximum ambient temperature in degrees Fahrenheit at which the instrument is
designed to operate.
The minimum ambient temperature in degrees Fahrenheit at which the instrument is
designed to operate.
Portable instruments are generally those instruments that can be easily carried in one hand.
They are usually battery-powered.
-------
DEFINITION OF TERMS
Movable:
Fixed:
Operating Time:
Charge Time:
Digital Display:
Analog Display:
Logarithmic Display:
Units:
Resolution:
Active:
Passive:
Injection:
Continuous:
Non-Continuous:
Time-Integrating:
Sample Cell-
Open Path:
Accuracy:
Response Time:
Linearity:
Zero Drift:
Movable or transportable instruments are generally those instruments that cannot easily be
hand-carried, but may be transported through the workplace by using a hand-operated
mechanical device such as a cart. May be battery or line powered.
A fixed instrument is that which is normally found at a process or a fenceline; it is usually
attached to a multiport sampling system; and is too large, heavy, or fragile to move easily.
Operating time refers to the typically number of hours of time a battery-powered instrument
can operate before the battery must be replaced or recharged.
Charge time defines the number of hours required to recharge a chargeable battery.
A LCD (liquid crystal display) or LED (light emitting diode) readout.
A display featuring a meter movement calibrated to a particular scale.
An analog meter movement with a logarithmic scale.
An analyzer's expression of measured concentration: e.g. ppm, ppb, %, etc.
Sensitivity of the instrument expressed as response per unit of concentration i.e. the lowest
unit of concentration to which the instrument will respond.
Active systems include air-sampling pumps to transport the sample to the detector.
Passive systems generally use sampling devices that apply Pick's First Law of Diffusion
and therefore do not require sampling pumps.
Sample injection systems typically apply to gas chromatographs only. The sample is
injected either manually or automatically into the detector.
Instrument provides a constant response upon continuous interaction with the air sample.
Instrument provides an intermittent response to pollutant concentration.
Instrument draws a sample over a fixed period of time; the sample is then analyzed and the
results integrated over the sample period.
Sample is pumped or diffuses into an instrument sample cell or sensor chamber for
analysis.
An instrument may analyze over an open path across the workplace over which the con-
centration of the air contaminant is spatially averaged.
The difference between the measured value and the true value which has been established
by an accepted reference method procedure.
The time interval between the initial response and a 90 % response after a step increase in
the inlet concentration.
Expresses the degree to which a plot of instrument response versus known pollutant
concentration falls on a straight line. A quantitative measure of linearity may be obtained
by performing a regression analysis on several calibration points.
The change with time in instrument output over a stated time period of unadusted con-
tinuous operation when the input concentration is zero (expressed as a percent of full
scale).
-------
DEFINITION OF TERMS
Intrinsically Safe:
Class I:
Class I, Division 1:
Class I, Division 2:
Class 11:
Class II, Division 1:
Class II, Division 2:
Class III:
Class III, Division 1:
Class III, Division 2:
Intrinsically safe apparatus is apparatus in which any spark or thermal effect is incapable of
causing ignition of a mixture of flammable or combustible material in air under prescribed
test conditions.
Class I locations are those in which flammable gases or vapors are or may be present in the
air in quantities sufficient to produce explosive or ignitible mixtures.
A Class I, Division 1 location is a location: (1) in which ignitible concentrations of
flammable gases or vapors can exist under normal operating conditions; or (2) in which
ignitible concentrations of such gases or vapors may exist frequently because of repair or
maintenance operations or because of leakage; or (3) in which breakdown or faulty
operation equipment or processes might release ignitible concentrations of flammable gases
or vapors, and might also cause simultaneous failure of electric equipment.
