United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Emergency Response Division
540R95131
Environmental
Response
Team
vvEPA
Air Monitoring
for Hazardous Materials
Environmental Response
Training Program
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FOREWORD
This manual is for reference use of students enrolled in scheduled training courses of the U.S.
Environmental Protection Agency (EPA). While it will be useful to anyone who needs information
on the subjects covered, it will have its greatest value as an adjunct to classroom presentations
involving discussions among the students and the instructional staff.
This manual has been developed with a goal of providing the best available current information;
however, individual instructors may provide additional material to cover special aspects of their
presentations.
Because of the limited availability of the manual, it should not be cited in bibliographies or other
publications.
References to products and manufacturers are for illustration only; they do not imply endorsement
by EPA.
Constructive suggestions for improvement of the content and format of the manual are welcome.
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CONTENTS
Section
Acronyms and Abbreviations
Air Monitoring Plans and Strategies 1
Exposure Limits and Action Levels 2
Oxygen Monitors, Combustible Gas Indicators, and
Specific Chemical Monitors 3
Total Vapor Survey Instruments 4
Air Sample Collection 5
Introduction to Gas Chromatography 6
Air Dispersion Modeling During Emergency Response 7
References 8
Manufacturers and Suppliers of Air Monitoring Equipment 9
Workbook: Air Monitoring for Hazardous Materials 10
10/93 v Contents
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AIR MONITORING FOR HAZARDOUS MATERIALS
(165.4)
5 Days
This course instructs participants in the practices and procedures for monitoring and sampling
airborne hazardous materials. It is designed for personnel who evaluate releases of airborne
hazardous materials at hazardous waste sites or accidental hazardous material releases.
Topics that are discussed include air monitoring and sampling programs, air monitoring and sampling
techniques, air monitoring and sampling equipment, instrument calibration, exposure guidelines, air
dispersion modeling, and health and safety considerations. The course will include operating
procedures for specific air monitoring and sampling equipment, as well as strategies for air
monitoring and sampling at abandoned hazardous waste sites and for accidental releases of hazardous
chemicals.
Instructional methods include a combination of lectures, group discussions, problem-solving sessions,
and laboratory and field exercises with hands-on use of instruments.
After completing the course, participants will be able to:
• Properly use the following types of air monitoring and sampling equipment:
Combustible gas indicators
Oxygen monitors
Detector tubes
Toxic gas monitors
Photoionization detectors
Flame ionization detectors
Gas chromatographs
Sampling pumps
Direct-reading aerosol monitors.
• Identify the operational parameters, limitations, and data interpretation requirements
for the instruments listed above.
• Identify the factors to be considered in the development of air monitoring and
sampling plans.
• Discuss the use of air monitoring data for the establishment of personnel and
operations health and safety requirements.
U.S. Environmental Protection Agency
Office of Emergency and Remedial Response
Environmental Response Team
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ACRONYMS AND ABBREVIATIONS
ACGIH American Conference of Governmental Industrial Hygienists
AID argon ionization detector
AIHA American Industrial Hygiene Association
ALOHA areal locations of hazardous atmospheres
ANSI American National Standards Institute
ASTM American Society for Testing and Materials
BEI biological exposure indices
C ceiling (precedes exposure limit)
cc/min cubic centimeters per minute
cfm cubic feet per minute
CFR Code of Federal Regulations
CGI combustible gas indicator
Cl chlorine
CO carbon monoxide
DNPH 2,4-dinitrophenylhydrazine
DQO data quality objective
BCD electron capture detector
EPA U.S. Environmental Protection Agency
ERT Environmental Response Team (EPA)
eV electron volt
FID flame ionization detector
FM Factory Mutual Research Corporation
GC gas chromatography
HC1 hydrogen chloride
ICS incident command system
IDLH immediately dangerous to life or health
IP ionization potential
KOH potassium hydroxide
LCD liquid crystal display
LED light-emitting diode
LEL lower explosive limit
LFL lower flammable limit
1pm liters per minute
JO/93
Acronyms and Abbreviations
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MACs maximum allowable concentrations
MAKs maximum concentrations at the workplace (Federal Republic of Germany)
MCE mixed cellulose ester
mg/m3 milligrams per cubic meter
ml milliliter
mm millimeter
MOS metal-oxide semiconductor
MSDS material safety data sheets
MSHA Mine Safety and Health Administration
NaOH sodium hydroxide
NEC National Electrical Code
NFPA National Fire Protection Association
NIOSH National Institute for Occupational Safety and Health
NRC Nuclear Regulatory Commission
OH hydroxide
OS HA Occupational Safety and Health Administration
OVA organic vapor analyzer (Foxboro®)
OVM organic vapor meter
PAH polycyclic (or polynuclear) aromatic hydrocarbon
PBK playback
PCB polychlorinated biphenyl
PEL permissible exposure limit
PID photoionization detector
ppb parts per billion
PPE personal protective equipment
ppm parts per million
ppt parts per trillion
PUF polyurethane foam
PVC polyvinyl chloride
REL recommended exposure limits
SA shift average
SCBA self-contained breathing apparatus
SEI Safety Equipment Institute
SOP standard operating procedure
SOSG Standard Operating Safety Guides
SS chemical-specific sensor
STEL short-term exposure limit
TCD thermal conductivity detector
TLV threshold limit values
TWA time-weighted average
Acronyms and Abbreviations 2 10/93
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UEL upper explosive limit
UL Underwriters' Laboratory, Inc.
UV ultraviolet light
VDC volts DC
WEEL® workplace environmental exposure level
70/93 3 Acronyms and Abbreviations
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AIR MONITORING PLANS
AND STRATEGIES
PERFORMANCE OBJECTIVES
At the end of this lesson, participants will be able to:
• List six objectives of air monitoring specified by the EPA
Standard Operating Safety Guides
• Identify the OSHA standard and EPA standard that cover
hazardous waste site operations and emergency response
• List four situations that initial entry monitoring is designed
to detect
• Differentiate between "personal monitoring" and "area
monitoring"
• Define, per 1910.120, when personnel monitoring is
required
• List documents that EPA has developed as guidance for
compliance with 1910.120
• Given the Personal Air Sampling and Air Monitoring
Requirements Under 29 CFR 1910.120 fact sheet, define air
monitoring and air sampling
• List three uses of meteorological data.
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NOTES
AIR MONITORING PLANS
AND STRATEGIES
AIR MONITORING
EPA Objectives
• Identify and quantify airborne
contaminants onsite and offsite
• Track changes in air contaminants that
occur over the lifetime of the incident
• Ensure proper selection of work practices
and engineering controls
Source: EPASOSGs
AIR MONITORING
EPA Objectives
• Determine the level of worker protection
needed
• Assist in defining work zones
• Identify additional medical monitoring
needs in any given area of the site.
Source: EPASOSGs
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Air Monitoring Plans and Strategies
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NOTES
WORKER PROTECTION
STANDARDS (OSHA)
29 CFR 1910.120 (HAZWOPER)
Applies to
- Federal employees
- Private industry employees
- State and local employees in
OSHA states
WORKER PROTECTION
STANDARDS (EPA)
• 40 CFR Part 311
• Applies to state and local employees
in non-OSHA states
• Wording same as 1910.120
MONITORING
REQUIREMENTS
Air Monitoring Plans and Strategies
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/VOTES
INITIAL ENTRY
or
Monitoring for:
• Immediately dangerous to life
health (IDLH) conditions
• Exposures over permissible
exposure limits (PELs) or published
exposure levels
INITIAL ENTRY
Monitoring for:
• Exposure over a radioactive
material's dose limits
• Other dangerous conditions
- Flammable atmospheres
- Oxygen-deficient environments
PERIODIC MONITORING
"Periodic monitoring (shall) be done
when the possibility of a dangerous
condition has developed or when there
is reason to believe that exposures
may have risen above PELs since prior
monitoring was conducted."
Source: EPA SOSGs
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Air Monitoring Plans and Strategies
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NOTES
PERSONAL MONITORING
Required
• During actual cleanup phase
• To evaluate high-risk employees
(i.e., employees likely to have
highest exposures)
• Evaluation pf other employees
needed if high-risk employees exceed
exposure limits
Source: 1910.120(h)(4)
PERSONAL MONITORING
AREA MONITORING
t&
S = Area samplers
Air Monitoring Plans and Strategies
JO/93
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NOTES
SITE SAFETY AND
HEALTH PLAN
Minimum requirement
"Frequency and types of air monitoring,
personnel monitoring, and environmental
sampling techniques and instrumentation
to be used, including methods of
maintenance and calibration of monitoring
and sampling equipment to be used."
Source: 1910.120(b)(4)(ii)(E)
GUIDANCE DOCUMENTS
OSHA
• Technical manual
• Analytical methods manual
GUIDANCE DOCUMENTS
EPA
EPA-ERT Standard Operating Safety
Guides (SOSGs), Publication
9285.1-03, June 1992
Personal Air Sampling and Air
Monitoring Requirements (PASAMR)
Under 29 CFR 1910.120 fact sheet,
Publication 9360.8-17FS, May 1993
4/94
Air Monitoring Plans and Strategies
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NOTES
AIR MONITORING vs.
AIR SAMPLING
Air monitoring refers to the use of
direct-reading instruments producing
instantaneous data
Air sampling refers to the use of a
sampling pump and collection media
that produce samples that must be
sent to a laboratory for analysis
AIR MONITORING
Features
"Real time" (direct reading)
Rapid response
Generally not compound specific
Limited detection levels
May not detect certain classes of
compounds
AIR SAMPLING
Features
Compound or class specific
Greater accuracy
Requires more time for results
Requires additional pumps, media,
and analytical support
Air Monitoring Plans and Strategies
JO/93
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NOTES
PERSONNEL AIR SAMPLING
Elements in Sampling Strategy
• Employee sampled
• Tasks performed
• Duration
• Hazardous substances
• Equipment to be used
Source: PASAMR fact sheet
AREA SAMPLING
Locations
Upwind
- Establish background
Support zone
- Ensure support area is clean
and remains clean
Source; EPASOSGs
AREA SAMPLING
Locations
Contamination reduction zone
- Ensure that personnel in zone are
properly protected
- Ensure that onsite workers are not
removing PPE in a contaminated area
Source: EPASOSGs
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Air Monitoring Plans and Strategies
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NOTES
AREA SAMPLING
Locations
• Exclusion zone
- Represents greatest risk of exposure
- Requires most sampling
- Use data to set boundaries
- Use data to select proper levels of
PPE
- Provide a record of air contaminants
Source: EPASOSGs
AREA SAMPLING
Locations
Fenceline/downwind
- Determine whether air contaminants
are migrating from site
Source: EPA SOSGs
AREA SAMPLING
Elements in Sampling Strategy
• Locations where air sampling will be
performed
• Hazardous substances that will be
sampled during the task
• Duration of the sample
Source: PASAMR fact sheet
Air Monitoring Plans and Strategies
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NOTES
AREA SAMPLING
Elements in Sampling Strategy
Equipment that will be used to sample
for the different hazardous substances
Collection of meteorological data
Source: PASAMR fact sheet
METEOROLOGICAL
CONSIDERATIONS
• Data needed
- Wind speed and direction
- Temperature
- Barometric pressure
- Humidity
METEOROLOGICAL
CONSIDERATIONS
• Data uses
- Placement of samplers
- Input for air models
- Calibration adjustments
• Data sources
- Onsite meteorological stations
- Government or private
organizations
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Air Monitoring Plans and Strategies
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NOTES
AIR DISPERSION MODELS
Public exposure assessment
Air monitoring and air modeling
should interact
LONG-TERM AIR MONITORING
PROGRAMS
Considerations
Type of equipment
Cost
Personnel
Accuracy of analysis
Time to obtain results
Availability of analytical
laboratories
Source: EPA SOSGs
LONG-TERM AIR MONITORING
PROGRAMS
ERT Approach
• Use total vapor survey instruments
for organic vapors and gases
- Initial detection
- Periodic site surveys
- Area monitors to track changes
Source: EPA SOSGs
Air Monitoring Plans and Strategies
10/93
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NOTES
LONG-TERM AIR MONITORING
PROGRAMS
ERT Approach
• Collect air samples
- Analyze with field gas
chromatographs
- Send selected samples to
laboratories
• Use survey instruments or gas
chromatographs to screen samples
for laboratory analysis
Source; EPASOSGs
LONG-TERM AIR MONITORING
PROGRAMS
ERT Approach
• When they are known to be present
or when there are indications that
they may be a problem, sample for
- Particulates
- Inorganic acids
- Aromatic amines
- Halogenated pesticides
Source: EPASOSGs
ADDITIONAL READING
Air/Superfund Technical Guidance Study
Series
- Volume IV - Guidance for Ambient Air
Monitoring at Superfund Sites (revised),
EPA-451/R-93-007, May 1993
- Compilation of Information on Real-Time
Monitoring for Use at Superfund Sites,
EPA-451/R-93-008, May 1993
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Air Monitoring Plans and Strategies
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NOTES
INSTRUMENT
CHARACTERISTICS
SELECTIVITY
• Selectivity is an instrument's ability to
differentiate a chemical from others in
a mixture
• Chemicals that affect an instrument's
selectivity are called interferences
SENSITIVITY
Sensitivity is the least change in
concentration that will register an
altered reading of the instrument
Source: Air Sampling and Analysis for Contaminants: An
Overview
Air Monitoring Plans and Strategies
10/93
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NOTES
ACCURACY AND PRECISION
• Accuracy refers to the difference
between the instrument reading and
the true or correct value.
• Precision is the grouping of the data
points around a calculated average.
Precision measures the repeatability
of data.
ACCURACY AND PRECISION
Accurate and Precise
0
Precise but Inaccurate
x
©
Accurate but Imprecise Inaccurate and Imprecise
Source: The Industrial Environment - Its Evaluation and Control
RELATIVE RESPONSE
Relative response is the relationship
between an instrument's reading and
the actual concentration
Calculation
Relative Response =
Instrument Reading
Actual Concentration
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NOTES
CALIBRATION
Process of checking an instrument to
see if it gives the proper response
and making any necessary
adjustments.
Direct-reading instruments generally
are calibrated to one chemical (the
standard).
RESPONSE TIME
Response time is the time between
initial sample contact and readout
of the full chemical concentration
(usually seconds to minutes)
Turnaround time is the time from
sample collection to receipt of
results (days to weeks)
MOBILITY
• Portable
- Handheld
- No external power supply
• Fieldable
- Particularly rugged
- Easily transported by vehicle
- Limited external power supply
• Mobile
- Small enough to carry in a mobile lab
Source: Field Screening Methods Catalog, EPA/540/2-881005,
September 7888
Air Monitoring Plans and Strategies
4/94
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NOTES
EASE OF OPERATION
• How easy is it to operate the
controls?
• How easy is it to learn to operate?
• How many steps must be performed
before an answer is obtained?
• How easy is it to repair?
INHERENT SAFETY
32L6
LISTED
APPROVED
INTRINSICALLY SAFE COMBINATION
COMBUSTIBLE GAS AND OXYGEN INDICATING
DETECTOR FOR HAZARDOUS LOCATIONS
CLASS I, DIVISION 1, GROUPS A, B, C & D
Source; Scoff Model S-105 Certification Label
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Air Monitoring Plans and Strategies
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AIR MONITORING PLANS AND STRATEGIES
INTRODUCTION
Airborne contaminants present at a hazardous waste site or a hazardous materials release can present
a risk to human health and the environment. One way to assess that risk is to identify and quantify
these contaminants by air monitoring. The U.S. Environmental Protection Agency's (EPA) Standard
Operating Safety Guides (SOSGs) state that the objectives of air monitoring during response
operations are to:
• Identify and quantify airborne contaminants onsite and offsite
• Track changes in air contaminants that occur over the lifetime of the incident
• Ensure proper selection of work practices and engineering controls
• Determine the level of worker protection needed
• Assist in defining work zones
• Identify additional medical monitoring needs in any given area of the site.
Several questions should be addressed when you develop an air monitoring plan. Why is the air
monitoring being done? How will the monitoring be done? Who will do the monitoring? When and
where will the air monitoring be done? What equipment will be used?
The above list gives several reasons why air monitoring is done. Some organizations have developed
guidelines on the why, how, who, where, when, and what of air monitoring. Some organizations
have procedures that are legal requirements. These organizations will be discussed. Also, general
equipment characteristics will be covered in the latter part of this section.
STANDARDS AND GUIDELINES
U.S. Department of Labor - Occupational Safety and Health Administration (OSHA)
Since 1971, OSHA has regulated exposure to chemicals in industry. 29 CFR Part 1910.1000
specifies limits on exposure to airborne concentrations of chemicals. See the section on Exposure
Limits and Action Levels for further information.
On March 6, 1990, OSHA's Hazardous Waste Operations and Emergency Response standard (29
CFR Part 1910.120) went into effect. This standard addressed the legal requirements for protecting
workers involved with hazardous waste or emergency responses to hazardous materials. Air
monitoring is one of the many activities regulated by this standard.
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The standard requires the site-specific safety and health plan to address:
Frequency and types of air monitoring, personnel monitoring, and environmental
sampling techniques and instrumentation to be used, including methods of
maintenance and calibration of monitoring and sampling equipment to be used.
Under section (c) Site characterization and analysis is:
(6) Monitoring. The following monitoring shall be conducted during initial site entry
when the site evaluation produces information that shows the potential for ionizing
radiation or IDLH (Immediately Dangerous to Life or Health) conditions, or when
the site information is not sufficient reasonably to eliminate these possible conditions:
(i) Monitoring with direct-reading instruments for hazardous levels
of radiation.
(ii) Monitoring the air with appropriate direct-reading test equipment
(e.g., combustible gas meter, detector tubes) for IDLH and other
conditions that may cause death or serious harm (combustible or
explosive atmospheres, oxygen deficiency, toxic substances).
(Hi) Visually observing for signs of actual or potential IDLH or other
dangerous conditions.
(iv) An ongoing air monitoring program in accordance with
paragraph (h) of this section shall be implemented after site
characterization has determined the site is safe for the startup of
operations.
This section states when monitoring should be done (site entry), why it is done (to identify IDLH
conditions), and what kind of equipment to use. Additional requirements are found under (h)
Monitoring.
(1) General
(i) Monitoring shall be performed in accordance with this paragraph
where there may be a question of employee exposure to hazardous
concentrations of hazardous substances in order to assure proper
selection of engineering controls, work practices and personal
protective equipment so that employees are not exposed to levels
which exceed permissible exposure limits or published exposure levels
for hazardous substances.
(ii) Air monitoring shall be used to identify and quantify airborne
levels of hazardous substances and safety and health hazards in order
to determine the appropriate level of employee protection needed on
site.
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Here the purpose (why) is to identify and quantify hazardous substances so that proper exposure
controls are used. The substances are identified and quantified so that the concentrations can be
compared to an exposure limit. See the Exposure Limits and Action Levels section for further
information on exposure limits.
(2) Initial entry. Upon initial entry, representative air monitoring shall be conducted
to identify any IDLH condition, exposure over permissible exposure limits or
published exposure levels, exposure over a radioactive material's dose limits or other
dangerous condition such as the presence of flammable atmospheres or oxygen-
deficient environments.
This paragraph expands on site characterization and analysis paragraph (c)(6) by including exposure
limits along with IDLH conditions to monitor.
(3) Periodic monitoring. Periodic monitoring shall be conducted when the possibility
of an IDLH condition or flammable atmosphere has developed or when there is
indication that exposures may have risen over permissible exposure limits or
published exposure levels since prior monitoring. Situations where it shall be
considered whether the possibility that exposures have risen are as follows:
(i) When work begins on a different portion of the site.
(ii) When contaminants other than those previously identified are
being handled.
(in) When a different type of operation is initiated (e.g., drum
opening as opposed to exploratory well drilling).
(iv) When employees are handling leaking drums or containers or
working in areas with obvious liquid contamination (e.g., a spill or
lagoon).
Again, where, when, and why are covered.
(4) Monitoring of high-risk employees. After the actual cleanup phase of any
hazardous waste operation commences; for example, when soil, surface water, or
containers are moved or disturbed; the employer shall monitor those employees likely
to have the highest exposure to hazardous substances and health hazards likely to be
present above permissible exposure limits or published exposure levels by using
personal sampling frequently enough to characterize employee exposures. If the
employees likely to have the highest exposure are over permissible exposure limits
or published exposure limits, then monitoring shall continue to determine all
employees likely to be above those limits. The employer may utilize a representative
sampling approach by documenting that the employees and chemical chosen for
monitoring are based on the criteria stated above.
Note to (h): It is not required to monitor employees engaged in site characterization
operations covered by paragraph (c) of this section.
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These paragraphs state that personal monitoring (how) must be done on high-risk employees (who)
during cleanup activities (when).
Section (q) of 1910.120 addresses emergency responses to hazardous substance releases. It states
in (q)(3)(ii) that
the individual in charge of the ICS (Incident Command System) shall identify, to the
extent possible, all hazardous substances or conditions present and shall address as
appropriate site analysis, use of engineering controls, maximum exposure limits,
hazardous substances handling procedures, and use of any new technologies.
Air monitoring is not specifically mentioned in section (q), but would be a useful, if not necessary,
tool for assessment.
29 CFR 1910.120 is a federal regulation. In states where there is an approved state OSHA (state-
plan state), requirements at least as stringent as 1910.120 must be developed. Thus, in some states
the air monitoring requirements may be more detailed.
U.S. Environmental Protection Agency (EPA)
On June 23, 1989, EPA adopted 40 CFR Part 311, Worker Protection Standards for Hazardous
Waste Operations and Emergency Response. This standard is a duplicate of 1910.120. The
difference in the standards is to whom they apply. The OSHA standard applies to federal agencies,
private industries, and public employees in OSHA state-plan states. The EPA standard applies to
public employees in states that have no OSHA state-plan.
As noted in the previous paragraph, EPA has regulations for monitoring for worker protection.
There are also requirements for monitoring for public protection. However, this subject will not be
discussed here in detail. Additional information is mentioned in this manual in the Exposure Limits
and Action Levels section.
EPA has published guidelines for hazardous material operations which include air monitoring
procedures. General guidelines can be found in the SOSGs. The following topics are discussed in
the SOSGs:
1. Objectives of air monitoring
2. Identifying airborne contaminants
3. Air sampling equipment and media
4. Sample collection and analysis
5. General monitoring practices
6. Meteorological considerations
7. Long-term air monitoring programs
8. Variables in hazardous waste site air monitoring
9. Using vapor/gas concentrations to determine level of protection.
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Other EPA guidance documents are:
• Personal Air Sampling and Air Monitoring Requirements Under 29 CFR 1910.120 fact sheet
• Guidance for Ambient Air Monitoring at Superfund Sites, Volume IV in the Air/Superfund
National Technical Guidance Series
• Compilation of Information on Real-Time Monitoring for use at Superfund Sites
• Removal Program Representative Sampling: Air
• A Compendium of Superfund Field Operations Methods.
EPA's Environmental Response Team (ERT) has developed standard operating procedures for their
air monitoring equipment and strategies. These documents provide information on the why, how,
when, where, and what of air monitoring. Because EPA is concerned with offsite migration and
public exposure along with worker protection, their sampling requirements are broader than OSHA's.
Air monitoring is done onsite to determine the type and quantity of chemicals being released.
Downwind monitoring is done to determine offsite migration. Upwind sampling is done to determine
what background concentrations may be contributing to the downwind and onsite measurements.
This helps determine what the site is contributing to the environment.
Some of the methods use air monitoring equipment to monitor for the presence of chemicals in media
other than air (e.g., soil gas sampling and water headspace).
Other Organizations
The National Institute for Occupational Safety and Health (NIOSH), the American Conference of
Governmental Industrial Hygienists (ACGIH), the American Industrial Hygiene Association (AIHA),
and the American Society for Testing and Materials (ASTM) have publications about air monitoring
strategies. See the References section of this manual for more information.
CHARACTERISTICS OF AIR MONITORING INSTRUMENTS
The selection of equipment to be used must be part of the air monitoring plan. There are many
factors to consider when determining the proper equipment to use. Specific instrument characteristics
related to the following factors can be found in later sections of this manual.
Hazard
The proper equipment must be selected to monitor the hazard or chemical at hand.
Selectivity
Selectivity is the ability of an instrument to detect and measure a specific chemical. If other
chemicals are detected, they are called interferences. Interferences can affect the accuracy of the
instrument reading. In some situations, an instrument (like the combustible gas indicator [CGI]) that
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responds to more than one chemical is desired. Again, the purpose of the monitoring must be
considered.
Sensitivity
Sensitivity is important when slight concentration changes can be dangerous. Sensitivity is defined
as the ability of an instrument to accurately measure changes in concentration. Therefore, 'sensitive"
instruments can detect small changes in concentration.
Accuracy
Accuracy is the measure of how close readings are to true values. It is expressed as % bias. For
example, if an instrument is tested and the average results are 15% higher than the true
concentration, ihen the instrument is said to have a bias of +15%. NIOSH recommends that a
portable direct-reading instrument be withi.1. 25% of the true value 95% of the time.
Precision
Precision is the grouping of the data points. It is a quantitative measure of the variability of a group
of measurements compared to their average value. It is defined by the standard deviation. This
value is a ± qualifier when a value is reported (e.g., 10+1 ppm).
Accuracy and precision are affected by factors such as the instrument's calibration and relative
response.
Calibration
An instrument must be properly calibrated, prior to use, in order to function properly in the field.
Calibration is the process of adjusting the instrument readout so that it corresponds to an actual
concentration. Calibration involves checking the instrument results with a known concentration of
a gas or vapor to see that the instrument gives the proper response. For example, if a combustible
gas meter is checked with a calibration gas that is 20% of the lower explosive limit (LEL), then the
instrument should read 20% of the LEL. If it does not read accurately, it is out of calibration and
should be adjusted until an accurate reading is obtained.
Although an instrument is calibrated to give a one-to-one response for a specific chemical (the
calibration gas), its response to other chemicals is usually different (see Relative Response below).
If the calibration is changed for an instrument, its relative responses will also change. Also, the
instrument may not give a one-to-one response to the chemical for the full range of detection (see
detection range).
Instruments come from the manufacturer calibrated to a specific chemical. The manufacturer
supplies information about how to maintain that calibration. If the user wants to change the
calibration gas, the manufacturer can supply information on how to do so.
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Relative Response
Whereas some instruments may detect more than one chemical, equal concentrations may not give
equal response. The relationship between the instrument's response and the actual concentration of
the chemical is termed the "relative response." Relative response can be calculated by using the
following formula:
Relative Response = Instrument Reading (x m% fof % Rekaive R^po^^
Actual Concentration
For example, if an instrument reading for a 100 ppm concentration of acetone is 63, then the relative
response for that instrument and acetone is 0.63 or 63%. Table 1 gives relative response
information for a particular CGI.
TABLE 1. RELATIVE RESPONSE OF SELECTED CHEMICALS
FOR A CGI CALIBRATED TO PENTANE
Concentration
Chemical {% LED
Methane
Acetylene
Pentane
1,4-Dioxane
Xylene
50
50
50
50
50
Meter Response
(% LED
85
60
50
37
27
Relative Response
(%)
170
120
100
74
54
Source: Portable Gas Indicator, Model 250 and 260, Response Curves,
Mine Safety Appliances Company, Pittsburgh, PA.
Relative responses vary with chemical and instrument. The same chemical may have a relative
response of 63% for one instrument and 120% response for another. Calibration also affects relative
response.
Instruments come from the manufacturer calibrated to a specific chemical. If the instrument is being
used for a chemical that is not the calibration standard, then it may be possible to look at the
manufacturer's information to get the relative response of that instrument for the chemical. Then
the actual concentration can be calculated. For example, if the instrument's relative response for
xylene is 0.27 (27%) and the reading is 100 ppm (parts per million), then the actual concentration
is 370 ppm (0.27 x actual concentration = 100 ppm; actual concentration = 100/0.27 = 370 ppm).
If there is no relative response data for the chemical in question, it may be possible to recalibrate
the instrument. If the instrument has adjustable settings and a known concentration is available, the
instrument may be adjusted to read directly for the chemical. Because recalibration takes time, this
is usually done only if the instrument is going to be used for many measurements of the special
chemical.
10/93 7 Air Monitoring Plans and Strategies
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Detection Range
The operating range is the lower and upper use limits of the instrument. It is defined by the lower
detection limit at one end and the saturation concentration at the other end. The lower detection limit
is the lowest concentration to which an instrument will respond. It is important to use an instrument
with an operating range that will accurately measure the concentration in the range of concern. For
example, a CGI could be used to monitor for methane because methane is combustible. However,
the upper limit of the CGI is the lower explosive limit (LEL) of the chemical. LEL is the lowest
concentration of gas or vapor (in air) that will burn or explode if an ignition source is present at
ambient temperatures. In this case, that would be 5 % methane. If higher concentrations of methane
need to be quantified, another type of instrument would be needed. Also, most CGIs are not
sensitive to ppm concentrations. A different instrument would be needed to measure that range.
Some instruments may respond to the chemical for a range of concentrations but not give a consistent
response throughout the range. The linear range is the range of concentrations over which the
instrument gives response proportional to the chemical concentration.
Response Time
Response time is the time between initial sample contact and readout of the full chemical
concentration. In direct-reading instruments, a rapid response time is desired. Response time for
direct-reading instruments can be from seconds to minutes. The HNU PI-101 gives 90% of full-scale
concentration in 3 seconds. Some hydrogen cyanide detectors may take 90 seconds to give a full
concentration reading. Factors that affect response time are temperature, type of detector, and
sample hose length.
For methods that require air sample collection and analysis, the response time is referred to as the
turnaround time. In other words, how long was the period of time between collection of the sample
and receipt of results from the laboratory?
Mobility
EPA's Field Screening Methods Catalog uses the following terms:
• Portable—Hand-held devices that can be easily carried by one person and require no
external power source.
• Fieldable—Easily transported in a van, pick-up, or four-wheel drive. Particularly
rugged and limited external power required.
• Mobile—Small enough to carry in a mobile lab. Power consideration may limit the
use of many instruments in mobile laboratories. (Size, durability, and power supply
are the main considerations in determining the mobility of an instrument.)
Air Monitoring Plans and Strategies g 10/93
-------
Ease of Operation
Because many of these instruments were designed for industrial use, allowances may not have been
made for using the instrument while wearing protective equipment. One must consider how easy it
is to use the instrument while wearing gloves or how difficult it is to read the meter while wearing
a respirator. Also, how quickly a user can learn to operate the instrument correctly should be
considered.
Preparation time for use of the instrument should be short. Rapid warm-up, easy attachment of
accessories, and quick instrument checks shorten preparation time.
Direct-Reading vs. Sample Analysis
Direct-reading instruments are those that give a response to a chemical within seconds or minutes
of contact. They are also meant to be taken to the location that is to be evaluated. Sample analysis,
however, involves collecting an air sample on a media or in a container and then sending it to an
analytical laboratory. This type of analysis involves much more time—sometimes days longer—than
using a direct-reading instrument.
Personal vs. Area Monitor/Sampler
A personal monitor/sampler is one that can be worn by the worker with the intent of obtaining the
exposure for the wearer. An area monitor/sampler obtains information for the area in which it is
placed. A personal monitor/sampler must be small enough to be worn by the worker and also must
have a battery supply if it is electronic. A personal monitor/sampler is the ultimate in portability.
They range in size from pocket size to a size that can be clipped to a belt without hindering the
wearer. Area samplers can be much larger and can use AC power. Many of the personal monitors
are equipped with warning alarms and with dataloggers to store and calculate exposures.
Inherent Safety
Many of the instruments used for air monitoring will be used in the atmosphere being monitored.
Therefore, they must be safe to use in that environment. Electrical devices, including instruments,
must be constructed to prevent the ignition of a combustible atmosphere. The sources of this ignition
could be an arc generated by the power source itself or the associated electronics, or a flame or heat
source necessary for function of the instrument. The National Fire Protection Association (NFPA)
publishes the National Electrical Code (NEC), which spells out types of areas in which hazardous
atmospheres can be generated and the types of materials that generate these atmospheres. It also lists
design safeguards acceptable for use in hazardous atmospheres.
10/93 9 Air Monitoring Plans and Strategies
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Hazardous Atmospheres
The term "hazardous atmosphere" causes response workers, depending on their backgrounds, to
imagine situations ranging from toxic air contaminants to flammable atmospheres. For NEC
purposes, an atmosphere is hazardous if it meets the following criteria:
• It is a mixture of any flammable material in air whose concentration is within the
material's flammable range (i.e., between the material's lower flammable limit and
its upper flammable limit).
• There is the potential for an ignition source to be present.
• The resulting exothermic reaction could propagate beyond where it started.
To adequately describe hazardous atmospheres, the NEC categorizes them according to their class, group,
and division. Class is a category describing the type of flammable material that produces the hazardous
atmosphere:
• Class I is flammable vapors and gases, such as gasoline and hydrogen. Class I is further
divided into Groups A, B, C, and D on the basis of similar flammability characteristics
(Table 2).
• Class II consists of combustible dusts like coal or grain and is divided into groups E, F,
and G (Table 3).
• Class III is ignitable fibers such as those produced by cotton milling.
TABLE 2. SELECTED CLASS I CHEMICALS BY GROUP
Group
Examples of Chemicals Within Group
Group A Atmospheres acetylene
Group B Atmospheres 1,3-butadiene
Group C Atmospheres carbon monoxide
diethyl ether
dicyclopentadiene
ethyl mercaptan
ethylene oxide
ethylene
hydrazine
hydrogen sulfide
methyl ether
hydrogen
nitropropane
tetrahydrofuran
tetramethyl lead
triethylamine
Group D Atmospheres
acetone
ammonia
benzene
ethanol
fuel oils
gasoline
liquified petroleum gas
methane
methyl ethyl ketone
propane
vinyl chloride
xylenes
Source: NFPA. 1991. Classification of Gases, Vapors, and Dusts for Electrical Equipment in
Hazardous (classified) Locations. National Fire Protection Association, ANSI/NFPA 497M.
Air Monitoring Plans and Strategies
10
10/93
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TABLE 3. SELECTED CLASS II CHEMICALS BY GROUP
Group Characteristics of Group
Group E Conductive Dusts Atmospheres containing metal dusts, including aluminum,
magnesium, and their commercial alloys, and other metals
of similarly hazardous characteristics
Group F Semivolatile Dusts Atmospheres containing carbon black, coal, or coke dust
with more than 8% volatile material
Group G Nonconductive Dusts Atmospheres containing flour, starch, grain, carbonaceous,
chemical thermoplastic, thermosetting and molding
compounds.
Source: NFPA. 1991. Classification of Gases, Vapors, and Dusts for Electrical Equipment
in Hazardous (classified) Locations. National Fire Protection Association, ANSI/NFPA
497M.
Division is the term describing the "location" of generation and release of the flammable material.
• Division 1 is a location where the generation and release are continuous, intermittent,
or periodic into an open, unconfined area under normal conditions. Instruments
certified for Division 1 locations are also called "intrinsically safe."
• Division 2 is a location where the generation and release are only from ruptures,
leaks, or other failures from closed systems or containers.
Using this system, a hazardous atmosphere can be routinely and adequately defined. As an example,
an abandoned waste site containing intact closed drums of methyl ethyl ketone, toluene and xylene
would be considered a Class I, Division 2, Group D environment. However, when transfer of the
flammable liquids takes place at the site, or if releases of flammable gases/vapors are considered
normal, those areas would be considered Class I, Division 1.
Certification
If a device is certified for a given class, division, and group, and it is used, maintained, and serviced
according to the manufacturer's instructions, it will not contribute to ignition. The device is not,
however, certified for use in atmospheres other than those indicated. All certified devices must be
marked to show class, division, and group (Figure 1). Any manufacturer wishing to have an
electrical device certified must submit a prototype to a recognized laboratory for testing. If the unit
passes, it is certified as submitted. However, the manufacturer agrees to allow the testing laboratory
to randomly check the manufacturing plant at any time, as well as any marketed units. Furthermore,
any change in the unit requires the manufacturer to notify the test laboratory, which can continue the
certification or withdraw it until the modified unit can be retested. NFPA does not do certification
testing. Testing and certification is done by such organizations as Underwriters' Laboratory, Inc.
(UL) or Factory Mutual Research Corporation (FM).
10/93 11 Air Monitoring Plans and Strategies
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32L6
LISTED
APPROVED
INTRINSICALLY SAFE COMBINATION
COMBUSTIBLE GAS AND OXYGEN INDICATING
DETECTOR FOR HAZARDOUS LOCATIONS
CLASS I, DIVISION 1, GROUPS A, B, C & D
FIGURE 1. CERTIFICATION LABEL FROM SCOTT® MODEL S-105
COMBUSTIBLE GAS AND 02 INDICATOR
To ensure personnel safety, only approved instruments can be used onsite and only in atmospheres
for which they have been certified. When investigating incidents involving unknown hazards, the
monitoring instruments should be rated for use in the most hazardous locations. The following points
will assist in selection of equipment that will not contribute to ignition of a hazardous atmosphere:
The mention of a certifying group in the manufacturer's equipment literature does
suarantee certification.
guarantee certification.
not
Some organizations test and certify instruments for locations different from the NEC
classifications. The Mine Safety and Health Administration (MSHA) tests
instruments only for use in methane-air atmospheres and in atmospheres containing
coal dust.
In an area designated Division 1, there is a greater probability of generating a
hazardous atmosphere than in Division 2. Therefore, the test protocols for
Division 1 certification are more stringent than those for Division 2. Thus, a device
approved for Division 1 is also permitted for use in Division 2, but not vice versa.
For most response work, this means that devices approved for Class 1 (vapors and
gases), Division 1 (areas of ignitable concentrations), Groups A, B, C, and D should
be chosen whenever possible. At a minimum, an instrument should be approved for
use in Division 2 locations.
There are so many groups, classes, and divisions that it may not be possible to certify
an all-inclusive instrument. Therefore, select a certified device based on the
chemicals and conditions most likely to be encountered. For example, a device
certified for a Class II, Division 1, Group E (combustible metal dust) would offer
little protection around a flammable vapor or gas.
Air Monitoring Plans and Strategies
12
10/93
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Accessories or Options
Many manufacturers offer accessories or options for their instruments. A useful option is an alarm
to alert the user that a concentration level has been exceeded. This is a common feature on CGIs
and oxygen meters.
A recent addition to instruments are microprocessors/dataloggers. This combination can help the
operator calibrate the instrument, store calibration information, make adjustments to the instrument,
store readings so that a readout of concentrations at specific locations or times can be made at the
end of a monitoring period, and report the data. Some units may even do time-weighted averaging
of the concentrations. Some instruments can transfer this information into an external computer for
storage and data manipulation.
Other accessories and options include special sample probes, special carrying cases, and the ability
to change detectors in an instrument.
DATA QUALITY
The Characteristics of Air Monitoring Instruments section discussed instrument characteristics (e.g.,
accuracy, selectivity, and sensitivity) that affect the quality of the data from the air monitoring
instruments. Data quality is a concern and EPA has published a document entitled Data Quality
Objectives for Remedial Response Activities (U.S. EPA 1987) that discusses how to address this
concern.
The data quality objectives (DQOs) basically state that the desired quality of data determines the
amount of time and effort needed to produce the result. There are different levels of data quality.
Table 4 illustrates this point. The higher the analytical level, the better the quality of data.
However, higher analytical levels usually require more time and money.
CONCLUSION
The desired air monitoring instrument is one that is portable, direct-reading, easy to use, and
accurate and precise. The instrument should also respond quickly, be capable of detecting ppb and
% concentrations, be inherently safe, identify and give concentrations of all the chemicals and
hazards in an atmosphere, and do its job while the operator is sitting at a safe distance from the
hazardous material site or spill. Unfortunately, no instrument meets these criteria. Thus, a variety
of instruments are needed depending on the air monitoring plan.
When preparing an air monitoring plan, the operator must determine why, how, when, and where
the monitoring is to be done and what equipment is necessary. In addition, there are legal
requirements to comply with. Guidance documents are available to assist in complying with these
requirements. Other factors must also be considered when selecting the monitoring equipment.
Additional information on why to sample, or what to sample for, will be covered in the Exposure
Limits and Action Levels section of the course. Characteristics of the various types of equipment will
also be discussed in later sections.
10/93 13 Air Monitoring Plans and Strategies
------- An error occurred while trying to OCR this image.
-------
EXPOSURE LIMITS AND
ACTION LEVELS
PERFORMANCE OBJECTIVES
At the end of this lesson, participants will be able to:
• Identify the three sources of exposure limits specified in
OSHA's 29 CFR 1910.120Hazardous Waste Operations and
Emergency Response standard
• Define the terms "time-weighted average (TWA) limit,"
"short-term exposure limit," and "ceiling limit"
• Given the identity and concentration of a chemical exposure,
determine whether an exposure limit is exceeded
• Calculate an 8-hour TWA exposure when given a chemical's
exposure concentration and the duration of the exposure
• List the three uses mentioned in 1910.120 for exposure
limits
• List three of the five applications for which the American
Conference of Governmental Industrial Hygienists states the
threshold limit values should not be used
• List EPA's action levels for oxygen, combustible gas, and
radiation and the actions associated with each level.
