ASTM E800-20

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E800 − 20 An American National Standard
Standard Guide for
Measurement of Gases Present or Generated During Fires
This standard is issued under the fixed designation E800; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 Analytical methods for the measurement of carbon
ization established in the Decision on Principles for the
monoxide, carbon dioxide, oxygen, nitrogen oxides, sulfur
Development of International Standards, Guides and Recom-
oxides, carbonyl sulfide, hydrogen halides, hydrogen cyanide,
mendations issued by the World Trade Organization Technical
aldehydes, and hydrocarbons are described, along with sam-
Barriers to Trade (TBT) Committee.
pling considerations. Many of these gases may be present in
any fire environment. Several analytical techniques are de-
2. Referenced Documents
scribed for each gaseous species, together with advantages and
2.1 ASTM Standards:
disadvantages of each. The test environment, sampling
D123 Terminology Relating to Textiles
constraints, analytical range, and accuracy often dictate use of
D512 Test Methods for Chloride Ion In Water
one analytical method over another.
D1179 Test Methods for Fluoride Ion in Water
1.2 These techniques have been used to measure gases
D1246 Test Method for Bromide Ion in Water
under fire test conditions (laboratory, small scale, or full scale).
D1293 Test Methods for pH of Water
With proper sampling considerations, any of these methods
D1356 Terminology Relating to Sampling and Analysis of
could be used for measurement in most fire environments.
Atmospheres
1.3 Thisdocumentisintendedtobeaguideforinvestigators
D2036 Test Methods for Cyanides in Water
and for subcommittee use in developing standard test methods.
D2777 Practice for Determination of Precision and Bias of
A single analytical technique has not been recommended for
Applicable Test Methods of Committee D19 on Water
any chemical species unless that technique is the only one
D3612 Test Method for Analysis of Gases Dissolved in
available.
Electrical Insulating Oil by Gas Chromatography
D4327 Test Method for Anions in Water by Suppressed Ion
1.4 The techniques described herein can be used to deter-
Chromatography
mine the concentration of a specific gas in the total sample
D5197 Test Method for Determination of Formaldehyde and
collected for analysis. These techniques do not determine the
OtherCarbonylCompoundsinAir(ActiveSamplerMeth-
total amount of fire gases that would be generated by a
odology)
specimen during a fire test.
D5466 Test Method for Determination of Volatile Organic
1.5 This standard is used to measure and describe the
Compounds in Atmospheres (Canister Sampling Method-
responseofmaterials,products,orassemblestoheatandflame
ology)
under controlled conditions but does not by itself incorporate
D6196 Practice for Choosing Sorbents, Sampling Param-
all factors required for fire hazard or fire risk assessment of the
eters and Thermal Desorption Analytical Conditions for
materials, products, or assemblies under actual fire conditions.
Monitoring Volatile Organic Chemicals in Air
1.6 This standard does not purport to address all of the
D6348 Test Method for Determination of Gaseous Com-
safety concerns, if any, associated with its use. It is the
pounds by Extractive Direct Interface Fourier Transform
responsibility of the user of this standard to establish appro-
Infrared (FTIR) Spectroscopy
priate safety, health, and environmental practices and deter-
D6696 Guide for Understanding Cyanide Species
mine the applicability of regulatory limitations prior to use.
D6888 Test Method for Available Cyanides with Ligand
Displacement and Flow InjectionAnalysis (FIA) Utilizing
ThisguideisunderthejurisdictionofASTMCommitteeE05onFireStandards
and is the direct responsibility of Subcommittee E05.21 on Smoke and Combustion
Products. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2020. Published September 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1981. Last previous edition approved in 2014 as E800 – 14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0800-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E800 − 20
Gas Diffusion Separation and Amperometric Detection 3.2.2 combustion products, n—airborne effluent from a
D7295 Practice for Sampling Combustion Effluents and material undergoing combustion; this may also include pyro-
Other Stationary Sources for the Subsequent Determina- lysates.