A Class I, Division 2 location is a location: (1) in which volatile flammable liquids or
flammable gases are handled, processed, or used, but in which the liquids, vapors or gases
will normally be confined within closed containers or closed systems from which they can
escape only in case of accidental rupture or breakdown of such containers or systems, or in
case of abnormal operation of equipment; or (2) in which ignitible concentrations of gases
or vapors are normally prevented by positive mechanical ventilation, and which might
become hazardous through failure or abnormal operation of the ventilating equipment; or
(3) that is adjacent to a Class I, Division 1 location, and to which ignitible concentrations
of gases or vapors might occasionally be communicated unless such communication is
prevented by adequate positive-pressure ventilation from a source of clean air, and effective
safeguards against ventilation failure are provided.
Class II locations are those that are hazardous because of the presence of combustible dust.
A Class II, Division 1 location is a location: (1) in which combustible dust is in the air
under normal operating conditions in quantities sufficient to produce explosive or ignitible
mixtures; or (2) where mechanical failure or abnormal operation of machinery or
equipment might cause such explosive or ignitible mixtures to be produced, and might also
provide a source of ignition through simultaneous failure of electric equipment, operation
of protection devices, or from other causes; or (3) in which combustible dusts of an
electrically conductive nature may be present in hazardous quantities.
A Class II, Division 2 location is a location where combustible dust is not normally in the
air in quantities sufficient to produce explosive or ignitible mixtures and dust accumulations
are normally insufficient to interfere with the normal operation of electrical equipment or
other apparatus, but combustible dust may be in suspension in the air as a result of
infrequent malfunctioning of handling or processing equipment and where combustible dust
accumulations on, in or in the vicinity of the electrical equipment may be sufficient to
interfere with the safe dissipation of heat from electrical equipment or may be ignitible by
abnormal operation or failure of electrical equipment.
Class III locations are those that are hazardous because of the presence of easily ignitible
fibers or flyings, but in which such fibers or flyings are not likely to be in suspension in
the air in quantities sufficient to produce ignitible mixtures.
A Class III, Division 1 location is a location in which easily ignitible fibers or materials
producing combustible flyings are handled, manufactured, or used.
A Class III, Division 2 location is a location in which easily ignitible fibers are stored or
handled.
-------
DEFINITION OF TERMS
Group A: Atmospheres containing acetylene.
Group B: Atmospheres containing hydrogen, fuel and combustible process gases containing more than
30% hydrogen by volume, or gases or vapors of equivalent hazard such as butadiene,
ethylene oxide, propylene oxide, and acrolein.
Group C: Atmospheres such as cyclopropane, ethyl ether, ethylene, or gases or vapors equivalent
hazard.
Group D: Atmospheres such as acetone, ammonia, benzene, butane, ethanol, gasoline, hexane,
methanol, methane, natural gas, naphtha, propane or gases or vapors of equivalent hazard.
Group E: Atmospheres containing combustible metal dusts regardless of resistivity, or other combus-
tible dusts of similarly hazardous characteristics having resistivity of less than l(f ohm-
centimeter.
Group F: Atmospheres containing carbon black, charcoal, coal or coke dusts which have more than
8% total volatile material (coal and coke dusts per ASTM 3175-82) or atmospheres con-
taining these dusts sensitized by other materials so that they present an explosion hazard,
and having resistivity greater than 102 ohm-centimeter but equal to or less than 108 ohm-
centimeter.
Group G: Atmospheres containing combustible dusts having resistivity of 108 ohm-centimeter or
greater.
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APPENDIX C
CALCULATION OF RESPONSE FACTORS
FOR MIXTURES OF COMPOUNDS
Source: Reference 3
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Mixtures of Chemicals
The calculation of response factors for mixtures of chemicals is not a well-
documented area. When asked how they dealt with chemical mixtures in process lines,
companies answered several different ways. The responses generally fell into three
categories: (1) the response factor (Rf) of the mixture was calculated using the Rfs of
the individual component and the mole fractions present, (2) the reading was recorded
"as methane" or, (3) a single component Rf was used to determine quantities.