-------
NOTES
EXPOSURE LIMITS AND
ACTION LEVELS
EXPOSURE LIMITS
(29 CFR Part 1910.120)
Permissible Exposure Limits (PELs)
- 29 CFR Part 1910, Subparts G
and 2, Occupational Safety and
Health Administration (OSHA)
EXPOSURE LIMITS
(29 CFR Part 1910.120)
Published Exposure Levels
- NIOSH Recommendations for
Occupational Health Standards,
1986
- American Conference of
Governmental Industrial Hygienists1
(ACGIH) Threshold Limit Values
(TLVs) and Biological Exposure
Indices (BEIs) for 1987-1988
10/93
Exposure Limits and Action Levels
-------
NOTES
EXPOSURE LIMITS
Sources
• OSHA
- PELs
- Legal requirements
- 1968 TLVs and American National
Standards Institute (ANSI)
- 29 CFR 1910.1000 (tables)
- Specific standards - benzene
EXPOSURE LIMITS
Sources
National Institute for Occupational
Safety and Health (NIOSH)
- Recommended exposure limits
(RELs)
- May be legal (1910.120)
- Rationale in criteria documents
- Immediately dangerous to life or
health (IDLH)
EXPOSURE LIMITS
Sources
• ACGIH
- TLVs
- Recommendations
- May be legal (1910.120)
- Yearly booklet
- Documentation
Exposure Limits and Action Levels
10/93
-------
NOTES
EXPOSURE GUIDELINES
Sources
American Industrial Hygiene
Association (AIHA)
- Workplace environmental
exposure levels (WEELs)
- Recommendations
- Yearly updates
- Documentation
EXPOSURE GUIDELINES
Sources
Other
- U.S. Army and U.S. Air Force
- Mine Safety and Health
Administration (MSHA)
- Other countries (e.g., Federal
Republic of Germany maximum
concentration values in the
workplace (MAKs))
TIME-WEIGHTED AVERAGE
(TWA)
c
o
c
Q)
O
C
o
O
750 /- r r\-~
TWA-EL
3PM
10/93
Exposure Limits and Action Levels
-------
NOTES
TIME-WEIGHTED AVERAGE CALCULATION
Exposures: 1500 ppm for 1 hour
500 ppm for 3 hours
200 ppm for 4 hours
(1 hr)(1500 ppm) + (3 hrs)(500 ppm) + (4 hrs)(200 ppm)
8hrs
1500 ppm + 1500 ppm + 800 ppm
8
475 ppm
SHORT-TERM EXPOSURE LIMIT
(STEL)
c
o
I
+-»
c
0)
o
c
0
o
1000
750 -
6AM
3PM
STEL
Excursions to the STEL
• Should not be longer than 15
minutes in duration (OSHA, NIOSH,
ACGIH)
• Should be at least 60 minutes
apart (ACGIH)
• Should not be repeated more than
4 times per day (ACGIH)
• Supplement TWA
Exposure Limits and Action Levels
10/93
-------
NOTES
CEILING
(C)
c
o
1
«->
0)
u
o
o
Calling
6AM
10AM
Time
3PM
CEILING
The exposure that shall not be exceeded
during any part of the work day. If
instantaneous monitoring is not feasible,
the ceiling shall be assessed as a 15-minute
TWA exposure (unless otherwise specified)
that shall not be exceeded at any time
during a work day
Source: NIOSH Recommendations lor Occupational Safety end Health. 1992.
COMPARISON OF EXPOSURE LIMITS
Chemical OSHA NIOSH
Acetone 1000* 250
Benzene 1/5 0.1 /C 1
Lead (mg/m3) 0.05 <0.1
Benzaldehyde NA NA
Note: • units are ppm; TWA/STEL
1 ) indicates intended change
ACGIH
750/1000
10 (0.1)
0.15 (0.05)
NA
4/94
Exposure Limits and Action Levels
-------
NOTES
IDLH
"...means an atmospheric concentration
of any toxic, corrosive, or asphyxiant
substance that poses an immediate threat
to lite or would cause irreversible or
delayed adverse health effects or would
interfere with an individual's ability to
escape from a dangerous atmosphere."
Source- 2P CFR TB10 T20(e)
IDLH
IDLH concentrations represent the maximum
concentration from which, in the event of
respirator failure, one could escape within
30 minutes without a respirator and without
experiencing any escape-impairing or
irreversible health effects.
Note: IDLH level defined by the Standards
Completion Program - NIOSH/OSHA -
only ior purposes oi respirator selection
IDLH VALUES
Examples
Chemical
IDLH
Acetone
Benzene
Lead
Tetraethyl lead
Benzaldehyde
Source: NIOSH Pockef Guide to Chemical Hazards. 1990.
20,000 ppm (LEL?)
Ca (3000 ppm)
700 mg/m3
40 mg/m3
Not available
Exposure Limits and Action Levels
JO/93
-------
NOTES
EVALUATION OF A MIXTURE
^ /i _i_ r* i\ _i_ c* i\
= U /L + U /L +... U /L
rn 11 z t n n
Em = the equivalent exposure for the mixture
C = the concentration of a particular contaminant
L = the exposure limit for that contaminant
EVALUATION OF A MIXTURE
Example
Chemical A C = 500 ppm L = 750 ppm (TWA)
Chemical B C = 200 ppm L = 500 ppm (TWA)
Chemical C C = 50 ppm L = 200 ppm (TWA)
Em = (500/750) + (200/500) + (50/200)
Em = 0.67 + 0.40 + 0.25
E =1.3
EVALUATION OF A MIXTURE
Em should not exceed 1
•m
The calculation applies to chemicals
where the effects are the same and
are additive
Do not mix TWAs, STELs, or ceilings
10/93
Exposure Limits and Action Levels
-------
NOTES
EXPOSURE LIMITS
Used to determine:
• Site characterization
• Medical surveillance
• Exposure controls
- Engineered controls
- Work practices
- Personal protective equipment
(PPE)
Source; 29 CFR 1910.120
THRESHOLD LIMIT VALUES
Not intended for use:
• As a relative index of toxicity
• In the evaluation or control of
community air pollution nuisances
• In estimating the toxic potential of
continuous, uninterrupted exposures
or other extended work periods
Source: ACGIH TLVs andBEIs for 1993-1994
THRESHOLD LIMIT VALUES
Not intended for use:
• As proof or disproof of an existing
disease or condition
• For adoption by countries whose
working conditions differ from those
in the United States of America and
where substances and processes differ
Source: ACGIH TLVs and BEIs for 1993-1994
Exposure Limits and Action Levels
10/93
-------
NOTES
ENVIRONMENTAL
EXPOSURE LIMITS
• U.S. EPA
- National Ambient Air Quality
Standards Program (NAAQS)
• State/Local
- NAAQS
- Modified TLVs
- Risk assessment
ACTION GUIDE
• The chemical concentration or instrument
reading at which a specific action should
be taken
• Sources:
- EPA Standard Operating Safety
Guides (SOSGs)
- OSHA standards for specific chemicals
may require an action (e.g., medical
monitoring) if one-half the PEL is
reached (action level)
EPA ACTION GUIDES
Combustible Gas Indicator
Level
Action
<10%LEL
10-25% LEL
>25% LEL
Continue monitoring
with caution
Continue monitoring,
but with extreme
caution
Explosion hazard!
Withdraw from area
immediately.
Confined space
4/94
Exposure Limits and Action Levels
-------
NOTES
EPA ACTION GUIDES
Oxygen Concentration
Level
Action
<18.5% Monitor wearing SCBA.
18.5-25% Continue monitoring
with caution. SCBA
not needed based only
on oxygen content
>25% Discontinue monitoring.
Fire potential!
Consult specialist
Exposure Limits and Action Levels
4/94
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EXPOSURE LIMITS AND ACTION LEVELS
INTRODUCTION
It is necessary, for response activities involving hazardous materials, to acknowledge and plan that
response personnel may become exposed. Most hazardous materials have levels of exposure that can
be tolerated without adverse health effects. However, it is imperative to determine:
• The identity of materials involved
• The type and extent of exposure
• The possible health effects from overexposure
• The exposure limits and/or action levels considered safe for each hazardous material
encountered.
SOURCES FOR EXPOSURE LIMITS FOR AIRBORNE CONTAMINANTS
Several organizations have proposed exposure limits for chemicals and other hazards. The
Occupational Safety and Health Administration (OSHA) is one such organization. It is charged with
protecting the health and safety of workers. In 29 CFR 1910.120, the Hazardous Waste Operations
and Emergency Response standard, OSHA specifies the use of certain exposure limits. The exposure
limits that are specified are OSHA's permissible exposure limits (PELs) and "published exposure
levels." The published exposure levels are used when no PEL exists. A published exposure level
is defined as:
the exposure limits published in "NIOSH Recommendations for Occupational Health
Standards" dated 1986 incorporated by reference. If none is specified, the exposure
limits published in the standards specified by the American Conference of
Governmental Industrial Hygienists in their publication "Threshold Limit Values and
Biological Exposure Indices for 1987-88" dated 1987 incorporated by reference. (29
CFR 1910.120 (a)(3))
Organizations that have developed exposure limits are discussed below. Not all of these groups are
specifically mentioned in 1910.120. Many of the following organizations have exposure guidelines
for exposures to hazards other than airborne contaminants (e.g. heat stress, noise, radiation). This
part will deal only with airborne chemical exposures.
Occupational Safety and Health Administration
In 1971, the OSHA promulgated PELs. These limits were extracted from the 1968 American
Conference of Governmental Industrial Hygienists' (ACGIH) threshold limit values (TLVs), the
American National Standards Institute (ANSI) standards, and other federal standards. The PELs are
found in 29 CFR 1910.1000. Since then, additional PELs have been adopted and a few of the
10/93 \ Exposure Limits and Action Levels
-------
originals have been changed. These initial changes have been incorporated into specific standards
for chemicals (e.g., 29 CFR 1910.1028 - benzene). There are also standards for 13 carcinogens for
which there is no allowable inhalation exposure.
OSHA is a regulatory agency. Therefore, its PELs are legally enforceable standards and apply to
all private industries and federal agencies. Depending on state or local laws, the PELs may also
apply to state and local employees.
National Institute for Occupational Safety and Health
NIOSH was formed at the same time as OSHA. NIOSH conducts scientific research and
recommends occupational safety and health standards. The exposure levels NIOSH has researched
have been used to develop new OSHA standards. However, many recommended exposure limits
(RELs) have not been adopted by OSHA. Unless OSHA adopts NIOSH RELs into a standard (like
1910.120), they are only recommendations. The RELs are found in the NIOSH Recommendations
for Occupational Health Standards.
NIOSH also publishes criteria documents that provide information on handling specific chemicals.
These documents also provide rationale for the chemical's exposure limit. Additionally, NIOSH
publishes immediately dangerous to life or health (IDLH) values in its Pocket Guide to Chemical
Hazards. IDLHs will be discussed later.
American Conference of Governmental Industrial Hygienists
One of the first groups to develop exposure limits was ACGIH. In 1941, ACGIH suggested the
development of maximum allowable concentrations (MACs) for use by industry. A list of MACs
was compiled by ACGIH and published in 1946. In the early 1960s, ACGIH revised those
recommendations and renamed them TLVs.
"Threshold Limit Values (TLVs) refer to airborne concentrations of substances and represent
conditions under which it is believed that nearly all workers may be repeatedly exposed day after day
without adverse health effects." (Threshold Limit Values for Chemical Substances and Physical
Agents and Biological Exposure Indices, ACGIH). The publication further states that the TLVs "are
developed as guidelines to assist in the control of health hazards. These recommendations or
guidelines are intended for use in the practice of industrial hygiene, to be interpreted and applied
only by a person trained in this discipline." (Policy Statement on the Uses of TLVs and BEIs).
Along with the TLVs, ACGIH publishes biological exposure indices (BEIs). BEIs are to be used
as guides for evaluation of exposure where inhalation is not the only possible route of exposure.
Because the TLVs are for inhalation only, they may not be protective if the chemical is ingested or
absorbed through the skin. Biological monitoring (e.g., urine samples and breath analysis) can be
used to assess the overall exposure. This procedure uses information about what occurs in the body
(e.g., metabolism of benzene to phenol) to determine if there has been an unsafe exposure. The
BEIs serve as a reference for biological monitoring just as TLVs serve as a reference for air
monitoring.
Exposure Limits and Action Levels 2 • 10/93
-------
The TLVs are reviewed yearly and are published in ACGIH's Threshold Limit Values for Chemical
Substances and Physical Agents and Biological Exposure Indices.
American Industrial Hygiene Association (AIHA)
The AIHA has provided guidance for industrial hygienists for many years. In 1984, AIHA
developed exposure guidelines that it calls Workplace Environmental Exposure Level Guides
(WEELs®). These are reviewed and updated each year. Although the list is not as large as others,
AIHA has chosen chemicals for which other groups have not developed exposure limits. Thus, they
are providing information to fill the gaps in information sources.
Other Organizations
In the United States, the Army and Air Force have also developed exposure limits for their purposes.
The Mine Safety and Health Administration (MSHA) has health standards for air contaminants that
may be encountered during mining activities.
Other countries have also developed exposure limits. An example are the Federal Republic of
Germany's maximum concentrations at the workplace (MAKs). They can be found in ACGIH's
Guide to Occupational Exposure Values along with PELs, RELs, and TLVs.
Even though the other organizations are not part of the list of published exposure limits in 1910.120,
they are sources that may be useful. 1910.120 (g) suggests looking at published literature and
material safety data sheets (MSDS) if PELs or published exposure limits do not exist.
TYPES OF EXPOSURE GUIDELINES
Although there are different organizations that develop exposure guidelines, the types of guidelines
they produce are similar.
Time-Weighted Average (TWA)
A TWA exposure limit is the average concentration of a chemical most workers can be exposed to
during a 40-hour work week and a normal 8-hour work day without showing any toxic effects.
Some TWA exposure limits (e.g., NIOSH) can also be used to evaluate exposures up to 10 hours.
The TWA permits exposure to concentrations above the limit, provided these excursions are
compensated by equivalent exposure below the TWA. Figure 1 shows an example that illustrates
this point for a chemical (e.g., acetone) with a TWA exposure limit of 750 ppm.
A TWA exposure is determined by averaging the concentrations during the different exposure periods
over an 8-hour period with each concentration weighted based on the duration of exposure. For
example, an exposure to acetone at the following concentrations and durations would have an 8-hour
TWA exposure of:
10/93 3 Exposure Limits and Action Levels
-------
1500 ppm for 1 hour
500 ppm for 3 hours
200 ppm for 4 hours
(1 /ir)(1500 ppm) + (3 hrs)(500 ppm) + (4
8 hrs
ppm) _
1500 ppm + 1500 ppm + 800 ppm
8
This exposure would be compared to an 8-hour TWA exposure limit.
c
o
0)
o
c
o
O
750
TWA-EL
3 PM
FIGURE 1. EXAMPLE OF AN EXPOSURE COMPARED TO A TWA EXPOSURE LIMIT
Short-Term Exposure Limit (STEL)
The excursions allowed by the TWA exposure could involve very high concentrations. This might
cause an adverse effect but still be within the allowable average. Therefore, some organizations felt
there was a need to limit these excursions. OSHA, NIOSH, and ACGIH define the STEL as a 15-
minute TWA exposure limit. ACGIH has the additional stipulation that excursions to the STEL
should not be longer than 15 minutes in duration, should be at least 60 minutes apart, and should not
be repeated more than 4 times per day. Figure 2 illustrates an exposure that does not exceed the
Exposure Limits and Action Levels
10/93
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15-minute limit for an STEL of 1000 ppm (note that in the previous example of an 8-hour TWA
calculation, the acetone STEL was exceeded but the TWA was not).
The STEL supplements the TWA and does not replace it. Both exposure limits should be used. The
STEL reflects an exposure limit protecting against acute effects from a substance which primarily
exhibits chronic toxic effects. This concentration is set at a level to protect workers against
irritation, narcosis, and irreversible tissue damage.
AIHA has some short-term TWAs that are similar to the STELs. The times used vary from 1 to 30
minutes. These short-term TWAs are used in conjunction with, or in place of, the 8-hour TWA.
There is no limitation on the number of these excursions or the rest period between each excursion.
C
o
Q)
O
C
O
O
1000
750
STEL
TWA-EL
6AM
10AM
Time
3PM
FIGURE 2. EXAMPLE OF AN EXPOSURE COMPARED TO AN STEL AND A TWA
Ceiling (C)
Ceiling values exist for substances for which exposure could result in a rapid and specific response.
The ceiling is that concentration that should not be exceeded during any part of the work day. If
instantaneous monitoring is not feasible, the ceiling shall be assessed as a 15-minute TWA exposure
(unless otherwise specified) that shall not be excluded at any time during a work day. A ceiling
value is denoted by a "C" preceding the exposure limit.
Figure 3 illustrates an exposure that exceeds a ceiling value of 5 ppm.
10193
Exposure Limits and Action Levels
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c
o
c
CD
O
C
o
O
0
Ceiling
6AM
10AM
Time
3 PM
FIGURE 3. EXAMPLE OF AN EXPOSURE COMPARED TO A CEILING EXPOSURE LIMIT
Peaks
"Acceptable maximum peak" concentrations can be found in OSHA's 1910.1000 Table Z-2.
Table Z-2 contains exposure limits that OS HA had adopted from ANSI. This peak exposure is an
allowable excursion above the ceiling values for the chemicals. The duration and number of
exposures at this peak value is limited. For example, for those industries not incorporated in
1910.1028, OSHA allows the 25-ppm ceiling value for benzene to be exceeded to 50 ppm, but only
for 10 minutes during an 8-hour period.
Skin Notation
Whereas these exposure guidelines are based on exposure to airborne concentrations of chemicals,
the organizations recognize that there are other routes of exposure in the workplace. In particular,
there can be a contribution to the overall exposure from skin contact with chemicals that can be
absorbed through the skin. Unfortunately, there are few data available that quantify the amount of
allowable skin contact.
Some organizations provide qualitative information about skin-absorbable chemicals. When a
chemical has the potential to contribute to the overall exposure by direct contact with the skin,
mucous membranes, or eyes, it is given a "skin" notation.
This skin notation not only points out chemicals that are readily absorbed through the skin, but also
notes that if there is skin contact, the exposure limit for inhalation may not provide adequate
Exposure Limits and Action Levels
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protection. The inhalation exposure limit is designed for exposures only from inhalation. If
additional routes of exposure are added, there can be detrimental effects even if the inhalation
exposure limit is not exceeded.
Immediately Dangerous to Life or Health (IDLH)
As defined in the NIOSH Pocket Guide to Chemical Hazards, "IDLH concentrations represent the
maximum concentration from which, in the event of respirator failure, one could escape within 30
minutes without a respirator and without experiencing any escape-impairing or irreversible health
effects." Although 30 minutes is stated in the definition, this is not a 30 minute allowable exposure
limit. NIOSH's purpose in developing this IDLH was for respirator selection.
Other organizations, such as ANSI, OSHA, and MSHA, have similar definitions for IDLH, but not
always the same application. It is accepted by all of these groups that IDLH conditions include 1)
toxic concentrations of contaminants, 2) oxygen-deficient atmospheres, and 3) explosive, or near-
explosive (above, at, or near the lower explosive limits), environments.
Guidelines for potentially explosive, oxygen-deficient, or radioactive environments can be found in
the EPA's Standard Operating Safety Guides and the NIOSH/OSHA/USCG/EPA publication entitled
Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities.
At hazardous material incidents, IDLH concentrations should be assumed to represent concentrations
above which only workers wearing respirators that provide the maximum protection (i.e., a positive-
pressure, full-facepiece, self-contained breathing apparatus [SCBA] or a combination positive-
pressure, full-facepiece, supplied-air respirator with positive-pressure escape SCBA) are permitted.
Specific IDLH concentration values for many substances can be found in the NIOSH Pocket Guide
to Chemical Hazards. For some chemicals, NIOSH gives a "Ca" designation along with a
concentration for IDLH. Ca denotes those chemicals that NIOSH considers to be potential human
carcinogens. NIOSH recommends the highest level of respiratory protection for exposure to these
substances, even below IDLH. However, carcinogenic effects were not considered when developing
the IDLH concentrations.
MIXTURES
The exposure limits that have been discussed are based on exposure to single chemicals. Because
many exposures include more than one chemical, values are adjusted to account for the combination.
When the effects of the exposure are considered to be additive, a formula can be used to determine
whether total exposure exceeds the limits. The following calculation is used:
Em = (C.-5-L.) + (Cz-5-Lz) + . . . (Cn-Ln)
where:
Em = the equivalent exposure for the mixture
C = the concentration of a particular contaminant
L = the exposure limit for that substance.
10/93 7 Exposure Limits and Action Levels
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The value of Em should not exceed unity (1).
An example using this calculation would be as follows:
Chemical A C = 500 ppm; L = 750 ppm (TWA)
Chemical B C = 200 ppm; L = 500 ppm (TWA)
Chemical C C = 50 ppm; L = 200 ppm (TWA)
Em = (500+750) + (200+500) + (50+200)
Em = 0.67 + 0.40 + 0.25
Em = 1.3
Because Em exceeds unity, the exposure combination may be a problem. The next step should be
to determine whether exposure limits are based on similar effects. This calculation applies to
chemicals where the effects are the same and are additive. If the combination is not additive, the
calculation is not appropriate. Also, mixing TWA, STEL, and ceiling limits in this equation is not
appropriate.
APPLICATION OF EXPOSURE GUIDELINES
OSHA's Hazardous Waste Operations and Emergency Response standard specifies uses for exposure
limits.
Site Characterization
29 CFR 1910.120 (c) (3) requires identification of IDLH conditions during site characterization.
29 CFR 1910.120 (h) (3) requires air monitoring upon initial entry to identify IDLH conditions,
other dangerous conditions, and exposures over the exposure limits.
Medical Surveillance
29 CFR 1910.120 (f) (2) (i) requires a medical surveillance program for all employees exposed to
substances or hazards above the PEL for 30 or more days per year. If there is no PEL, then the
published exposure levels are used for evaluation. The exposures are considered even if a respirator
was being used at the time of exposure.
Exposure Controls
Engineered Controls and Work Practices
29 CFR 1910.120 (g) (1) (i) states "Engineering controls and work practices shall be instituted to
reduce and maintain employee exposure to or below the permissible exposure limits for substances
regulated by 29 CFR Part 1910, to the extent required by Subpart Z, except to the extent that such
Exposure Limits and Action Levels g 10/93
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controls and practices are not feasible." [emphasis added] Whenever engineering controls and work
practices are not feasible, personal protective equipment shall be used to reduce and maintain
exposures.
For those substances or hazards where there is no PEL, the published exposure levels are used. If
there are no PELs or published exposure limits, published literature and MSDS may be used for
evaluation. In these circumstances, a combination of engineering controls, work practices, and
personal protective equipment (PPE) shall be used to reduce and maintain exposures.
Personal Protective Equipment
Because the selection of PPE must be based on the hazards present at the site, the exposure limits
are used to evaluate the appropriate PPE. Comparing the actual or expected exposure to the PEL
or other exposure limits gives the wearer information on selection of the proper PPE.
LIMITATIONS AND RESTRICTIONS OF USE
The exposure guidelines discussed in this section are based on industrial experience, experimental
human studies, experimental animal studies, or a combination of the three. The guidelines were
developed for workers in the industrial environment. Thus, they are not meant to be used for other
purposes. ACGIH in its Threshold Limit Values and Biological Exposure Indices states:
These limits are intended for use in the practice of industrial hygiene as guidelines
or recommendations in the control of potential health hazards and for no other use,
e.g., in the evaluation or control of community air pollution nuisances; in estimating
the toxic potential of continuous, uninterrupted exposures or other extended work
periods; as proof or disproof of an existing disease or physical condition; or adoption
by countries whose working conditions differ from those in the United States of
America and where substances and processes differ. These limits are not fine lines
between safe and dangerous concentration nor are they a relative index of toxicity.
They should not be used by anyone untrained in the discipline of industrial hygiene.
As can be seen from this qualifier, these exposure limits are not intended as exposure limits for
exposure to the public.
There is the limitation on the use of the exposure guideline as a relative index of toxicity. This is
because the exposure limits are based on different effects for different chemicals. For example, the
TLV-TWA for acetone is chosen to prevent irritation to the eyes and respiratory system. The TLV-
TWA for acrylonitrile is chosen to reduce the risk to cancer. Exposures to these chemicals at other
concentration levels could lead to other effects. Thus, when evaluating the risk of chemical
exposure, consult the documentation for the exposure limit along with other toxicological data.
10/93 9 Exposure Limits and Action Levels
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NON-OCCUPATIONAL EXPOSURE LIMITS
As mentioned earlier, the occupational exposure limits are not intended for use in evaluating public
health hazards. However, they are often used because there may not be anything else available. In
other situations, a group may feel that the exposure may be for a short duration and the occupational
exposure limits are adequate. For example, many computer air dispersion models for emergency
response use the TLVs as action levels.
Some agencies have applied modifiers to the occupational exposure limits to adjust them for public
health use. These modifiers may include adjustments for exposure time (168 hours for the public
compared to 40 hours for occupational situations) and safety factors for sensitive populations
(dividing the exposure limit by 10). While groups like ACGIH discourage this application of their
data, the users argue that modification of human data is preferred to extrapolation of animal data.
In some cases, ambient air quality standards or guidelines have been developed for application to
public exposure. The federal government and many states have developed them. They are based
on modification of occupational exposure limits, risk assessment data, or both. EPA has developed
national ambient air quality standards in response to the Clean Air Act. The current list is very
limited and only some chemicals (e.g., lead and particulates) are applicable to waste sites.
In the risk assessment approach for chemical exposure, it is recognized that the public exposure to
a chemical may involve more than one route of exposure. With this approach, it is not appropriate
to use just an inhalation exposure limit. Results from air sampling are combined with other sample
results (e.g., drinking water and soil) to determine total exposure and risk.
ACTION LEVELS
Action levels can be developed for specific chemicals, hazards, or situations. The concept of an
action level is that if the action level is not exceeded, then there is little probability that a hazardous
exposure will occur.
In some of its specific standards, OSHA uses an action level that is one-half of the PEL. For
example, the action level for benzene is 0.5 ppm calculated as an 8-hour TWA. If this level is
exceeded, continual air monitoring and medical surveillance can be required.
EPA in its Standard Operating Safety Guides gives actions to take if certain instrument readings
(levels) are obtained during monitoring. These are listed in Table 1.
In some situations, site-specific action levels for direct-reading instruments may be developed. This
is done by using knowledge about what chemicals are present on the site and the instrument's
response to the chemicals. Whereas this may not be as accurate as using special monitoring
equipment and laboratory analysis, it allows rapid response to a potentially hazardous situation.
Exposure Limits and Action Levels \Q 10/93
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CONCLUSION
There are many sources for exposure limits and action levels. Some of these are legal requirements;
some are guidelines. The goal is to use these numbers to protect personnel working with hazardous
materials.
10/93 11 Exposure Limits and Action Levels
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TABLE 1. ATMOSPHERIC HAZARD ACTION GUIDES
Monitoring
Equipment
Atmospheric
Hazard'
Level
Action
Combustible gas
indicator
Explosive <10%LEL Continue monitoring with caution.
10-25% LEL Continue monitoring, but with
extreme caution, especially as higher
levels are encountered.
>25% LEL Explosion hazard! Withdraw from
area immediately.
<19.5% Monitor wearing SCBA. Note:
Combustible gas readings not valid in
atmospheres with less than 19.5%
oxygen.
19.5-25% Continue monitoring with caution.
SCBA not needed based only on
oxygen content.
>25% Discontinue monitoring. Fire
potential! Consult specialist.
Oxygen
concentration
Radiation survey
instrument
Gamma
radiation
Above
background:
< 1mR/hr
mR/hr
Continue monitoring. Consult a
Health Physicist.
Withdraw. Continue monitoring only
upon the advice of a Health Physicist.
Colorimetric Organic and Depends on Consult reference manuals for air
tubes inorganic chemical concentration vs. PEL/TLV and
vapors/gases toxicity data.
Photoionization
detector
Flame ionization
detector
Organic Depends on Consult reference manuals for air
vapors/gases chemical concentration vs. PEL/TLV and
toxicity data.
Organic Depends on Consult reference manuals for air
vapors/gases chemical concentration vs. PEL/TLV and
toxicity data.
" Hazard classes are general and not all compounds in these classes can be measured by realtime
instruments.
Note: The correct interpretation of any instrument readout is difficult. If the instrument operator
is uncertain of the significance of a reading, especially if conditions could be unsafe, a technical
specialist should immediately be consulted. Consideration should be given to withdrawing personnel
from the area until approval by the safety officer is given to continue operations.
Exposure Limits and Action Levels
12
10/93
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OXYGEN MONITORS,
COMBUSTIBLE GAS INDICATORS, AND
SPECIFIC CHEMICAL MONITORS
PERFORMANCE OBJECTIVES
At the end of this lesson, participants will be able to:
• Identify the purpose for oxygen monitoring
• List the four factors that can affect oxygen monitor response
• Identify the purpose for combustible gas monitoring
• List the four factors that can affect combustible gas indicator
response
• Identify the purpose of toxic atmosphere monitoring
• List three types of toxic atmosphere monitors
• List four types of specific chemical monitors
• List four factors that can affect the response of specific
chemical monitors.
-------
NOTES
OXYGEN MONITORS,
COMBUSTIBLE GAS INDICATORS,
AND
SPECIFIC CHEMICAL MONITORS
HAZARDS
Oxygen-deficient atmospheres
Combustible/explosive atmospheres
Toxic atmospheres
Radiation
OXYGEN MONITORING
Aid in determining:
• Type of respirator needed
• Flammability risk
• Sufficient oxygen for combustible
gas indicators (CGIs)
• Presence of contaminants
JO/93
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
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NOTES
OXYGEN SENSOR
I III
Membrane / Cover
Electrode
OXYGEN MONITORS
Considerations
Life span
Operating temperature
Interfering gases
Atmospheric pressure
ALTITUDE/OXYGEN
METER READING
Instrument calibrated
at sea level
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
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NOTES
FLAMMABLE
ATMOSPHERE MONITORING
• Used to determine risk of fire or
explosion
• CGI readings are indicative of
relatively high concentrations of
contaminants
COMBUSTIBLE GAS INDICATORS
Catalytic Sensors
KHHDl
Filament
Bead
COMBUSTIBLE GAS INDICATORS
Wheatstone Bridge Circuit
Sensor
Compensating
Filament
JO/93
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
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NOTES
COMBUSTIBLE GAS INDICATORS
Instrument Reading vs Concentration
Concentration
0%
LEL UEL
5%* 15%*
100%
0% 100%
Meter Reading (% LEL)
Note: * = methane
LEL = lower explosive limit
UEL = upper explosive limit
COMBUSTIBLE GAS INDICATORS
Readouts
UEL
COMPARISON OF LEL READINGS
WITH ACTUAL CONCENTRATIONS
HexaneLEL = 1.1%
For an instrument calibrated to hexane measuring hexane:
100% =1.1% (11,000ppm)
50% =0.55% (5,500 ppm)
25% =0.275% (2,750 ppm)
10% =0.11% (1,100 ppm)
1% =0.011% (110 ppm)
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
10/93
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NOTES
COMBUSTIBLE GAS INDICATORS
Readout Ranges
"Normal" units
- 0-100%LEL
- 0-10%LEL
"Supersensitive" units
- Parts per million (ppm)
- Example: TLV Sniffer,
Gastech Model 1314
COMBUSTIBLE GAS INDICATORS
Considerations
Oxygen requirements
Contaminants that foul sensor
Temperature
Relative response
COMBUSTIBLE GAS INDICATORS
Relative Response Curves
100,
Mathin*
Pentane
o>
TJ
s
? 50
»
"5
£-
1
St/rtiM
Source: MSA 260
0 50 100
Percent LEL
JO/93
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
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NOTES
TOXIC ATMOSPHERE
MONITORING
The purpose of monitoring is to:
• Identify chemicals and their
concentrations
• Evaluate worker/public exposures
• Evaluate protective equipment
selection
• Help develop exposure controls
TOXIC ATMOSPHERE
MONITORS
• Specific chemical monitors
• Total vapor survey monitors
• Gas chromatographs
• Aerosol monitors
SPECIFIC CHEMICAL
MONITORS
Designed to respond to a specific
chemical
Common types include
- Electrochemical
- Metal-oxide semiconductor (MOS)
- Colorimetric indicators
- Mercury detectors
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
4/94
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NOTES
METAL-OXIDE
SEMICONDUCTOR (MOS)
• Metal-oxide coating on a ceramic substrate
wrapped around a wire
• Contaminant alters conductivity by
removing oxygen
• Change in current is proportional to the
amount of contaminant present
• Also called "solid-state" sensor
MOS
Considerations
• Interferences
• Saturation
Temperature
Minimum oxygen requirements
COLORIMETRIC INDICATORS
Contaminant reacts with a chemical on
a tape, badge, or tube and causes a
color change
10/93
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
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NOTES
COLORIMETRIC INDICATORS
Considerations
• Interferences
• Humidity
• Temperature
MERCURY DETECTORS
• Ultraviolet light absorption
- Mercury vapor absorbs a specific
wavelength of light
• Gold film
- Mercury reacts with film and
changes the electrical resistance
of the film
MERCURY DETECTORS
Considerations
• Ultraviolet light
- Interferences
- Humidity
• Gold film
- Factory calibration
- AC power needed to "clean"
Oxygen Monitors, CGIs, and
Specific Chemical Monitors
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OXYGEN MONITORS, COMBUSTIBLE GAS INDICATORS,
AND SPECIFIC CHEMICAL MONITORS
INTRODUCTION
Many hazards may be present when responding to hazardous materials spills or uncontrolled waste
sites. These include oxygen-deficient atmospheres, combustible/explosive atmospheres, toxic
atmospheres, and radiation. There are several types of instrumentation for detecting hazardous
atmospheres. This section will discuss oxygen monitors, combustible gas indicators (CGIs), and
monitors for specific chemicals.
OXYGEN MONITORS
Oxygen monitors are used to evaluate an atmosphere for:
• Oxygen content for respiratory purposes. Normal air contains 20.8% oxygen
Generally, if the oxygen content decreases below 19.5%, it is considered oxygen-
deficient and special respiratory protection is needed.
• Increased risk of combustion. Generally, concentrations above 25% are considered
oxygen enriched and increase the risk of combustion.
• Use of other instruments. Some instruments require sufficient oxygen for operation.
For example, CGIs do not give reliable results at oxygen concentrations below 10%.
Also, the inherent safety approvals for instruments are for normal atmospheres and
not for oxygen-enriched ones.
• The presence of contaminants. A decrease in oxygen content can be due to the
consumption (by combustion or a reaction such as rusting) of oxygen or the
displacement of air by a chemical. If it is due to consumption, then the concern is
the lack of oxygen. If it is due to displacement, then there is something present that
could be flammable or toxic. Because oxygen makes up only 20.8% of air, a 1%
drop in oxygen means that about 5% air (air being 1 part oxygen and 4 parts
nitrogen) has been displaced. This means that 5% or 50,000 ppm (1% = 10,000
ppm) of "something" could be there.
Most indicators have meters that display the oxygen concentration from 0 to 25%. There are also
oxygen monitors available that measure concentrations from 0 to 5% and from 0 to 100%. The most
useful range for hazardous material response is the 0-25 % oxygen content readout because decisions
involving air-supplying respirators and the use of CGIs fall into this range.
The oxygen sensor can be on the outside (external) or inside (internal) of the instrument. Internal
sensors need a pump—battery operated or hand operated—to draw a sample to it. Units that combine
O2 meters and CGIs into one instrument are available from many manufacturers. Also, flashing and
audible alarms can be found on many instruments. These alarms go off at a preset oxygen
Oxygen Monitors, CGIs, and
10/93 1 Specific Chemical Monitors
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concentration to alert the users even if they are not watching the meter. A list of manufacturers of
oxygen monitors is found in this manual under Manufacturers and Suppliers of Air Monitoring
Equipment.
Principle of Operation
Oxygen monitors use an electrochemical sensor to determine the oxygen concentration in air. A
typical sensor consists of two electrodes, a housing containing a basic electrolytic solution, and a
semipermeable Teflon* membrane (Figure 1).
Display
Membrane / Cover
Electrode
Electrode
Electrolyte
FIGURE 1. SCHEMATIC OF OXYGEN SENSOR
Source: Atmospheric Monitoring for Employee Safety, BioMarine Industries Inc.
Oxygen molecules (O2) diffuse through the membrane into the solution. Reactions between the
oxygen, the solution, and the electrodes produce a minute electrical current proportional to the
oxygen content. The current passes through an electronic circuit which amplifies the signal. The
resulting signal is shown as a needle deflection on a meter or as a digital reading.
In some units, air is drawn into the oxygen detector with an aspirator bulb or pump; in other units,
the ambient air is allowed to diffuse to the sensor.
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Specific Chemical Monitors
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Limitations and Considerations
The operation of oxygen monitors depends on the absolute atmospheric pressure. The concentration
of atmospheric oxygen is a function of the atmospheric pressure at a given altitude. Whereas the
actual percentage of oxygen does not change with altitude, at sea level the weight of the atmosphere
above is greater, and more O2 molecules (and the other components of air) are compressed into a
given volume than at higher elevations. As elevation increases, this compression decreases, resulting
in fewer air molecules being "squeezed" into a given volume. Consequently, an O2 indicator
calibrated at sea level and operated at an altitude of several thousand feet will falsely indicate an
oxygen-deficient atmosphere because less oxygen is being "pushed" into the sensor. Therefore, it
is necessary to calibrate at the altitude the instrument is used.
The reaction that produces the current in the sensor is nonreversible. Thus, once the sensor is
exposed to oxygen, it begins to wear out. The normal life span of a sensor is 6 months to 1 year.
Sensors are shipped in sealed packages that have been purged with nitrogen. The packet should not
be opened until the sensor is to be used. Storing the sensor in an oxygen absent atmosphere after
opening the package can prolong the sensor life, but may not be practical.
High concentrations of carbon dioxide (CO2) may shorten the useful life of the oxygen sensor. As
a general rule, the unit can be used in atmospheres greater than 0.5% C02 only with frequent
replacing or rejuvenating of the sensor. Lifetime in a normal atmosphere (0.04% COa) can be from
6 months to 1 year depending on the manufacturer's design. The service life of one sensor is 100
days in 1% CO2 and 50 days in 5% CO2.
Strong oxidizing chemicals, like ozone and chlorine, can cause increased readings and indicate high
or normal O2 content when the actual content is normal or even low.
Temperature can affect the response of oxygen indicators. The normal operating range for them is
between 32°F and 120°F. Between O°F and 32°F the response of the unit is slower. Below O°F
the solution may freeze and damage the sensor. High temperature can also shorten the sensor life.
The instrument should be calibrated at the temperature at which it will be used.
COMBUSTIBLE GAS INDICATORS
CGIs measure the concentration of a flammable vapor or gas in air, indicating the results as a
percentage of the lower explosive limit (LEL) of the calibration gas. The LEL (or LFL - lower
flammable limit) of a combustible gas or vapor is the minimum concentration of the material in air
which will propagate flame on contact with an ignition source. The upper explosive limit (UEL) is
the maximum concentration. Below the LEL there is insufficient fuel to support combustion. Above
the UEL, the mixture is too "rich" to support combustion, so ignition is not possible. Concentrations
between the LEL and UEL are considered flammable.
CGIs are available in many styles and configurations. The combustible gas sensor can be on the
outside (external) or inside (internal) of the instrument. Internal sensors need a pump—battery
operated or hand operated—to draw a sample to it. Many units are "combination meters." This
means they have an O2 meter and a CGI (and sometimes one or two specific gas indicators)
Oxygen Monitors, CGIs, and
JO/93 3 Specific Chemical Monitors
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combined in the same instrument. Flashing and audible alarms are options on many units. The
alarms go off at a preset concentration to warn the instrument operator of potentially hazardous
concentrations. Other options such as longer sampling lines, moisture traps, and dust filters are also
available. Manufacturers of CGIs are listed in Manufacturers and Suppliers of Air Monitoring
Equipment.
Principle of Operation
CGIs use a combustion chamber containing a filament that combusts the flammable gas. To facilitate
combustion, the filament is heated or is coated with a catalyst (like platinum or palladium), or both.
The filament is part of a balanced resistor circuit called a Wheatstone bridge (Figure 2), The hot
filament combusts the gas on the immediate surface of the element, thus raising the temperature of
the filament. As the temperature of the filament increases, so does its resistance. This change in
resistance causes an imbalance in the Wheatstone bridge. This is measured as the ratio of
combustible vapor present compared to the total required to reach the LEL. For example, if the
meter reads 50% (or 0.5, depending upon the readout), this means that 50% of the concentration of
combustible gas needed to reach a flammable or combustible situation is present. If the LEL for the
gas is 5%, then the meter would be indicating that a 2.5% concentration is present. Thus, the
typical meter indicates concentration up to the LEL of the gas (Figure 3a).
Sensor
Compensating
Filament
FIGURE 2. WHEATSTONE BRIDGE CIRCUIT
Source: Atmospheric Monitoring for Employee Safety, BioMarine Industries Inc.
Oxygen Monitors, CGIs, and
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If a concentration greater than the LEL and lower than the UEL is present, then the meter needle
will stay beyond the 100% (1.0) level on the meter (Figure 3b). This indicates that the ambient
atmosphere is readily combustible. When the atmosphere has a gas concentration above the UEL,
the meter needle may rise above the 100% (1.0) mark and then return to zero (Figure 3c). This
occurs because the gas mixture in the combustion cell is too rich to burn. This permits the filament
to conduct a current just as if the atmosphere contained no combustibles at all. Some instruments
have a lock mechanism that prevents the needle from returning to zero when it has reached 100%.
This mechanism must be reset in an atmosphere below the LEL.
< LEL
LEL - UEL
> UEL
OVER
(a)
(b)
(C)
FIGURE 3. COMPARISON OF METER READINGS TO
COMBUSTIBLE GAS CONCENTRATIONS
Limitations and Considerations
The instruments are intended for use only in normal oxygen atmospheres. Oxygen-deficient
atmospheres will produce lowered readings. Also, the safety guards that prevent the combustion
source from igniting a flammable atmosphere are not designed to operate in an oxygen-enriched
atmosphere.
Organic lead vapors (e.g., leaded gasoline), sulfur compounds, and silicone compounds will foul the
filament. Acid gases (e.g., hydrogen chloride and hydrogen fluoride) can corrode the filament.
Most units have an optional filter that protects the sensor from leaded vapors.
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The response of the instrument is temperature dependent. If the temperature at which the instrument
is zeroed differs from the sample temperature, the accuracy of the reading is affected. Hotter
temperatures raise the temperature of the filament and produce a higher than actual reading. Cooler
temperatures will reduce the reading. The instrument should be calibrated and zeroed at the same
temperature that a reading will be taken. Some instruments have a compensating filament
(Figure 2). This filament is similar to the sensor and is exposed to the same atmosphere, but it does
not combust the atmosphere. It compensates for any temperature changes not caused by the
combustible gas.
There is no differentiation between petroleum vapors and combustible gases. If the flammability of
the combined vapors and gases in an atmosphere is the concern, this is not a problem. However,
if the instrument is being used to detect the presence of a released flammable liquid—like
gasoline—in a sewer system where methane may be present, the operator cannot tell whether the
reading is the contaminant or the methane. A prefilter can be used to remove the vapors, but it will
not remove the methane. Thus, if readings are made with and without the filter, the user can
compare the readings and can conclude that differences in the values indicate that a petroleum vapor
(i.e., the contaminant) is present.
Relative response is also a concern. If the CGI is used to monitor a gas/vapor that the unit is not
calibrated to, it can give inaccurate results. Figure 4 illustrates the effect of relative response.
TOXIC ATMOSPHERE MONITORS
Along with oxygen concentration and flammable gases or vapors, there is also a concern about
chemicals present at toxic concentrations. This usually involves measurements at concentrations
lower than what would be indicated by oxygen indicators or CGIs. There is a need to determine
whether toxic chemicals are present and identify them so the environmental concentration can be
compared to exposure guidelines. Toxic atmosphere monitoring is done to:
• Identify airborne chemicals and their concentrations
• Evaluate the exposure of workers and the public
• Evaluate the need for and type of personal protective equipment
• Develop controls for exposure in the form of engineered safeguards, work practices,
safety plans, and work zones.
Several different groups of instruments can be used for these functions. In this manual the following
types will be discussed:
• Specific chemical monitors are instruments designed to respond to a specific chemical.
Common types include instruments that use electrochemical cells or metal-oxide
semiconductors (MOS), colorimetric indicators, and mercury detectors.
Oxygen Monitors, CGIs, and
Specific Chemical Monitors 6 10/93
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Total vapor survey meters have detectors (e.g., photoionization detector [PID] or
flame ionization detector [FID]) that respond to a variety of chemicals. Additional
information can be found in Total Vapor Survey Instruments.
Gas chromatographs are used to help identify what chemicals are present in the
atmosphere. Additional information is available in Introduction to Gas
Chromatography.
100.
Methane
O)
c
T5
(0
o
? 50
-------
movement or a digital response on a meter. The selectivity of the sensor depends on the selection
of the chemical solution and the electrodes.
In addition to the previously mentioned oxygen monitors (Figure 1), there are electrochemical
sensors for ammonia, carbon monoxide, carbon dioxide, chlorine, hydrogen chloride, hydrogen
cyanide, and hydrogen sulfide. Examples of these instruments are Compur's Monitox® Personal
Monitor Alarms, MDA's MSTox 8600 series, and National Draeger's PAC series of personal
monitors.
Limitations and Considerations
Like the oxygen sensor, these electrochemical sensors also can wear out and are affected by
temperature and humidity.
Electrochemical cells are also affected by interferences. For example, many of the carbon monoxide
sensors will also respond to hydrogen sulfide. In fact, one manufacturer uses the same sensor for
both carbon monoxide and hydrogen sulfide detectors. The user must inform the instrument which
chemical is being monitored so the readout is in the proper units.
Metal-Oxide Semiconductors
MOS detectors, also called solid-state sensors, consist of a metal-oxide film coating on heated
ceramic substrate fused or wrapped around a platinum wire coil. When a gas conies in contact with
the metal oxide, it replaces oxygen in the oxide and alters the conductivity of the semiconductor.
The change in conductivity can be expressed in a meter readout. The substrate is heated to give a
constant baseline as oxygen in the air can combine with the oxide. Selectivity can be determined by
selecting specific metal oxides and/or using specific temperatures from the heater to prevent
chemicals from reacting.
There are MOS detectors for ammonia, carbon monoxide, hydrogen chloride, hydrogen cyanide,
hydrogen sulfide, methyl chloride, nitrogen oxides, and sulfur dioxide. Examples of instruments that
use an MOS to detect specific toxic compounds are the Enmet Tritechtor® and Biosystem's Model
100 series.
Even though the choice of metal oxide and sensor temperature can make the detector somewhat
selective, interferences are a major problem.
Because the sensor reaction is based on presence (or absence) of oxygen in the metal-oxide film,
factors that affect oxygen concentration affect meter response. The sensor needs a minimum 14%
ambient oxygen for operation. High concentrations can saturate the sensor, causing a slow recovery.
A minimum of 10% humidity is need for some sensors (check the manufacturer's specifications).
Oxygen Monitors, CGIs, and
Specific Chemical Monitors 8 10/93
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Colorimetric Indicators
Colorimetric indicators use a chemical to react with the contaminant to produce a color change. The
chemical can be impregnated on a tape or a badge or put inside a glass tube. The color change can
be read by the human eye or by a spectrophotometer to determine the concentration of the
contaminant.
The chemicals are not always specific and can be affected by interfering chemicals. Humidity can
act as an interference by producing a reaction. Cold temperatures can slow the chemical reaction.
Hot temperatures may also cause the chemicals to indicate a reaction.
Examples of Colorimetric indicators are the Envirometrics, Inc. ACT™ cards (badges), MDA
Scientific's 7100 Series (tape), 2 J Draeger detector tubes.
Mercury Detectors
Mercury detectors use either ultraviolet light absorption or a gold film detector. Mercury vapor
absorbs a certain wavelength of ultraviolet light. The instrument draws a sample into a chamber and
exposes it to the ultraviolet light source. The concentration of mercury vapor is measured by the
amount of light absorbed.
Some organic chemicals can absorb the ultraviolet light and act as an interference. Water vapor also
absorbs ultraviolet light, but can be adjusted for if the instrument is zeroed in the same humidity as
the sample area.
The gold film detector has a gold film as part of a circuit. Mercury reacts with the gold and changes
the resistance of the film. The change in resistance is used to determine concentration.
Because most operators do not have a mercury vapor standard, the gold film detector must be factory
calibrated. After long exposures or high concentrations, the film needs to be "cleaned." This
requires heating the film and using an AC power source.
An example of an ultraviolet absorption instrument is the Bacharach Model MV-2. An example of
a gold film instrument is the Jerome Instruments Model 411.
CONCLUSION
Many hazards can be present at a hazardous materials operation. Instruments are available for
determining the presence of hazardous situations like combustible atmospheres, oxygen-deficient
atmospheres, and toxic atmospheres. The instruments discussed in this section can only identify
certain hazardous situations and should be selected and used accordingly. Additional information
on identifying and evaluating toxic atmospheres will be discussed in the following sections.
Oxygen Monitors, CGIs, and
JO/93 9 Specific Chemical Monitors
-------
TOTAL VAPOR SURVEY INSTRUMENTS
PERFORMANCE OBJECTIVES
At the end of this lesson, participants will be able to:
• Explain the principle of detection for the PID, FID,
supersensitive CGI, and metal-oxide semiconductor (MOS)
• Determine whether a chemical can be detected by
photoionization, given the ionization potential of the
chemical and the lamp energy of the photoionization detector
• Identify three considerations when using a PID
• Identify three considerations when using a FID
• Identify three consideration when using a supersensitive CGI
• Explain the difference between a CGI and a supersensitive
CGI.
-------
TOTAL VAPOR
SURVEY INSTRUMENTS
TOTAL VAPOR SURVEY
INSTRUMENTS
Instruments using detectors that
respond to a wide variety of chemicals
and give readings in the parts per
million range
WHAT ARE TOTAL VAPOR SURVEY
INSTRUMENTS USED FOR?
Site characterization
Exposure monitoring
Soil and water sample screening
Soil gas monitoring
NOTES
10/93
Total Vapor Survey Instruments
-------
NOTES
TYPES OF TOTAL VAPOR
SURVEY INSTRUMENTS
• Photoionization detector (PID)
• Flame ionization detector (FID)
• Supersensitive CGI
• Metal-oxide semiconductor (MOS)
PHOTOIONIZATION
\ A
i
><
O
jXj
U
8
PHOTOIONIZATION
R-L hu
^ n
T ll*7 ' \\
R = chemical-abs
h(nu) = photon wi
> ionizatic
(IP) of che
++ e' -^ R
orbing UV
th energy
>n potential
mical
Total Vapor Survey Instruments
10/93
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NOTES
PHOTOIONIZATION DETECTOR
Amplifier
Meter
Sample Out
Electrode
UV
Lamp
t
Electrode
Sample In
10/93
Total Vapor Survey Instruments
-------
IONIZATION
POTENTIAL
Chemical
Carbon monoxide
Hydrogen cyanide
Methane
Hydrogen chloride
Water
Oxygen
Chlorine
Propane
Hydrogen sulfide
Hexane
Ammonia
Acetone
Trichloroethylene
Benzene
Triethylamine
V
IP (eV)
14.0
13.9
13.0
12.7
12.6
12.1
11.5
11.1
10.5
10.2
10.1
9.7
9.45
9.2
7.5
NOTES
Total Vapor Survey Instruments 10/93
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NOTES
EXAMPLES OF LAMP ENERGIES
AND DETECTABLE CHEMICALS
Halourbonf
Muthanol
Other «ngt« C compounds
Vinyl chlorid*
MEK
MIBK
TCE
Other 2-4 C compounds
Aromatics
Lwgt moleculM
Lamp
SELECTIVE DETERMINATION
OF VINYL CHLORIDE
Compound
IP
Carbon dioxide 13.8
Propane 11.1
Vinyl chloride 10.0
Acetone 9.7
PHOTOIONIZATION DETECTOR
11.7 vs. 10.2 Lamp
• 11.7 wears out faster than 10.2
• 11.7 is more susceptible to humidity
• 10.2 provides better response to
chemicals it can detect
10/93
Total Vapor Survey Instruments
-------
NOTES
PHOTOIONIZATION DETECTOR
Considerations
Lamp energy/chemical IP
Dust/humidity
Interferences
Electromagnetic interferences
Lamp aging
Relative response
High concentrations
PHOTOIONIZATION DETECTOR
Relative Response
Chemical
m-Xylene
Benzene
Phenol
Acetone
Isobutylene
Hexane
Ammonia
Relative
Response*
1.12
1.00
0.78
0.63
0.55
0.22
0.03
IP
8.56
9.25
8.69
9.69
9.25
10.18
10.15
* HNU PI-101 with 10.2 eV lamp calibrated to benzene
PHOTOIONIZATION DETECTOR
High Concentration Effects
Ol
.£
Benzene
(gain = 9.8)
ppm (by volume)
Total Vapor Survey Instruments
10/93
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NOTES
FLAME IONIZATION DETECTOR
Exhaust Vent
r-fWr^-i
c
Igniter and
Electrode ,
u
1
Hydrogen Inlet
r
p Collector
Electrode
\
J
FLAME IONIZATION
RH 1 0 "ame > F
Note: This ionization proces
H+ + e"-^C02 + H20
>s is destructive.
COMPOUNDS GIVING LITTLE OR
NO RESPONSE IN THE FID
He N2 HCHO (formaldehyde)
Ar NO CO
02 N02 C02
H20 N20 CS2
H2S NH3 Ethanolamine
S02 HCN
10/93
Total Vapor Survey Instruments
-------
NOTES
FLAME lONIZATION
Considerations
• Detects only organics
• Detects methane
• Hydrogen gas needed
• Flame out
• Electromagnetic interferences
• Relative response
FLAME lONIZATION
Relative Response
Chemical
% Relative Response*
Benzene 185
Toluene 126
Methane 100
Acetone 82
Trichloroethylene 54
Freon-12 13
Carbon tetrachloride 8
OVA-128 calibrated to methane
SUPERSENSITIVE CGI
Detects combustible gases and
vapors
Detector is the same as a regular CGI,
but an amplifier is used to obtain ppm
readings
Total Vapor Survey Instruments
10/93
-------
NOTES
SUPERSENSITIVE CGI
Considerations
• Detects only combustibles
• Detects methane
• Temperature
• Chemicals that foul sensor
• Minimum oxygen
• Electromagnetic interference
• Relative response
METAL-OXIDE
SEMICONDUCTOR (MOS)
• Metal-oxide coating on a ceramic substrate
wrapped around a wire
• Contaminant alters conductivity by
removing oxygen
• Change in current is proportional to the
amount of contaminant present
• Also called "solid-state" sensor
MOS
Considerations
• Saturation
• Temperature
• Minimum oxygen requirements
• Relative response
10/93
Total Vapor Survey Instruments
-------
NOTES
CONCLUSION
Considerations
• What the instrument can detect
• Survey, not identification
• Logistical factors
• Environmental factors
• Special features
Total Vapor Survey Instruments
10/93
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TOTAL VAPOR SURVEY INSTRUMENTS
INTRODUCTION
Total vapor survey instruments are designed to respond to a wide range of gases and vapors.
Although they lack selectivity, this broad response allows the operator to detect the presence of
chemicals with one instrument. This allows the instrument to be used as a warning device during
survey operations.
If the identity of a chemical is known, the instruments can be calibrated to give a one-to-one response
for that chemical. If there is a mixture present, the instrument gives a total vapor reading. The
detectors themselves cannot identify the components of an atmosphere. The detectors can be used
in instruments, like the gas chromatograph (see Introduction to Gas Chromatography that are used
for identification.
This section will focus on total vapor survey instruments that are used for parts per million (ppm)
concentrations. It will discuss four types of toxic vapor survey instruments: photoionization
detectors (PIDs), flame ionization detectors (FIDs), supersensitive combustible gas indicators (CGIs),
and metal oxide semiconductors.
APPLICATIONS
Because of their ability to detect a wide range of chemicals, total vapor survey instruments are used
in site survey and characterization. Although they cannot identify what chemicals are present, they
can indicate what areas may have higher concentrations (hot spots) than others and delineate work
areas based on levels of concentrations.
If the identities of the contaminants are known, the instruments can also be used in exposure
assessment. The readings can give an approximate concentration and the information can be used
in selecting exposure controls.
The instruments are also used to screen water and soil samples to determine whether further, and
more complicated and expensive, analysis is needed. Usually specific reading (or any response) is
used to determine which samples need further analysis.
Total vapor survey instruments are also used in soil gas sampling as a screening tool to indicate
"hits" and hot spots that need further sampling.
PHOTOIONIZATION DETECTORS
These instruments detect concentrations of gases and vapors in air by using an ultraviolet light source
to ionize the airborne contaminant. Once the gas or vapor is ionized in the instrument, it can be
detected and measured.
10/93 1 Total Vapor Survey Instruments
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Principle of Operation
The photoionization process can be illustrated as:
R + hv -» R+ + e" -* R
where R is an organic or inorganic molecule and hj/ represents a photon of ultraviolet (UV) light with
energy equal to or greater than the ionization potential (IP) of that particular chemical species. R+
is the ionized molecule.
When a photon of ultraviolet radiation strikes a chemical compound, it ionizes the molecule if the
energy of the radiation is equal to or greater than the IP of the compound. Because ions are charged
particles, they may be collected on a charged plate and produce a current. The measured current
will be directly proportional to the number of ionized molecules. The R in the above equation
indicates that photoionization is nondestructive and the chemical exits the detector unchanged.
PIDs use a fan or a pump to draw air into the instrument's detector. There the contaminants are
exposed to UV light and the resulting negatively charged particles (ions) are collected and measured
(Figure 1).
Amplifier
Sample Out
Electrode
Electrode
Sample In
FIGURE 1. DIAGRAM OF PHOTOIONIZATION DETECTOR LAMP
AND COLLECTING ELECTRODES
The energy required to remove the outermost electron from the molecule is called the ionization
potential (IP) and is specific for any compound or atomic species (Table 1). Ionization potentials
are measured in electron volts (eV).
Total Vapor Survey Instruments
10/93
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The ultraviolet light used to ionize the chemicals is emitted by a gaseous discharge lamp. The lamps
contain low-pressure gas through which a high-potential current is passed. A variety of lamps with
different ionization energies are made by varying the composition of the lamp gas. The energy of
lamps available are 8.4, 9.5, 10.0, 10.2, 10.6, and 11.7 eV. Not all lamps are available from a
single manufacturer.
The lamp energy designation is for the predominant UV wavelength emitted by the lamp. The
spectra from the lamp may have other wavelengths. Wavelengths of less energy do not have a major
impact because chemicals ionized by those wavelengths will also be ionized by the predominant
wavelength. The higher energy (but less photons) wavelengths will ionize the higher IP chemicals
but the response will be low. Thus, a 10.2 lamp may give a response (although a small one) for a
chemical with an IP of 10.9.
Photoionization Detector Considerations
Because the ability to detect a chemical depends on the ability to ionize it, the IP of a chemical to
be detected must be compared to the energy generated by the UV lamp of the instrument. As
discussed earlier, it may be possible to detect a chemical even if the chemical's IP is slightly greater
than the lamp energy. However, the response will be poor.
TABLE 1. IONIZATION POTENTIALS OF SELECTED CHEMICALS
Ionization Potential
Chemical
Carbon monoxide
Hydrogen cyanide
Methane
Hydrogen chloride
Water
Oxygen
Chlorine
Propane
Hydrogen sulfide
Hexane
Ammonia
Acetone
Trichloroethylene
Benzene
Triethyl amine
(eV)
14.0
13.9
13.0
12.7
12.6
12.1
11.5
11.1
10.5
10.2
10.1
9.7
9.45
9.2
8.0
10/93 3 Total Vapor Survey Instruments
-------
One use for the different lamps is for selective determination of chemicals. For example, if a spill
of propane and vinyl chloride were to be monitored with a PID, the first check would be to see
whether the chemicals can be detected. The IP of propane is 11.1 eV and the IP of vinyl chloride
is 10.0 eV. To detect both, a lamp with an energy greater than 11.1 eV is needed (like a 11.7).
If vinyl chloride was the chemical of concern, then a lamp with an energy greater than 10.0 but less
than 11.1 (such as 10.2 or 10.6) could be used. The propane would neither be ionized nor detected.
Thus, propane would not interfere with the vinyl chloride readings.
The lamp window also affects response. The two types of windows are magnesium fluoride and
lithium fluoride. The former is used for the lower energy lamps and the latter is for the 11.7 eV
lamp. The lithium fluoride is used to permit the higher energy photons to be emitted. Lithium
fluoride has two disadvantages. The first is that humidity and the high-energy photons degrade the
window. This reduces the life span of the lamp. The 11.7 eV lamps are expected to have a life
expectancy one-tenth of that of 10.2 or 10.6 lamps. The second disadvantage is that lithium fluoride
also limits the amount of photons being emitted. Thus, if both a 10.2 and an 11.7 lamp have enough
energy to ionize a chemical (e.g., a chemical with an IP of 9.7), the 10.2 may give a higher response
because it is emitting more light.
The sample drawn into the instrument passes over the lamp to be ionized. Dust in the atmosphere
can collect on the lamp and block the transmission of UV light. This will cause a reduction in
instrument reading. The lamp should be cleaned regularly. Newer models of PIDs have dust filters.
Humidity can cause two problems. When a cold instrument is taken into a warm moist atmosphere,
the moisture can condense on the lamp. Like dust, this will reduce the available light. Moisture in
the air can also reduce the readings. It is thought that the water molecules collide with the ionized
chemical and deactivate them. This reduction in response has been reported to be as much as 50%
for a relative humidity of 90%. As mentioned earlier, the 11.7 lamp window is especially sensitive
to moisture.
Because an electric field is generated in the sample chamber of the instrument, radio-frequency
interference from pulsed DC or AC power lines, transformers, generators, and radio wave
transmission may produce an error in response.
As the lamp ages, the intensity of the light decreases. It will still have the same ionization energy,
but the response will decline. This will be detected during calibration and adjustments can be made.
However, the lamp will eventually burn out.
Methane can act as an interference by absorbing the UV energy without ionization. This reduces
the ionization of other chemicals present. The net effect is a reading lower than the true
concentration.
Although oxygen is not needed for photoionization, a change in oxygen will affect the response.
Thus, there are oxygen limits for their use. The instruments are calibrated and used in normal
oxygen atmospheres. The HNU PI-101 requires a minimum of 10% oxygen for reliable results.
Photoionization detectors are calibrated to a single chemical. The instrument's response to chemicals
other than the calibration gas/vapor can vary. Table 2 shows the relative responses of several
chemicals for a specific PID.
Total Vapor Survey Instruments 4 • 10/93
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In some cases, at high concentrations the instrument response can decrease. While the response may
be linear (i.e., 1 to 1 response) from 1 to 400 ppm for an instrument, a concentration of 900 ppm
may only give a meter response of 700 (Figure 2). Some instruments use a microprocessor to
compensate for this effect by storing calibration information for the high concentrations.
Manufacturers who make photoionization detectors can be found in this manual in the Manufacturers
and Suppliers of Air Monitoring Equipment section.
TABLE 2. RELATIVE RESPONSES FOR SELECTED
CHEMICALS USING THE HNU MODEL PI 101
WITH 10.2 eV PROBE CALIBRATED TO BENZENE
Chemical
m-Xylene
Benzene
Acetone
Isobutylene
Vinyl chloride
Hexane
Phosphine
Ammonia
Relative Response
1.12
1.00
0.63
0.55
0.50
0.22
0.20
0.03
Source: Instruction Manual for Model PI 101, Portable
Photoionization Analyzer, HNU Systems, Inc., Newton,
MA, 1986.
Examples of Photoionization Detector Instruments
HNU Systems, Inc.
HNU Systems, Inc., manufactures four models of photoionization detector survey instruments:
PI-101, IS-101, HW-101, and the DL-101.
All four consist of two modules connected via a single power cord (Figure 3):
• A readout unit having an analog meter or digital display, a rechargeable battery, and
power supplies for operation of the amplifier and the UV lamp
• A sensor unit consisting of the UV light source, pump, ionization chamber, and a
preamplifier.
10/93 5 Total Vapor Survey Instruments
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The PI-101 has a fan instead of a pump and cannot draw a sample through a resistance (like a piece
of long tubing). The PI-101 is rated for Class I, Division 2, Group A, B, C, and D locations.
The IS-101 is similar to the PI-101 except it is intrinsically safe for Division 1 locations.
The HW-101 has a pump instead of a fan, so it can be used to draw a sample through tubing or
through a probe used for soil gas sampling. The HW-101 also has a dust filter and is more moisture
resistant than the other models. It also has a light-emitting diode (LED) display on the handle that
indicates concentration changes.
The DL-101 has a pump and dust filter like the HW-101. However, it has many different fixtures
than other units. It has a pistol grip for holding the probe. There is a LED display on the handle.
The instrument has a datalogger to store calibration information and to record time and location of
readings. Information from the datalogger can be transferred to a computer. It has a digital readout
instead of an analog meter.
These units have a separate sensor unit because the lamps available - 9.5, 10.2 (standard), and 11.7
eV - require separate electronic circuits. To change the energy of ionization, the whole sensor or
O)
C 600
0)
DC
0)
400
200
Benzene
(gain = 9.8)
100
300
500
700
900
ppm (by volume)
FIGURE 2. TYPICAL CALIBRATION CURVE FOR PHOTOIONIZATION ANALYZER
Source: Instruction Manual for Model PI-101 Photoionization Detector, copyright 1975, HNU
Systems, Inc.; reprinted with permission of publisher.
Total Vapor Survey Instruments
10/93
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probe has to be switched, not just the lamp. The exception is the DL-101. With the DL-101, lamps
can be interchanged and the datalogger/microprocessor makes the proper adjustments. In all models
the lamps are replaceable.
Ion Chamber
\
o 1
.
rfT
.
•
I 4- SAMPLE
PROBE
FIGURE 3. PORTABLE PHOTOIONIZATION DETECTOR
Source: Instruction Manual for Model PI-101 Photoionization Detector, copyright 1975, HNU
Systems, Inc.; reprinted with permission of publisher.
Photovac, Inc.
Photovac has three versions of its MicroTIP®. All three have a microprocessor that is used to
calibrate the instrument and a datalogger to store data. Information from the datalogger can be
transferred to a computer. The standard lamp is 10.6 eV, but it can be easily replaced with a 8.4,
9.5, 10.2 or 11.7 eV lamp. The readout is digital with a range of 0 to 2000. They all have a dust
filter. The MP-1000 does not have a inherent safety approval. The HL-2000 is approved for Class
I, Division 2, Groups A, B, C, and D locations. The IS-3000 is intrinsically safe.
10/93
Total Vapor Survey Instruments
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Thermo Environmental Instruments
The Organic Vapor Meter (OVM) Model 580B is 5" by 5" by 10" with a handle in the center on
top. It can use any of four different lamps - 9.6, 10.0, 10.6 and 11.8 eV. The instrument has a
digital readout with a range of 0 to 2000. It has a maximum hold feature so that you can get two
readings - the current concentration or the maximum concentration during the survey. The meter
has a lock-out if the readout exceeds 2000 so that high concentrations are not missed. It must be
reset in an area of low concentrations. The instrument has a microprocessor for assistance in
calibration and lamp changing.
The OVM-580S is similar to the 580B, but is intrinsically safe.
Both have connections and software for interfacing the unit with a personal computer. They also
have a datalogger for recording readings at coded locations so that the readings can be looked at later
or downloaded into a computer.
Photoionization detectors are also used in gas chromatographs made by Photovac, HNU and Thermo
Environmental Instruments. Gas chromatography will be discussed in a later section.
FLAME IONIZATION DETECTOR
These units use a flame to ionize airborne contaminants. Once they are ionized, they can be detected
and measured.
Principle of Operation
FIDs use a hydrogen flame as the means to ionize organic vapors. FIDs respond to virtually all
organic compounds; that is, compounds that contain carbon-hydrogen or carbon-carbon bonds. FIDs
will not respond to inorganic compounds.
Inside the detector chamber, the sample is exposed to a hydrogen flame which ionizes the organic
vapors (Figure 4):
RH + O2 -» RH+ + e~ - CO2 + H2O
When most organic vapors burn, positively charged carbon-containing ions are produced. These can
be collected by a negatively charged collecting electrode in the detector chamber. An electric field
exists between the conductors surrounding the flame and a collecting electrode. As the positive ions
are collected, a current proportional to the hydrocarbon concentration is generated on the input
electrode. This current is measured with a preamplifier which has an output signal proportional to
the ionization current. A signal conducting amplifier is used to amplify the signal from the detector
and to condition it for subsequent meter or external recorder display.
Flame ionization detectors have a more generalized response in detecting organic vapors. This
generalized sensitivity is due to the breaking of chemical bonds which require a set amount of energy
and is a known reproducible event. When this is compared to photoionization (PID), a major
Total Vapor Survey Instruments % . 10/93
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difference should be noted between the detectors. PID detection is dependent upon the ionization
potential (in eV) and the ease in which an electron can be ionized (displaced) from a molecule. This
mechanism is variable, highly dependent on the individual characteristics of a particular substance.
This results in a more variable response factor for the vast majority of organics that are ionizable.
Therefore, in general, one does not see large sensitivity shifts between different substances when
using an FID as compared to a PID. FIDs are the most sensitive for saturated hydrocarbons
(alkanes), unsaturated hydrocarbons (alkenes and alkynes), and aromatic hydrocarbons. Substances
that contain substituted functional groups, such as hydroxide (OH) and chloride (Cl), tend to reduce
the detector's sensitivity.
Companies that manufacture FIDs are listed in the Manufacturers and Suppliers of Air Monitoring
Equipment section. The Foxboro Century Organic Vapor Analyzer (OVA) will be discussed as an
example later\
Exhaust vent
-^77777^
Igniter and
electrode
Hydrogen inlet
Collector
electrode
Sample (air) inlet
FIGURE 4. EXAMPLE OF A FLAME IONIZATION DETECTOR SCHEMATIC
Flame Ionization Detector Considerations
Flame ionization detectors respond only to organic compounds. Thus, they do not detect inorganic
compounds like chlorine, hydrogen cyanide, or ammonia. There are some carbon containing
chemicals for which the FID gives little or no response also. Table 3 illustrates this situation.
10/93
Total Vapor Survey Instruments
-------
TABLE 3. CHEMICALS GIVING LITTLE OR NO RESPONSE
WITH FLAME IONIZATION DETECTORS
He N2 HCHO (formaldehyde)
Ar NO CO
02 N02 C02
H20 N20 CS2
H2S NH3 TDI
S02 HCN ethanol amine
Source: Relative Response Data Sheet for Organic Vapor Analyzer,
January 16, 1989. The Foxboro Company.
Flame ionization, unlike photoionization, is a destructive form of monitoring. Typically, the
combustion products are carbon monoxide and water. However, substituted hydrocarbons (e.g.
chlorinated compounds) may produce toxic or corrosive byproducts.
The FID responds very well to methane. Methane is used as a calibration gas for many FIDs.
However, if monitoring is being done near a landfill or in a sewer system, the methane can mask
the response to low concentrations of other organics.
Hydrogen gas is used as fuel for the flame. This requires the extra logistics of maintaining a
hydrogen gas supply and recharging the instrument. It also involves working with a flammable
compressed gas.
Inadequate oxygen can cause the flame to go out. High concentrations of organics can also cause
a flame out. Without the flame, there is no detection.
Cold weather can also cause the flame to extinguish or inhibit startup (ignition) of the instrument.
Because an amplifier is used to enhance the signal from the detector, radio-frequency interference
from pulsed DC or AC power lines, transformers, generators, and radio wave transmission may
produce an error in response.
As with all instruments, flame ionization detectors respond differently to different compounds.
Table 4 is a list of the relative responses of the Foxboro CENTURY OVA to some common organic
compounds. Since that instrument is factory calibrated to methane, all responses are relative to
methane and are given by percentage, with methane at 100%.
Total Vapor Survey Instruments \Q 10/93
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TABLE 4. RELATIVE RESPONSES FOR SELECTED
CHEMICALS USING THE OVA CALIBRATED TO METHANE
Compound
Methane
Ethane
Propane
Acetylene
Benzene
Toluene
Acetone
Methanol
Isopropyl alcohol
Carbon tetrachloride
Freon-12
Trichloroethylene
Relative Response
(%)
100
77
70
225
185
126
. 82
12
65
8
13
54
Source: Product Literature, The Foxboro Company; used
with permission of The Foxboro Company.
Examples of Flame lonization Detector Instruments
Foxboro CENTURY Organic Vapor Analyzer (OVA)
One of the more common FID instruments is the Foxboro CENTURY OVA. There are two models:
the OVA-128 and the OVA-108. Both consist of two major parts (Figure 5):
• A 12-pound package containing the sampling pump, battery pack, support electronics,
flame ionization detector, hydrogen gas cylinder, and an optional gas chromatography
(GC) column.
• A hand-held meter/sampling probe assembly.
10/93 11 Total Vapor Survey Instruments
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INTERNAL HYDROGEN
CYLINDEP
SIGNAL PROCESSOR
v_y
ELECTRODE *H
I u I
SAMPLE
FIGURE 5. ORGANIC VAPOR ANALYZER SCHEMATIC
Source: Product Literature, The Foxboro Company, used with permission of The Foxboro
Company.
The OVA-128 has a range of 0-1000 ppm. The OVA-108 reads from 0-10,000. Both are
intrinsically safe for Class 1, Division 1, Groups A, B, C and D. Both models are factory calibrated
to methane, but can be calibrated to other chemicals.
Other FID units are the Sensidyne Portable FID, Heath Consultants Porta-FID II, and Summit
Industries SIP-1000. The Portable FID and the SIP-1000 have gas chromatograph options.
Combination PID and FID
Foxboro also manufactures the TVA-1000. The instrument can use a PID, an FID, or both. The
instrument has datalogging capabilities and digital readouts on a probe and side pack.
Total Vapor Survey Instruments
12
10/93
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SUPERSENSITIVE COMBUSTIBLE GAS INDICATORS
The CGI is a type of total vapor survey monitor. However, the normal range for a CGI is in the
percent LEL concentration. This range is too high for toxic concentration monitoring. Super-
sensitive combustible gas indicators use the combustible gas sensor with circuitry to amplify the
signal. Instead of measuring per cent of the LEL, the readout is in part per million. Because the
detection is based on combustion, the instruments can detect both organic and inorganic combustible
gases/vapors.
Some units—like the Bacharach TLV Sniffer—only measure in the ppm range. Other units (e.g.,
the GasTech Model 1314) can be switched from percent LEL to ppm readout.
These units have the same limitations and considerations as the regular combustible gas indicators.
In some cases, like sensitivity to temperature changes, the effects are a bigger problem because of
the amplifier circuit. Because of the amplifier, they are more sensitive to electromagnetic radiation
than standard combustible gas indicators.
METAL-OXIDE SEMICONDUCTORS (MOS)
MOS, also called solid-state sensors, consist of a metal oxide film coating on a heated ceramic
substrate fused or wrapped around a platinum wire coil. When a gas comes in contact with the metal
oxide, it replaces oxygen in the oxide and alters the conductivity of the semiconductor. The change
in conductivity can be expressed in a meter readout. The bead is heated to give a constant baseline
as oxygen in the air can combine with the oxide. Oxygen can combine with the sensor to cause an
instrument response.
Selectivity can be determined by selecting specific metal oxides and/or using specific temperatures
from the heater to prevent chemicals reacting. To use as a toxic atmosphere survey monitor, the
sensor should respond to a wide variety of chemicals. Thus, the sensor should be designed to be
nonselective.
Examples of instruments using a MOS for a total vapor sensor are the AIM 2000/3000 and the
Dynamation Model CGM™.
CONCLUSION
This section has described several types of detectors used for monitoring the presence of a wide
range of gases and vapors. While these are not the only types of detectors or monitors available,
they are the more commonly used devices for field surveys.
10/93 13 Total Vapor Survey Instruments
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AIR SAMPLE COLLECTION
PERFORMANCE OBJECTIVES
At the end of this lesson, participants will be able to:
• List four advantages to using air sample collection
• List three sources of sampling and analysis methods
• List three considerations when using liquid sorbent samplers
• List three considerations when using solid sorbent samplers
• List three considerations when using whole air samplers
• Describe two methods of collecting whole air samplers.
-------
NOTES
AIR SAMPLE
COLLECTION
DIRECT-READING INSTRUMENTS (DRI)
vs. AIR SAMPLE COLLECTION
Features
Response time
Quantitative
Identification
Detection range
Cost
DB1
Seconds to minutes
Yes
No
Parts per million (ppm)
to percent
Inexpensive
Air Sample Collection
Hours to days
Yes
Yes
Parts per trillion (ppt)
to parts per million (ppm)
Expensive
AIR SAMPLE COLLECTION
Uses
• Identify and quantify airborne
chemicals onsite
• Evaluate personal exposures
• Evaluate releases from site
• Data for public health/ecological risk
assessment
10/93
Air Sample Collection
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NOTES
AIR SAMPLE COLLECTION
Components
Laboratory
analysis
Contaminant
Pump
COLLECTION AND
ANALYTICAL METHODS
EPA
- Compendium of Methods for
Determination of Toxic Organic
Compounds in Ambient Air
- Compendium of Methods for
Determination of Air Pollutants in
Indoor Air
- Compendium of Methods for
Determination of Toxic Inorganic
Compounds in Ambient Air
COLLECTION AND
ANALYTICAL METHODS
• NIOSH Manual of Analytical Methods
• OSHA Analytical Methods Manual
• American Society for Testing and
Materials
• Specialty methods
Air Sample Collection
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NOTES
COLLECTION AND
ANALYTICAL METHODS
• Air Methods Database
- Combines previous methods into
a database
- Free from EPA
- See fact sheet
COLLECTION MEDIA
Types of Contaminants
Aerosols/particulates (nonvolatile)
Gases and vapors (volatile)
Combination (semivolatile)
FILTER MEDIA
Examples
Filler Media
0.8-micron (fj)
mixed cellulose ester (MCE)
Glass fiber
Polyvinyl chloride (PVC)
Polytetrafluoroethylene
Application
Metals; asbestos
Pesticides
Total particulates;
hexavalent chromium
Alkaline dusts
10/93
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NOTES
Air Sample Collection
AEROSOLS/PARTICULATES
Size Selection Terminology
• Total suspended particulate (TSP)
• Particulate matter - 10/Y (PM-10)
• Total
• Respirable
AEROSOL SIZE SELECTION
Inertial Impactor
Air flow
Filter
Pump
AEROSOL SIZE SELECTION
Cascade Impactor
Collector
Air flow
A
Pump
/
Plates
N,
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/VOTES
GASES AND VAPORS
Examples
Organic vapors
- Benzene
- Trichloroethylene
- Ethyl alcohol
Inorganic gases
- Ammonia
- Hydrogen cyanide
- Hydrogen chloride
SOLID SORBENT MEDIA
Examples
Solid Sorbent
Activated carbon
T ®
Tenax
Carbon molecular sieve
Silica gel
Compound
Nonpolar organics (NIOSH)
Volatile, nonpolar organics (EPA)
Highly volatile, nonpolar organics (EPA)
Polar organics (NIOSH)
SOLID SORBENT TUBE
Example
t t t
Dividers
A = Solid sorbent
B = Solid sorbent (backup or different sorbent)
10/93
Air Sample Collection
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/VOTES
SOLID SORBENT
CONSIDERATIONS
• Breakthrough
• Sorption efficiency
• No universal media
• Stability/handling
• Desorption
- Thermal
- Solvent
LIQUID SORBENT MEDIA
Examples
Media
O.INNaOH
Aniline
DNPH reagent + isooctane
0.1MHCI
Compound
Cresol/phenol (EPA)
Phenol (NIOSH)
Phosgene (EPA)
Aldehydes/ketones (EPA)
Hydrazine (NIOSH)
LIQUID SORBENT
CONSIDERATIONS
Spillage
Fragile holders
Hazardous liquids?
Stability
Evaporation
Air Sample Collection
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NOTES
WHOLE AIR COLLECTION
"Sampling Lung"
Sample flow
Air flow
Source: "Sampling and Analysis ol Emissions from Stationary Sources,' Schuatzto st
•I., Joumtl ollhtAir Pollution Control Aaodttion. Voluma 25, No. 8, Sapt 1975.
BAG SAMPLING vs. CANISTER
SAMPLING
Baa
Grab
Need field pump
Less stable sample
Cannot clean
Disposable
Cannot pressurize
Canister
Integrated
Need lab pump
More stable sample
Clean to reuse
Reusable
Can pressurize
COMBINATION MEDIA
Examples
Media Compound
Quartz fitter PCBs/pesticides (EPA)
+ polyurethane foam (PUF) PAHs (EPA)
Quartz filter + XAD-2 PAHs (EPA)
Glass filter + Florisil® PCBs (NIOSH)
MCE filter + 0.1 N KOH Cyanides (NIOSH)
4/94
Air Sample Collection
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NOTES
SAMPLING PUMPS
Most collection methods require a
pump to pull air through medium
Exceptions
- Evacuated canister
- Passive dosimeter
PASSIVE DOSIMETER
Example
Contaminant
Sorbent
Chemical permeates membrane and/or ditluses into
sampler
PASSIVE DOSIMETERS
Considerations
No pump
Sorbent limits
- Breakthrough
- Humidity
- Temperature
Early and late exposure problems
Gases and vapors only
Air Sample Collection
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NOTES
SAMPLE PUMPS
High Flow Rates
Greater than 10 cubic feet per minute
Ambient air sampling
SAMPLE PUMPS
Medium/High Flow Rates
1 to 6 liters per minute
Personal sampling
Aerosol sampling
SAMPLE PUMPS
Low Flow Rates
• 10 to 750 cubic centimeters
(milliliters) per minute
• Personal sampling
• Gas and vapor sampling
10/93
Air Sample Collection
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/VOTES
SUMMARY
Collect sample for laboratory analysis
Determine whether air sampling is
appropriate
Identify appropriate air sampling
method
Air Sample Collection
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AIR SAMPLE COLLECTION
INTRODUCTION
The types of equipment discussed in this section are media (filters and sorbents), containers (gas bags
and canisters) and pumps for collecting air samples. Unlike direct-reading instruments that give
immediate results, these samples must be analyzed by instruments that are not usually taken onsite.
The analysis may be done in the support area of a site or at a laboratory many miles away. This
causes a delay in receiving information. However, there are advantages to their use.
• The chemicals in the atmosphere can be concentrated so that the detection limit can
be lower than for a direct-reading instrument, even when the same type of detector
is used.
• Specialized detectors can be used. Some detectors (e.g., PID and FID) are used in
both direct-reading instruments and analytical instruments. However, some detectors
are only found in analytical instruments (e.g., electron capture detector). For specific
analysis of aerosols (e.g., lead), there are no direct-reading instruments. A sample
must be collected and then analyzed by a nonportable instrument.
• The analytical instruments used generally allow identification and quantification of
the chemicals. Instead of a total vapor reading, it may be possible to get an
identification and concentration of the components.
• The collection devices allow long duration (hours to days) and unattended sampling.
SAMPLE COLLECTION COMPONENTS
General
The basic components of a sample collection system are:
• A collection media for separating the contaminants from the atmosphere or a
collection container for holding part of the atmosphere.
• A pump to pull air through the media to push the sample into a container. When a
pump is used, the method is called "active" sampling. Some methods do not require
a pump and are called "passive" samplers.
• A method to analyze the collected sample. This part will not cover the analysis of
a sample. A limited discussion of analyses and detector types is found in Total Vapor
Survey Instruments and Introduction to Gas Chromatography.
10/93 1 Air Sample Collection
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Selection of Components
Several factors affect the selection of the components for a sample collection system. These include
1) the chemical and physical properties of the chemical to be collected, 2) the purpose of the sample,
3) the analytical method used by the laboratory, 4) the laboratory's capability to do a specific
procedure and their experience with the method, and 5) equipment characteristics. The following
elaborate on these factors:
• Chemical and physical properties of the chemical—The chemical/physical properties
of the chemical to be collected affect the type of media used. Volatile chemicals pass
readily through a filter. Therefore, some kind of sorbent is needed. In some cases,
a reaction, like an acid gas with an alkaline solution, may be used instead of sorption.