Method 21 does not describe a specific method for computing the response factor
for a mixture of chemicals. About half of the respondents used the method below or a
slight variation in dealing with mixtures. A response factor for a mixture was calculated
as:
= (Mole Fraction Gas 1 * Rf Gas 1) + (Mole Fraction Gas 2 * Rf Gas 2) + ....
(Mole Fraction Gas i * Rf Gas i)
One variation of the above equation used an average of the Rfs multiplied by the
weight percent of the chemical of interest to determine the Rf of the mixture. Another
variation used the mole fraction of the chemical of interest multiplied by the Rf of the
chemical of interest multiplied by the instrument response to obtain an emission
concentration, as follows:
Concentration = Instrument Reading * Rfj * Mole Fraction,
Several companies reported using a notation of "as methane" when they recorded
values. One company responded that the raw value was used to determine leaks for the
"leak-no leak" method1 of reporting, which classifies a component as either leaking or not
leaking if it is under or over 10,000 ppm, respectively.
33
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The method of using one Rf to determine total concentration was reported by two
respondents. One used the highest Rf in the mixture, and one used the Rf of the
predominant compound in the mixture. Neither used any mole fraction or weight
percent of the chemical of interest in its calculation.
One contractor reported using the Rf and percentage stream codes provided by its
client for application against the instrument responses.
3.5 Calculation of Response Factors for Mixtures
In the absence of specific instructions for calculation of a response factor for
mixtures in Method 21, members of the user community are using a variety of
procedures (Section 3.4) to determine some response factor for a mixture. A small study
of binary mixtures with individual component response factors as well as mixture
compositions encompassing a wide range indicated that the response factor of the
mixtures was not a simple algebraic average of component response factors.2 Individual
response factors must be weighted appropriately to reflect the composition of the
mixture. An appropriate weighting scheme which has been suggested is shown below.
RFA RFB
where
VFA = volume fraction of component A
RFA = response factor for component A.
The expression has a [VF/RF] term for every component of the mixture.
Z7V065-09/cafU»4op
Rr»JB«port 34
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For example, what is the response factor of a mixture which has equal volumes of
two components with response factors of 2 and 10, respectively, where the true total
volume concentration is 500 ppm?
The observed response of 250 ppm of the mixture with a response factor of 2 is
250 ppm/2, or 125 ppm.
The observed response of 250 ppm of the mixture with a response factor of 10 is
250 ppm/ 10 or 25 ppm.
The total observed response of this mixture should be 125 ppm + 25 ppm, or 150
ppm. The response factor for the mixture is therefore [actual value/observed value] =
500/150, or 333. The algebraic mean of the two response factors would be 6 (10+2/2),
nearly twice the actual value.
Mathematically, the response factor for the mixture is calculated as:
1 = 0.50/2 + 0.50/10 = 025 + 0.05 = 030
= 333
On* Report 35
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-451/R-93-008
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Air/Superfund National Technical Guidance Study
Series - Compilation of Information on Real-Time
Air Monitors for Use at Superfund Sites
5. REPORT DATE
May 1993
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Radian Corporation
8501 Mo-Pac Boulevard
Austin, Texas 78159
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report summarizes the results of a U.S. Environmental Protection Agency (EPA)-
sponsored study to compile and evaluate information on commercially-available real-time air
monitoring equipment for use at Superfund sites. In this document, real-time (RT) and near real-
time (NRT) monitors are broadly defined as those instruments or methods that provide
information either instantaneously or within a relatively short time period (i.e., <30 minutes).
The objectives of this study were to review the available literature on real-time (RT) air
monitoring; compile a comprehensive list of real-time and near real-time (NRT) air sampling
techniques, equipment, and vendors; contact vendors and users to collect information on the
technical specifications of their applicable instruments; and prepare a guidance document that
summarizes the results of the study. The available literature was reviewed to identify the most
current methods for real-time or near real-time measurement of ambient air concentrations of
toxic pollutants commonly found at Superfund sites.
17.
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