• Purpose of the sample—Two types of samples are the "personal" sample and the
"area" sample:
Personal sample—A personal sample requires a pump that can be worn by the
person being sampled. This means the pump must be compact and battery
operated. A personal sample is used to evaluate the exposure level of the
person being sampled. The sample results are usually compared to an
exposure limit (see Exposure Limits and Action Levels'). A personal sample
collects the contaminants in the "breathing zone," a 12-inch-radius
hemisphere in front of the wearer's nose.
Area sample—An area sample, to determine chemicals and concentrations in
a specific area, can use the same type of pump. However, area samples
generally are for checking lower concentrations than personal samples. This
is because they are used for identification or evaluation of public exposure.
The lower concentrations require a larger volume of air to concentrate the
sample. This can be done by using a higher flow rate, by sampling longer,
or both. Longer sampling times are used because public exposure can be 24
hours each day compared to a site worker's exposure of 8 to 10 hours each
day. A long sampling time and a high flow rate require a pump that is AC
powered. Battery pumps are only rated for 8 to 10 hours of use.
• Analytical method used by the laboratory—The analytical method used by the
laboratory also affects the collection devices used. There are commonly used
methods developed by the U.S. Environmental Protection Agency (EPA), National
Institute of Occupational Safety and Health (NIOSH), and Occupational Safety and
Health Administration (OSHA) that specify sampling and analysis procedures. These
methods are found in EPA's Compendium of Methods for the Determination of Toxic
Organic Compounds in Ambient Air, NIOSH's Manual of Analytical Methods, and
OSHA's Analytical Methods Manual.
Air Sample Collection 2 10/93
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Although these methods were developed for similar chemicals, there are differences
in the procedures. The laboratory being used may also have different requirements.
The laboratory should be consulted prior to sampling.
EPA's Environmental Response Team (EPA-ERT) has developed an Air Methods
Database so that the user can determine what methods are available for sampling a
chemical. The database includes EPA, NIOSH, OSHA, and American Society for
Testing and Materials (ASTM) methods. Further information is found in a technical
bulletin (Appendix A).
Capability of the laboratory—When you choose a laboratory for analysis, make sure
you consider its capability to do a specific procedure and its experience with the
desired method. For NIOSH and OSHA methods, use an American Industrial
Hygiene Association (AIHA) accredited laboratory.
Equipment characteristics—This is an important consideration. For example, some
pumps have timers that may be useful or even necessary. Some collection devices
are fragile and may not be desirable under certain operating conditions.
AEROSOL (NONVOLATILE CHEMICALS) SAMPLERS
Media
Airborne aerosols include both dispersed liquids (mists and fogs) and solids (dusts, fumes, and
smoke). The most common method of sampling aerosols, especially the solids or particulates, is to
trap them on filters using active systems. Impingers (see Liquid Sorbents in the Gas and Vapor
(Volatiles) Samplers section) have been used, but filters are more convenient. Two types of filters
are used.
• Fiber filters are composed of irregular meshes of fibers forming openings or pores
of 20 /xm in diameter or less. As particulate-laden air is drawn through such filters,
it is forced to change direction. Particulates then impinge against the filter fibers and
are retained. A number of fiber filters are available (Table 1). The two with the
greatest application to hazardous materials operations are cellulose and glass. Filters
of these materials typically consist of thick masses of fine fibers and have low mass-
to-surface area ratios. Of the two, cellulose is the least expensive, is relatively low
in ash, has high tensile strength, and is available in a variety of sizes. Its greatest
disadvantage is its tendency to absorb water, thus creating problems in weighing.
• Membrane filters are microporous plastic films formed by precipitating a resin. Pore
sizes of 0.01-10 j*m can be formed during manufacture. Membrane filters act as a
sieve with collection of most particulates on the surface. This can be useful for
visual examination of the sample. This group of filters includes such materials as
cellulose ester, polyvinyl chloride, and polytetrafluoroethylene (Table 1). These
filters have an extremely low mass and ash content. Some are completely soluble in
10/93 3 Air Sample Collection
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organic solvents. This allows particulates to be concentrated into a smaller volume
for analysis.
TABLE 1. FILTER MEDIA FOR AIRBORNE PARTICULATES
Filter Medium Representative Application/Analysis
Mixed cellulose ester (MCE), Metals/atomic adsorption; asbestos/phase
0.8-fjm pore contrast microscopy
Glass fiber Pesticides/various
Polyvinyl chloride (PVC) Total particulates/gravimetric; hexavalent
chromium/visible spectrophotometry
Polycarbonate Fibers
Polytetrafluoroethylene Alkaline dusts/acid-base titration
Source: N1OSH Manual of Analytical Methods, Third Edition, Volume 1,
February 1984 and supplements.
Piker sizes range from 13 mm in diameter to 40 by 40 inches. Small sizes (25 mm and 37 mm
diameter) are generally used for personal samples and the larger sizes are normally used for Hi-Vol
sampling. Selection of the size and type of filter depends on the user application and analysis.
Table 1 gives examples of different filters and their applications.
The common filter holder used for personal samples is the polystyrene plastic cassette (Figure 1).
It consists of two or three stacked sections, the number depending on the contaminant and the
collection method. The sections of a cassette are molded to fit tightly when stacked and to tightly
grip the outer edge of the filter. Each cassette has end plugs to seal the inlet and tubing connector
part once the sample collection is completed.
Other materials than polystyrene can be used. Metal is used in large samplers with high flow rates.
Carbon-filled polypropylene is used for asbestos sampling because it prevents an accumulation of a
static charge, which would result in the attraction of the asbestos fibers to the cassette walls.
Air Sample Collection 4 10/93
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Ring piece
Filter paper
Backup pad
FIGURE 1. ASSEMBLY OF A THREE-PIECE FILTER CASSETTE
Source: OSHA Technical Manual, U.S. Department of Labor, OSHA, 1990.
Size Selection
Unlike gases and vapors, not all aerosols reach the deeper portions of the respiratory system. The
nose and bronchioles remove the larger sizes. Environmental or public health samples are usually
classified as total suspended particulates (TSP) or paniculate matter - 10 fi (PM1Q). PMi0 samples
collect particulates that are 10 n and smaller. This represents the fraction of airborne particles that
would be inhaled. PMi0 samples are used to assess the inhalation route of exposure. TSP is used
to assess exposure to contaminants that may be deposited downwind and available through ingestion.
Occupational samples are classified as total or respirable. Total samples are equivalent to TSP.
Respirable samplers are designed to collect particles that would reach farther into the respiratory
system. Most occupational exposure limits for particles are based on total samples. A few, silicon
dust, coal dust, and nuisance dust, are based on respirable samples.
The most common devices used for aerosol size separation are the inertial impactor, the centrifugal
separator, and the cascade impactor.
10/93
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The inertial impactors rely on a sudden change in velocity and direction to separate
the sizes of particles. Figure 2 illustrates the principle. The example shows that the
larger particles (having more inertia) cannot follow the change in air direction and
impact in the separator. The smaller particles can make the turns and are collected
at the filter.
The centrifugal separator or cyclone is similar to the inertial impactors. Cyclones
commonly are conical or cylindrical in shape, with an opening through which
particulate-laden air is drawn along a concentrically curved channel. Larger particles
impact against the interior walls of the unit due to their inertia and drop into the base
of the separator. The lighter particles continue on through and are drawn up through
the separator and collected on a filter. Cyclones can be very compact and thus are
often used for personal sampling.
Air flow
Filter
Pump
FIGURE 2. ILLUSTRATION OF AN INERTIAL IMPACTOR
Cascade impactors (Figure 3) are composed of a number of stacked perforated
collection beds or plates, each with openings narrower than the one before it. The
cascade impactor separates particulates in an airstream by directing them toward a
dry or coated flat surface. As the particulate-laden air moves through the plates,
larger particles are deposited near the top and smaller near the bottom.
Air Sample Collection
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One major difference between the cascade impactor and other separators is that it can
be used to collect each separate fraction for analysis. The other separators are used
to separate the "respirable" fraction for analysis from the "total" mass of particulates.
With all preselectors, the separation efficiency is dependent on flow rate control. A specific flow
rate is needed for the device to do proper separation.
Air flow
Collector
Plates
Pump
FIGURE 3. CASCADE IMPACTOR
GAS AND VAPOR (VOLATILES) SAMPLERS
Gases and vapors have different physical properties than aerosols and thus would pass through
untreated filters without being collected. For gas and vapor collection, a sorbent is needed to
separate the contaminant from the atmosphere or a container is needed to collect a whole air sample.
The sorbents may be solid or liquid and the containers can be glass, plastic, or metal.
10/93
Air Sample Collection
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Solid Sorbents
Solid sorbents are a class of media widely used in hazardous materials sampling operations. Table 2
gives some examples and their applications. These materials collect by sorption and are often the
media of choice for insoluble or nonreactive gases or vapors. Their advantages include high
collection efficiencies, indefinite shelf lives while unopened, ease of use and specific analytical
procedures.
TABLE 2. COMMONLY USED SOLID SORBENTS
Solid Sorbent Representative Gas or Vapor Adsorbed
Activated charcoal Nonpolar organics (NIOSH)
Tenax® Volatile, nonpolar organics (EPA)
Carbon molecular sieve Highly volatile, nonpolar organics (EPA)
Silica gel Polar organics (NIOSH)
Sources: NIOSH Manual of Analytical Methods, Third Edition,
Volume 1, February 1984 and Supplements; EPA's Compendium of
Methods for the Determination of Toxic Organic Compounds in
Ambient Air, EPA/600/4-89/017, June 1988.
There are several considerations when using solid sorbents. One of the major concerns with the use
of solid sorbents is the potential for "breakthrough." Breakthrough occurs when the sorptive capacity
of the media is exceeded. There is a limit to the amount of chemical that the sorbent can hold.
Most methods limit the volume of air pulled through the sorbent to prevent this problem; hence, the
use of low flow pumps for sorbent tube sampling. A way to check for breakthrough is to use a
double section tube (Figure 4) and analyze each section separately. If a excessive amount of the
total sample—one agency uses 25%—is found in the "back-up" section, then the sample is considered
incomplete. Breakthrough is affected by humidity, temperature, total amount of chemicals in air,
and the type and amount of sorbent. The problem of breakthrough can be reduced by reducing the
air sample volume, increasing the amount of sorbent (e.g., use a 750 mg tube instead of a 150 mg
tube) or using tubes in series. For example, the NIOSH methods for vinyl chloride and methylene
chloride use two tubes in series.
A sorbent may not be able to collect all of a chemical. The efficiency will vary with sorbent and
chemical. That is why there is no universal collection media. The sampling method usually selects
the sorbent that will get the highest sorption efficiency (the closer to 100% the better).
Storage and handling of the sorbent samples can also be a problem. They cannot be stored
indefinitely. Analysis usually must be done within 2 weeks. Some sorbents require special handling.
The EPA method that uses Tenax® tubes for sampling requires the operator to wear cotton gloves
so as not to contaminate the media with skin oils. The method requires storage away from sunlight.
Air Sample Collection g 10/93
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B
t t
Dividers
A = Solid sorbent
B = Solid sorbent (backup or different sorbent)
FIGURE 4. TYPICAL 150 MG SOLID SORBENT TUBE
When the samples are analyzed, the chemicals must be desorbed from the media. This can be done
with solvents (e.g., carbon disulfide) or with heat (thermal desorption). Solvent desorption can
involve hazardous liquids and needs a controlled laboratory environment. Thermal desorption can
be done with automated equipment and does not need hazardous chemicals. However, the elevated
temperatures may cause a change in some unstable chemicals.
Once the sample is desorbed, it can be analyzed by a variety of detectors.
Liquid Sorbents
Liquid sorbents are used to collect soluble or reactive gases and vapors (Table 3). Only a relatively
few analytical methods use liquid sorbents. Further, most of the common liquid absorbers tend to
be contaminant-specific and have limited shelf lives.
The liquid sorbents need a sampler to hold the liquid during sampling. These samplers ensure that
contaminants in the sampled air are completely absorbed by the liquid sampling medium. There are
several varieties of samplers. Differences in design are due to the efficiency needed for absorption.
• Impingers, or simple gas washers (Figure 5a), are a basic liquid holding sampler.
This device consists of an inlet tube connected to a stopper fitted into a graduated vial
such that the inlet tube rests slightly above the vial bottom. A measured volume of
liquid is placed into the vial, the stopper inlet is put in place, and the unit is then
connected to the pump by flexible tubing. When the pump is turned on, the
contaminated air is channeled down through the liquid at a right angle to the bottom
of the vial. The air stream then impinges against the vial bottom, mixing the air with
the liquid and the necessary air-to-liquid contact achieved by agitation. The
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Air Sample Collection
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TABLE 3. COMMONLY USED LIQUID ABSORBERS
Absorbing Liquid
Gas/Vapor Absorbed
0.1 N NaOH Cresol/phenol (EPA); phenol (NIOSH)
0.1 M HCI Hydrazine (NIOSH)
Aniline Phosgene (EPA)
DNPH reagent and isooctane Aldehydes/ketones (EPA)
Sources: NIOSH Manual of Analytical Methods, Third Edition,
Volume 1, February 1984 and supplements; EPA Compendium of
Methods for the Determination of Toxic Organic Compounds in
Ambient Air, EPA/600/4-89/017, June 1988.
popularity of impingers rests on such qualities as simple construction, ease of cleaning, the
small quantity of liquid used (typically less than 25 to 30 milliliters), and a size suitable for
use as a personal monitor.
B
FIGURE 5. A - IMPINGER; B • FRITTED BUBBLER
Source: The Industrial Environment - Its Evaluation and Control, NIOSH, 1973.
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10
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• Fritted bubblers (Figure 5b) are generally used when a high degree of air-liquid
mixing is desired. They are similar in construction to the impinger, but have a mass
of porous glass, called frits, at the end of the submerged air tube. The frits break
the air stream into numerous small bubbles. The frits are categorized as fine, coarse,
or extra coarse, depending on the number of openings per unit area. By producing
smaller sized bubbles, a greater surface area of the air sample is in contact with the
liquid medium.
One of the major disadvantages with liquid sorbent sampling is that the samplers are generally made
of glass and, thus, are fragile. Other disadvantages are the need for low, controlled flow rates to
prevent overflow of liquid; spillage of liquid if the sampler is worn as a personal sampler; extra
handling and storage of liquids; possible evaporation of liquid sorbent during sampling and thus loss
of sample; and a need for a safety device (extra impinger, for example) between sampler and pump
to prevent liquid contamination of the pump.
Passive Dosimeters
Passive dosimeters now available apply to gas and vapor contaminants only. These devices primarily
function as personal exposure monitors, although they have some usefulness in area monitoring.
Passive dosimeters are commonly divided into two groups, primarily on how they are designed and
operated.
• Diffusion samplers (Figure 6) function by the passive movement of contaminant
molecules through a concentration gradient created within a stagnant layer of air
between the contaminated atmosphere and the collection material.
• Permeation dosimeters rely on natural permeation of a contaminant through a
membrane. The efficiency of these devices depends on finding a membrane that is
easily permeated by the contaminant of interest and not by other contaminants.
Permeation dosimeters are therefore useful in picking out a single contaminant from
a mixture of possibly interfering contaminants.
There are liquid and solid sorbents available for passive dosimeters. However, solid sorbents are
the most common.
10/93 11 Air Sample Collection
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Contaminant
Sorbent
Chemical permeates membrane and/or diffuses into
sampler
FIGURE 6. DIFFUSION TYPE PASSIVE DOSIMETER
Quantitative passive dosimeters have become available only since the early 1970s, though a
semiquantitative passive monitor for carbon monoxide was patented as early as 1927. The key
advantage of dosimeters is their simplicity (Figure 6). These small, lightweight devices do not
require a mechanical pump to move a contaminant through the collection media. Thus, calibration
and maintenance of sampling pumps are not needed. However, the sampling period must still be
accurately measured. Like active systems, these devices can be affected by temperature and
humidity. Sources of error unique to passive dosimeters arise from the need for minimum face
velocities and the determination of contaminant diffusion or permeation coefficients.
Container Sampling
Because of the problems associated with sorbent sampling (breakthrough, sorbent efficiency, etc.),
methods have been used to collect a whole air sample in a container. Several types of containers
have been used.
Glass bottles have been used because of the relative inertness of glass. The procedure can be done
several ways. The glass container can be evacuated to produce a vacuum and then opened in the
sampling area. While this technique does not use a sampling pump, some way of evacuating the
container is needed. Another method uses a pump to pull air through the container. When the air
sample has replaced the air in the container, the container is closed. Another device uses a container
Air Sample Collection
12
10/93
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filled with water. When the water is drained, the air sample fills the space left by the departing
water. This method is undesirable if water vapor is a problem in the analysis.
The devices have two problems. The containers are fragile and only give a sample at ambient
pressure. To get a sample out, a vacuum needs to be pulled on the container or air added to equalize
pressure as a sample is taken out. As more and more samples are removed, it becomes harder and
harder to get the sample out. This also requires a pressure correction when calculating the
contaminant concentration. If air is added to equalize pressure, the sample becomes diluted.
Sample collection bags can be constructed of a number of synthetic materials, including polyethylene,
Saran™, Mylar™, Teflon™. They are square or rectangular with heat-sealed seams, hose valve
fittings, inlet valves, and septums for syringe extraction of samples. They come in a variety of
volumes. The selection of a bag should be based on a number of characteristics, including resistance
to adsorption and permeation, tensile strength, performance under temperature extremes, construction
features (seams, eyelets, and fittings), and intended service life.
Bag sampling can be done by connecting the bag inlet valve with flexible tubing to the exhaust outlet
of a sampling pump. The bag inlet valve is opened, the pump turned on, and the.sample collected.
Once sampling is completed, the pump is turned off, the bag valve closed and the bag disconnected.
The bag contents may be analyzed by connecting the bag to a direct-reading instrument; or a portion
of the contents can be taken from the bag by a syringe and injected into a gas chromatograph.
In situations where there is concern about sample contamination due to passing through a pump, an
alternate sampling apparatus can be constructed. This apparatus involves using the pump to evacuate
a chamber (a desiccator or a scalable box) in which the sample bag is installed (Figure 7). As the
pump creates a partial vacuum, the sample bag expands and draws the sample in through a sample
tube.
The major disadvantage of gas sample bags is sample stability. Chemicals in the sample may sorb
to the bag material or permeate through the bag walls. This would cause a decrease in sample
concentration. The sample can also be affected by contaminants outside the bag by permeation
through the bag walls. If a bag is reused, sorbed chemicals may desorb into the new sample and
cause contamination. Because of these problems, bags are seldom reused, and samples are analyzed
as quickly as possible (usually within 24 hours).
Chemicals in the bag can degrade with exposure to sunlight. The bags should be stored in a
container (e.g., a cooler or garbage bag) to prevent exposure to sunlight.
Recently, metal canisters have gained popularity. Until recently, there have been problems with
reactions occurring with the metal on the insides of the container. New polishing techniques have
greatly reduced the problem. Metal canisters are used similarly to glass containers. They are
evacuated to produce a vacuum. Unlike glass containers, metal canisters can be filled several ways.
The valve can be opened to get a instantaneous, or grab, sample. The canister can also be connected
to a controlled flow orifice so that the sample fills the canister at a fixed rate. This gives a long term
sample.
A pump can also be used to pressurize the canister so that a sample volume greater than the canister
size is obtained. This latter capability is not available for glass containers or gas bags.
10/93 13 Air Sample Collection
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Sample flow
Air flow
Source: 'Sampling and Analysis of Emissions from Stationary Sources,* Schuetzle et
al., Journal of the Air Pollution Control Association, Volume 25, No. 9, Sept. 1975.
FIGURE 7. NEGATIVE PRESSURE BAG SAMPLING APPARATUS
Metal canisters are more durable than glass containers. They have better sample stability than gas
bags. There are special cleaning procedures that allow the canister to be reused.
Metal canisters have a problem with recovery of polar compounds (e.g., alcohols).
Syringes can also be used to take a sample. Although 1-liter syringes are available, most are rather
small and there may be a problem with having an adequate amount of sample.
Container sampling allows whole atmosphere sampling. This type of sampler eliminates the
problems associated with sorbent media. It also allows the use of more than one analytical method
per sample. Glass containers are fairly inert but are fragile. They also are limited in size. Gas bags
are more durable and have a variety of sizes, but have sample stability problems. Metal canisters
are durable, have good sample stability and can get a larger sample than their actual size (but only
if special equipment is used). There are systems for taking personal samples with a gas bag. Gas
bags and metal canisters can also obtain long term samples with controlled flow pumps.
SEMIVOLATILE SAMPLERS
Some chemicals, because of their physical properties, may be present in both solid and vapor form.
There are also chemicals that are not very volatile, but will vaporize gradually if air is passed over
them. This could happen is the chemical was captured on a filter. Because of these situations, some
methods use more than one type of media. Usually a filter (for the aerosol phase) is followed by
a sorbent (for the vapor phase). Table 4 gives examples of chemicals that are in this category and
the methods used to collect them.
Air Sample Collection
14
20/93
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Because two separate media are used, both will probably be analyzed by different methods. It will
also take more time and be more expensive for the analysis.
TABLE 4. COMMON MULTIMEDIA SAMPLERS
Media Used Chemical Being Sampled
0.8-/t/m MCE filter + 0.1 N KOH Cyanides (NIOSH)
13-mm glass fiber filter and Florisil Polychlorinated biphenyls
(PCBs) (NIOSH)
Quartz filter and polyurethane foam (PUF) PCBs/pesticides (EPA)
Polycyclic aromatic
hydrocarbons - PAHs (EPA)
Quartz filter + XAD-2 PAHs (EPA)
Sources: NIOSH Manual of Analytical Methods, Third Edition, Volume
1, February 1984 and supplements; EPA Compendium of Methods for the
Determination of Toxic Organic Compounds in Ambient Air, EPA/600/4-
89/017, June 1988.
SAMPLING PUMPS
Pump Characteristics
Air sample collection systems, with the exception of evacuated canisters and passive dosimeters, rely
on electrically powered pumps to mechanically induce air movement. The power source may be
batteries or an AC source. Battery-powered pumps can operate for 6-10 hours. AC-powered pumps
can operate longer, but are not usable as personal samplers.
Generally, sampling pumps incorporate several of the following features:
• A diaphragm or a piston-type pumping mechanism
• A flow regulator to control the sampling flow rate
• A rotameter or stroke counter to indicate flow rate or sample volume
• A pulsation dampener to maintain a set flow rate
• A programmable timer to start the pump at a set time and/or to stop the pump after
a set sampling period
• An inherent safety approval for gas/vapor and dust atmospheres
10/93 15 Air Sample Collection
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Other than differences in features mentioned above, the main difference in pumps is their
flow rate. Low flow pumps have a flow rate range from 10 cubic centimeters per minute
(cc/min) to about 750 cc/min. Medium flow pumps have a flow rate of about 1-6 liters per
minute (1pm). High volume (Hi-Vol) pumps are AC powered and can achieve up to 40 cubic
feet per minute (cfm). That is equivalent to 1130 1pm.
The choice of flow rate depends on the type of sampling done. Sorbent media, like carbon
tubes, cannot be used with a high flow rate. The capacity of the sorbent would be exceeded
and there would be a loss of sample (breakthrough). Also, the Hi-Vol pumps are not used
as personal samplers. Some pumps have the ability to do both low and medium flow
sampling, but not Hi-Vol.
Calibration
All pumps must be calibrated. The flow rate must be known so that a sample concentration can be
calculated. Calibration is also necessary to ensure the constant flow rate needed for some methods.
The flow rate stability of a pump should be accurate to within +5% of its set flow rate.
An active sampling system must be calibrated prior to and after sampling. The overall frequency
of calibration depends upon the general handling and use a system received and the quality control
considerations of the user. Pump mechanisms must be recalibrated after they have been repaired,
when newly purchased, and following any suspected abuse. The sampling system as a whole must
be calibrated to the desired flow rate rather than the pump alone. The sampling system should be
calibrated prior to and after each use. The system can be adequately examined under field-like
conditions only with all components connected.
There are several devices for calibrating sampling pumps:
• The soap bubble meter represents a basic method of calibration and is a primary
standard. This device typically consists of an inverted graduated burette connected
by flexible tubing to the sampling train. Figure 8 shows one example.
Do the calibration as follows:
Start the system's pump to create airflow into the burette
Dip the open end of the burette into a soap solution to create a soap film
bubble across the opening
Remeve the solution and allow the bubble to rise up through the burette
Measure the travel time of the bubble between two graduated points on the
burette; vary the flow rate by adjusting the pump flow regulator.
The general formula used for the calculation of the flow rate is:
PI _ volumetric distance traveled by bubble (ml)
travel time of bubble (sec)
Air Sample Collection 16 10/93
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Inverted
buret
250
Filter
cassette
Soap bubble trap
Pump
Beaker
Soap solution
FIGURE 8. CALIBRATION SETUP FOR FILTER SAMPLER
USING A SOAP BUBBLE METER
Source: OSHA Technical Manual, U.S. Department of Labor, OSHA, 1990.
If the desired flow rate is 1pm, then the units need to be converted by multiplying the previous
equation by the following:
60 seconds/minute
1000 mill
• There are electronic bubble meters that use sensors to detect the soap bubble and start
and stop an electronic timer. The calibrator then automatically calculates and
displays the pump flow rate.
10/93
17
Air Sample Collection
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The precision rotameter consists of a vertically mounted tapered tube with a float
inside the tube. When attached to an operating pump, the float rises until the rate of
flow is sufficient to hold the float stationary. The flow rate is read from markings
on the tube at the point the float is stationary. Figure 9 illustrates a precision
rotameter.
•
1
3500
=_ 3000
~ 2500
I— 2000
Z_ 1500
£_ 1000
5_ 500
cc/min
| ' p rump
I 4 - Air Flow
FIGURE 9. EXAMPLE OF A PRECISION ROTAMETER
Whereas the precision rotameter usually is more compact and portable than the soap bubbler meter,
it is considered a secondary standard. This means that the rotameter must be checked occasionally
with a primary standard such as a bubble meter.
• A manometer is sometimes used to calibrate Hi-Vol samplers because of the high
flow rates. A manometer is a tube filled with a liquid. The level of the liquid
changes due to pressure changes at the end attached to the sampling pump. A
calibration chart is used to convert the change in liquid level to flow rate.
CONCLUSION
When taking air samples for laboratory analysis, several factors need to be considered. Sampling
and analytical methods have been developed for many chemicals by several agencies that have looked
at these considerations. The References section provides a list of references on air monitoring and
sampling.
Air Sample Collection
18
10/93
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United States
Environmental Protection
Agency
Office of
Solid Vteste and
Emergency Response
January 1993
Air Sampling Methods
Database
Office of Emergency and Remedial Response
Emergency Response Division
Technical Bulletin
Volume 1, Number 1
What is the Air Sampling Methods
Database?
The Air Sampling Methods Database is a PC-based
software package which allows its users to access sum-
marized standard methods for chemical analysis. The
program, which was designed to be used in conjunction
with the Representative Air Sampling Guidance for the
Removal Program document, formulate sampling plans
to give the best possible site characterization. This al-
lows users to make quick determinations about which
methods are most appropriate to use and which best
suit their informational needs in order to plan a sam-
pling event that most aptly depicts the objectives of a
particular site investigation.
The user can search the software by method name and
number, chemical name, or Chemical Abstracts Num-
ber (CAS #). The method summary can be viewed and
the method marked for printing. Furthermore, the soft-
ware can be tailored to its users since they have the ca-
pacity to input their own user-developed methods into
the database without affecting the established stand-
ardized methods. Users can submit supporting docu-
mentation for their methods to the United States
Environmental Protection Agency's Environmental Re-
sponse Team (U.S. EPA/ERT) for possible permanent
inclusion to the database.
Who Are the Anticipated Users?
On-Scene Coordinators (OSC), Technical Assistance
Team (TAT) members, Emergency Response Contrac-
tors (ERCs), site Health and Safety air personnel, and
U.S. EPA air plan reviewers are the primary users of
the Air Sampling Methods Database. By using the pro-
gram, these individuals gain access to the sampling ob-
jectives which best characterize a site. Then, users can
assimilate this information into an acceptable repre-
sentative sampling program. The Air Sampling Methods
Database also can aid any U.S. EPA personnel or
agency that performs air monitoring at hazardous waste
sites.
Why Was the Air Sampling
Methods Database Designed?
The Air Sampling Methods Database was created to ex-
pand the knowledge base during remedial emergency
response actions. It gives insight to two major criteria
for preparation of a representative air sampling plan:
selecting the appropriate air sampling approach and
choosing the proper equipment to collect and analyze a
sample. Timely decisions regarding health and safety
and acute health risks can be made by utilizing these
summarized methodologies:
• National Institute of Occupational Safety and
Health (NIOSH) 2nd and 3rd Edition Methods.
• Occupational Safety and Health Administration
(OSHA) Methods.
• Selected American Society of Testing and Materi-
als (ASTM) Methods. Volume 11.03 Atmospheric
Analysis; Occupational Health and Safety.
• EPA Toxic Organic Compounds Methods.
• Contract Laboratory Program - Statement of Work
Methods.
• Indoor Air Compendium Methods.
• Code of Federal Regulations (CFR) Methods.
This facilitates a greater variety of options for the users,
who then can select the appropriate air sampling objec-
tives and plans that best suit the needs of a particular
assignment.
-------
Features of the Air Sampling
Methods Database
• Is user friendly.
• Requires no other software for support (self-con-
tained).
• Adds, deletes, and edits methods added by a user.
• Traces information by on-line references.
• Provides single point of update.
• Givessemi-annualJy updates.
• AlJows access to update information available via
Environmental Response Center (ERC), Office of
Solid Waste and Emergency Response (OSWER),
U.S. EPA/ERT, and Dataport bulletin boards by
modem.
• Generates hard copy.
Future Features:
• Hot-Key on-line help.
• Hot-Key on-line glossary of terms.
50-100 word text summaries discussing sampling
trains, flow rates, interferences, detection limits,
analysis information, etc.
Synonym searching of chemical names.
Requirements
To run the Air Sampling Database, you must have the
following:
• An IBM PC or IBM-compatible computer
• A hard drive
• 640KRAM
• A printer (for hard copy output)
For more information about the Air Sampling Database,
contact:
Mr. Thomas Pritchett. Phone: (908) 321-6738
U.S. Environmental Response Team
2890WoodbridgeAve
Building 18, MS-101
Edison, N'ew Jersey 08837-3679
-------
APPENDIX A
Air Sampling Methods Database
-------
INTRODUCTION TO GAS
CHROMATOGRAPHY
PERFORMANCE OBJECTIVES
At the end of this lesson, participants will be able to:
• List the components of a gas chromatograph
• Define retention time
• List the factors that affect retention time
• Name the two types of columns and describe their
differences.
-------
NOTES
INTRODUCTION TO GAS
CHROMATOGRAPHY
GAS CHROMATOGRAPHY
Definition
A technique for separating
volatile substances in a mixture
by percolating a gas stream
over a stationary phase
Source: Basic Gas Chromatography
SEPARATION OF A MIXTURE
BY GAS CHROMATOGRAPHY
B
ConpmnlA
mi
IZ2
ConpmntA
Conpannt 6
4/94
Introduction to Gas Chromatography
-------
NOTES
RETENTION TIME
Definition
Retention time is the time
from sample injection to peak
maxima (signal maxima)
InjMtlon
Tim*
RETENTION TIME
Application
Used for qualitative identification of
chemicals by comparing the retention
time of an unknown chemical with
retention times of known (standard)
chemicals
RETENTION TIME
Peak Comparisons
Injection
Standard
Unknown
1 2 3
Tim*
Introduction to Gas Chromatography
4/94
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FACTORS AFFECTING
RETENTION TIME
• Column
- Type
- Temperature
- Length
• Carrier gas flow rate
EFFECT OF COLUMN TYPE
AND TEMPERATURE
Chemical
Benzene
Temperature
CO)
0
40
Retention Time
(min.)
G-8 Column T-6 Column
1:16
0:25
Carbon tetrachloride
1:43
0:32
0:37
40
0:25
0:17
Source Th* Foxboro Company Chromatographic Column Guide lor the
Century OVA, 1986
PEAK RESOLUTION
Problems
Overlapping peaks
NOTES
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Introduction to Gas Chromatography
-------
NOTES
PEAK AREA
Application
Peak area is used to quantify chemical
/S*mpl«v
Concentration Sample
Concentration Standard Area Standard
GAS CHROMATOGRAPH
Components
Flow
control
Infection port
V I Column
Output
Carrier go
CARRIER GAS
Characteristics
• Suitable for detector
• High purity
• Does not interfere with sample
Introduction to Gas Chromatography
4194
-------
NOTES
GAS CHROMATOGRAPH
Columns
Packed
Liquid ttalionary phate
coated on solid stationary
support
Capillary
Liquid stationary phase
coated on wall
COLUMN TEMPERATURE
• Ambient
- Variable
• Isothermal
- Constant temperature
• Temperature programming
- Temperature increases over time
DETECTORS USED IN
PORTABLE GCs
Common detectors
- Flame ionization detector (FID)
- Photoionization detector (PID)
Specialized detectors
- Thermal conductivity detector (TCD)
- Argon ionization detector (AID)
- Electron capture detector (BCD)
4/94
Introduction to Gas Chromatography
-------
NOTES
SPECIALIZED DETECTORS
Why Are They Used?
One detector may be more sensitive
than another for certain compounds.
e.g. The BCD is best detector for
halogenated compounds.
MASS SPECTROMETER
Chemical exposed to electrons
Molecule or fragments are ionized
Ions separated by magnetic field
Separation based on speed and
mass-to-charge ratio
Only detector capable of providing
additional compound identification beyond
retention time
MASS SPECTRUM
Benzene
1001
50-
Relative
abundance
«* 74
40 SO 10 70 60 90 100 110 120
Mass-to-charge ratio
Introduction to Gas Chromatography
4/94
-------
NOTES
MASS SPECTRUM
Toluene
1001
50-
Relative
abundance
IB 51
45 . .1
I I, I 70 n Ml
L..||| ll UI 11.1 ..l
40 80 «0 70 80 »0 100 110 120
Mass-to-charge ratio
GAS CHROMATOGRAPHY
Field Applications
• Air analysis
• Field screening
• Soil gas
SUMMARY
Gas chromatography is used to
identify and quantify chemicals
Qualified operators are needed
Right tool for the job?
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Introduction to Gas Chromatography
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INTRODUCTION TO GAS CHROMATOGRAPHY
INTRODUCTION
Gas chromatography is a separation technique wherein components of a sample are separated by
differential distribution between a gaseous mobile phase (carrier gas) and a solid (gas solid
chromatography) or liquid (gas liquid chromatography) stationary phase held in a column. The
sample is injected into the carrier gas as a sharp plug and individual components are detected as they
come out ("elute") of the column at characteristic "retention times" after injection. Figure 1
illustrates this concept with a two component mixture.
A + B
Gas
Flow
Column
Component A
in Detector
Component A
Component B
FIGURE 1. SEPARATION OF A TWO COMPONENT MIXTURE
BY GAS CHROMATOGRAPHY
As different components elute from the column, they pass through a detector which generates a
response (or "peak") based upon the amount of each compound present and upon the sensitivity of
the detector. The signal vs. time plot is called the "chromatogram."
10/93
Introduction to Go? Chromatography
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QUALITATIVE ANALYSIS
If the temperature of the column and the flow rate of the carrier gas are constant, compounds will
elute from the column at a characteristic time (retention time). The retention is characteristic of the
compound and the type of column used. Retention time is the time from injection of the sample to
peak response of the detector to the eluted compound (Figure 2).
Retention time
Injection
8 9
Time
FIGURE 2. CHROMATOGRAM ILLUSTRATING RETENTION TIME
Qualitative analysis can be done by comparing the retention times of the compounds in an unknown
sample with the retention times of known compounds in a standard analyzed under identical
conditions. Figure 3 shows a comparison of a sample with a standard.
Retention Time
Retention times are governed by several factors:
1. The type of column used. Different packings and liquid coatings change retention
time.
2. The column temperature. As the column temperature increases, the retention time
decreases. This is why temperature controls are used to keep the column temperature
constant.
Introduction to Gas Chromatography
10/93
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3. The column length. Double the column length and double the retention time.
4. The carrier gas flowrate. Double the flowrate and halve the retention time.
Injection
Standard
Unknown
Time
FIGURE 3. EXAMPLE OF A GC CHROMATOGRAM AND THE USE OF
RETENTION TIMES TO IDENTIFY COMPOUNDS
Resolution
Resolution, or relative peak width, governs the number of discrete, detectable components of a
sample that can be identified and quantified during the GC run. Resolution is governed by:
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Introduction to Gas Chromatography
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3.
The type of column. Capillary columns have much greater resolution (narrower peak
widths) than a packed column.
Column length. The longer the column, the narrower the peak weak width at a given
retention time. However, with ambient temperature GCs, increasing the column
length will increase the retention times.
The carrier gas flowrate. There exists an optimum value for peak resolution.
Increasing or decreasing the flowrate from this optimum will widen the peaks.
A problem with poor resolution is co-eluting and overlapping. If two chemicals elute at the same
time—co-elute—identification is hindered. If peaks overlap, quantitation of the compounds is
difficult. Figure 4 illustrates overlapping peaks.
Overlapping peaks
FIGURE 4. EXAMPLES OF OVERLAPPING PEAKS
QUANTITATIVE ANALYSIS
Signal Output
The size of the chromatogram peak for a specific compound is proportional to the amount of
chemical in the detector. Quantitative analysis is done by comparing the peak size of the sample
compound with the peak size of a known amount of the compound (the standard). The peak size can
be quantified in several ways.
Introduction to Gas Chromatography
10/93
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Planimetering
Planimetering uses a planimeter to trace the peak. A planimeter is a mechanical device that
measures area by tracing the perimeter of the peak. The area is presented digitally on a dial. This
method is considered tedious, time-consuming, and less precise than other methods.
Peak Height
Peak height compares the height of the sample compound with the height of the standard. This is
a quick and simple method for quantitation. However, peak heights and widths are dependent on
sample size and sample feed rate.
Height x Width at Half-Height
The height x width at half-height uses the height of the peak times the width of the peak at the half-
height of the peak. The normal peak base is not used because large deviations may be caused by
peak tailing.
Triangulation
Triangulation (Figure 5) transforms the peak into a triangle using the sides of the peak to form the
triangle and the baseline to form the base of the triangle. The area of the peak is calculated using
Area = 1/2 Base X Height.
Integrators
Peak height, height x width at half-height, and triangulation are done manually using the
chromatogram and a pencil and straight edge. Integrators calculate the peak size electronically and
record the output. Because of ease of operation, integrators are most frequently used in portable
GCs.
When a microprocessor is used, the retention times of the compounds in the sample are compared
to the compounds in the standard and the readout identifies the compounds in the sample.
Quantitative analysis is done by an integrator. If a compound has been identified, the peak size in
the sample is compared to the peak size of the compound in the standard and a sample concentration
is given. Thus, the sample is evaluated both qualitatively and quantitatively.
10/93 5 Introduction to Gas Chromatography
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Area = 1/2 x base x height
Area = 1/2 b h
FIGURE 5. MEASUREMENT OF AREA BY TRIANGULATION
Source: An Introduction to Gas Chromatography, National Training Center, Water Program
Operations, U.S. Environmental Protection Agency, Cincinnati, OH.
COMPONENTS OF A GAS CHROMATOGRAPH
A gas chromatograph (GC) consists of (Figure 6):
A carrier gas
A flow control for the carrier gas
A sample inlet or injector
A column
A temperature control for the column
A detector
A recorder.
Carrier Gas
A high pressure gas cylinder serves as the source of the carrier gas. The carrier gas should be:
1. Inert to avoid interaction with the sample or solvent
2. Able to provide a minimum of gaseous diffusion
3. Readily available and of high purity
4. Inexpensive
5. Suitable for the detector used.
Commonly used gases are helium, nitrogen, and hydrogen.
Introduction to Gas Chromatography 5 10/93
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Flow
control
\
Injection port
I
Output
Detector
Carrier gas
FIGURE 6. COMPONENTS OF A GAS CHROMATOGRAPH
Source: The Industrial Environment - Its Evaluation & Control, 1973, National Institute for
Occupational Safety and Health.
Portable gas chromatographs (GCs) have internal cylinders that usually have an 8- to 10-hour gas
supply. Many of these also have connections for external cylinders to provide longer duration
analysis.
Flow Control
Because compounds elute at a characteristic time (retention time) based on a given temperature and
a constant flow rate, carrier gas flow control and column temperature are important. A flow
controller is necessary to maintain a constant flow rate.
Sample Injection System
Samples are introduced into the column as a single sharp plug. The sample injection system allows
introduction of the sample rapidly and in a reproducible manner. Samples can be manually injected
by a syringe. Syringe injection allows the operator to control the sample volume. Some GCs have
a built-in sample loop that injects a known and consistent volume by manual operation or automatic
10/93
Introduction to Gas Chromatography
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programming. Sample volume is important in that the quantitative evaluation of a chromatogram is
affected by the sample volume. Also, some columns are limited by the size of sample that can be
injected onto them.
Column
The column is a tube made of stainless steel, glass, aluminum, or Teflon®. Packed columns contain
a solid adsorbent (gas-solid chromatography) or an inert solid support coated with liquid stationary
phase (gas-liquid chromatography). Capillary columns consist of a liquid stationary phase coated to
the inside wall of a thin tube. Gas-liquid chromatography columns and capillary columns are the
more common types for the portable GCs.
Tube sizes range from 0.5- to 6-mm outside diameter and from 20 cm to 50 m in length. Capillary
columns are usually longer than packed columns. Portable GC columns are typically 4 m in length.
Columns can be coiled to fit inside portable units.
Capillary columns give better resolution than packed columns. However, they require smaller
injection volumes than packed columns and thus need sample inlets and detectors that can handle
small volumes.
Temperature Control
Column temperature affects the retention time of a chemical. A constant temperature is desired to
ensure comparison of sample and standards. Temperature control can be:
• Ambient temperature control—The column temperature is the same as ambient air.
As ambient temperature changes, the retention times change. Consequently, frequent
calibration checks are needed. Ambient temperature limits use to volatile
compounds. The time to run a sample is longer and thus limits the number of
samples that can be run per day.
• Isothermal temperature control—The column temperature is maintained at constant
temperature by an oven. Retention times are much more stable. Temperatures can
be adjusted to reduce analysis time or expand the range of compounds that can be
analyzed. Retention times are halved for every 30'C increase in temperature.
Isothermal temperature control consumes more electricity than ambient.
• Temperature programming—Column temperature is slowly increased under very
controlled conditions. This allows simultaneous analysis of compounds with a wide
range of boiling points. A lower temperature is used for the volatile components.
The temperature is raised to elute the less volatile compounds. More electrical power
is needed for this operation.
Temperature control can also be used on the injector and the detector. Heating the injector prevents
condensation of the sample (if a vapor) or can ensure vaporization of a liquid sample. The detector
may need to be heated to prevent chemical condensation.
Introduction to Gas Chromatography g . 10/93
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Detector
There are a variety of detectors available for GCs. Flame ionization detectors (FID) and
photoionization detectors (PJD) are frequently used. Characteristics of these two detectors are
discussed in the Total Vapor Survey Instruments section. Other detectors include:
• Thermal conductivity detector (TCD)—This detector is based on the principle that a
hot object will lose heat at a rate that is dependent on the composition of the
surrounding gas. When a compound enters the detector, there is a change in the
thermal conductivity of the carrier gas. Its advantage is that it is a universal detector
for noninert gases and all organics. Its drawback is limited sensitivity—ppm levels.
Preconcentration of samples has been used to offset this limitation.
• Electron capture detector (ECD)-A radioactive source is used to ionize the carrier
gas. Secondary electrons are produced and an electrical current flows between the
electrodes in the detector. When a separated compound which has an affinity for the
slow electrons enters the detector, electrons are captured with a resultant decrease in
electrical current in the detector. This decrease of current is a function of the
concentration of the electron capturing compound.
The detector is especially selective for polyhalogenated (e.g., pesticides) and nitro
compounds. It has a high sensitivity—mid ppb to high ppt. Sensitivity is a direct
function of halogen atoms per molecule.
Its main limitation is that a radioactive source (tritium or nickel-63) is needed, which
requires a Nuclear Regulatory Commission (NRC) license.
• Argon ionization detector (AID)-Argon ionization detector depends upon two
reactions: the excitation of argon to its metastable state by electron bombardment and
the ionization of vapor molecules by the transfer of energy from the metastable
atoms. When an ionization chamber contains argon and a source of free electrons,
the addition of vapor causes an increase in current flow. The current flow change
is detected and used as the signal for the presence of the compound in the sample.
Ionization is caused by a radioactive source. As with the ECD, an NRC license is
required for use of the radioactive source.
The reaction of the metastable argon atoms with the vapor molecules applies to all
molecules with an ionization potential equal to, or less than, the stored energy of the
metastable atoms, which is 11.7 eV.
• Mass Spectrometer (MS)—]n an MS, the chemical is first exposed to a source of
electrons. The molecules or fragments are ionized. The ions are passed through a
magnetic field. The magnetic field separates the ions based on their speed and mass-
to-charge ratio. The ions are collected and a mass spectrum is produced showing the
relative abundance of each type of ion. Each chemical has a distinctive mass
spectrum. Thus, this detector is the only one listed here that is capable of providing
additional compound identification beyond retention time.
10/93 9 Introduction to Gas Chromatography
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Recording Devices
A device is needed to record when a signal is produced in the detector and to record the strength of
that signal. A plot of signal vs. time is called a chromatogram. The chromatogram is used for
qualitative and quantitative analysis of the sample. Integrators and microprocessors can be used to
electronically evaluate the chromatogram.
Power Supply
A power supply is needed to operate the detector, recorder, oven, and additional electronics of the
gas chromatograph. To make them portable, field portable GCs usually have a built-in rechargeable
battery supply. If only using the battery, time of operation is limited to 8-10 hours. These units
are also designed to operate off AC power sources. A few field GCs only operate on AC power.
APPLICATIONS
Portable gas chromatographs allow analysis in the field. Although the results may not be as accurate
and precise as a laboratory GC analysis, they can be used for screening purposes. This can reduce
the number of samples that need to be handled by a more sophisticated (and more expensive)
analysis.
Ambient Air Analysis
Portable GCs can analyze ambient air samples through several methods. Some units can be taken
to the area where the sampling is required and an analysis can be performed on the spot. Some units
can be programmed to do periodic sampling and store the chromatograms for later retrieval. Newer
units can do continual total vapor monitoring and run a sample if the total vapor reading exceeds a
designated level. The GC can also be set up in a more stable environment, and grab samples (e.g.,
a Tedlar bag of ambient air) can be brought to the GC for analysis.
Sample Screening
Soil and water samples can be screened for further analysis by doing headspace sampling.
Headspace sampling involves drawing a sample from above the surface of a liquid or soil in a
container. The sample is usually drawn with a small syringe which is also used to inject the sample
into the GC.
Soil Gas
Gas chromatography can be used to screen soil gas samples. Dissolved volatile organic compounds
have a tendency to partition into the atmosphere between the soil particles. By sampling this
atmosphere, underground contamination can be tracked.
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EXAMPLES OF PORTABLE GAS CHROMATOGRAPHS
The Foxboro Company
The Foxboro Century organic vapor analyzer (OVA) is the instrument described in the Total Vapor
Survey Instruments section. The OVA-128GC is equipped with a column. The detector used is an
FID. The column is at ambient temperature unless an optional temperature pack is used. The
portable isothermal pack allows column temperatures of O'C, 40'C and 100'C. The unit can be
purchased with an external recorder/plotter. The company does not supply an integrator, but there
are models from other suppliers that can be used.
Photovac International, Inc.
The Photovac series of GCs use photoionization detection. The temperature of the column is
controlled by an oven. The currently available models (10S50, 10S70, 10S Plus, Snapshot) have a
built-in microprocessor that aids in calibration and handles compound identification and quantitation.
These units can be programmed for automatic sampling. The 10S Plus can be programmed to do
total vapor monitoring and to do an analysis if an action level is reached. Options include a
telephone connection for transferring data from the instrument to a computer and for notifying the
user of unusual results during remote monitoring.
Sentex Sensing Technology, Inc.
The Sentex Scentograph is capable of using an AID or an ECD. One of the most notable features
of the Scentograph is that a lap-top computer is used for handling the data. This gives a more
graphic visual display of the chromatogram and makes operator use easier because of the normal size
keyboard. The GC can do automatic functions. It has a temperature controlled column. There is
the capability of concentrating the sample before injection. The air sample is pulled through and
collected on a sorbent. The sample is then desorbed and injected using a smaller volume than was
pulled through the sorbent. A primary consideration with the Scentograph is that, if an AID or an
ECD is used, a radioactive source is needed and thus an NRC license is required. A PID and TCD
are also available.
The Sentex Scentoscreen is similar to the Scentograph except it uses a PID and can also do total
hydrocarbon analysis. It can be switched to an AID/BCD, but can not do total hydrocarbon readout
with those detectors.
HNU Systems, Inc.
The HNU Systems' Model 311 is available with a PID or an ECD for its dete.ctor. The unit has a
microprocessor for data handling. The instrument does not have a battery supply and thus, needs
a line power or a portable generator.
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Microsensor Technology, Inc.
Microsensor Technology's M200 Microsensor Gas Analyzer uses a TCD. Although this is a more
universal detector, it suffers from poor sensitivity. A preconcentrator has been developed and used
to reduce this limitation. The more notable characteristic of the M200 is that it sends a sample
through two columns at the same time. This gives a better chance of correctly identifying the
compounds present.
Thermo Environmental Instruments
Thermo Environmental Instruments manufactures the Model 511 Portable Gas Chromatograph. The
main features of this GC is the variety of available detectors (FID, PID, ECD, TCD) and their easy
changeability. The unit does not have a built-in data handler, so an external integrator or
microprocessor is needed.
SUMMARY
Gas chromatography is a separation technique that can be used for identification of the components
of a mixture. Portable GCs can be used in the field for a variety of applications. This process of
identification can be affected by many factors that must be considered to ensure quality of data.
Because the equipment is more complicated to operate than most direct-reading instruments,
operators require more training and experience.
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DISPERSION MODELING
DURING
EMERGENCY RESPONSE
-------
Dispersion Modeling During Emergency Response
Objectives: • \_\s\ fjve major atmospheric dispersion considerations
• Describe the concept of stability as it applies to air
modeling
Given a set of environmental conditions, choose the
relevant stability class
Dispersion Modeling During Emergency Response
Objectives: • Describe the concept of Gaussian plume distribution
• Define near-field meandering and its effects to onsite
receptors
• Given an air dispersion model, list the data inputs needed
to run the model for an emergency response
• Given an emergency response scenario, list the elements
of the modeling plan
Notes:
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Collect site data
i
r
Collect source data
Collect contamination data
Collect meteorological data
i
r
Choose appropriate accidental release model
^
r
Input collected data to model and run model
T
r
Compare output to air action limits
'
//\ Do the
<^ require «
^^ proce
^
r
dures ^^
Yes
r
Evacuate affected onsite/offsite populations as necessary
Figure 1. Dispersion modeling during emergency removal.
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Dispersion Model Classes
Physical Models
Small-scale, laboratory
representations of the overall
process (e.g., wind tunnel, water
tank)
Mathematical Models
A set of analytical or mathematical
algorithms that describe the
physical and chemical aspects of
the problem (e.g., ALOHA, ISC,
and PAL)
Dispersion Model Classes
Mathematical models are primarily used because physical models (especially in an emergency response)
are much less practical for most Superfund applications.
Mathematical models can be:
• Deterministic models, based on fundamental mathematical descriptions of atmosphere processes,
in which effects (i.e., air pollution) are generated by causes (i.e., emissions).
• Statistical models, based on semi-empirical statistical relationships among available data and
measurements.
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Diffusion Model Footprint
750
250
750
500 0 500 1000
Yards
Reproduced with permission from The National Safety Council
1500
Diffusion Model
An example of a deterministic model is a diffusion model from which the output (the concentration field
or footprint) is computed from mathematical manipulations of specified inputs (emission rates and
atmospheric parameters).
A statistical model is given by the forecast, in a certain region, of the concentration levels in the next
few hours as a statistical function of:
1. The current available measurements
2. The past correlation between these measurements and the concentration trends.
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Source-Receptor Relationship
Wind Direction
Receptor Location
Transport Medium
(Air)
Release
Mechanism
(Volatilization)
Waste Pile
(Source)
Source-Receptor Relationship
The source-receptor relationship is the goal of studies aimed either at improving ambient air quality
(usually the Superfund site goal) or preserving the existing concentration levels from future urban and
industrial development. Only a deterministic model can provide an unambiguous assessment of the
fraction of the responsibility of each pollutant source to each receptor area. This information then allows
the definition and implementation of appropriate emission control strategies.
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Dispersion Modeling Applications
The two major dispersion modeling applications for Superfund are:
• To design an air monitoring program
• To estimate concentrations at receptors of interest
Dispersion Modeling Applications
Dispersion models can be used when designing an air monitoring program to see how offsite areas of
high concentration relate to actual receptor locations. Places where high concentration areas correspond
to actual receptors are priority locations for air monitoring stations.
Dispersion models can also be used to provide seasonal dispersion concentration patterns based on
available representative historical meteorological data (either onsite or offsite). These dispersion patterns
can be used to evaluate the representativeness of any air monitoring data collection period. Data
representativeness is determined by comparing the dispersion concentration patterns for the air
monitoring period with historical seasonal dispersion concentration patterns.
It is often not practical to place air monitoring stations at actual offsite receptor locations of interest.
It will be necessary, however, to characterize concentrations at these locations to conduct a health and
environmental assessment. In these cases, dispersion patterns based on modeling results can be used to
extrapolate concentrations monitored at the site to offsite receptor locations.
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Atmospheric Dispersion Considerations
Stability
Inversions
Wind speed and direction
Air temperature
Terrain effects
Atmospheric Dispersion Considerations
There are many different types of dispersion models, ranging from simple models that only require a
few basic calculations to three-dimensional models that require massive amounts of input data and
intense computational platforms to handle the complexity. Choosing the model to use depends on the
scale of the problem, the level of detail available for input, the required output, the background of the
user, and the turnaround time needed for an answer.
The five atmospheric dispersion considerations (i.e., stability, inversions, wind speed and direction, air
temperature, and terrain effects) must all be considered throughout the modeling process.
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Stability Class
B
\ \
Weak Winds
Sunshine %l
Strong Heating <§H
Strong Winds
\ \
\ \
Weak Winds
Night Cooling
(Ground
Trapping)
The Relationship Between Stability Class, Heating, and Wind Speed
Stability Class
Atmospheric stability is the extent of physical stirring and mixing on the vertical plane. When an
atmosphere is stable, there will be little mixing, which results in a persistent concentration. Stable
conditions will also generally result in longer, narrower plume shapes.
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Inversions
Inversions
Inversions limit upward movement of air masses due to temperature differentials. The inversion height
a modeler is concerned with is generally less than 100 feet. Inversions are generally an evening/night-
time phenomenon and their presence results in increased stability.
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Effects of Wind Speed and Direction
CD
CD \o
C7>
CD CD
CD
'CD
CD
x:
;^°TC;
/
Weak Winds
CD
CD
High Winds
^D~
CD
CD
Moderate Winds
CD
CD
CD
CD
CD
CD
Effect of Wind Speed and Direction on a Plume
Effects of Wind Speed and Direction
Weak winds result in a decrease in stability. As wind speed increases, a corresponding increase in
atmospheric stability is produced.
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Ground Roughness - Terrain Steering Effects
Ground Roughness - Terrain Steering Effects
Areas with hills or valleys may experience wind shifts where the wind actually flows between hills or
down into the valleys, turning where these features turn.
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Gaussian Dispersion
Source of Spill
Crosswind
Gaussian Dispersion
In a Gaussian dispersion model, a curve is used to describe how a contaminant will be dispersed in the
air after it leaves the source. At the source, the concentration of the contaminant is very high and the
Gaussian distribution looks like a spike or a tall column. As the contaminant drifts farther downwind,
it spreads out and the "bell shape" gets continually wider and flatter.
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Near-Field Meandering
Near-Field Meandering
Near-field meandering is caused by individual drifting eddies in the wind that push the plume from side
to side. These eddies, or small gusts, are also responsible for much of the mixing that makes the plume
spread out. As the plume drifts downward from the spill source, these eddies shift and spread the
plume until it takes on the form of a Gaussian distribution.
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Emission Rates
APA Guidelines
Volumes II & III
EPA Modeling
Guidelines
Yes
COLLECT AND REVIEW INFORMATION
• Source data
• Urban/rural classification data and
receptor data
• Environmental characteristics
Available
Monitoring Data
SELECT MODEL CLASS AND
SOPHISTICATION LEVEL
• Screened
• Refined
DEVELOP MODELING PLAN
Select model
Select constituents to be modeled
Define model input requirements (emissions,
meteorology, receptors)
Select receptors
Select modeling period
Evaluate modeling uncertainty
EPA
Review/Approval
CONDUCT MODELING
Develop emission inventory
Process meteorological data
Develop receptor grid
Run model test cases
Verify input files
Perform calculation for averaging times under
consideration
SUMMARIZE/EVALUATE RESULTS
• Determine concentrations
• Prepare meteorological summaries
• Consider modeling uncertainty
No
ADDITIONAL ANALYSES NEEDED?
Reproduced from NTGS Volume IV
Input to EPA
Remedial/Removal
Decision-Making
Figure 2. Superfund air impact assessment dispersion modeling protocol.
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Superfund Air Impact Assessment Dispersion Modeling Protocol
Associated guidance documents:
• National Technical Guidance Study (NTGS) Volumes II and III
• Air quality modeling at Superfund sites factsheet
• Guidelines on air quality models (revised).
Notes:
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Dispersion Modeling Protocol
Emission Rates
APA Guidelines
Volumes II & III
COLLECT AND REVIEW
INFORMATION
• Source data
• Urban/rural classification
data and receptor data
• Environmental characteristics
Available
Monitoring Data
Reproduced from NTGS Volume IV
Step 1:
Step 1 involves collecting and compiling existing information pertinent to air dispersion modeling. This
information is obtained during a literature survey. Information that should be collected and compiled
includes source data, receptor data, and environmental data (e.g., land use classification, demography,
topography, and meteorology). Once the existing data have been collected and compiled, a thorough
evaluation will define the data gaps. A coherent dispersion modeling plan can then be developed using
site-specific parameters and requirements.
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Dispersion Modeling Protocol
SELECT MODEL CLASS AND
SOPHISTICATION LEVEL
• Screened
• Refined
Reproduced from NTGS Volume IV
Step 2:
Step 2 involves the selection of the dispersion modeling sophistication level and screening and refined
modeling techniques. The selection process depends on program objectives as well as available resource
and technical constraints. Screening models generally use limited and simplified input information to
produce a conservative estimate of exposure. Screening models assist in the initial determination of
whether the Superfund site, or site activity, will present an air impact problem. The emission source(s)
should then be evaluated with either a more sophisticated screening technique or a refined model. When
selecting a more sophisticated modeling technique or approach, the following aspects should be
considered: availability of appropriate modeling techniques for the Superfund list of toxic constituents;
site-specific factors, including source configuration and characteristics; applicability; limitations;
performance for similar applications; and comparison of advantages and disadvantages of alternative
modeling techniques and approaches.
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Dispersion Modeling Protocol
EPA Modeling
Guidelines
DEVELOP MODELING PLAN
• Select model
• Select constituents to be modeled
• Define model input requirements
(emissions, meteorology, receptors)
• Select receptors
• Select modeling period
• Evaluate modeling uncertainty
EPA Review/
Approval
Reproduced from NTGS Volume IV
Step 3:
Step 3 involves preparing a dispersion modeling plan. Elements that should be addressed in the plan
include overview of the Superfund site area, selection of constituents to be modeled, modeling
methodology (emission inventory, meteorology, receptor grid, rural/urban classification, models to be
used, concentration averaging time, and special situations such as wake effects), and documentation of
the air modeling plan.
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Dispersion Modeling Protocol
CONDUCT MODELING
• Develop emission inventory
• Process meteorological data
• Develop receptor grid
• Run model test cases
• Verify input files
• Perform calculation for averaging
times under consideration
Reproduced from NTGS Volume IV
Step 4:
Step 4 specifies the actual activities involved in conducting air dispersion modeling for a Superfund site.
Activities that are performed include developing an emission inventory, preprocessing and verifying
modeling, setting model switches, running model test cases, performing dispersion calculations, and
obtaining a printout of modeling input and output.
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Dispersion Modeling Protocol
SUMMARIZE/EVALUATE RESULTS
• Determine concentrations
• Prepare meteorological summaries
• Consider modeling uncertainty
Yes
No
ADDITIONAL ANALYSES NEEDED?
Input to EPA
Remedial/Removal
Decision Making
• > Return to Select Model Class and Sophistication Level
Reproduced from NTGS Volume /V
Step 5:
Step 5 involves the review and assessment of the dispersion modeling results.
Additional components of this step include preparation of data summaries, concentration mapping (i.e.,
isopleths), estimation of uncertainties, and assessment.
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Accidental Release Modeling
• Provides worst-case results
• Results used to determine evacuation of shelter-in-place options
• Cannot account for near-field patchiness
• Examples: ALOHA ™ ARCHIE, CHARM ™, TRACE, and TSCREEN
Accidental Release Modeling
Accidental release modeling is performed when results are needed immediately. Accidental release
models that assist in making source-term calculations, or provide probability warnings, are best when
real-time solutions are essential.
ALOHA™, ARCHIE, CHARM™, TRACE, and TSCREEN are examples of accidental release models.
Each model is a relatively simple estimation technique that provides conservative estimates of air quality
impact(s).
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Accidental Release Models
ALOHA™ (NOAA/EPA)
Areal
Locations
Of
Hazardous
Atmospheres
ALOHA
TM
The Areal Locations of Hazardous Atmospheres (ALOHA) model was developed through a joint venture
between the National Oceanic and Atmospheric Administration (NOAA) and EPA. It is an emission
estimation and air quality dispersion model for estimating the emission rate, movement, and dispersion
of gases released into the atmosphere. The model estimates pollutant concentrations downwind from
the source of a release, taking into account the toxicological and physical characteristics of the material.
ALOHA considers the physical characteristics of the release site, the atmospheric conditions, and the
initial source conditions.
The model has a built-in database of chemical names and properties that the model uses to calculate
emission rates. The program performs buoyant gas dispersion based on Gaussian dispersion equations
and heavier-than-air dispersion based on algorithms in the DEnse GAs DISpersion (DEGADIS) model.
Emission estimations can be made for puddles, tanks, and pipe releases or for direct input of material
into the atmosphere. The model uses hourly meteorological data that can be entered by the user or
obtained from real-time measurements. The results of the model can be displayed as concentration
plots or in text summary screens. The concentration outputs are limited to a 1-hour (or less) exposure.
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Accidental Release Models
ARCHIE (FEMA/DOT/EPA)
Automated
Resource for
Chemical
Hazard
Incident
Evaluation
ARCHIE
The Automated Resource for Chemical Hazard Incident Evaluation (ARCHIE) model was developed
through a joint effort by the Federal Emergency Management Agency (FEMA), the U.S. Department
of Transportation (DOT), and EPA. It is an emission estimation and atmospheric dispersion model that
can be used to assess the vapor dispersion, fire, and explosion impacts associated with episodic
discharges of hazardous materials into the environment. The model can estimate the emissions and
duration of liquid/gas releases from tanks, pipelines, and liquid pools, as well as the associated ambient
concentrations downwind of these releases. ARCHIE can also evaluate the thermal hazards resulting
from the ignition of a flammable release and the consequences of an explosion caused by a flammable
gas, tank overpressurization, or ignition of an explosive material. In addition, it can estimate the size
of the downwind hazard zone that may require evacuation or other public protection because of the
release of a toxic gas or vapor into the atmosphere.
To estimate downwind concentrations, simulated meteorological conditions are input to the model. The
user must input chemical properties of the material released from information contained in the material
safety data sheets.
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Accidental Release Models
CHARM™ (Radian Corporation))
Complex
HAzardous
Release
Mode!
CHARM
TM
The Complex Hazardous Release Model (CHARM™) is a proprietary Gaussian puff model for
continuous and instantaneous releases of gases or liquids. The model is configured to handle chemicals
that are buoyant, neutrally buoyant, or heavier-than-air. CHARM™ can estimate the emission rates of
chemicals using a modification of the SHELL spill model and a multiphase pressurized gas release
model. CHARM™ contains a database of chemical information that is used in calculating emission
estimates. The program is menu driven and can accept simulated meteorological data for up to 24
hours. The CHARM™ model can simulate the transport of chemicals in spatially and temporally
varying wind fields. The results from the program may be displayed graphically on a screen or output
to a printer.
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Accidental Release Models
TRACE (E.I. Dupont de Nemours)
Toxic
Release
Analysis of
Chemical
Emissions
TRACE
The SAFER System TRACE model is an engineering analysis tool for dispersion modeling. It models
accidental toxic releases, including those caused by pipe/flange leaks, aqueous spills, hydrogen fluoride
spills, fuming acid spills, stack emissions, or elevated dense gas emissions. The program is menu
driven and contains several modules to estimate the evaporation and dispersion of chemicals and analyze
the effect of certain parameters on downwind concentrations. The program has a built-in database of
chemicals and their properties and various source-term modules. The model uses real-time or simulated
meteorological data for atmospheric dispersion calculations. These data can vary with time during the
release. The results of the modeling analysis can be displayed visually on graphs or stored in tables.
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Accidental Release Models
TSCREEN (EPA)
• Model for screening toxic air pollutant concentrations
TSCREEN
TSCREEN, a model for screening toxic air pollutant concentrations, is an air quality dispersion model
that implements the procedures in A Workbook of Screening Techniques for Assessing Impacts of Toxic
Air Pollutants (EPA-450-88-009). The TSCREEN model is an atmospheric dispersion model that uses
the dispersion algorithms of SCREEN, Release Valve Discharge (RVD), and PUFF models. It
automatically selects the worst-case simulated meteorological conditions based on the criteria presented
in the workbook. The model contains a data table of chemicals and their associated parameters (limited
to two chemicals at this time) that TSCREEN can access. It can calculate the source term for dust
particles within a pile of a specified dimension. The model can also simulate the dispersion of gaseous,
liquid, and particulate matter releases. TSCREEN outputs graphical and tabular summaries of predicted
pollutant concentrations.
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REFERENCES
The following list represents a partial list of background references on the subject of air monitoring
and sampling. Although other sources may be available, it is believed that these will provide the
reader with a good understanding of the subject.
The references are listed alphabetically by title and include author, publisher, and place of
publication. The year of publication is given for governmental sources only. For the remainder,
the reader should attempt to obtain the most recent edition. An * after the title indicates that a copy
of the document is part of the course library and is available for review.
1. Advances in Air Sampling'
Lewis Publishers, Inc.
121 South Main Street
P.O. Drawer 519
Chelsea, MI 48118
(Also available through ACGIH. See #4.)
2. Air Methods Database
Available on the Cleanup Information electronic bulletin board (CLU-IN), formerly OSWER
BBS. For further information, call 301 589-8366.
3. Air Monitoring For Toxic Exposures: An Integrated Approach", 1991
Shirley A. Ness
Van Nostrand Reinhold
115 Fifth Avenue
New York, NY 10003
4. Air Monitoring Instrumentation: A Manual for Emergency, Investigatory, and Remedial
Responders', 1993
C. Maslonsky and S. Maslonsky
Van Nostrand Reinhold
115 Fifth Avenue
New York, NY 10003
5. Air Sampling Instruments*
American Conference of Governmental Industrial Hygienists
6500 Glenway Avenue, Building D-E
Cincinnati, OH 45211
513 661-7881
6. Air/Superfund National Technical Guidance Series:
• Volume IV—Guidance for Ambient Air Monitoring at Superfund Sites (revised). EPA-
451/R-93-007,May 1993
10/93 1 References
-------
• Compilation of Information on Real-Time Air Monitoring for Use at Superfund Sites.
EPA-451/R-93-008, May 1993
7. Atmospheric Analysis: Occupational Health and Safety, ASTM Standards, Volume 11.03
American Society for Testing and Materials
1916 Race Street
Philadelphia, PA 19103-1187
215 299-5400
8. Basic Gas Chromatography
H.M. McNair and E.J. Bonelli
Varian Instrument Division
Purchase from Supelco, Inc.
Supelco Park
Bellefonte, PA 16823-0048
9. Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air,
EPA/600/4-89/017, June 1988
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Office of Research and Development
Research Triangle Park, NC 27711
10. A Compendium of Superfund Field Operations Methods', EPA/540/P-87/001, December 1987
U.S.Environmental Protection Agency
Office of Emergency and Remedial Response
Office of Waste Programs Enforcement
Washington, DC 20460
11. Data Quality Objectives for Remedial Response Activities: Development Process,
EPA/540/G-87/003, March 1987
U.S. Environmental Protection Agency
Office of Emergency and Remedial Response
Office of Waste Programs Enforcement
Washington, DC 20460
12. Fundamentals of Industrial Hygiene
National Safety Council
444 North Michigan Avenue
Chicago, IL60611
13. Guidance on Applying the Data Quality Objectives Process for Ambient Air Monitoring
Around Superfund Sites (Stages I & II), EPA-450/4-89-015; (Stage III), EPA-450/4/90-005
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
References 2 • 10/93
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14. Guide to Occupational Exposure Values*
American Conference of Governmental Hygienists
6500 Glenway Avenue, Building D-E
Cincinnati, OH 45211
513 661-7881
15. Guide to Portable Instruments for Assessing Airborne Pollutants Arising from Hazardous
Wastes
International Organization of Legal Metrology
Paris, France
(Available through ACGIH)
16. The Industrial Environmental - Its Evaluation and Control, 1973
National Institute for Occupational Safety and Health
Rockville, MD
(Available from the Superintendent of Documents, U.S. Government Printing Office,
Washington, DC 20402 [202 783-3238])
17. Industrial Hygiene and Toxicology, Volumes I and III
Frank A. Patty
John Wiley and Sons, Inc.
New York, NY
18. Manual of Recommendation Practice for Combustible Gas Indicators and Portable Direct
Reading Hydrocarbon Detectors, 1980, 1st edition
John Klinsky (ed)
American Industrial Hygiene Association
Akron, OH
19. Methods of Air Sampling and Analysis"
Lewis Publishers, Inc.
121 South Main Street
P.O. Drawer 519
Chelsea, MI 48118
(Also available through ACGIH)
20. NIOSH Manual of Analytical Methods, Editions 1, 2, and 3"
National Institute for Occupational Safety and Health
Rockville, MD
(Available from the Superintendent of Documents, U.S. Government Printing Office,
Washington, DC 20402 [202 783-3238])
21. OSHA Analytical Methods Manuaf
Superintendent of Documents
U.S. Government Printing Office
Washington, DC 20402
202 783-3238
10/93 3 References
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22. OSHA Technical Manual", 1990
(See ACGIH)
23. Removal Program Representative Sampling Guidance: Air
U.S. Environmental Protection Agency
Office of Emergency and Remedial Response
Emergency Response Division
Environmental Response Branch
Washington, DC
24. Standard Operating Safety Guides, June 1992
U.S. Environmental Protection Agency
Environmental Response Team
2890 Woodbridge Avenue
Building 18 (MS-101)
Edison, NJ 08837-3697
908 321-6740
25. Standard Operating Guide for the Use of Air Monitoring Equipment for Emergency Response
(See #21)
26. Standard Operating Guide for Air Sampling and Monitoring at Emergency Responses
(See #21)
27. Technical Assistance Document for Sampling and Analysis of Toxic Organic Compounds in
Ambient Air, EPA-600/4-83-027
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
Research Triangle Park, NC 27711
References 4 10/93
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MANUFACTURERS AND SUPPLIERS OF
AIR MONITORING EQUIPMENT
AIR MONITORING EQUIPMENT
Aerosol/Particulate Direct-Reading Monitors:
Air Techniques Incorporated
HUND Corporation
Met One, Inc.
MIE, Inc.
MST Measurement Systems, Inc.
Pacific Scientific (HIAC/ROYCO Instrument Division)
Particle Measuring Systems, Inc.
PPM Enterprises
TSI Incorporated
Calibration Gases: (most manufacturers of instruments provide calibration gases for
use with their instruments; these companies provide a variety of calibration gases)
Airco Industrial Gases
Alphagaz
Bryne Specialty Gases
Digicolor
Environics, Inc.
GC Industries
Kin-Tek laboratories, Inc.
Liquid Air Corporation
National Specialty Gases
Norco, Inc.
Scott Specialty Gases
VICI Metronics
Calibrators, Pump:
Accura Flow Products Co., Inc.
Air Systems International
AMETEK
BGI Incorporated
BIOS International Corp
DuPont
Gillian Instrument Co.
Sensidyne
10/93 1 Manufacturers and Suppliers
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SKC, Inc.
Spectrex Corporation
Canister Samplers:
Andersen Samplers Incorporated
Nutech Corporation
Scientific Instrumentation Specialists
Wedding & Associates, Inc.
Xontech, Inc.
Collection Media:
Ace Glass Incorporated
BGI Incorporated
DACO Products
Gelman Sciences
Gilian Instrument Corporation
Hi-Q Environmental Products Company
LaMotte Chemical Products Company
Micro Filtration Systems
Millipore Corporation
Mine Safety Appliances Company
Nuclepore Corporation
Omega Specialty Instruments Company
Paliflex, Inc.
Poretics Corporation
Schleicher & Schuell
Sipin, Anatole, J., Co., Inc.
SKC, Inc.
Supelco, Inc.
Colorimetric Detectors: (B = badges or dosimeters; DT = regular detector tubes; LT = long term
detector tubes)
American Gas & Chemical Co., Ltd. (B)
Analytical Accessories International (B)
Bacharach, Inc. (B)
Chemsense (B)
Crystal Diagnostics (B)
Enmet Corporation (DT, LT)
GMD Systems, Inc. (B)
Matheson Safety Products (DT, LT)
MDA Scientific (B)
Mine Safety Appliances Co. (B, DT, LT)
Manufacturers and Suppliers 2 10/93
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National Draeger, Inc. (B, DT, LT)
PPM Enterprises (B)
Sensidyne (DT), Inc.
SKC, Inc. (B, LT)
VICI Metronics (B)
Willson Safety Products (B)
Combustible Gas Meters:
Gas Bags:
A.I.M. Safety Company, Inc.
Astro International Corp.
Bacharach Instruments
Biosystems, Inc.
Chestec, Inc.
Control Instruments Corp.
Dynamation Incorporated
Energy Efficiency Systems,Inc.
Enmet Corporation
Gas Tech, Inc.
GfG America Gas Detection Ltd.
Grace Industries, Inc.
Heath Consultants Incorporated
Industrial Scientific Corporation
J and N Enterprises, Inc.
Lumidor Safety Products e.s.p., Inc.
Mine Safety Appliances Co.
National Draeger, Inc.
Neotronics N.A., Inc.
Quatrosense Environmental Ltd.
Scott Aviation
Sieger Gas Detection
Sierra Monitor Corporation
Texas Analytical Controls, Inc.
TIP Instruments, Inc.
AeroVironment, Inc.
The Anspec Company, Inc.
BGI Incorporated
Calibrated Instruments, Inc.
Digicolor
Jensen Inert
KVA Analytical Systems
Norton Performance Plastics
Nutech Corporation
10/93 3 Manufacturers and Suppliers
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Plastic Film Enterprises
Pollution Measurement Corporation
Science Pump Corporation
SKC, Inc.
Gas Chromatographs: (types of detectors available: AID = argon ionization; ECD
electron capture; FID = flame ionization; MS = mass spectroscopy; PID
photoionization; SS = chemical specific sensor; TCD = thermal conductivity)
Bruker Instruments (MS)
Canaan Scientific Products
CMS Research Corporation (SS)
The Foxboro Company (FID)
GOW-MAC (FID, TCD)
HNU Systems, Inc. (PID, FID)
Microsensor Systems Inc.
Microsensor Technology, Inc. (TCD)
Photovac Incorporated (PID, FID)
S-Cubed (ECD)
Sensidyne (FID)
Sentex Sensing Technology, Inc. (ECD, PID, PID, TCD)
Summit Interests (FID, PID, TCD)
Thermo Environmental Instruments, Inc. (ECD, FID, PID, TCD)
Viking Instruments (MS)
XonTech, Inc. (AID, ECD)
Oxygen Meters:
A.I.M. Safety Company, Inc.
Bacharach, Inc.
Biosystems, Inc.
Dynamation Incorporated
Energy Efficiency Systems, Inc.
Enmet Corporation
GasTech, Inc.
GC Industries
GfG America Gas Detection Ltd.
Industrial Scientific Corporation
Lumidor Safety Products e.s.p., Inc.
MDA Scientific, Inc.
Metrosonics, Inc.
Mine Safety Appliances Co.
National Draeger, Inc.
Neotronics N.A., Inc.
Rexnord Safety Products
Scott Aviation
Manufacturers and Suppliers 4 10/93
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Sensidyne
Sieger Gas Detection
Sierra Monitor Corporation
Teledyne Analytical Instruments
Passive Dosimeters: (these devices require laboratory analysis; for direct-reading
dosimeters see G. Colorimetric Detections)
Advanced Chemical Sensors
Air Technology Labs, Inc.
Assay Technology
EnSys, Inc.
Gilian Instrument Corporation
Landauer, R.S. Jr. & Company
Mine Safety Appliances Co.
National Draeger, Inc.
Pro-Tek Systems, Inc.
Sensidyne
SKC, Inc.
3M
Sampling Pumps and Accessories: (letters denote primary function of pumps and
apparatus: P = Personal; A = Area; B = Bag filling)
AeroVironment, Inc. (B)
Air Systems International, Inc. (A)
AMETFK (P)
Analytical Accessories International (A,P)
Andersen Samplers Incorporated (A)
Arjay Equipment Corporation (A)
Barnant Company (A)
BGI Incorporated (P, A)
BIOS International Corp
Calibrated Instruments, Inc. (B)
California Measurements, Inc. (A)
DuPont (P)
Environmetrics, Inc. (A)
General Metal Works, Inc. (A)
Gillian Instrument Corp. (P)
LaMotte Chemical Products Company (A)
Midwest Environics, Inc. (A)
Mine Safety Appliances Co. (P)
Omega Specialty Instrument Co. (A)
Wedding & Associates, Inc. (A)
Sensidyne (P)
Sipin, Anatole J., Co., Inc. (P)
JO/93 5 Manufacturers and Suppliers
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SKC, Inc. (P)
Spectrex Corporation (P)
Staplex Air Sampler Division (A)
Supelco, Inc. (P)
Thermedics, Inc. (P)
Wedding & Associates (A)
Toxic Monitors: (direct-reading instruments for low concentrations of contaminants;
letters denote types of detectors available; PID = photoionization; FID = flame
ionization; IR = infrared spectroscopy; TCD = thermal conductivity; GS = general
sensor, e.g., MOS or super-sensitive CGI; SS = sensor for specific chemical, e.g.,
CO, H2S)
A.I.M. Safety Company, Inc.(GS, SS)
Anacon Detection Technology (SS)
Analect Instruments (IR)
Arizona Instrument, Jerome Division (SS)
Astro International Corp. (SS)
Bacharach, Inc. (GS, SS)
Biosystems, Inc. (SS)
Bruel & Kjaer (IR)
CEA Instruments, Inc. (GS, SS)
Dynamation Incorporated (GS, SS)
Enmet Corporation (SS)
Environmental Technologies Group (GS)
The Foxboro Company (FID, IR)
GasTech, Inc. (GS, SS)
GfG America Gas Detection Ltd. (SS)
GMD Systems, Inc. (colorimetric)
GOW-MAC (TCD)
Grace Industries, Inc. (GS)
Graesby Ionics Ltd. (Ion Mobility Spectrometry)
Heath Consultants Incorporated (FID)
HNU Systems, Inc. (PID)
Industrial Scientific Corporation (SS)
International Gas Detectors, Inc.
InterScan Corporation (SS)
J and N Enterprises, Inc. (GS)
MDA Scientific, Inc. (SS)
Macurco, Inc. (GS, SS)
Mast Development Corporation (SS)
Matheson Safety Products (TCD)
Metrosonics, Inc. (SS)
Microsensor Systems, Inc. (SS)
Mine Safety Appliances Co. (PID, FID, SS)
National Draeger (SS)
Neotronics N.A., Inc. (SS)
Manufacturers and Suppliers 6 ' 10/93
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Nicolet Instrument Corp. (IR)
Photovac Incorporated (PID)
Quatrosense Environmental Ltd. (SS)
Scott Aviation (SS)
Sensidyne (SS, FID)
Sentex Sensing Technology, Inc. (FID)
Servomax Company (IR)
Sieger Gas Detection (SS, IR)
Sierra Monitor Corporation (SS)
Spectrex Corporation (SS)
Summit Interests (FID, PID, TCD)
Tekmar Company (TCD)
Texas Analytical Controls, Inc. (SS)
Thermo Environmental Instruments, Inc. (FID, PID, TCD)
TIF Instruments, Inc. (GS)
Transducer Research, Inc. (SS)
MANUFACTURERS' AND SUPPLIERS' ADDRESSES
AccuRa Flow Products Co., Inc. A.I.M. Safety Company, Inc.
P.O. Drawer 100 P.O. Box 720540
Warminster, PA 18974 Houston, TX 77272-0540
214 674-4782 713 240-5020
1-800-ASK-4AIM
Ace Glass Company
P.O. Box 688 Air Systems International
Vineland, NJ 814-P Greenbrier Circle
609 692-3333 Chesapeake, VA 23320
1-800-866-8100
Advanced Chemical Sensors
350 Oak Lane Air Techniques Incorporated
Pompano Beach, FL 33069 1801 Whitehead Road
305 979-0958 Air Techniques Incorporated
1801 Whitehead Road
Advanced Calibration Designs, Inc. Baltimore, MD 21207
7960 S. Kolb Rd. 301 944-6037
Tucson, AZ 85705
602 574-9509 Airco Industrial Gases
Division of Airco, Inc.
AeroVironment, Inc. 575 Mountain Avenue
145 Vista Avenue Murry Hill, NJ 07974
Pasadena, CA 91107 201 464-8100
818 357-9983
10/93 7 Manufacturers and Suppliers
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Alphagaz
Specialty Gases Division
Liquid Air Corporation
2121 N. California Blvd.
Walnut Creek, CA 94596
415 977-6506
AMETEK
Mansfield & Green Division
8600 Somerset Drive
Largo, FL 34643
813 536-7831
American Gas & Chemical Co., Ltd.
220 Pegasus Avenue
North vale, NJ 07647
201 767-7300
1-800-288-3647
Anacon Detection Technology
117 South Street
Hopkinton, MA 01748
508 435-6973
Analect Instruments
Division of Laser Precision Corp.
1231 Hart Street
Utica, NY 13502
315 797-4449
Analytical Accessories International
P.O. Box 922085
Atlanta, GA 30092
1-800-282-0073
Anderson Instruments, Inc.
4801 Fulton Industrial Blvd.
Atlanta, GA 30336
404 691-1910
The Anspec Company, Inc.
122 Enterprise Drive
Ann Arbor, MI 48107
313 665-9666
1-800-521-1720
Arizonia Instrument Corp.
P.O. Box 1930
Tempe, AZ 85280
602 731-3400
1-800-528-7411
Arjay Equipment Corp.
P.O. Box 2959
Winston-Salem, NC 27102
919 741-3582
Assay Technology
1070 E. Meadow Cir.
Palo Alto, CA 94303
1-800-833-1258
Astro International Corp.
100 Park Avenue
League City, TX 77573
713 332-2484
BGI, Inc.
58 Guinan Street
Waltham, MA 02154
617 891-9380
BIOS International Corporation
756 Hamburg Turnpike
Pompton Lakes, NJ 07442
201 839-6908
Bacharach, Inc.
625 Alpha Drive
Pittsburgh, PA 15238
412 963-2000
Barnant Company
28W092 Commercial Avenue
Barrington, IL 60010
312 381-7050
Biosystems, Inc.
P.O. Box 158
Rockfall, CT 06481
203 344-1079
Manufacturers and Suppliers
10/93
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Bruel & Kjaer Instruments, Inc.
185 Forest Street
Marlborough, MA 01752
508 481-7000
Bruker Instruments, Inc.
Manning Park
Billerica, MA 01821
617 667-9580
Byrne Specialty Gases, Inc.
118 S. Mead Street
Seattle, WA 98108
206 764-4633
Calibrated Instruments, Inc.
200 Saw Mill River Road
Hawthorne, NY 10502
914 741-5700
CEA Instruments, Inc.
16 Chestnut Street
Emerson, NJ 07630
201 967-5660
CMS Research Corporation
100 Chase Park, Suite 100
Birmingham, AL 35244
205 733-6900
California Measurements, Inc.
150 E. Montecito Avenue
Sierra Madre, CA 91024
818 355-3361
Canaan Scientific Products
P.O. Box 50527
Indianapolis, IN 46250
317 842/1088
1-800-842-8578
ChemSense
3909 Beryl Rd.
Raleigh, NC 27607
919 821-2929
Chestec, Inc.
P.O. Box 10362
Santa Ana, CA 92705
714 730-9405
Compur Monitors
7015 West Tidwell
Suite Glll-A
Houston, TX 77092
713939-1103
Control Instruments Corp.
25 Law Drive
Fairfield, NJ 07006
201575-9114
Costar/Nucleopore
One Alewife Center
Cambridge, MA 02140
617 868-6200
Crystal Diagnostics, Inc.
600 West Cummings Park
Woburn, MA 01801
617933-4114
DACO Products, Inc.
12 S. Mountain Avenue
Montclair, NJ 07042
201 744-2453
Digicolor
2770 East Main Street
P.O. Box 09763
Columbus, OH 43209
614236-1213
Dynamation Incorporated
3784 Plaza Drive
Ann Arbor, MI 48104
313 769-0573
Enmet Corporation
P.O. Box 979
2308 S. Industrial Highway
Ann Arbor, MI 48106-0979
313761-1270
10/93
Manufacturers and Suppliers
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Energy Efficiency System, Inc.
1300 Shames Drive
Westbury, NY 11590
516 997-2100
1-800-645-7490
EnSys, Inc.
P.O. Box 14063
Research Triangle Park, NC
919 941-5509
Envirometrics, Inc.
1019 Bankton Dr.
Charleston, SC 29406
1-800-255-8740
Environics, Inc.
33 Boston Post Road West
Marlborough, MA 01752
617 481-3600
Environmental Technologies Group
1400 Taylor Avenue
Baltimore, MD 21284-9840
301 635-4598
The Foxboro Company (EMO)
P.O. Box 500
600 N. Bedford St.
East Bridgewater, MA 02333
508 378-5556
GasTech, Inc.
8445 Central Avenue
Newark, CA 94560
415 745-8700
GC Industries, Inc.
8976 Oso Ave., Unit C
Chatsworth, CA 91311
818 882-7852
GfG Gas Electronics, Inc.
6617 Clayton Rd., Suite 209
St. Louis, MO 63144
314 725-9050
GMD Systems, Inc.
Old Route 519
Hendersonville, PA 15339
412 746-3600
Gelman Sciences, Inc.
600 South Wagner Road
Ann Arbor, MI 48106
313 665-0651
General Metal Works, Inc.
145 South Miami
Village of Cleves, OH 45002
513 941-2229
Gilian Instrument Corporation
35 Fairfield Place
West Caldwell, NJ 07006
201 808-3355
GOW-MAC
P.O. Box 32
Bound Brook, NJ 08805
201 560-0600
Grace Industries, Inc.
P.O. Box 167
Transfer, PA 16154
412 962-9231
Graseby Ionics Ltd.
Analytical Division
Park Avenue, Bushey
Watford Herts Wb2 2BW
England
0923 816166
Heath Consultants, Inc.
100 Tosca Drive
P.O. Box CS-200
Stoughton, MA 02072-1591
617 344-1400
Hi-Q Filter Environmental Products
7386 Trade Street
San Diego, CA 92121
619 549-2820
Manufacturers and Suppliers
10
10/93
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HNU Systems, Inc.
160 Charlemont Street
Newton Highlands, MA 02161
617 964-6690
1-800-527-4566
HUND Corporation
777 Passaic Ave.
Clifton, NY 07012-1804
202 473-5009
Industrial Scientific Corporation
355 Steubenville Pike
Oakdale, PA 15071-1093
412 788-4353
1-800-338-3287
International Gas Detectors, Inc.
11221 Richmond Ave., Suite C-109
Houston, TX 77082
713 558-4099
InterScan Corporation
P.O. Box 2496
21700 Nordoff Street
Chatsworth, CA 91313-2496
1-800-458-6153
J and N Enterprises, Inc.
P.O. Box 108
Wheeler, IN 46393
219759-1142
Jensen Inert
P.O. Box 660824
Miami, FL 33266-0824
305 871-8839
1-800-446-3781
Kin-Tek Laboratories
2395 Palmer Highway
Texas City, TX 77590
409 945-3627
KVA Analytical Systems
281 Main St.
P.O. Box 574
Galmouth, MA 02541-99811
508 540-0561
LaMotte Chemical Products Co.
P.O. Box 329
Chestertown, MD 21620
301 778-3100
1-800-344-3100
Lumidor Safety Products/E.S.P., Inc.
5364 NW 167th Street
Miami, FL 33014
305 625-6511
Macurco, Inc.
3946 S. Mariposa Street
Englewood, CO 80110
303 781-4062
Mast Development Company
Air Monitoring Division
2212 East 12th Street
Davenport, IA 52803
319 326-1041
Mateson Chemical Corporation
1025 E. Montgomery Avenue
Philadelphia, PA 19125
215 423-3200
Matheson Gas Products, Inc.
30 Seaview Drive
Secaucus, NJ 07096-1587
215 641-2700
MDA Scientific, Inc.
405 Barclay Blvd.
Lincolnshire, IL 60069
312 634-2800
1-800-323-2000
MG Industries
175 Meister Avenue
North Branch, NJ 08876
201/231-9595
10/93
11
Manufacturers and Suppliers
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MIE, Inc.
213 Burlington Road
Bedford, MA 01730
617 275-5444
MST Measurement Systems, Inc.
327 Messner Drive
Wheeling, IL 60090
708 808-2500
Met One, Inc.
481 California Avenue
Grants Pass, OR 97526
503 479-1248
Metrosonics, Inc.
P.O. Box 23075
Rochester, NY 14692-3075
716 334-7300
Micro Filtration Systems
6800 Sierra Court
Dublin, CA 94568
415 828-6010
Microsensor Systems, Inc.
6800 Versar Center
Springfield, VA 22151
703 642-6919
Microsensor Technology, Inc.
47747 Warm Springs Blvd.
Fremont, CA 94539
415 490-0900
Midwest Environics, Inc.
10 Oak Glen Court
Madison, WI 53717
608 833-0158
Millipore Corporation
Lab Products Division
80 Ashby Road
Bedford, MA 01730
617 275-9200
Mine Safety Appliances
P.O. Box 427
Pittsburgh, PA 15230
412 967-3000
1-800-MSA-INST
National Draeger, Inc.
P.O. Box 120
101 Technology Drive
Pittsburgh, PA 15230-0120
412 787-8383
National Specialty Gases
630 United Drive
Durham, NC 27713-9985
Neotronics N.A., Inc.
P.O. Box 370
411 North Bradford Street
Gainesville, GA 30503
404 535-0600
1-800-535-0606
Nicolet Instrument Corp.
5225 Verona Rd.
Madison, Wl 53711
608 271-3333
Norco, Inc.
1121 W. Amity
Boise, ID 83705
208 336-1643
North Performance Plastics
150 Dey Road
Wayne, NJ 07470-4699
1-800-526-7844
Nutech Corporation
2806 Cheek Road
Durham, NC 27704
919 682-0402
Omega Specialty Instruments Company
4 Kidder Road, Unit 5
Chelmsford, MA 01842
508 256-5450
Manufacturers and Suppliers
12
10/93
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Pacific Scientific
HAIC-ROYCO Instruments Division
141 Jefferson Drive
Menlo Park, CA 94025
Paliflex, Inc.
125 Kennedy Drive
Putnam, CT 06260
203 929-7761
Particle Measuring Systems
1855 South 57th Court
Boulder, CO 80301-2886
303 443-7100
Photovac International, Inc.
25-B Jefryn Blvd. W.
Deer Park, NY 11729
516 254-4199
Plastic Film Enterprises
2011 Bellaire Avenue
Royal Oak, MI 48067
313 399-0450
Pollution Measurement Corporation
P.O. Box 6182
Chicago, IL 60680
708 383-7794
Poretics Corporation
151 I Lindbergh Avenue
Livermore, CA 94550-9412
415 373-0500
1-800-922-6090
PPM Enterprises
11428 Kingston Pike
Knoxville, TN 37922
615 966-8796
Pro-Tek Systems, Inc.
64 Genung Street
Middletown, NY 10940
914 344-4711
Quatrosense Environmental Ltd.
5935 Ottawa Street
P.O. Box 749
Richmond, Ontario, Canada KOA 2ZO
613/838-4005
S-Cubed
P.O. Box 1620
La Jolla, CA 92038-1620
619/453-0060
Schleicher & Schuell, Inc.
10 Optical Street
Kenne, NH 03431
603/352-3810
800/245-4024
Scientific Instrumentation Specialists
P.O. Box 8941
Moscow, ID 83843
208/882-3860
Science Pump Corporation
1431 Ferry Avenue
Camden, NJ 08104
609/963-7700
Scott Aviation
225 Erie Street
Lancaster, NY 14086
716/683-5100
Scott Specialty Gases
Route 161 North
Plumsteadville, PA 18949
215/766-8861
Sensidyne, Inc.
16333 Bay Vista Dr.
Clearwater, FL 34620
813/530-3602
800/451-9444
Sentex Sensing Technology, Inc.
553 Broad Avenue
Ridgefield, NJ 07657
201/945-3694
10/93
13
Manufacturers and Suppliers
-------
Servomax Company
90 Kerry Place
Norwood, MA 02062
617 769-7710
Sieger Gas Detection
405 Barclay Blvd.
P.O. Box 1405
Lincolnshire, IL 60069-1405
1-800-221-1039
Sierra Monitor Corporation
1991 Tarob Court
Milipitas, CA 95035
408262-6611
Anatole J. Sipin Co., Inc.
505 Eighth Avenue
New York, NY 10018
212 695-5706
SKC, Inc.
334 Valley View Road
Eighty Four, PA 15330-9614
412 941-9701
1-800-752-8472
Spectrex Corporation
3580 Haven Avenue
Redwood City, CA 94063
415 365-6567
Staplex Company
Air Sampler Division
777 Fifth Avenue
Brooklyn, NY 11232-1695
212 768-3333
1-800-221-0822
Summit Interests
P.O. Box 1128
Lyons, CO 80540
303 444-8009
Supelco, Inc.
Supelco Park
Bellefonte, PA 16823-0048
814 359-3441
3M OH & ESD
3M Center
Building 220-3E-04
St. Paul, MN 55144-1000
612 733-5608
TIF Instruments Inc.
9101 NW 7th Avenue
Miami, FL 33150
305757-8811
TSI Incorporated
500 Cardigan Road
P.O. Box 43394
St. Paul, MN 55164
612 483-0900
Tekmar Company
P.O. Box 371856
Cincinnati, OH 45222
1-800-543-4461
Teledyne Analytical Instruments
16830 Chestnut Street
City of Industry, CA 91749
213 283-7181
Texas Analytical Controls, Inc.
P.O. Box 42520
Houston, TX 77242
713 240-4160
Thermedics, Inc.
470 Wildwood Street
Woburn, MA 01888
617 938-3786
Thermo Environmental Instruments, Inc.
8 West Forge Parkway
Franklin, MA 02038
508 520-0430
Transducer Research, Inc.
999 Chicago Ave.
Naperville, IL 60540
708 357-0004
Manufacturers and Suppliers
14
10/93
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VICI Metronics
2991 Corvin Drive
Santa Clara, CA 95051
408 737-0550
Viking Instruments Corp.
12007 Sunrise Valley Drive
Reston, VA 22091-3406
703 758-9339
Wedding & Associates, Inc.
P.O. Box 1756
Fort Collins, CO 80522
303 221-0678
Whatman Paper Division
9 Bridewell Place
Clifton, NJ 07014
201 773-5800
Wheaton Scientific
1000 North 10th Street
Millville, NJ 08332
609 825-1400
Willson Safety Products
P.O. Box 622
Reading, PA 19603-0622
215 376-6161
Xetex, Inc.
600 National Avenue
Mountain View, CA 94043
415 964-3261
XonTech Inc.
6862 Hayvenhurst Avenue
Van Nuys, CA 91406 -
818 787-7380
10/93
15
Manufacturers and Suppliers
-------
AIR MONITORING FOR HAZARDOUS MATERIALS
WORKBOOK
CONTENTS
Exercise Page
1 Oxygen Monitor, Combustible Gas Indicators,
and Specific Chemical Monitors 1
2 Photoionization Detectors - Survey 13
3 Flame lonization Detectors - Survey 21
4 Gas Chromatography - Organic Vapor Analyzer 29
5 Detector Tubes '. 39
6 Direct-Reading Aerosol Monitors 53
7 Gas Chromatography - Photoionization Detector 63
8 Sampling Pumps and Collection Media 71
9 Field Exercise 87
10/93 \ Contents
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EXERCISE 1
Oxygen Monitors, Combustible Gas Indicators,
and Specific Chemical Monitors
OBJECTIVE
In this exercise, students will calibrate or check the calibration of a variety of combustible gas
indicators (CGIs), combination CGI/O2 monitors, and combination CGI/O2/toxic monitors. The
instruments will then be used to sample a variety of test atmospheres and the results will be
interpreted.
PROCEDURE
The exercise is divided into three different stations. Each station is equipped with an air monitoring
instrument or group of instruments.
Station 1: MSA Model 260/261 combination CGI/O2 monitor
Station 2: MSA Model 360 combination CGI/O2/carbon monoxide monitor
Station 3: GasTech Model 1314 combination CGI/O2/toxic monitor
There may be more than one of each numbered station to reduce crowding. Follow the instructions
given for each instrument. Sample the indicated gas bags and record your results. At the end of
the exercise, answer the questions. The instructor will then hold a brief discussion.
The instructions given for each instrument are based on the manufacturers' operating manuals.
However, some steps may have been added for illustration purposes and some may have been
shortened for purposes of time or space. As with any instrument, consult the operator's manual
before using in the field.
10/93 \ Exercise 1
-------
STATION 1
MSA Model 260/261 Combination CGI/0, Monitor
The MSA Model 260/261 is a combination combustible gas and oxygen monitor. There are meter
displays for both indicators. Visual and audible alarms for a % LEL reading and a low oxygen
reading are included. The Model 261 also has a high oxygen reading alarm. The audible alarm can
be deactivated. Air is drawn into the instrument by a battery-operated pump.
SETUP
1. Record the instrument serial number or ID number on the data sheet.
2. Attach the sampling hose to the instrument. Make sure that the connection is hand tight.
STARTUP
3. Turn the center "ON-OFF" control clockwise to the "HORN-OFF" position. Both meter
pointers will move, both alarm lights will light, and the center green lamp will blink on and
off. (Note: On the Model 261, the light will not turn on until after the reset button is
pushed.) The green light indicates alarms status. When it glows continuously, the audible
alarm is operable. When it blinks on and off, it indicates that the audible alarm has been
deactivated.
4. Adjust the meter pointer on the % oxygen monitor by pulling and turning the "O2
CALIBRATE KNOB." The knob is supplied with a clutch to prevent accidental field
decalibration. Adjust the pointer to read 20.8%, which is the hatch mark below the 21%
mark.
5. Adjust the meter pointer on the %LEL meter by pulling and turning the "LEL ZERO
KNOB." Adjust the pointer to read 0%.
6. Press the red alarm "RESET" button to reset the alarms. Both red lights should stop
flashing. (Note: The "RESET" button will not reset the alarms if the meter pointers exceed
the alarm levels.)
7. Press the black "CHECK" button and observe the pointer on the %LEL meter. The pointer
should move above 80% LEL into the BATTERY zone of the meter. This indicates that the
battery is okay. If it does not reach the BATTERY zone, inform an instructor/technician.
LEAK TEST
8. Momentarily hold a finger over the sample inlet or end of sample probe. Observe that the
flow indicator float (lower right hand corner of instrument face) drops out of sight, indicating
Exercise 1 2 10/93
-------
no flow. If the float does not drop out of sight, check the system for leaks. If the
instrument does not pass the leak test, inform an instructor/technician.
ALARM CHECK
The purpose of these steps is to check the meter readings at which the alarms will sound.
9. Turn the O2 CALIBRATE knob counterclockwise (decreasing the % oxygen reading) while
watching the % oxygen meter and the oxygen alarm light. Note the reading at which the
alarm sounds and the light starts flashing. Adjust the reading back to 20.8% and press the
reset button. Record the reading on the data sheet. The lower alarm reading should be
19.5%.
10. (MSA 261 only) Turn the O2 CALIBRATE knob clockwise (increasing the % oxygen
reading) while watching the % oxygen meter and the oxygen alarm light. Note the reading
at which the alarm sounds and the light starts flashing. Adjust the reading back to 20.8%
and press the reset button. Record the alarm reading on the data sheet. . The upper alarm
reading should be 25 %.
11. Turn the zero LEL knob clockwise until the alarm is activated. Record this reading. Return
the meter pointer to zero and press the reset button. The alarm should have activated at 25%
LEL.
12. If any of the alarm points are not what they should be, inform an instructor/technician.
13. The instrument is ready for calibration.
CALIBRATION
14. Open the clamp to the gas bag labeled "PENTANE 0.75%" and attach the sample line to the
bag. Draw a sample into the instrument until a constant reading is obtained.
15. Record your reading on the data sheet. The instrument should give a reading of 50% LEL.
Inform the instructor if it does not.
16. Disconnect the sample line and clamp the bag. Allow fresh air to flow through the
instrument until the reading returns to zero. Rezero the instrument, if needed.
SAMPLING
17. Please note that the Model 261 has a latching mechanism that engages the %LEL meter
pointer if it reaches or exceeds 100. To disengage the lock, the instrument must be turned
10/93 -\ Exercise 1
-------
off and then turned back on in an area where the LEL readings are less than 100%. Room
air will do.
18. For field monitoring, the alarm should be in the operable mode. For this exercise, you may
keep the audible alarm deactivated to reduce noise levels.
19. Sample each of the gas bags listed on the data sheet. Record the readings.
SHUTDOWN
20. When sampling is complete, flush fresh air through the instrument. Turn the instrument
OFF.
Exercise 1 4 10/93
-------
STATION 2
MSA Model 360 Combination CGI/OJCO Monitor
The MSA Model 360 is a combination combustible, oxygen, and carbon monoxide (CO) monitor.
It has a digital display that shows only one reading. It has alarms for a specific % LEL reading, low
and high oxygen, and a specific carbon monoxide reading. If the alarm levels are reached for any
of these responses, there will be a visual and audible indication. This will occur no matter what
function is being displayed at the time. The audible alarm can be deactivated. Air is drawn into the
instrument by a battery-powered pump.
SETUP
1. Record the instrument serial number or ID number on the data sheet.
2. Attach the sampling hose to the instrument. Make sure the connection is- hand tight.
STARTUP
3. Turn the FUNCTION control to the "HORN-OFF" position. Alarm signals will flash for
all three chemicals, the "HORN OFF" green/yellow lamp will be off and % LEL will show
in the readout.
4. A low battery condition is indicated by a BATT sign in the readout or by a steady horn.
Inform an instructor/technician if this occurs.
5. Set the readout to zero (00) by lifting and turning the LEL ZERO knob. This must be done
within 30 seconds of turning ON to prevent the possibility of activating the off-scale, LEL
latching alarm.
6. Press the SELECT button firmly to obtain % OXY on the readout. Then set the readout to
20.8% by adjusting the OXY CALIBRATE knob.
7. Press the SELECT button firmly to obtain PPM TOX on the readout. Then set the readout
to zero (00) by adjusting the TOX ZERO knob.
8. Press the RESET button. (Note: The "RESET" button will not reset the alarms if the
exceed the alarm levels.) The "HORN OFF" green/yellow lamp will start flashing. The
light indicates alarm status. When it glows continuously, the audible alarm is operable.
When it blinks on and off, as it does now, it indicates that the audible alarm has been
deactivated.
10/93 5 Exercise 1
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LEAK TEST
9. Momentarily hold a finger over the sample inlet or end of sample probe. Observe that the
flow indicator float (lower right hand corner of instrument face) drops out of sight, indicating
no flow. If the float does not drop out of sight, check the system for leaks. If the
instrument does not pass the leak test, inform an instructor/technician.
ALARM CHECK
The purpose of these steps is to check the meter readings at which the alarms will sound.
10. Press the SELECT button until % LEL is displayed. Adjust the LEL ZERO knob until the
alarm sounds. Record the % LEL reading. Set the reading back to zero and press the
RESET button. The alarm should activate at 25%.
11. Press the SELECT button until OXY is displayed. Turn the OXY CALIBRATE knob
counterclockwise (decreasing the % oxygen reading) until the alarm sounds. Record the %
OXY reading. Adjust the reading back to 20.8% and press the RESET button. The lower
alarm reading should be 19.5%.
12. Turn the OXY CALIBRATE knob clockwise (increasing the % oxygen reading) until the
alarm sounds. Record the % OXY. Adjust the reading back to 20.8% and press the RESET
button. The upper alarm reading should be 25%.
13. Press the SELECT button until TOX is displayed. Turn the TOX ZERO knob clockwise
until the alarm is activated. Record this reading. Adjust the reading back to zero and press
the RESET button. The alarm should have activated at 35 ppm.
14. If any of the alarm points are not what they should be, inform an instructor/technician.
15. Turn the FUNCTION control to MANUAL for continuous readout of any one gas or to
SCAN for automatic scanning of the three gas readings. Note: All alarm functions operate
in either position.
16. The instrument is ready for sampling.
CALIBRATION
17. Open the clamp to the gas bag labeled "PENTANE 0.75%" and attach the sample line to the
bag. Draw a sample into the instrument until a constant reading is obtained.
18. Record your readings on the data sheet. The instrument should give a reading of 50% LEL.
Consult the instructor for proper oxygen and carbon monoxide readings.
19. Disconnect the sample line and clamp the bag. Allow fresh air to flow through the
instrument until the reading returns to zero. Rezero the instrument, if needed.
Exercise 1 6 10/93
-------
SAMPLING
20. For field monitoring, the alarm should be in the operable mode (SCAN or MANUAL
setting). For this exercise, you may keep the audible alarm deactivated to reduce noise
levels.
21. Note: The Model 360 has a latching mechanism that engages if the % LEL exceeds 100.
To disengage the lock, the instrument must be turned off and then turned back on in an area
where the LEL readings are less than 100%. Room air will do.
22. Sample each of the gas bags listed on the data sheet. Record the readings.
SHUTDOWN
23. When done sampling, flush fresh air through the instrument. Turn the instrument OFF.
10/93 7 Exercise 1
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STATION 3
Gastech Model 1314 Gastechtor
The GasTech Model 1314 is a combination combustible, oxygen, and toxic monitor. There is no
separate toxic sensor. The "toxic" response is provided by an amplification of the combustible
sensor (supersensitive CGI). Thus the toxic response is actually ppm combustible. The readout is
an analog meter that only displays one reading. The readout being displayed depends on the position
of the buttons on the side of the instrument. It has a specific % LEL, low and high oxygen, and
toxic level alarms. The oxygen alarm will sound even if % LEL is being displayed and vice versa.
The toxic alarm, however, will only sound if in the "PPM" mode. The unit has a battery-powered
pump for drawing air.
STARTUP
1. Attach the hose to instrument by means of the quick release fitting.
2. Put the PPM/LEL switch in the LEL (out) position, with the black indicator showing, and
OXY/LEL switch also in the LEL (out) position.
3. Press the POWER switch to turn the instrument on, with orange indicator dot showing. The
meter will normally rise upscale and a pulsing or steady alarm signal may sound. Audible
hum of pump will be noticed. The cause of the alarm condition (combustibles, oxygen, or
both) can be identified by the blinking lights.
4. Press the BATT CK button and note the meter reading. If reading is close to or below the
BATT CHECK mark on the meter, consult an instructor/technician.
5. Allow the instrument to warm up until the meter stabilizes (about a minute). If a pulsed
oxygen alarm continues to sound, turn the OXY CAL potentiometer clockwise to stop it.
If the sound is steady, turn the potentiometer counterclockwise.
6. With the hose inlet in a clean air location, turn the ZERO LEL potentiometer to bring the
meter to "0" indication. If this is not possible, consult an instructor/technician.
7. Put the OXY/LEL switch in the OXY (in) position, so that the orange indicator shows. Turn
the OXY CAL potentiometer to bring the meter to the 02 CAL mark (21 %).
8. As a quick check, gently breathe into hose inlet and allow instrument to sample exhaled air.
Reading should come down to about 16%, and alarm should sound at 19.5%. Allow it to
return to 21%, then put switch back in LEL position.
9. These particular units have a high oxygen alarm that will sound in a steady tone and the
amber alarm lights will blink when reading reaches or exceeds 25%.
Exercise 1 » 10/93
-------
10. The instrument will automatically test for oxygen whenever it is used, and will give a pulsed
audible and an amber light alarm if oxygen content drops to 19.5%. It is not necessary to
use the instrument with the switch in the OXY position unless oxygen measurements are of
primary interest. If both abnormal gas conditions exist simultaneously, both lights will blink
in their normal pattern, but alarm will sound continuously.
11. For readings in the 0-100% LEL range, hold inlet at point to be tested. Watch meter and
observe maximum reading as taken from the upper set of graduations. 0-100% scale. If
reading rises above the alarm setting (20% LEL), a pulsed red light and an audible alarm will
commence, and will continue as long as reading remains above alarm point.
12. If the reading on the 0-100% range is imperceptible or very small, use the sensitive range,
0-500 ppm. First allow to warm up in the LEL range, and then push range switch to put
circuit in PPM range (colored indicator showing). Rezero carefully with the ZERO LEL
potentiometer.
Because of the very high sensitivity of this range, the meter will tend to drift until instrument
is thoroughly warmed up. Always let it run for 5 minutes or more, whenever possible,
before operating on the PPM range. Take the reading immediately after zeroing, and
observe maximum deflection as taken from the middle set of graduations, 0-500 PPM scale.
The alarm will sound whenever the reading rises above the preset alarm level - 100 ppm.
CALIBRATION
13. Put the PPM/LEL switch in the LEL (out) position.
14. Unclamp the bag labeled "HEXANE 0.55%" and attach it to the sample inlet. Record the
reading when it has stabilized. The reading should be 50%. If not, please inform the
instructor.
SAMPLING
15. Sample each of the gas bags listed on the data sheet. Record the readings. DO NOT USE
THE PPM SETTING UNLESS THE LEL RESPONSE IS VERY LOW.
SHUTDOWN
16. When sampling is complete, flush fresh air through the instrument. Turn the instrument
OFF.
Exercise 1
-------
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Exercise 1
10
-------
QUESTIONS
1. Did the alarms activate at the appropriate readings? Which instruments did not?
2. Why do the different instruments give different responses to similar combustible gases?
3. What are the hazards (if any) associated with each unknown bag?
10/93 11 Exercise 1
-------
4. List the limitations and advantages of each instrument for monitoring an unknown
atmosphere.
MSA 260/261:
MSA 360:
GasTech 1314:
Exercise 1 12 . 10/93
-------
EXERCISE #2
Photoionization Detectors - Survey
OBJECTIVE
Participants will learn how to calibrate and operate the HNU Model PI-101 Photoionization Detector.
PROCEDURE
Students will divide into groups as directed by the laboratory instructor. Each group will have an
HNU PI-101 Photoionization Detector with either a 10.2 eV or 11.7 eV lamp, and eight gas bags.
Also, five containers with unknown chemicals will be placed around the room.
STATION 1: Bag A 100 parts per million (ppm) toluene
Bag B 100 ppm acetone
Bag C 100 ppm toluene/100 ppm acetone
Bag D 800 ppm acetone
Bag E 250 ppm acetone
Bag F 50 ppm acetone
Bag G 50 ppm hexane
Bag CH4 100 ppm methane
STATION 2: Five containers with unknowns
By following the instructions, sample each station and record your results. A discussion of your
findings will be held at the end of the exercise.
10/93 13 Exercise 2
-------
SETUP
1. Record the instrument serial number or ID number on the data sheet.
2. Record the lamp energy.
STARTUP
Refer to Figure 1 for location of instrument controls.
3. Connect the probe.
4. Turn the FUNCTION SWITCH to the BATTERY CHECK position. The needle should
deflect within or above the green arc. If not, inform the instructor. If the red indicator light
(low battery) comes on, do not use the instrument.
5. To ensure that the lamp will light, turn the FUNCTION switch to any RANGE setting and
place a solvent based marker near the sample intake on the probe. A needle deflection
should occur, thus indicating that the lamp is on.
6. There are two methods of zeroing an instrument. For this lab, use METHOD 1.
• METHOD 1 - Turn the FUNCTION SWITCH to the STANDBY
position and zero the instrument using the ZERO knob. This
procedure is used to zero the instrument electronically. If the SPAN
setting is altered, the zero should be rechecked and adjusted. Wait
fifteen to twenty seconds to ensure that the zero reading is stable. If
necessary, readjust the zero.
• METHOD 2 - Turn the FUNCTION SWITCH to the range being
used and rotate the ZERO knob until the meter reads zero. Now you
have zeroed out background. If the SPAN setting is changed after the
zero is set, the zero should be rechecked and adjusted.
You are now ready to calibrate your instrument.
CALIBRATION
7. The instructor will assist the students in the calibration procedure. A compressed gas
cylinder containing isobutylene will be used to calibrate the instrument. Set the FUNCTION
SWITCH to the 0-200 RANGE setting.
8. Connect the probe to the tubing from the ISOBUTYLENE cyclinder. Unlock the SPAN
knob by moving the black lock handle counter clockwise. By adjusting the SPAN setting
between 0-100, obtain the appropriate instrument reading. The instructor will tell you the
Exercise 2 14 10/93
-------
appropriate reading. Do not lock the SPAN knob at all during this lab exercise. Record the
SPAN setting at calibration on the data sheet.
SAMPLING
9. When taking readings, adjust the FUNCTION SWITCH to get the maximum on scale needle
deflection. If the reading exceeds the meter range, adjust the FUNCTION SWITCH.
10. Measure for contaminants in BAGS A, B, C, G, and CH, and record the results.
11. Take readings over the openings of each of the unknown containers. Record the readings.
CALIBRATION CHANGE
12. By adjusting the SPAN, calibrate the instrument to BAG B (acetone). Measure the
concentration of BAGS C, D, E, and F and record your results. Then plot the instrument
readings vs. actual concentration from BAGS B, D, E, and F on Graph 1.
SHUTDOWN
13. Turn the FUNCTION SWITCH to the OFF position.
10/93 15 Exercise 2
-------
Low Battery Indicator
Light (LED)
Power Off
Sensitivity
Adjustment
Hi-Voltage
Interlock
Battery Check
Position
Ranges (ppm)
Function
Switch
12 Pin Interface Connector
between readout unit and
season
Zero Adjustment
Recorder Output
1-5V DC)
FIGURE 1. HNU PI 101 CONTROLS
Source: Instruction Manual for Model PI 101 Photoionization Analyzer, 1975, HNU Systems, Inc.
Used with permission of HNU Systems, Inc.
Exercise 2
16
10/93
-------
DATA SHEET
TABLE 1
INSTRUMENT MODEL
I.D. NUMBER
LAMP ENERGY
GAS
CONCENTRATION
INSTRUMENT READING
SPAN SETTING
TABLE 2
BAG
CONCENTRATION
INSTRUMENT
READING
RELATIVE
RESPONSE*
A - TOLUENE
100 ppm
B - ACETONE
C - TOLUENE/
ACETONE
G-HEXANE
100 ppm
100/100
50 ppm
CH4 - METHANE
100 ppm
* Relative Response = Instrument Reading
% Relative Response.
+ Actual Concentration. Multiply by 100% to get
10/93
17
Exercise 2
-------
DATA SHEET
TABLE 3
SAMPLE LOCATION*
1
2
3
4
5
READING
*Add information about location of probe when taking the reading.
TABLE 4
ACETONE CALIBRATION
BAG
ACTUAL
CONCENTRATION
INSTRUMENT
READING
B
100 ppm
100/100
800 ppm
250 ppm
50 ppm
Exercise 2
18
10/93
-------
GRAPH 1. INSTRUMENT READING VS. TRUE CONCENTRATION
900
800
700
D)
600
CO
0
rr 500
CD
400
300
200
100
10/93
0 100 200 300 400 500 600 700 800 900
True Concentration (ppm)
19
Exercise 2
-------
QUESTIONS
1. Calculate and record the relative response for each of the chemicals in Table 2.
2. Why is the reading for Bag C in Table 2 different from the reading in Table 4?
3. From Graph 1, does the instrument accurately measure all four concentrations? If you were
going to measure acetone vapors at concentrations of 0-10 ppm, would this calibration curve
be of value to you?
4. Unknown 2 is found to be acetone. Develop a method(s) using the HNU to determine the
concentration of acetone at the location.
5. You are using an HNU to survey a site and obtain a reading of 200. How do you report
your findings and what additional information would you like recorded?
Exercise 2 20 10/93
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EXERCISE #3
Flame lonization Detectors - Survey
OBJECTIVE
Participants will learn how to calibrate and operate the Foxboro Organic Vapor Analyzer OVA-128
in the survey mode.
PROCEDURE
Students will divide into groups as directed by the laboratory instructor. Each group will have an
Foxboro OVA-128 plus eight gas bags. Also, five containers with unknown chemicals will be placed
around the room.
Station 1: Bag A 100 parts per million (ppm) toluene
Bag B 100 ppm acetone
Bag C 100 ppm acetone/100 ppm toluene
Bag D 800 ppm acetone
Bag E 250 ppm acetone
Bag F 50 ppm acetone
Bag G 50 ppm hexane
Bag CH4 100 ppm methane
Station 2: Five sampling containers
By following the instructions, sample each station and record your results. A discussion of your
findings will be held at the end of the exercise.
10/93 21 Exercise 3
-------
Please read each paragraph completely before following the directions and proceeding to the next
paragraph.
SETUP
1. Record the instrument serial number or ID number on the data sheet.
STARTUP
2. Turn off the charger and disconnect the charger cable from the instrument.
3. Unlock the GAS SELECT dial and adjust it to 300 (i.e., a 3 in the window and 00 on the
dial).
4. Turn the VOLUME knob fully counter clockwise.
5. Ensure that the SAMPLE INJECT VALVE and BACK FLUSH VALVE are in the full pjai
position.
6. The toggle switches on this instrument have a lock to prevent accidental changes. To move
the toggle switch, lift and then move the lever.
7. Move the INSTRUMENT switch to ON and allow 5 minutes for warm-up.
8. Move the PUMP switch to ON. You should hear the pump running. Place the instrument
in a vertical position and look at the SAMPLE FLOW RATE (rotameter at lower left of
panel). The flow rate (read at center of ball) should be 2.0 (liters/minute). A reading
between 1.5 and 2.5 is considered adequate.
9. Set the CALIBRATE switch to X10. Adjust the CALIBRATE knob until the meter reads
0.
10. Open the H2 TANK VALVE and H2 SUPPLY VALVE one and one-half turns counter
clockwise. The TANK gauge should be 500 psi or higher. The SUPPLY gauge should read
between 10 and 12 psi. If they do not, inform the instructor.
11. Wait about 1 minute. Depress the red IGNITER BUTTON (on the side of the pack) until
the flame ignites or until 6 seconds have passed. Flame ignition is indicated by a sharp
meter needle deflection towards 10 along with a small "pop" sound. Also, the meter needle
should return to a reading above 0 instead of 0. Do not depress the button longer than 6
seconds. If the flame does not ignite on the first try, wait a minute, and try again. If it does
not ignite on a second try, check that steps 1 through 10 have been completed. Then consult
an instructor or technician for assistance.
12. Use the CALIBRATE knob to adjust the meter reading to zero. Move the CALIBRATE
switch to XI and rezero.
Exercise 3 22 10/93
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CALIBRATION
13. Set the CALIBRATE switch to X10.
14. Locate the METHANE calibration gas bag. Methane is the normal calibration gas for the
OVA.
15. Open the bag clamp and attach the methane bag to the probe inlet. It is important that the
bag be open before attaching it so that a "flame out" does not occur from oxygen starvation.
16. Unlock and adjust the GAS SELECT knob so that the meter reading is equal to the bag
concentration divided by the CALIBRATE switch setting. For example, if the bag
concentration is 90 ppm, then the reading should be 9 (90 divided by 10).
17. Disconnect the gas bag and close the clamp.
18. The GAS SELECT setting should be about 300. 300 is the "ideal" setting, but your
instrument may have a different reading. If the setting must be adjusted above 400 or below
200, internal calibration may be advisable.
19. The instrument is now calibrated to methane and ready for survey purposes.
SAMPLING
20. During the next two steps, change the CALIBRATE switch setting as necessary to get the
maximum on-scale reading. If the meter reads above 10 on the X100 setting, report the
reading as greater than 1000.
21. Take readings of bags A, B, C and G. Record the data.
22. Take readings at the five containers. Record the readings and locations.
CALIBRATION
23. Change the CALIBRATE switch to X10.
24. Open and connect Bag B to the probe inlet. Adjust the GAS SELECT knob until the
instrument reads 10 on the X10 range.
25. Disconnect and close the bag. Use the CALIBRATE ADJUST knob to rezero, if needed.
26. Take readings of bags C, D, E, and F. Record the readings. Plot the readings from bags
B, D, E, and F on GRAPH 1.
10/93 23 Exercise 3
-------
SHUTDOWN
27. Close the H2 SUPPLY valve, then the H2 TANK valve.
28. Move the INSTRUMENT switch to OFF.
29. When the SUPPLY pressure gauge falls to zero, move the PUMP switch to OFF.
Exercise 3 24 10/93
-------
DATA SHEET
TABLE 1
INSTRUMENT MODEL
I.D. NUMBER
CALIBRATION
GAS
CONCENTRATION
INSTRUMENT READING
GAS SELECT SETTING
TABLE 2
BAG
CONCENTRATION
INSTRUMENT
READING
RELATIVE
RESPONSE*
A - TOLUENE
100 ppm
B - ACETONE
C - TOLUENE/
ACETONE
G-HEXANE
100 ppm
100/100
50 ppm
*Relative Response = Instrument Reading + Actual Concentration. Multiply by 100% to get
% Relative Response.
10/93
25
Exercise 3
-------
DATA SHEET
TABLE 3
SAMPLE LOCATION*
1
2
3
4
5
READING
* Add information about location of probe when taking the reading.
BAG
TABLE 4
ACETONE CALIBRATION
ACTUAL
CONCENTRATION
100 ppm
100/100
800 ppm
250 ppm
50 ppm
INSTRUMENT
READING
GAS SELECT
SETTING
Exercise 3
26
10/93
-------
GRAPH 1. INSTRUMENT READING VS. ACTUAL CONCENTRATION {from Table 4)
900
800
700
G)
600
CtJ
CD
rr 500
400
300
200
100
0 100 200 300 400 500 600 700 800 900
True Concentration (ppm)
10/93
27
Exercise 3
-------
QUESTIONS
1. Calculate the relative response for each of the chemicals in Table 2.
2. Why is the reading for Bag C in Table 2 different from the reading in Table 4?
3. From Graph 1, does the instrument accurately measure all four concentrations? If you were
going to measure acetone vapors at concentrations of 0-10 ppm, would this calibration curve
be of value to you?
4. Unknown 2 is found to be acetone. Develop a method(s) using the OVA to determine the
concentration of acetone at the location.
5. You are using an OVA to survey a site and obtain a reading of 200. How do you report
your findings and what additional information would you like recorded?
Exercise 3 28 10/93
-------
EXERCISE #4
Gas Chromatography - Organic Vapor Analyzer
OBJECTIVE
Participants will learn how to operate the Foxboro OVA-128 with gas chromatograph option as a
portable gas chromatograph.
PROCEDURE
The students will divide into groups as directed by the laboratory instructor. Each group will have
a Foxboro OVA-128 with gas chromatograph option and three gas bags.
Bag CH4: Calibration gas
Bag C: Standard of 100 ppm toluene and 100 ppm acetone
Unknown #1
By following the instructions of the lab manual and instructor, each group will produce a gas
chromatograph for each bag. By comparing the results from the standard to the unknown, the group
will try to determine what chemicals are present and at what concentrations. The results will be
recorded and discussed at the end of the exercise.
10/93 29 Exercise 4
-------
Please read each paragraph completely before following the directions and proceeding to the next
paragraph.
SETUP
1. Record the instrument serial number or ID number on the data sheet.
STARTUP
2. For gas chromatograph use, the charger can remain on and connected to the OVA.
3. Unlock the GAS SELECT dial and adjust it to 300 (i.e., a 3 in the window and 00 on the
dial).
4. Turn the VOLUME knob fully counter clockwise.
5. Ensure that the SAMPLE INJECT VALVE and BACK FLUSH VALVE are in the full out
position.
6. The toggle switches on this instrument have a lock to prevent accidental changes. To move
the toggle switch, lift and then move the lever.
7. Move the INSTRUMENT switch to ON and allow 5 minutes for warm-up.
8. Move the PUMP switch to ON. You should hear the pump running. Place the instrument
in a vertical position and look at the SAMPLE FLOW RATE (rotameter at lower left of
panel). The flow rate (read at center of ball) should be 2.0 (liters/minute). A reading
between 1.5 and 2.5 is considered adequate.
9. Set the CALIBRATE switch to X10. Adjust the CALIBRATE knob until the meter reads
0.
10. Open the H2 TANK VALVE and H2 SUPPLY VALVE one and one-half turns counter
clockwise. The TANK gauge should be 500 psi or higher. The SUPPLY gauge should read
between 10 and 12 psi. If they do not, inform the instructor.
11. Wait about 1 minute. Depress the red IGNITER BUTTON (on the side of the pack) until
the flame ignites or until 6 seconds have passed. Flame ignition is indicated by a sharp
meter needle deflection toward 10 along with a small "pop" sound. Also, the meter needle
should return to a reading above 0 instead of 0. Do not depress the button longer than 6
seconds. If the flame does not ignite on the first try, wait a minute, and try again. If it does
not ignite on a second try, check that steps 1 through 10 have been completed. Then consult
an instructor or technician for assistance.
12. Use the CALIBRATE knob to adjust the meter reading to zero. Move the CALIBRATE
switch to XI and rezero.
Exercise 4 30 10/93
-------
CALIBRATION
13. Set the CALIBRATE switch to X10.
14. Locate the METHANE calibration gas bag. Methane is the normal calibration gas for the
OVA.
15. Open the bag clamp and attach the methane bag to the probe inlet. It is important that the
bag be open before attaching it so that a "flame out" does not occur from oxygen starvation.
16. Unlock and adjust the GAS SELECT knob so that the meter reading is equal to the bag
concentration divided by the CALIBRATE switch setting. For example, if the bag
concentration is 90 ppm, then the reading should be 9 (90 divided by 10).
17. Disconnect the gas bag and close the clamp.
18. The GAS SELECT setting should be about 300. 300 is the "ideal" setting, but your
instrument may have a different reading. If the setting must be adjusted above 400 or below
200, internal calibration may be advisable.
GAS CHROMATOGRAPH SETUP
19. Connect the strip chart recorder to the OVA. Move the HI/LO switch (on the side of the
recorder) to the LO position. The chart paper should start moving and you should hear a
clicking sound. If the chart does not operate, check the cable connections. Inform the
instructor if the chart doesn't work.
20. Turn the ZERO knob on the recorder (next to HI/LO switch) completely clockwise.
21. Turn the OVA CALIBRATE knob to adjust the baseline (black line produced by the pin) on
the chan. Do not use the ZERO knob on the recorder. The baseline should be about 1/4
inch (two thin brown lines) above the thick brown line next to the sprocket holes.
22. Locate the stopwatch. Practice with the stopwatch until you can do lap counting. The
instructor will demonstrate. Lap counting involves stopping the readout without stopping the
stopwatch timing. This is useful for timing more than one peak.
STANDARD CHROMATOGRAM
23. Open and connect the STANDARD (Bag C: Acetone/Toluene) bag to the probe inlet.
Watch the meter needle. When the needle has deflected to its highest point, depress the
SAMPLE INJECT VALVE and start the stopwatch. Disconnect and close the gas bag. If
the needle passes 10, wait 3 seconds, then depress the INJECT VALVE.
Keep the SAMPLE INJECT VALVE depressed until the end of the chromatogram. The
instructor will discuss how to determine when the chromatogram is done.
10/93 31 Exercise 4
-------
24. Strike a line across the chart with a pen or pencil to indicate the start of a chromatogram.
Write the OVA CALIBRATE SWITCH setting (XI, X10, X100) and the recorder HI/LO
setting on the chart paper.
25. Watch the chart paper or meter face for an upward needle deflection. When the needle
reaches a maximum reading and starts to drop, note the time. This is the top of the peak and
the time is the retention time for the peak. Do this for each peak. Record the retention
times for each peak.
26. If a peak is too small or goes off scale, you will need to rerun the standard at a different
CALIBRATE SWITCH setting and/or different HI/LO setting. Table 1 shows the
relationship between peak size and instrument settings. For example, if a peak is off scale
on a HIX10 setting, changing the settings to LOX10 or HIX100 would make the peaks 1/2
or 1/10 the size of the original peaks.
TABLE 1
RECORDER RANGE
FACTOR
HI
LO
HI
LO
HI
LO
OVA SCALE
X1
X1
X10
X10
X100
X100
RELATIVE
PEAK SIZE
1
1/2
1/10
1/20
1/100
1/200
27. When a chromatogram is done (i.e, the last peak is out and the baseline is back to normal),
lift the SAMPLE INJECT VALVE. The instrument is ready for another run.
SAMPLE CHROMATOGRAM
28. Repeat steps 22 through 26 using the UNKNOWN sample bag.
SHUTDOWN
29. Close the H2 SUPPLY valve, then the H2 TANK valve.
30. Move the INSTRUMENT switch to OFF.
Exercise 4
32
10/93
-------
31. Move the RECORDER RANGE SETTING switch to OFF.
32. When the SUPPLY pressure gauge falls to zero, move the PUMP switch to OFF.
CALCULATIONS FOR QUALITATIVE EVALUATION
27. (Optional) Tear off the strip chart and measure the distance from the injection point to the
middle of the peak in mm (see Figure 1 below).
Retention time
Injection
Time
FIGURE 1. RETENTION TIME (DISTANCE) ILLUSTRATION
28. Compare the retention times of the known standard and the unknown. If the retention times
are relatively close, then the unknown can possibly be identified through comparison to the
known. For example, if a standard of acetone released at 144 seconds and a peak on our
unknown was at 136 seconds, then we can assume that the peak was acetone.
QUANTITATIVE ANALYSIS
29. To find the concentration of a chemical that has been identified with a standard, you will
need a ruler, a calculator, and a pencil.
30. Draw a triangle that approximates the area of the curve similar to the example (Figure 2)
below.
10/93
33
Exercise 4
-------
Area = 1/2 x base x height
Area = 1/2 b h
FIGURE 2. PEAK AREA ILLUSTRATION
31. Calculate the area of the triangle for the standards and unknowns by using the following
formula:
32.
33.
Area = V4(b)(h)
To compensate for the different instrument settings a corrected area formula must be used:
Corrected Area = OVA Setting x Recorder Range Factor x Area of Triangle
X100
X10
XI
HI = .5
LO = 1.0
To obtain the actual concentration of the unknown, divide the corrected area of the unknown
by the corrected area of the standard and multiply by the standard concentration.
Corrected Areaun]mnm
Concentration of unknown - — ——unamwn x Standard concentration
Corrected Area
standard
Exercise 4
34
10/93
-------
TABLE 2
CONCENTRATION
RETENTION TIME
RETENTION
DISTANCE (mm)
PEAK BASE (mm)
PEAK HEIGHT (mm)
PEAK AREA (mm2)
OVA SCALE
SETTING
RECORDER
SETTING
CORRECTED AREA
(mm2)
STANDARD BAG C
ACETONE
TOLUENE
UNKNOWN #1
PEAK 1
PEAK 2
PEAK 3
10/93
35
Exercise 4
-------
CALCULATIONS
Exercise 4 36 10/93
-------
QUESTIONS
1. Identify the peaks in Unknown #1. For the peaks that can not be positively identified, list
the possible candidates.
2. What are the concentrations of the identified peaks? Compare your numbers with the actual
concentrations (from the instructor). Give reasons why your results may vary from the actual
concentrations.
10/93 37 Exercise 4
-------
CHROMATOGRAPHY AND SURVEY GUIDE
FOXBORO CENTURY ORGANIC VAPOR ANALYZERS
COMPOUND
ACETONE
ACETONTTRILE
ACRYLONITRILE
ALLYL ALCOHOL
ALLYL CHLORIDE
BENZENE
BROMOETHANE
BROMOMETHANE
BROMOPROPANE
BUTADIENE.1.3-
BUTANE
BUTANOL
BUTANOL.2-
BUTANONE.2-
BUTENE
BUTYL ACETATE
BUTYL ACRYLATE
BUTYL ACRYLATE.tert-
BUTYL FORMATE
BUTYL FORMATE.tert-
BUTYL METHACRYLATE
BUTYL METHYL ETHER.tert-
CARBON TETRACHLORIDE
CKLOROBENZENE
CHLOROFORM
CHLOROMETHANE
CHLOROPROPANE
CHLOROPROPANE.2-
CUMENE
CYCLOHEXANE
CYCLOHEXANONE
DECANE
DIACETONE ALCOHOL
D1BROMOETHANE.1.2-
DICHLOROBENZENE.1.2-
DICHLOROETHANE.1.1-
DICHLOROETHANE.1.2-
D1CHLOROETHYLENE, 1.1-
DICHLOROETHYLENE.trans-l
DICHLOROMETHANE
DICHLOROPROPANE.1.2-
DICHLOROPROPANE.1.3-
DIOXANE.p-
. . • ':•< :'"
TWA .
• ppo» ..
750
40
2
2
1
1
200
5
*
1000
800
100
100
200
*
150
10
*
*
*
•
*
10
75
2
50
*
*
50
300
25
*
50
20
50
100
I
1
200
100
75
*
25
T-1Z COLUMN
RR
*
82
6*
98
27
45
185
72
23
73
36
58
46
55
75
43
67
60
75
48
64
60
57
3
179
57
56
79
55
18
92
43
69
56
56
119
70
89
49
40
84
96
76
28
tR':
sec
118
384
252
623
36
116
23
13
51
3
12
725
340
203
5
572
1099
293
338
at
1600
21
41
713
122
4
25
13
690
16
225
950
1168
4060
66
289
11
37
73
258
677
760
i
2.23
7.25
4.75
11.75
0.68
2.19
0.43
0.25
0.96
0.06
0.23
13.68
6.42
3.83
0.09
10.79
20.74
5.53
6.38
2.09
30.19
0.40
0.77
13.45
2.30
0.08
0.47
0.25
13.02
0.30
0.00
4.25
17.92
22.04
76.60
1.25
5.45
0.21
0.70
1.38
4.87
12.77
14.34
. 024COLUMN , :;' .,.':.-"' -. ': . -i; 1 ".^
• tR'
sec
36
39
45
98
38
142
35
14
100
7
3
243
131
93
12
782
1577
567
319
112
3950
70
143
866
91
5
48
26
1910
161
1256
1017
536
66
124
36
55
43
203
397
242
a.
'6.29
0.32
0.37
0.80
0.31
1.15
0.28
0.11
0.81
0.06
0.02
1.98
1.07
0.76
0.10
6.36
12.82
4.61
2.59
0.91
32.11
0.57
1.16
7.04
0.74
0.04
0.39
0.21
15.53
1.31
10.21
0.00
8.27
4.36
0.00
0.54
1.01
0.29
0.45
0.35
1.65
3.23
1.97
..-'.' . SYNONYM ; ;.;;:":.::.::U:
;,-.."x.:: .-.".--
-PROPANONE
VUs'YL CYANIDE
ETHYL BROMIDE
METHYL BROMIDE
PROPYL BROMIDE
BUTADIENE
BUTYL ALCOHOL
sec-BUTYL ALCOHOL
METHYL ETHYL KETONE
2-BUTYL ACRYLATE / PROPYLENE
2-BUTYL FORMATE
MONOCHLOROBENZENE
TRICHLOROMETHANE
METHYL CHLORIDE
PROPYL CHLORIDE
ISOPROPYL CHLORIDE
ISOPROPYL BENZENE
HEXAMETHYLENE
4-HYDROXY-4-METHYL-2-PENTANON'
ETHYLENE DIBROMIDE
o-DICHLOROBENZENE
ETHYLENE DICHLORIDE
VINYLIDENE CHLORIDE
METHYLENE CHLORIDE
PROPYLENE DICHLORIDE
DIETHYLENE DIOXIDE
-------
COMPOUND
ENFLURANE
ETHANE
ETHANETHIOL
ETHANOL
ETHENE
ETHER
ETHYL ACETATE
ETHYL ACRYLATE
ETHYL BENZENE
ETHYL BUTYRATE
ETHYL FORMATE
ETHYL METHACRYLATE
ETHYL PROPIONATE
ETHYLENE OXIDE
FREON-11
FREON-113
FREON-114
FREON-123
FREON-12
FREON-21
FREON-22
HALOTHANE
HEPTANE
HEXADECANE
HEXAFLUOROPROPENE
HEXANE
ISOBUTANE
ISOBUTENE
ISOPRENE
ISOPROPYL ACETATE
METHANE
M ETHANOL
METHYL ACETATE
METHYL ACRYLATE
METHYL CYCLOHEXANE
METHYL CYCLOPENTANE
METHYL ISOBUTYL KETONE
METHYL METHACRYLATE
METHYL SULFIDE
NITROMETHANE
NITROPROPANE
NITROPROPANE,2-
NONANE
OCTANE
PENT AN E
PENTANOL
PENTANONE.2-
TWA
pptn
•
*
0.5
1000
*
400
400
5
100
*
100
•
*
1
1000
1000
1000
too
1000
10
1000
*
400
•
*
50
*
*
*
250
*
200
200
10
400
V
50
100
*
too
25
10
200
300
600
•
200
T-12. COLUMN
RR.
%
146
77
23
20
47
47
67
71
111
91
44
73
83
49
7
91
110
86
13
71
67
49
80
52
81
70
70
64
59
71
100
10
46
39
67
81
82
54
20
35
65
71
85
87
65
39
76
tR'
ice
79
1
24
173
I
13
143
263
495
398
78
375
241
31
4
3
3
19
3
20
5
53
16
1764
1
7
3
2
9
155
1
139
93
197
20
9
468
291
27
1053
1893
1030
103
44
3
1771
365
a
1.49
0.02
0.45
3.36
0.02
0.25
2.70
4.96
9.34
7.51
1.47
7.08
4.55
0.58
0.03
0.15
0.06
0.36
0.06
0.38
0.09
1.00
0.30
33.28
0.02
0.13
0.06
0.04
0.17
2.92
0.02
2.62
1.75
3.72
0.38
0.17
8.33
5.49
0.51
19.37
35.72
19.43
1.94
0.83
0.06
33.42
6.89
G-24 COLUMN
tR'
sec
29
I
31
45
1
38
108
254
1054
538
43
514
274
35
24
43
3
22
5
17
3
51
232
2
88
14
10
32
130
1
64
49
107
230
114
353
266
35
73
285
191
1939
748
29
728
227
a.
'0.24
0.0 1
0.25
0.37
0.01
0.31
0.38
2.07
8.57
4.73
0.35
4.18
2.23
0.23
0.20
0.35
0.07
0.18
0.04
0.14
0.02
0.41
1.89
0.00
0.02
0.72
0.11
0.08
0.26
1.46
0.0 1
0.52
0.40
0.37
2.23
0.93
2.37
2.16
0.28
0.59
2.32
1.53
15.76
6.0
0.24
5.92
1.8
-C
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SYNONYM
-CHLORO-1,1.2TTRIFLUOROETHYL-DI-
FLUOROMETHYL ETHER / ETHRANE
ETHYL MERC APT AN
ETHYL ALCOHOL
ETHYLENE
IETHYL ETHER
:?OXYETHANE
FLUOROTRICHLOROMETHANE
RICHLOROTRIFLUOROETHANE
.2-DICHLORO-l 122-TETRAFLUOROETH,
.2-DICHLORO-l. 1,1-TRIFLUOROETHANE
DICHLORODIFLUOROMETHANE
DICHLOROFLUOROMETHANE
CHLORODfFLUOROMETHANE
2-BROMO-2CHLORO-11ITRIFLUOROETH,
ERFLUOROPROPENE
2-BUTANE / 2-METHYL PROPANE
SOBUTYLENE / 2-METHYL PROPENE
2-METHYL-1,3-BUT AD IENE
METHYL ALCOHOL
.7 4-METHYL-2-PENTANONE / HEXONE
DIMETHYL SULFIDE
PENTYL ALCOHOL
METHYL PROPYL KETONE
-------
COMPOUND
PENTANONE.3-
PROPANE
PROPANOL
PROPANOL.2-
PROPYL ACETATE
PROPYL ETHER
PROPYL FORMATE
PROPYLENE
FROPYLENE OXIDE
PYRIDINE
3TYRENE
TETRACHLOROETHANE, 1.1.1.
TETRACHLOROETHYLENE
TETRAHYDROFURAN
TOLUENE
TRICHLOROETH ANE, 1.1.1-
TRICHLOROETHANE, 1.1.2-
TRICHLOROETHYLENE
TRIETHYLAMINE
TRIMETHYLPENTANE.2.2.4-
VINYL ACETATE
VINYL CHLORIDE
XYLENE.m-
XYLENE.o-
XYLENE.p-
KEY:
• No TWA levels available.
TWA 8 Hour Time Weighted Average for
Maximum allowable exposure.
RR Relative Response to METHANE in Percent =
(Measured Response / Prepared Concentration) x 100.
tR data not available
TWA.
ppm
200...
1000
200
400
200
•
•
*
20
5
50
•
25
200
too
350
to
50
10
•
to
1
too
too
too
T-12 COLUMN
RR
%
.61
70
35
60
60
56
53
36
66
109
92
81
67
47
126
101
95
54
59
91
40
38
107
106
106
tR'
. sec
355
1
351
153
283
36
157
2
46
1384
956
141
106
262
53
1158
104
14
116
5
563
804
545
a.
6.70
0.02
6.62
2.S9
5.34
0.68
2.96
0.04
0.87
0.00
26.11
18.04
2.66
2.00
4.94
1. 00
21.85
1.96
0.00
0.26
2.19
0.09
10.62
15.17
10.28
G-24 COLUMN
tR'
sec
257
5
102
57
286
217
111
4
40
1355
810
603
125
391
123
378
222
34
221
77
9
1135
1366
1140
a.
2.09
0.04
0.83
0.46
2.33
1.76
0.90
0.03
0.33
0.00
11.02
6.59
4.90
1.02
3.18
1.00
3.07
1.80
0.28
1.30
0.63
0.07
9.23
11.11
9.27
SYNONYM
DIETHYL KETONE
PROPYL ALCOHOL
ISOPROPANOL
1.2-EPOXYPROPANE
PERCHLOROETHYLENE
METHYL BENZENE
METHYL CHLOROFORM
ISOOCTANE
1.3-DIMETHYL BENZENE
1.2-DIMETHYL BENZENE
1.4-DIMETHYL BENZENE
tR * Solute Retention Time from point of injection
tR'= Adjusted Retention Time in seconds
tM = Gas Hold-Up, or Dead Time
tR1 = tR - tM
a = Relative Retention as compared to a Reference
Reference Compound is 1.1,1-Trichloroethane
Data collected at a chart speed = 1 cm/min. at
concentrations of 50 or 100 ppm. and at ambient
temperature
-------
HOW TO USE THIS CHART FOR IDENTIFICATION OF UNKNOWNS BY GC
1. Calculate the Adjusted Retention time of the Unknown solutes and of the Reference compound for the selected
column. This can be accomplished by either running the reference compound separately, under similar conditions
as che unknown will be run, or along with the questioned sample by introducing it into the sample stream via
direct injection, dilutor accessory, or other like means. The tR' for any solute is equal to the time elapsed
from the point of injection to the projection of the peak maximum, minus the gas hold-up time of the column.
The gas hold-up time is the time elapsed from the point of injection to the minimum deflection of che air peak.
(NOTE: approximate hold-up times are 5 sees for a T-12 column and 10 sees for a C—24 column.)
2. In order to minimise the effects of minor variation in operating conditions and in the stationary phase
loading of the columns, the parameter of Relative Retention (a) is used. To calculate a. for a particular
solute on a given column, divide the tR' of the solute by the tR' of the reference compound. If the value of a
falls within W- 10% of the chart value, then the chances are good that the questioned solute is one of the
compounds in this range.
3. To increase the probability of identifying an unknown solute, this chart provides the user with the option
of Two-Column dimensional chromaiography. By utilizing a second type column, one can calculate a second a value
for the questioned solute. If this value of a falls within */- 10% of the chart value, and the value of a for
the previous columnn falls within +/- 10% of that chart value, then there is a high probability that the unknown
has been identified. *
i. Laboratory GC analysis and standard preparation may be required for confirmation, depending upon the
application.
-------
EXERCISE #5
Detector Tubes
OBJECTIVE
During this exercise, participants will learn how to do a leak check and a volume check of both a
Draeger and a Sensidyne detector tube pump and how to use detector tubes quantitatively and
qualitatively.
INTRODUCTION
There are chemical indicators that use the reaction of a chemical reagent with the airborne chemical
of interest to produce a color change. The intensity of the color change or the length of color change
is used to determine the amount of airborne chemical present. The chemical reagent may be
impregnated on a piece of paper or tape and the color change read by eye or by an electronic device.
The chemical could also be placed in a glass tube called a colorimetric indicator tube or detector
tube.
PRINCIPLE OF OPERATION
Colorimetric indicator tubes or detector tubes (Figure 1) consist of glass tube impregnated with an
indicating chemical. A known volume of contaminated air passes through or into the tube. The
contaminant reacts with the indicator chemical in the tube, producing a change in color whose length
or intensity is proportional to the contaminant concentration.
The tubes may have a preconditioning filter preceding the indicating chemical to:
• Remove contaminants (other than the one in question) that may interfere with the
measurement. Many have a prefilter for removing humidity.
• React with a contaminant to change it into a compound that reacts with the indicating
chemical.
TYPES OF TUBES
Detector tubes can be classified by the way air is drawn into the tube:
• Short-term tubes use a hand pump to draw air through the tube for a sample duration
of a few seconds to a few minutes. This is used to give an instantaneous sample.
The hand pump may be a piston or bellows type pump. This exercise will use both
types. A piston pump has a handle that is pulled to evacuate a cylinder of known
volume. Air is pulled through the tube to equalize the pressure in the cylinder.
10/93 39 Exercise 5
-------
MSA, Sensidyne, Enmet, and Matheson manufacture piston pumps. In a bellows
pump, the bellows is squeezed and released. Air is pulled through the tube as the
bellows expands. Draeger and MSA manufacture bellows-type pumps.
Plug
Glass
vial
10
20
30
40
50
n » 5
Prefilter
or reagent
Indicating
chemical
on silica gel
Plug
FIGURE 1. DETECTOR TUBE EXAMPLE
Long-term tubes (pump) use a battery-operated pump to draw air through the tube
over a longer period of time, usually 8 hours. These are used to determine 8-hour,
time-weighted average exposures.
Long-term tubes (dosimeter) do not use a pump. Contaminants diffuse into the tube
over a long period of time, usually 8 hours. These also are used for 8-hour, time-
weighted average exposure determination. However, a pump is not required for
operation.
The three types of tubes are not interchangeable. They are calibrated for their specific applications.
There are many more short-term tubes than there are long-term tubes.
Exercise 5
40
10/93
-------
Detector tubes can also be classified by the information generated the results:
• Chemical groups—Some tubes will react to a class of chemicals (e.g., alcohols or
hydrocarbons). They will only indicate that a chemical of a certain class is present.
• Specific chemicals—There are a few tubes that only react to that specific chemical.
Most tubes have a specific chemical listed for the tube, but can react to other
chemicals (interferences).
• Concentration ranges—There may also be different concentration ranges for the same
chemical. For example, there are tubes for carbon monoxide with concentration
ranges of 5-150 ppm, 10-300 ppm, 0.1-1.2% and 0.3-7%.
DETECTOR TUBE CONSIDERATIONS
There are several factors that determine the effective use of detector tubes. These factors can be
found in the instructions issued with each box of tubes.
Chemical Group: Some tubes are for a specific chemical and some are for a group of chemicals.
Lot #: The instructions for the tubes may change with different model numbers or different lots.
Thus, the instructions should be matched with the proper tubes.
Expiration Date: The chemicals used in the tubes deteriorate over time. Because of this, the tubes
are assigned a shelf life and the expiration date is printed on the box. This varies from 1 to 3 years.
Pump Strokes/Volume/Time: The total volume of air to be drawn through the tube varies with the
type of tube. The volume needed is given as the number of pump strokes needed, i.e., the number
of times the piston or bellows is manipulated. Also, the air does not instantaneously go through the
tube. It may take 1 to 2 minutes for each volume (stroke) to be completely drawn. Therefore,
sampling times can vary from 1 to 30 minutes per tube. This can make the use of detector tubes
time consuming.
Color Change: The instructions will give the appropriate color change for indicating the chemical
of concern. Other color changes may be noted for interferences. This information can be used to
check for the presence of other chemicals.
Interferences: As mentioned previously, not every tube is specific. For example, an acetone tube
will also respond to other ketones. Thus, methyl ethyl ketone would be considered an interference
if one were checking for acetone. The instructions will give known interferences or color changes
that are not for the chemical of interest.
Temperature/Humidity/Pressure: The length of color change (stain) can be affected by temperature,
humidity and barometric pressure. If this is a problem, the instructions will note it and may give
correction factors. Cold weather slows the chemical reaction in the tube and reduces the reading.
Hot temperatures increase the reaction and can cause a problem by discoloring the indicator even
JO/93 41 Exercise 5
-------
when a contaminant is not present. This can happen even in unopened tubes. Therefore, the tubes
should be stored at a moderate temperature or even be refrigerated during storage.
Reusable?: Most tubes can only be used once, even if there is a negative result. There are some
tubes, however, that can be reused the same day until a positive result is obtained.
Accuracy: The accuracy of detector tubes vary. Some studies have reported error factors of 50%
and higher for some uncertified tubes. Some tubes are certified to be +25% accurate at readings
from 1 to 5 times the OSHA Permissible Exposure Limit (PEL) and ±35% at concentrations one-
half the PEL. Only a few tubes are presently certified. Certification of detector tubes is being done
by a private organization - Safety Equipment Institute (SEI).
One factor that affects accuracy is the interpretation of the end of the color change. Some color
changes are diffused and the endpoint is not definite; others may have an uneven endpoint
(Figure 2). When in doubt, use the highest value that would be obtained from reading the different
aspects of the tube.
APPLICATIONS
Although there are many limitations and considerations for using detector tubes, detector tubes allow
the versatility of being able to measure a wide range of chemicals with a single pump. Also, there
are some chemicals for which detector tubes are the only direct-reading indicators.
They can be used to get a reading for a specific chemical in an atmosphere where a total vapor
survey instrument would response to all the chemicals in the atmosphere. They also give an
immediate response. Laboratory analysis (see the Air Sample Collection section) that can identify
and quantify a chemical in a mixture takes time.
Manufacturers use general tubes for identification in their HazMat kits. These kits identify or
classify the contaminants as a member of a chemical group such as acid gas, halogenated
hydrocarbon, etc. This is done by sampling with certain combinations of tubes at the same time by
using a special multiple tube holder or by using tubes in a specific sampling sequence. All
manufacturers of detector tubes have some kind of system for hazard categorization. Detector tube
manufacturers are listed in the Manufacturers and Suppliers of Air Monitoring Equipment section of
this manual.
SAFETY
Do not directly inhale the contents of the bags and keep the bags closed when not in use. The
contents of the gas bags, if released into the room, will not pose a hazard to the occupants.
Breaking the tips off the detector tubes can create a hazard. Please ensure that the glass tips are
discarded into the containers provided and not onto the table or floor. The tube breakers built into
the pumps can propel bits of glass. Direct the glass into the container provided. The instructor will
demonstrate proper procedures. The ends of the detector tubes are also sharp, so handle them
carefully.
Exercise 5 42 10/93
-------
Eating or drinking is not allowed during this exercise because it is nearly impossible to prevent small
shards of glass from being deposited on the desk, table, or floor. Also, check the work area so that
you do not pick up glass on your hands or arms.
PUMP CHECK - DRAEGER
Leak Test
The purpose of this test is to ensure that air is going through the tube and not around it or through
a leaky valve.
1. Insert an unopened tube into the socket of the pump. Do not use your finger to seal the
orifice. The instructor will demonstrate why not.
2. Squeeze the pump completely and release. If the indicator mark has not appeared in 15
minutes, the pump passes the test. You may want to go to the Sensidyne pump check while
this is taking place.
3. If the pump fails the test, inform the instructor.
4. Remove tube from the socket.
5. (New model pump) Press counter reset button with a ball point pen or end of unopened tube
to set at zero.
Volume Check
The purpose of this step is make sure that the pump is drawing the specified volume (100 cubic
centimeters or milliliters). The tubes are calibrated for this volume. If the volume is not within
limits, the tubes can not be used quantitatively.
6. Break off the tips of a tube or use a previously opened tube.
7. Connect the detector tube and pump to the apparatus as shown in Figure 2.
43 Exercise 5
-------
Flexible tubing
Buret
Soap
solution^
Detector tube
Detector tube
^ pump
FIGURE 2. DETECTOR TUBE PUMP VOLUME CHECK APPARATUS
8. Start a bubble at the mouth of the inverted buret by just touching the soap solution to the
mouth of the buret.
9. Squeeze the bellows pump in order to pull the bubble up the buret. Continue to squeeze and
release the pump until the bubble stops above the "0" mark on the buret. This maneuver
may require disconnecting the flexible tubing after the bubble passes the "0" mark.
10. Start with the bellows fully expanded. Reconnect the detector tube to the tubing. Record
the start point (ml) in Table 1.
11. Squeeze and release the pump.
12. When the bubble stops, record the stopping point (ml).
13. The difference in the two points (the travel volume) is the volume pulled by one stroke of
that pump. This volume should be between 95 and 105 ml (100 ml ±. 5%).
14. You may repeat the test to see whether the results are consistent.
Exercise 5 44
-------
PUMP CHECK - SENSIDYNE
Leak Test
1. Insert an unbroken tube into the orifice of the pump.
2. Align the index marks on the pump handle and the pump cap. Pull the handle straight out
as far as it will go. It should lock in place.
3. Wait 1 minute. Turn the handle 1/4 turn and release the handle. Hold the pump barrel
firmly as the handle will pop back rapidly if the pump does not leak. The handle should
return to within 1/4 inch of the cap. If the pump is equipped with a "Flow Finish Indicator,"
the red button will remain down if there is no leak.
4. If the pump fails the test, inform the instructor.
Volume Check
5. Break off the tips of a tube or use a previously opened tube.
6. Connect the detector tube and pump to the apparatus as shown in Figure 2. An adapter may
be needed because of the small diameter of the tube.
7. Start a bubble at the mouth of the inverted buret by just touching the soap solution to the
mouth of the buret.
8. Pull the handle back in order to pull the bubble up the buret. Continue to pull the handle
until the bubble stops above the "0" mark on the buret. This maneuver may require
disconnecting the flexible tubing after the bubble passes the "0" mark.
9. Start with the piston empty (handle fully in). Reconnect the detector tube to the tubing.
Record the start point (ml) in Table 1.
10. Pull back the pump handle all the way.
11. When the bubble stops, stop the stopwatch. Record the time and the stopping point (ml).
12. The difference in the two points (the travel volume) is the volume pulled by one stroke of
that pump. This volume should be between 95 and 105 ml (100 ml + 5%).
13. You may repeat the test to see if the results are consistent.
JO/93 45 Exercise 5
-------
QUANTITATIVE RESULTS - DRAEGER AND SENSIDYNE
The pumps and detector tubes will be used to determine the concentration of two chemicals. The
Draeger pump and tube will be used to determine the concentration of carbon dioxide in the gas bag.
The Sensidyne pump and tube will be used to determine the concentration of isopropyl alcohol in the
air above a beaker of liquid.
1. Read the instructions for the detector tube.
2. Determine the number of pump strokes needed; the color change expected; and any
adjustments to the reading.
3. Use a fresh tube. Break off both ends of the tube. Insert the opened tube into the pump
orifice with the arrow on the tube pointing towards the pump. Sample the bag (carbon
dioxide) and the air above the liquid (isopropyl alcohol). Do not pull liquid into the tube.
(This is air, not water, monitoring.) Liquid drawn into the tube can produce a change even
if the chemical is not present.
4. Record your results on Table 1.
CHEMICAL CLASSIFICATION - DRAEGER
In this step, a series of Draeger tubes will be used to determine the types of chemicals in an
unknown mixture. The flow chart on the next page will be used to determine the mixture's
components. The chart was provided by National Draeger, Inc. Other manufacturers have similar
systems for chemical classification.
This sample taking schedule refers to a selection of substances which occur frequently in practice.
Other situations may necessitate another sequence of measurements and, the case being, the use of
additional detector tubes, or measurements according to other procedures must be carried out. (from
National Draeger, Inc.)
The information on the next two pages has been reprinted with the permission of National Draeger,
Inc., Pittsburgh, PA. This information can also be found in their Haz Mat Kit. Similar flow
charts/decision logics have also been developed by MSA and Sensidyne for use with their detector
tubes.
1. Read the instructions for the tubes.
2. Use the tubes to sample the unknown atmosphere.
3. Record the result in the appropriate space in Table 2.
4. Repeat process with all the tubes provided.
5. Extra space is provided should any special tubes be used.
Exercise 5 46 10/93
-------
Safety Tips
The POLYTEST and HYDROCARBON tubes use sulfuric acid as a reagent. When the bellows is
squeezed, an aerosol (smoke-like) containing the acid will be emitted. Avoid breathing the "smoke."
If you think you may have some problems with the aerosol, please inform your instructor. You
should not have any problems unless you are more sensitive than the average person.
10/93 47 Exercise 5
-------
Detection of unknown substances by means of DRAEGER detector tubes*
Detection of various organic and some inorganic substances:
Polytest
i.g.. Acetone Gasoline (engine fuels)
Acetylene Benzene
Arsenic hydride Ethylene
Liquid gases
(propane, butane)
Carbon monoxide. Monostyrene
Perchloroethylene Municipal gas (with more than 2 vol. % of CO)
Carbon disuHkte Nitrogen monoxide (NO)
Hydrogen sulfide Toluene, xylene. trichloroethytene
positive
positive
Detection of various organic substances:
Ethyl acetate 200/a
Detection of some
halogenated hydrocarbons:
Methyl bromide 5/b
e.g., esters of acetic acid, alcohols, ketones, benzene,
toluene, benzine hydrocarbons
e.g., methyl bromide UN N°
1062 (chloroform, dichlo-
roethylene, dichloroethane,
dichloropropane), trichlo-
>.
>.
V
r
Detection of important
aromatic hydrocarbons:
Benzene 0.05
e.g.. benzene UN N" 1114
(ethyl benzene, toluene
and xylene in small
quantities discolor the
prelayer)
Acetone 100/b
e.g.. acetone UN N° 1090
methylisobutyl ketone,
methylethyl ketone
.
Alcohol 100/a
Detection of
propane butane:
Hydrocarbon 0.1 %/b
e.g.. propane UN N° 1 978
. r*r\
Carbon monoxide 10/b
e.g.. CO UN N° 1016
of other substances may be
>
j
^
Detection of amines:
Hydrazine 0.25/a
e.g., triethylamine UN N° 1296
(ethylene diamine,
hydrazine, ammonia)
Detection of acid-
reacting substances:
Formic acid 1 /a
e.g.. hydrochloric acid UN N°
1789, HNOj. Clj, NOj, SO2
Further detection
e.g., methane, ethane. H2.
CO2 and other substances
may be necessary
negative
e.g., alcohol UN N° 1096
butanol, methanol,
propanol
'Important: This sample taking schedule refers to a selection of substances which occur frequently in practice. Other situations may
necessitate another sequence of measurements and, the case being, the use of additional detector tubes, or measurements
according to other procedures must be carried out.
©\ National Draeger, Inc.
101 Technology Drive (Shipping) • P.O. Box 120 (Mailing) • Pittsburgh, PA 15230 • 412/787-8383 • Telex: 86-6704
Exercise 5
48
10/93
-------
Examples for the (qualitative) indication response of the DRAEGER Polytest tubes
The results were obtained under the following test conditions:
Temperature 20°C; Humidity 50% relative; All tests carried out with pure substances
Substance
Acetone
Acetone
Acetylene
Acetylene
Ursine
Arsine
Benzine (Gasoline)
Benzine (Gasoline)
Benzene
Benzene
Butane
Butane
Carbon disulfide
Carbon disulfide
Carbon monoxide
Carbon monoxide
Ethylene (ethene)
Ethylene (ethene)
Nitrogen monoxide (NO)
Nitrogen monoxide (NO)
Perchloroethylene
Perchloroethylene
Propane
Propane
Styrene (monostyrene)
Styrene (monostyrene)
Toluene
Toluene
Trichloroethylene
Trichloroethylene
Xylene
Xylene
Concentration
5000 ppm
above liquid
2OO ppm
high cone.
(over 1 %)
10 ppm
high cone.
(over 1 %)
50 ppm
above liquid
100 ppm
above liquid
100 ppm
high cone.
(over 1%)
10 ppm
above liquid
100 ppm
high cone.
(over 1 %)
500 ppm
high cone.
(over 1 %)
50 ppm
high cone.
(over 1 %)
50 ppm
above liquid
500 ppm
high cone.
(over 1%)
500 ppm
above liquid
200 ppm
above liquid
50 ppm
above liquid
500 ppm
above liquid
Number
of strokes
of the bel-
lows pump
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Length of Discoloration
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
approx. 10 mm
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
approx. 10 mm
approx. 10 mm
approx. 10 mm
approx. 10 mm
completely colored
approx. 10 mm
approx. 1 0 mm
Notes on the indication
brownish green
brownish
brownish green
brownish
brownish green
brownish
brownish green
brownish
brownish
brownish
faded green (spotty)
brownish green
greenish
brownish green
brownish green
brownish
brownish green
brownish
brownish green
brownish with
bleaching effect
greenish
brownish green
faded green (spotty)
brownish green
brownish
• brownish
brownish
brownish
brownish green
faded yellow
brownish
brownish
Examples for the (qualitative) indication response of the DRAEGER tubes for ethyl acetate 200/a
The results were obtained under the following test conditions:
Temperature 20°C; Humidity 50% relative; All tests carried out with pure substances
Substance
Acetone
Acetone
Benzene
Benzene
Ethyl alcohol
Ethyl alcohol
Octane
Octane
Toluene
Toluene
Xylene
Xylene
Concentration
3000 ppm
above liquid
500 ppm
above liquid
20OO ppm
above liquid
10O ppm
above liquid
500 ppm
above liquid
500 ppm
above liquid
Number
of strokes
of the bel-
lows pump
5
5
5
5
5
5
5
5
5
5
5
5
Length of Discoloration
approx. 1 0 mm
completely colored
completely colored
completely colored
approx. 5 mm
approx. 20 mm
approx. 10 mm
completely colored
approx. 10 mm
completely colored
approx. 10 mm
completely colored
Notes on the indication
greenish
greenish
very pale grey
greenish grey
greenish
greenish
grey-brown-greenish
greenish
greenish grey
greenish grey
greenish brown
greenish brown
10/93
National Draeger, Inc.
101 Technology Drive (Shipping) • P.O. Box 120 (Mailing) • Pittsburgh. PA 15230 • 412/787-8383 • Telex: 86-6704
49 Exercise 5
-------
TABLE 1
SENSIDYNE
DRAEGER
ID NUMBER
LEAK CHECK
VOLUME CHECK
BURET STOP POINT (ml)
PASS FAIL
PASS FAIL
BURET START POINT (ml)
TOTAL VOLUME
SAMPLE TIME
ACCEPTABLE VOLUME?'
PASS FAIL
SAMPLES
ISOPROPYL ALCOHOL
UNADJUSTED READING
READING ADJUSTED FOR
TEMPERATURE
READING ADJUSTED FOR
BAROMETRIC PRESSURE"
• The acceptable volume for a full pump stroke is 100 ml ± 5% (i.e., between 95 and 105 ml).
b Assume the sampling conditions were 30*C and 720 mm barometric pressure.
Exercise 5
50
10/93
-------
TABLE 2
NAME OF TUBE
POLYTEST
METHYL BROMIDE
ETHYL ACETATE
BENZENE
ACETONE
ALCOHOL
HYDROCARBON
CARBON MONOXIDE
HYDRAZINE
FORMIC ACID
READING/INDICATION
What types of chemicals are present in the mixture?
10/93
51
Exercise 5
-------
QUESTIONS
1. Based on your test results, how long should you wait between pump strokes for the MSA?
2. What factors could affect the detector tube results?
3. Does the CO2 concentration exceed the PEL? REL? TLV? IDLH?
4. Does the isopropyl alcohol concentration exceed the PEL? REL? TLV? IDLH?
Exercise 5 52 10/93
-------
EXERCISE #6
Direct-Reading Aerosol Monitors
OBJECTIVE
Participants will learn how to operate the MIE Real-Time Aerosol Monitor Model RAM-1 and the
MIE MINIRAM Personal Monitor Model PDM-3.
DESCRIPTION OF EQUIPMENT
The RAM-1 and the MINIRAM are portable, self-contained aerosol monitors. Their detection
system is based on the detection of near-forward, scattered, near-infrared radiation.
The RAM-1 uses a pump to draw air into the unit to the sensors. It uses an air screen to prevent
contamination of the sensors. The MINIRAM does not require a pump. Air passes through the
sensing volume by convection, circulation, ventilation and personnel motion. The sensors are also
in direct contact with the environment. Thus, there is a chance the sensors may get covered with
dust. The MINIRAM sensors require cleaning on a regular basis.
Both units indicate the aerosol concentration in milligrams per cubic meter (mg/m3). Both use a
digital display. The MINIRAM's displayed reading is updated every 10 seconds. The RAM-1 has
a variable time display.
The RAM-1 has a range of 0.000-200.0 mg/m3. The readout range is selected by the operator. The
MINIRAM normally operates in the 0.00 to 9.99 mg/m3 range. Whenever a 10-second concentration
exceeds 9.99 mg/m3, the MINIRAM automatically switches to the 0.0 to 99.9 mg/m3 range and
remains in that range as long as the measured 10-second concentration exceeds 9.99 mg/m3.
Otherwise the MINIRAM reverts to its lower range display.
The RAM-1 only displays real-time concentrations. A output device can be connected to record
data. The MINIRAM can store data for later output and for TWA calculations. Thus, it can be used
as a direct-reading monitor and a dosimeter.
Both instruments can be powered by internal batteries or an external AC source.
It is important to remember that these instrument only give total or respirable quantities of aerosols.
They do not give the composition of the aerosol. To determine the composition of the aerosol, a
sample must be taken and analyzed. Refer to the Air Sample Collection section of the course
manual.
10/93 53 Exercise 6
-------
MIE MINIRAM PERSONAL MONITOR MODEL PDM-3
Before using the instrument without the charger, charge the MINIRAM for a minimum of 8 hours.
Initial Condition
• Blank display—Indicates that the MINIRAM has not been in the measurement mode
for 48 hours or more, and is in the minimum power off mode.
• "OFF" display—MINIRAM has been in the off mode for less than 48 hours.
• Concentration display that changes or "blinks" once every 10 seconds: the
MINIRAM is in the measurement mode.
Controls (refer to Figure 1)
"MEAS'
"ZERO"
"TIME"
When this button is pressed, the measurement mode will start. Once the MEAS
mode has been entered, this sequence can only be interrupted by pressing OFF.
Pressing ZERO, TWA, SA, TIME, or ID# only affects the display during the time
the keys are pressed.
The readout will first display "GO" (or "CGO" if TIME is also pressed) followed by
the last concentration reading or ".00."
Approximately 36 seconds later, the first new 10-second-averaged concentration
reading is displayed. The reading will be updated and displayed every 10 seconds.
The MINIRAM will now run in the measurement mode for 500 minutes (8 hours and
20 minutes), after which time it will stop, displaying the OFF reading. It will retain
in storage the concentration average and elapsed time information.
If both MEAS and TIME are pressed at the same time (press TIME first and while
depressing it actuate MEAS) the MINIRAM will display "CGO," and will then
operate as above (i.e., pressing MEAS only), except that after the first 8.3-hour run,
it will restart automatically and continue to measure for an indefinite number of
8.3-hour runs, (with the battery charger) until the OFF key is pressed, or until the
batteries are exhausted. Concentration averages and timing information for the last
seven 8.3-hour runs will remain in storage at any give time.
When instrument displays "OFF," pressing this button initiates the ZERO procedure.
During the measurement mode, if TIME is pressed, the display will show the elapsed
time, in minutes, from the start to the last measurement run. The MINIRAM will
automatically return to concentration display after the TIME key is released.
Exercise 6
54
10/93
-------
1.85 -
-4 OVR
~4 ID
•4 BAT
— MIE
^ MINIRAM
AEROSOL
MONITOR
MODEL PDM-3
(CLIP)
"TWA"
"SA"
"PBK"
"OFF"
FIGURE 1. FRONT PANEL OF MINIRAM
During the measurement mode, if the time-weighted average (TWA) is pressed, the
display will indicate the average concentration in milligrams per cubic meter (mg/m3)
up to that instant, from the start of the last run. The value of TWA is updated every
10 seconds. After releasing the TWA key, the MINIRAM display returns to the 10-
second concentration display.
During the measurement mode, pressing SA (Shift-Average) will provide a display
of the aerosol concentration, up to that moment, averaged over an 8-hour shift
period.
With the MINIRAM in the off mode, the stored information can be played back by
pressing PBK (Play Back). Pressing the PBK key for more than 1 second will cause
stored data to be automatically played back through the MINIRAM display: First,
the identification number is displayed with the ID indicator bar on; next the shift or
run number (i.e., 7 through 1, starting with the last run) is shown (with the OVR
indicator bar on as identification); followed by the sampling time in minutes, for that
run; followed by the off-time between the last and next run (in tens of minutes:;
finally, the average in mg/m3. This sequence is repeated seven times. An average
reading of 9.99 indicates that a significant overload condition occurred during that
run. The total time required for the complete automatic playback on the MINIRAM
display is approximately 70 seconds.
When this key is pressed, the MINIRAM will discontinue whatever mode is
underway displaying "GCA" followed by the display segments check ("8.8.8=") and
finally "OFF." The MINIRAM will then remain in this reduced power condition
(displaying "OFF").
10/93
55
Exercise 6
-------
Display
During the measurement mode, the display indicates the present concentration in mg/m3. If one of
the function buttons is pushed, the information indicated in CONTROLS is displayed. If a bar
appears in the display, the bar's location indicates one or more of the following:
"OVR" The concentration exceeds the range of the instrument or there is an overload due to
reflected line (e.g., sunlight).
"ID" This indicates that the ID number is being displayed and not a concentration.
"BAT" This indicates a low battery.
Zero Procedure
1. Zeroing must be performed in a clean-air environment. This can be done by using a clean
room or clean-bench, flowing clean air through the sensing chamber, or using an air-
conditioned office (without smokers).
2. Press OFF and wait until the display indicates "OFF."
3. Depress the ZERO button. Wait until the display again indicates "OFF." The average of
four consecutive 10-second zero level measurements will then be stored by the MINIRAM
as the new ZERO reference value. The ZERO reference value will be subtracted from
subsequent readings. When operating the MINIRAM is high particle concentration
environments (>5 mg/m3) the zero value should be updated approximately every 8 hours.
At aerosol concentrations below approximately 1 mg/m3 this update may only be required
once a week.
Start Measurement Cycle
4. Place the MINIRAM in the area to be monitored. The instrument should be placed vertically
(i.e., display/control panel facing upwards) by clipping it to a belt, shoulder strap, etc.
5. If the MINIRAM shows a blanked display, press OFF and wait until the display reads "OFF"
(approximately 5 seconds after pressing OFF) before pressing MEAS to initiate measurement
cycle.
6. If the MINIRAM shows "OFF," press MEAS directly to initiate measurement cycle (there
is no need to press OFF first, in this case).
7. Press MEAS.
8. Observe the readings for 1 minute to verify that the levels change every 10 seconds and that
the OVR bar is not displayed.
Exercise 6 56 10/93
-------
9. Avoid objects being placed in the sensing chamber. Also avoid direct sunlight scattering in
the sensing chamber.
10. At the end of the sampling period, press "TIME." Record the sample duration in Table 1.
11. Press the TWA button. Record the reading in Table 1.
12. Press OFF.
TABLE 1
INFORMATION
INSTRUMENT SERIAL #
START TIME
TWA
SHIFT AVERAGE (SA)
OFF TIME
RESULTS
MIE REAL-TIME AEROSOL MONITOR MODEL RAM-1
In the following procedure, the numbered buttons, displays, and switches refer to the illustration of
the RAM-1 in Figures 2 and 3.
Startup
1. Lift up protective cover of control panel.
2. Place selector switch (1) in battery (BATT) position.
3. Place inlet valve (2) in CLEAR position (horizontal).
4. Replace sealed cap on inlet valve with the restrictor orifice.
5. Switch instrument on (3) and check battery voltage. The digital readout (4) should indicate
between 6.0 and 6.6 volts. If not, inform the instructor. The reading should be identified
by a display of VDC (volts DC). Low battery voltage is indicated by a flashing "VDC" on
the right-hand side of the display, whenever the selector switch is not in the BAT position.
10/93 57 Exercise 6
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Zeroing
6. Check that the inlet valve is in the CLEAR position (horizontal). Place the selector switch
in the 0-200 position. The letter "m" should appear to the right of the display reading,
indicating that the instrument is set to read concentration measurements.
7. Place the time constant switch (5) in the 2-second position.
8. Allow 1 minute for instrument to stabilize (warm-up). IMPORTANT!
9. If necessary, lift the cover over the ZERO control (6) and adjust the control until a reading
of 00.0 is obtained.
10. Switch the selector to the 0-20 position and repeat step #9.
11. Switch the selector to the 0-2 position and repeat step #9. Readings may fluctuate. Try to
obtain an average reading of 0±0.005.
Secondary Calibration
12. Keep inlet valve in its CLEAR position.
13. Set the range selector to the 0-20 position.
14. Unlock the hinged flow chamber cover and place in the horizontal position.
2,
SAMPLE
«VDC CHARGE
CAL
Sf~»,
'
ZERO \
RANGEV. POWER
8 6
s^r
'
FIGURE 2. RAM-1 TOP VIEW
Exercise 6
58
10/93
-------
Filters
Desiccant
12 11
FIGURE 3. RAM-1 SIDE VIEW
15. Push the reference scatterer knob (REF SCAT) (9) inward until a positive stop is detected.
The pump will automatically shut off. The letter "K" should be flashing in the upper right
side of the display. Allow the reading to stabilize for 30 seconds.
16. See if the instrument reading corresponds with the factory calibration label (10) by the (REF
SCAT).
17. If the indicated readings differ by more than 5%, adjust the CAL control (7) as required.
The CAL control has a lock that must be disengaged before attempting to turn the knob.
Allow to stabilize and repeat if required. Relock the CAL control.
18. Pull the REF SCAT back out.
19. Close the flow chamber cover and tighten thumb-screws.
Measurement Procedures
20. Switch RAM on.
21. Select measurement range (usually the 0-20 position).
22. Select desired time constant (usually 2 seconds).
23. Place inlet valve in SAMPLE position (vertical downwards).
24. Check the flow meters. The TOTAL (11) should read about 2 and the PURGE (12) should
read about 0.2 (or 10% of TOTAL). Adjust the total flow rate with the flow adjust screw
10/93
59
Exercise 6
-------
(8). Adjust the purge flow with the black valve on the rotameter. If the rotameter is pegged,
check that the inlet valve is in the SAMPLE position.
25. Measure the aerosol concentrations in the areas designated by the instructor.
26. If the aerosol concentration exceeds the maximum selected range, the RAM-1 will indicate
1 with all zeros blanked out. If this occurs, change the range selection to higher ranges as
needed.
27. Check and update zero periodically.
28. BEFORE SHUTTING OFF THE RAM-1, CLOSE THE INLET VALVE (CLEAR
POSITION) AND OPERATE FOR 3 MINUTES TO ALLOW PURGING OF THE
DUSTS INSIDE THE OPTICAL CAVITY.
29. When sampling and purging is complete, turn the instrument OFF.
Exercise 6 60 10/93
-------
QUESTIONS
1. Discuss the advantages and disadvantages of these instruments.
2. Analysis of the site soil or analysis of a filter sample shows the soil composition to be 5%
lead. You obtain a reading of 1.35 mg/m3 with the RAM-1. Determine (approximately) the
airborne lead concentration based on your reading.
3. The action level for lead at your site has been determined to be 1.5 /*g/m3. The soil on the
site is 5% lead, a) What instrument reading would be equivalent to your lead action level?
b) What reading would you be concerned about if your action level was 50 jig/m3?
a)
b)
10/93
61
Exercise 6
-------
EXERCISE #1
Gas Chromatography - PID
OBJECTIVE
The student will learn the basic operation of the Photovac 10S50 portable gas chromatograph and
analyze several air samples.
PROCEDURE
The instructor will describe and illustrate the different parts of the Photovac 10S50 and their
functions. Since the 10S50 needs a certain amount of warm-up time, the student will not be able to
go through start-up of the instrument. After the introduction, students will run a calibration standard
and an unknown sample. Students will also collect an air bag sample and analyze it.
OPERATING INSTRUCTIONS FOR THE PHOTOVAC 10S50 (CAPILLARY COLUMN
OPERATION)
Preparation for Use
Refer to the Photovac 10S50 instrument panel and Figure 1."
Recharge the Carrier Gas
1. Connect the fill line for the Photovac 10S50 to a cylinder of "Ultra-Zero Air" (contents <0.1
ppm hydrocarbon).
2. Attach the "Quick-Connect" from the fill line to the REFILL receptacle on the upper right-
hand corner of the Photovac 10S50.
3. Turn on the cylinder and rotate the valve for the fill line so that the pointed end points
toward the cylinder. Be sure not to stand directly in front of the regulator.
4. The reservoir in the instrument will be filled to the maximum pressure of the supply cylinder.
The pressure is indicated on the CONTENTS gauge on the upper left of the instrument panel.
(The maximum pressure at which the instrument can be filled is 1750 psi.) The delivery
pressure is indicated on the DELIVERY gauge. This pressure should be 40 psi. When the
reservoir is filled, the excess air will be expelled at the fritted outlet on the supply cylinder
regulator. This will be indicated by a "hissing" sound. Turn off the supply cylinder valve
and then turn off the valve on the fill line.
5. Disconnect the fill line.
10/93 63 Exercise 7
-------
•o
QJ
rs
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j_ W
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5 £
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cc
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1
-------
Set the Carrier Gas Flow Rate
6. The pieces of tubing to the flow meter are attached to the ports on the instrument panel.
7. Attach the line on the left side of the meter to the DETECTOR OUT port.
8. Attach the line on the right side of the meter to the needle valve marked AUX OUT.
9. Connections should be secured with a 7/16 inch open-ended wrench (1/4 turn past tight).
10. Adjust the flow rates on the meter.
a. If the instrument is being set up to stabilize overnight, set the DETECTOR OUT
FLOW using the red FLOW adjustment knob on the left side of the panel to 5
ml/min. Note: Turn knob clockwise to decrease the flow or counterclockwise to
increase the flow. Set AUX OUT flow using the needle valve to 0 ml/min. Allow
to stabilize overnight.
b. If the instrument is being set up for analysis, set the DETECTOR OUT flow using
the red FLOW adjustment knob to 10 ml/min. Set AUX OUT flow using the needle
valve to 10 ml/min.
Activate the Power Source
11. When the instrument is ready for use, attach the power cord for the instrument to the 3-prong
socket in the upper left-hand corner of the instrument. The cord is then plugged into an AC
outlet.
12. Press the ON key. The instrument will respond with "LAMP NOT READY, PLEASE
WAIT."
13. Wait until the display reads "READY ENTER COMMAND."
Set Instrument Parameters
14. Locate the LIBRARY block and press the USE key. The instrument will respond with
"LIBRARY IN USE?" There are four libraries numbered 1 to 4. Library #1 is the default.
We will use #1 for this exercise. Press the 1 key and then the ENTER key.
15. The instrument will prompt for "DAY" (1-31). Press the appropriate value for the day of
the month and then press the ENTER key.
10/93 65 Exercise 7
-------
16. The following information is entered in the same manner:
a. MONTH (1-12), then press ENTER
b. YEAR (e.g., 1993), then press ENTER
c. HOUR (0-23), then press ENTER
d. MINUTE (0-59), then press ENTER.
17. The instrument will read: "READY ENTER COMMAND."
Obtain a Status Report
18. Locate the STATUS block and press the TEST key. The instrument will respond with
"FUNCTION, USE < >, STATUS REPORT." Respond by pressing the ENTER key.
19. The instrument will print a status report containing the following information:
a. Current field date and time.
b. Field: The # represents the detector field in volts/10.
c. Power: The # indicates the current lamp consumption at mA/10.
d. EVENT settings show the ON and OFF times of the 10S50 sample pump and
solenoid valves. The instructors will have set the following EVENT values:
SAMPLE
CAL
EVENT #3
EVENT #4
EVENT #5
EVENT #6
EVENT #7
EVENT #8
(EVENT #1)
(EVENT #2)
0
0
10
0
13
0
0
0
10
0
60*
10
60*
0
0
0
* Some units may have a longer time (e.g., 80) instead.
20. Allow the instrument to stabilize for approximately 45 minutes. The instrument has been
stabilizing prior to the exercise so we may continue.
Select the Analytical Parameters
21. Locate the SETUP block on the instrument panel.
Exercise 7 66 10/93
-------
22. Press the GAIN key. The gain controls the amplification from the detector. The default
value is "2" For higher values, press the UP ARROW key until the desire value appears.
For this exercise, choose a gain setting of "5" and then press ENTER.
23. Press the CHART key. The instrument will respond with "CHART ON" or some other
readout. "CHART ON" means the chromatogram will be displayed along with identification
information and some instrument settings (e.g., GAIN). "CHART OFF" means that the
chromatogram will not be displayed, but identification information and some instrument
settings will be displayed. "CHART ON WITH BASELINE" prints out the same information
as "CHART ON," but also shows the baseline the instrument uses to calculate peak area.
"CHART ON WITH SETUP" prints out the same information as "CHART ON WITH
BASELINE" but also includes the setup information (e.g., SENS, WINDO). Use the UP
ARROW or DOWN ARROW key until "CHART ON WITH SETUP" is displayed. Press
ENTER. The next display is the chart speed. The default is 0.1 cm/min. Press the UP
ARROW key until 0.5 appears. Press ENTER.
24. Press the SENS key. The key controls the instrument integrator. The following settings
specify the minimum response that will be recognized as a peak on the chromatogram.
SLOPE UP; Use the arrow keys to display 18 mv. Then ENTER.
SLOPE DOWN; Use the arrow keys to display 16 mv. Then ENTER.
PW (Peak Width) at 4 minutes; Use the arrow keys to display 6 (sec). Then
ENTER.
25. Press the WINDO key. This key adjusts the lOSSO's tolerance to retention time drift. A
peak, must be within a specified percentage of a stored retention to be identified as that
chemical by the instrument. Choose a value of "10" (i.e., 10%) and press ENTER.
26. Press the AREA key. This key sets a peak size threshold. All peaks smaller than the AREA
setting are deleted from the "PEAK INFORMATION" listing at the end of the analysis.
(However, these peaks will still be numbered on the chromatogram.) Set the minimum area
at "50" and ENTER.
27. Locate the PROGRAM block and press the CYCLE key. The instrument will prompt for
the following information:
a. "TIMER DELAY." This setting determines the delay in time from when the
START/STOP key is pressed and when the instrument will start looking for peaks.
Choose "10" seconds and ENTER.
b. "ANALYSIS TIME." The duration of the analysis is dependent upon the types of
compounds that are being considered for analysis. Select an analysis time of 600
seconds for this exercise. Press ENTER.
c. "CYCLE TIME." These times refer to the mode for continuous monitoring. This
mode will not be used in this exercise. Choose "0" min and ENTER. The
instrument will respond with "CYCLING DISABLED, COUNTERS RESET."
10/93 67 Exercise 7
-------
Establish a Baseline for the Chromatogram
28. The baseline will be established by analyzing a bag of ultrazero air (a BLANK sample).
Connect the "zero" bag to the PROBE IN CONNECTION. Open the bag. To initiate the
analysis, locate the ANALYSIS block and press the START/STOP key. The instrument will
respond: "PROBE IN?" Press ENTER.
29. As soon as the ENTER key is pressed, the pump should start and run 10 seconds. If the
pump does not start, inform the instructor.
30. Allow the chromatogram to be generated. Examine the baseline for significant drift or
extraneous peaks. The baseline should be flat and smgoth. Repeat this procedure until a
stable (zero slope) baseline is obtained or until the instructor informs you to stop.
Analyze the Standard Gas Bag
31. For this exercise, we will use the chemicals in Library 1 as the standard. The "standard gas
bag" will be used to check retention times and allow you to see a chromatogram.
32. Connect the "sample bag" bag to the PROBE IN CONNECTION. Open the bag. To initiate
the analysis, locate the ANALYSIS block and press the START/STOP key. The instrument
will respond: "PROBE IN?" Press ENTER.
33. Allow the chromatogram to be generated. This will take 600 seconds (the analysis time we
selected).
34. At the end of the chromatogram, the printout will print the peak numbers that exceed the area
setting, the identity of the peaks (if they match the retention times in the library) and the
concentration of identified peaks. Consult the instructor for the expected results. If the
peaks are not properly identified, a update adjustment or calibration run will be necessary.
See Updating the Library and Creating a Library before analyzing any samples.
Updating the Library
35. If library does not recognize all of chemicals in the standard, the library should be updated.
36. Select a peak (one that you can identify) as a reference point. Press the CAL key. The
instrument will request a plotter peak number. Enter the peak number you have selected.
Press ENTER.
37. The instrument will request an ID number. Look at the previous printout of the library.
Enter the number for the chemical that matches the peak. Press ENTER.
38. The instrument will request a concentration. Enter the concentration of the compound
corresponding to the plotter peak used. Press ENTER.
Exercise 7 68 10/93
-------
39. The plotter will print out a listing of the peaks from the recent analysis and hopefully identify
the peaks using retention times and peak areas adjusted by the reference peak.
Creating a Library
40. Connect the "sample bag" bag to the PROBE IN CONNECTION. Open the bag. To initiate
the analysis, locate the ANALYSIS block and press the START/STOP key. The instrument
will respond: "PROBE IN?" Press ENTER.
41. Allow the chromatogram to be generated.
42. The information from the chromatogram must be stored in the library IMMEDIATELY
FOLLOWING completion of the analysis. IF ANY OTHER KEY IS PRESSED BEFORE
STEP #43, THE STANDARD CHROMATOGRAM WILL NEED TO BE GENERATED
AGAIN TO UTILIZE ITS INFORMATION.
43. Locate the LIBRARY block and press the STORE key. The instrument will prompt for:
a. PLOTTER PEAK #: Select the number of the first peak of interest on the
chromatogram and press ENTER.
b. CHEMICAL NAME: Select the name of the compound using the alpha-numeric
keys on the key pad. After the name is complete press ENTER. (To change to
numbers, press the CAL (NUM) key. This key must also be pressed again to return
to letters.)
c. CONCENTRATION (in ppm): Select the actual concentration of the compound in
ppm. Press ENTER.
d. LIMIT VALUE: The limit value is the concentration, which if exceeded, causes the
plotter to print the concentration value in red instead of green. This "flags" the
compound. Press ENTER. This will instruct the instrument to use 0 as the limit, so
all concentrations will be in red.
e. This procedure is repeated for subsequent compounds in the chromatogram by
pressing the STORE key and following steps a through d.
f. To check the contents of the library, press CAL. The instrument prompts with
"PLOTTER PEAK #?" ENTER TO RELIST. Press ENTER. The plotter will print
out the added compounds and their concentrations.
Note: DO NOT enter a value here or the instrument will prompt for recalibration.
10/93 69 Exercise 7
-------
Editing the Library
44. A compound can be added to the library after any analysis. A compound can be added to
the library even if it is already in the library. However, the new entry will not replace the
old entry. There will be two listings for the compound.
45. To remove a compound from the library, first press EDIT.
46. The instrument will prompt with "ID NUMBER." Enter the ID number for the compound
in the library. The instrument will list the name of the compound.
47. Press CLEAR, then press ENTER. The instrument will respond with "COMPOUND
REMOVED FROM LIBRARY."
48. Repeat for any additional compounds.
Analyse the Samples
49. Using steps 31 through 34, analyze the unknown samples provided.
50. IMPORTANT! DO NOT USE ANY GAS BAGS, other than those provided by the
instructors, WITHOUT THE PERMISSION OF THE INSTRUCTORS. High concentrations
can contaminate the column.
Exercise Shutdown
51. When sample analysis is complete, do not turn the instrument off.
Shutdown (Overnight)
52. Generate a chromatogram of the baseline to ensure that there are no residual materials in the
column.
53. Locate the POWER block and press the OFF key. The instrument will respond with
"ENTER=OFF." Press ENTER.
54. Adjust the flow rate for the DETECTOR OUT to 5 ml/min. Make sure the air supply is
adequate for overnight operation.
Shutdown (Long Term)
55. Follow the same steps as in Shutdown (Overnight).
56. Disconnect the power cord from the AC source.
57. Before shipping, drain the carrier gas supply reservoir.
Exercise 7 70 10/93
-------
EXERCISE #8
Sampling Pumps and Collection Media
OBJECTIVE
Participants will assemble a variety of sampling trains and calibrate them using an electronic
bubble meter. They will also check the pump's flow compensator. The students will review
sample results and evaluate exposure levels.
PROCEDURE
The class will be divided into teams. Each team will be given a Gilian® HFS 113UT air
sampling pump.
The instructor will explain the operation of the Gilian* HFS 113UT sampling pump.
The students will calibrate the Gilian* sampling pump using different media and an electronic
bubble meter.
Demonstration: Calibration of Gilian* pump with filter media using a bubble-meter
(page 82).
Station 1: Calibration of Gilian* pump with filter media and with sorbent tube
media using an electronic bubble-meter (page 85).
Station 2: Check flow compensator of Gilian* pump using Gilian* Calibrator
Pack (page 92).
Note: The procedures shown here apply only to this specific sampling pump. The actual
procedures for other pumps may vary. Consult the manufacturer's instructions for
the pump you use in the field.
After calibrating their sampling pump, the students will look at sampling results and calculate
concentration levels (page 94).
10/93 71 Exercise 8
-------
OPERATION AND CONTROLS OF GILIAN® HFS 113UT SAMPLER
The Gilian® HFS 113UT sampler is a lightweight, battery-powered air sampling pump. It has a
high flow range—0.5-3.5 liters per minute (1pm) and a low flow range—1-500 cubic centimeters
per minute (cc/min). It has a built-in timer to shut off the pump after a preset time. The pump
is equipped with a flow compensation control that provides for constant air flow from the pump
at any preset flow within its performance limits.
The following is a brief description of the controls for operating the pump.
1. ON - OFF Switch. This turns pump on and off.
2. PRESS TO TEST Button. When the pump is on, pressing this button gives battery power
indication and also gives an elapsed time indication in TIME MIN window. If the pump
has stopped because of end of time or fault, pressing this button before turning the pump
off gives the pump run time.
3. PROGRAMMABLE TIMER. Allows operator to set sample time from 10 minutes to 990
minutes in ten minute increments. Note: The pump will not start if the timer is set at
00. When setting the timer, the dials should be turned clockwise past the zero point
several times.
4. BAT CK - Battery Check. Turn on pump and press the test button. If the BAT CK
illuminates, then the battery is fully charged.
5. FAULT. This light illuminates and the pump shuts down, if the pump is unable to
maintain the preset flow rate.
6. TIME OUT. This illuminates when the pump stops at the programmed time.
7. FLOW ADJUST. Turning clockwise increases flowing; turning counterclockwise
decreases flow.
8. PUMP INLET. Inlet to pump. Point where tubing and sampling media are connected.
9. DISCHARGE AIR CAP SCREW. Removing mis screw provides access to discharge
port. Inserting adapter allows pump to be used to fill gas bag.
10. REGULATOR SHUTOFF CAP SCREW. Removing screw provides access to (he
regulator shutoff valve. The valve is used to switch the pump from high to low flow.
11. FLOW METER. Rotameter used to show flow. Read center of flow meter ball.
Reading is ±20% of true flow.
Exercise 8 72 10/93
-------
DEMONSTRATION: CALIBRATING GILIAN® PUMP
USING A BUBBLE METER
During this demonstration, the Gilian® pump will be calibrated for lead paniculate sampling.
The NIOSH analytical method for lead sampling (Method 7802) uses a 0.8-p cellulose ester
membrane filter. The appropriate filter is provided with the calibration setup. The
recommended flow rate is between 1 and 4 liters per minute. For this exercise, calibrate the
pump to about 2 liters per minute (between 1.8 and 2.2 is okay). The important thing is to
know the actual flow rate of your pump. Step 4 explains how to convert the pump to the high
flow range.
BUBBLE METER PREPARATION
During this step, the Gilian® pump will be calibrated using an inverted buret and soap bubbles
(bubble meter). This method is considered a primary calibration method because the buret
volume and the stopwatch time can be traced to an original standard.
1. Check the calibration set-up (Figure 1). It should contain all the parts shown in the
figure. If not, inform the instructor.
2. Wet the buret by pouring a small amount of soap solution into it, and tilting it up and
down while rotating. Seal the outlet end to prevent soap from getting into the tubing.
3. Reassemble the calibration setup.
PUMP PREPARATION
4. Remove the Pump Regulator Shutoff Protective Cap. Turn the exposed screw clockwise
until closed - DO NOT OVERTIGHTEN. Replace the protective cap.
5. Using the small screwdriver provided, set the programmable timer to 240 minutes. Turn
each dial clockwise past zero several times before setting the time.
6. Turn the pump on.
7. Press the test button. The BAT CK light should illuminate or flicker.
10/93 73 Exercise 8
-------
Inverted
burst
250
Filter
cassette
Soap bubble trap
Pump
Beaker
Soap solution
FIGURE 1. BUBBLE METER CALIBRATION SETUP
8. Connect the tubing and filter to the pump. The filter pad should be nearest to the pump.
Connect the filter to the tubing attached to the bubble meter.
9. Start a bubble in the buret by briefly touching the surface of the soap solution to the open
end of the buret. When the bubble passes the "0" mark, start the stopwatch. Stop the
stopwatch when the bubble passes the "250" mark.
10. Flow rate is calculated using the following formula:
FLOW RATE (L/min)
VOLUME TRAVELED (ml)
60 sec/min
TIME (sec) BUBBLE TRAVELED 1000 mllL
11. Use Data Sheet 1 to record your calibration data.
Exercise 8
74
10/93
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DATA SHEET 1
1. PUMP MFG. AND MODEL:
2. PUMP IDENTIFICATION #:
3. BATTERY CHECK YES NO
4. LOCATION/TEMP & BAROMETRIC PRESSURE:
5. CALIBRATION METHOD:
6. FLOW RATE CALCULATIONS
FLOW RATE 0/min)- VOLUME ^4KgI£D (TO/) x 60 secondslminute
TIME (seconds) 1000 mt/L
VOLUME TRAVELED TIME FLOW RATE AVERAGE
(Continue calibration until three consecutive flow rates are within ± 5% of the average.)
7. FLOW RATE:
8. ROTAMETER SETTING:
9. SIGNATURE:
10. DATE/TIME:
10/93 75 Exercise 8
-------
STATION 1: CALIBRATING THE GILIAN® PUMP USING
AN ELECTRONIC BUBBLE METER
The Gilibrator™ is an example of an electronic bubble meter. It is a primary calibration method.
A fixed volume is located in the center tube of the flow cell. A quartz-controlled timer is used to
measure the travel time for a bubble between two sensors. A microprocessor calculates the
volume per unit time. The flow rate is displayed in cc/min for this model.
The control unit will display the actual flow for each sample and will accumulate and average
each successive reading.
AVERAGE - To display average and number of samples, depress and hold the
AVERAGE BUTTON. Releasing the button will display the last flow reading. Pressing
the button again and the number of reading made will be displayed. Release and the
display returns to the last flow reading.
DELETE - To delete obvious false readings, push the DELETE BUTTON. This will
delete the false information from the average and reset the average and sample number
back to the previous reading.
RESET - To reinitiate the sequence, hit the RESET BUTTON. This will zero out all
sample and average registers within the Control Unit. The Reset Button is also used if a
malformed bubble is generated and has not been subtracted from the average by use of
the DELETE Function.
GILIBRATOR™ PREPARATION
1. Remove the storage tubing between the air inlet and air outlet of the Gilibrator™. Pour a
small amount of soap through the BOTTOM AIR INLET of the Gilibrator™ to thoroughly
cover the bottom of the flow cell. Skip this step if already done.
2. Connect a pump to the UPPER AIR OUTLET using the piece of tubing provided.
3. Turn the regulator shutoff valve on the Gilian® pump (the screw under the brass cap on
•i top of the pump) fully clockwise. DO NOT OVERTIGHTEN. Turn on the pump.
Initiate soap film up the flow tube by rapidly pressing the CALIBRATOR BUTTON
down and releasing. Repeat this procedure until a bubble travels the length of the tube
without breaking.
4. After the Flow Tube walls have been "primed" (Step 3), turn on the Power switch of the
Control Unit. Wait approximately 10 seconds while the system runs through its check
sequence. The RUN LED will light at this time as well and a LO Battery indication and
a series of five dashes will be displayed on the LCD Readout. Do not operate the
Gilibrator until the RUN LED signal extinguishes. Ready operation is indicated by a
series of 4 dashes.
5. Calibrate the pump using the following steps.
Exercise 8 76 10/93
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Exercise 8
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HIGH-FLOW CALIBRATION (1 to 4 liters/min)
6. Insert a filter cassette and tubing between the pump and the tubing attached to the
calibrator.
7. Turn on the pump.
8. Depress the BUBBLE INITIATE BUTTON and hold to initiate 1 bubble up the Flow
Tube. Release the button to initiate a second bubble up the flow tube. At low flow rates,
the button can be depressed and released quickly for a single bubble.
9. After a bubble completes passage up the FLOW TUBE, a flow reading will appear on the
LCD display.
10. Adjust the flow rate (pump adjustment) and repeat Steps 8 and 9 until you have a flow
rate of about 2 liter/min.
11. RESET the calibrator.
12. Repeat Steps 8 and 9 until you have three consecutive readings that are within 5% of their
average.
13. If the first set of 3 readings are not within the 5% allowable range, press the RESET
Button. Then repeat step 15 for 3 more readings. The Reset Button is used because the
Gilibrator™ averages all readings and not just the last 3. If the first reading was outside
the 5% limits, you wouldn't know till readings 2 and 3 were made. Readings 2, 3, and 4
may be within the limits, but you would not be able to check because reading 1 would
still be in the average.
14. If a bubble breaks before completing the timing sequence, timing will continue until
another bubble is generated to trip the second sensor. This will cause an erroneous
reading and should be subtracted from the average by hitting the Delete Button.
15. Record each run, the average, and other pertinent information on Data Sheet 2
LOW-FLOW CALIBRATION (20-500 cc/min)
16. Connect the pump to the Gilibrator™ with a piece of tubing.
17. Turn on the pump.
18. Using the steps above, adjust the pump to about 1 liter/min.
19. Open the regulator shutoff valve (located under the brass cap on top of the pump) by
turning it counterclockwise at least 5 turns.
Exercise 8 78 10/93
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20. Put a carbon tube in the sorbent tube holder. Connect the inlet side of the holder to the
upper outlet of the calibrator (Figure 2). Connect the outlet side of the holder to the
pump inlet.
21. Depress the Bubble Initiate Button to initiate a bubble up the Flow Tube. After the
bubble completes passage up the Flow Tube, a flow reading will appear on the LCD
display.
22. Remove the knurled cap from the end of the tube holder. Repeat Step 21 and adjust the
variable flow controller screw to get the desired flow rate. For this exercise, try to
obtain about 50 cc/min.
23. RESET the calibrator after each run if not at the desired flowrate. Reset after each flow
adjustment. Do three runs at the desired flow rate. Record your results on Data Sheet 3.
SHUTDOWN
24. Turn off the pump.
25. Turn off the calibrator.
26. Remove the air sampler from the Gilibrator™. Replace the Storage Tubing between the
upper and lower cell chambers.
27. Disconnect the pump from the tube holder.
28. Replace the cap on the tube holder.
10/93 79 Exercise 8
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DATA SHEET 2
1. PUMP MFG. AND MODEL:
PUMP IDENTIFICATION #:
BATTERY CHECK PASS FAIL
2. CALIBRATOR MFG. AND MODEL:
CALIBRATOR IDENTIFICATION #:
3. COLLECTION MEDIA:
4. LOCATION/TEMP & BAROMETRIC PRESSURE:
5. FLOW RATES: (Continue calibration until three consecutive flow rates are within ±5%
of average.)
FLOW RATE AVERAGE FLOW RATE AVERAGE
6. ROTAMETER SETTING:
7. FLOW RATE:
8. SIGNATURE:
9. DATE/TIME:
ExerciseS 80 10/93
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DATA SHEET 3
1. PUMP MFG. AND MODEL:
PUMP IDENTIFICATION #:
BATTERY CHECK
PASS
2. CALIBRATOR MFG. AND MODEL:
CALIBRATOR IDENTIFICATION #:
3. COLLECTION MEDIA:
FAIL
4. LOCATION/TEMP & BAROMETRIC PRESSURE:
5. FLOW RATES: (Continue calibration until three consecutive flow rates are within ±5%
of average.)
FLOW RATE
AVERAGE
FLOW RATE
AVERAGE
6. FLOW RATE:
7. SIGNATURE:
8. DATE/TIME:
10/93
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Exercise 8
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STATION 2: CHECKING GILIAN® PUMP WITH CALIBRATOR PACK
The Gilian® Calibrator Pack has precision rotameters that can be used to calibrate a pump. A
rotameter is considered a secondary calibration standard since it needs to be calibrated or checked
with a primary calibration method periodically. The pack also has a magnehelic to produce a
pressure drop along the flow of a pump. This, in combination with the rotameters, can be used
to check the constant flow compensator on the Gilian* pump.
In this step, the precision rotameter will be used to check the constant flow compensator.
COMPENSATOR CHECK
1. Remove the Regulator Shutoff Protective Cap on the pump. Turn the exposed screw
clockwise until closed - DO NOT OVERTIGHTEN. Replace the protective cap.
2. On the Calibrator pack, move the BYPASS/CAL switch to the BYPASS position.
3. Move the CAL SELECT (V2) switch to the upward position (3 liters/minute).
4. Connect the pump to the PUMP SUCTION (Bl) outlet on the calibrator pack.
5. Turn on the pump.
6. Adjust (on the pump) the flow rate so that precision rotameter on the calibrator (not the
pump rotameter) reads "3.0" (3 liters/min or 3000 cc/min). The flow rate is read at the
center of the rotameter ball.
7. Move the CAL/BYPASS switch to the CAL position.
8. Turn the V3 knob until the magnehelic dial reads 10 inches of back pressure.
9. Read the flow rate on the rotameter. If the difference in flow rates with and without back
pressure is more than ±5% (i.e., if the flow rate is not between 2850 and 3150), the
pump needs adjustment. Consult the instructor.
10. Move the BYPASS/CAL switch to the BYPASS position.
11. Move the CAL SELECT (V2) switch to the downward position (1 liter/minute).
12. Adjust the flow rate to "1.0" (1 liter/min or 1000 cc/min) - reading the precision
rotameter on the calibrator.
13. Move the BYPASS/CAL switch to the CAL position.
14. Turn the V4 knob until the magnehelic dial reads 20 inches of back pressure.
Exercise 8 82 10/93
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IS. Read the flow rate on the rotameter. If the difference in flow rates with and without the
back pressure is more than ±5% (i.e., if the flow rate is not between 950 and 1050), the
pump needs adjustment. Consult the instructor.
SHUTDOWN
16. When completed with the compensator check, turn off the pump and disconnect the pump
from the pack.
10/93 83 Exercise 8
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QUESTIONS AND CALCULATIONS
1. Calculate the concentrations in the sampled atmospheres based on the following
information.
Units: 1000 liter = 1 m3
1000 ml = 1000 cc = 1 liter
1 mg = 1000 micrograms
(A) Lead samples. Pump flow rate = 2.0 liters per minute.
SAMPLE DURATION
4HR
2HR
2HR
LAB ANALYSIS
0.041 mg
0.029 mg
0.008 mg
AVERAGE
CONCENTRATION
To calculate the Average Concentration (for each sample):
r _ mg chemical
\* ~
sample volume (m3)
where:
sample volume (m3) = pump flow rate (liters/minute) x sample time (minutes) x —
1000 liters
To calculate an 8-hour TWA:
C.T, + CJ". + . . C T.
8 hour TWA
8 hours
where T is sample time in hours. Minutes can be used for T if 480 minutes is used
instead of 8 hours in equation.
Exercise 8 84 10/93
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(B) Solvent vapor sampling. Flow rate = 50.0 cc/min.
SAMPLE
TIME
1 HR
2HR
1 HR
15 MIN
15 MIN
15 MIN
30 MIN
15 MIN
30 MIN
2HR
CONCENTRATION (ppm)
TOLUENE
10
32
21
175
140
100
93
85
54
10
XYLENE
5
11
8
70
50
67
40
30
10
ND
ACETONE
ND
ND
100
300
1000
820
1000
50
45
30
Calculate an 8-hour TWA exposure for the three chemicals.
Calculate an 8-hour TWA exposure for the mixture. Is this calculation valid?
10/93
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Exercise 8
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(C) Do any of the concentrations in (A) and (B) exceed an exposure limit?
2. Calibration of a pump prior to sampling gave a flow rate of 2.0 liters/minute. Calibration
after sampling gives a flow rate of 1.8 liters/minute. What do you do?
Exercises 86 10/93
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EXERCISE #9
Field Exercise
OBJECTIVE
Using the instruments and information provided, participants will:
1. Perform a survey of the zones on the "hazardous waste site."
2. Characterize the "hazards" present at each "zone" on the site.
3. Identify as completely as possible the materials present on the site.
4. Quantify the airborne concentrations in each "zone" and evaluate the risk associated with
these concentrations.
PROCEDURE
The class will be divided into teams. Each team will select a leader/spokesperson. Each team will
receive the same equipment. The equipment available is the same equipment used earlier in the
week. Before each entry, the team must submit plan of action for that entry to an instructor.
The "site" simulates a much larger site. It is divided into six zones. A description of each zone is
on the next page. A "map" of the site also follows. Treat the readings obtained with the instruments
taken inside the containers as representing the average airborne concentrations in the "zone."
10/93 87 Exercise 9
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DESCRIPTION OF EXERCISE AREA
ZONE 1:
100 to 200 drums. Some with "FLAMMABLE" labels.
ZONE 2:
About 100 drums. Some with "CORROSIVE" labels.
ZONE 3:
Box trailer containing drums. Records indicate that the following chemicals were in the load. (Note:
This zone can be treated as a transportation incident separate from the site.)
Acetone
Methyl ethyl ketone
Methyl isobutyl ketone
Ethyl alcohol
Butyl alcohol
Toluene
Benzene
Xylenes
1,1,1 -Trichloroethane
Trichloroethylene
Tetrachloroethylene
Readings taken in the drum represent readings at the trailer.
ZONE 4:
About 50 drums with "Waste Cleaner" labels.
ZONE 5:
Opening to underground vault. The vault could contain many drums. Readings inside container are
equivalent to readings taken inside vault (using extended probes).
ZONE 6:
50 to 100 drums. Some with hand-painted labels reading "Paint Waste."
Exercise 9 88 10/93
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Exercise 9
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