tion of Hydrogen Cyanide 3.2.2.1 Discussion—combustion products without mass,
D7309 Test Method for Determining Flammability Charac- such as heat or other radiation, are not addressed in this guide.
teristics of Plastics and Other Solid Materials Using
3.2.3 firetest,n—aprocedure,notnecessarilyastandardtest
Microscale Combustion Calorimetry
method, in which the response of materials to heat or flame, or
D7365 Practice for Sampling, Preservation and Mitigating
both, under controlled conditions is measured or otherwise
Interferences in Water Samples for Analysis of Cyanide
described.
E84 Test Method for Surface Burning Characteristics of
3.2.4 sample integrity—the unimpaired chemical composi-
Building Materials
tion of a test sample upon the extraction of said test sample for
E176 Terminology of Fire Standards
analysis.
E337 Test Method for Measuring Humidity with a Psy-
3.2.5 sampling—a process whereby a test sample is ex-
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
tracted from a fire test environment.
peratures)
E535 Practice for Preparation of Fire-Test-Response Stan-
3.2.6 test sample—a representative part of the experimental
dards environment (gases, liquids, or solids), for purposes of analy-
E603 Guide for Room Fire Experiments
sis.
E662 Test Method for Specific Optical Density of Smoke
4. Significance and Use
Generated by Solid Materials
E1354 Test Method for Heat and Visible Smoke Release
4.1 Because of the loss of life in fires from inhalation of fire
Rates for Materials and Products Using an Oxygen Con-
gases,muchattentionhasbeenfocusedontheanalysesofthese
sumption Calorimeter
species. Analysis has involved several new or modified
E2257 Test Method for Room Fire Test of Wall and Ceiling
methods, since common analytical techniques have often
Materials and Assemblies
proven to be inappropriate for the combinations of various
2.2 NFPA Standards:
gases and low concentrations existing in fire gas mixtures.
NFPA 265 Standard Methods of Fire Tests for Evaluating
4.2 In the measurement of fire gases, it is imperative to use
Room Fire Growth Contribution of Textile or Expanded
procedures that are both reliable and appropriate to the unique
Vinyl Wall Coverings on Full Height Panels and Walls
atmosphere of a given fire environment. To maximize the
NFPA 286 Standard Methods of Fire Tests for Evaluating
reliability of test results, it is essential to establish the follow-
Contribution of Wall and Ceiling Interior Finish to Room
ing:
Fire Growth
4.2.1 That gaseous samples are representative of the com-
2.3 ISO Standards:
positions existing at the point of sampling,
ISO 5659-2:2017 Plastics — Smoke generation — Part 2:
4.2.2 That transfer and pretreatment of samples occur with-
Determination of optical density by a single-chamber test
out loss, or with known efficiency, and
ISO 9705-1:2016 Reaction to fire tests — Room corner test
4.2.3 That data provided by the analytical instruments are
for wall and ceiling lining products — Part 1:Test method
accurateforthecompositionsandconcentrationsatthepointof
for a small room configuration
sampling.
ISO 16000-3:2011 Indoor air — Part 3: Determination of
4.3 This document includes a comprehensive survey that
formaldehyde and other carbonyl compounds in indoor air
will permit an individual, technically skilled and practiced in
and test chamber air — Active sampling method
the study of analytical chemistry, to select a suitable technique
ISO 16000-6:2011 Indoor air — Part 6: Determination of
from among the alternatives. It will not provide enough
volatile organic compounds in indoor and test chamber air
information for the setup and use of a procedure (this infor-
by active sampling on Tenax TA sorbent, thermal desorp-
mation is available in the references).
tion and gas chromatography using MS or MS-FID
4.4 Data generated by the use of techniques cited in this
3. Terminology
document should not be used to rank materials for regulatory
3.1 Definitions—Definitions used in this guide are in accor-
purposes.
dancewithTerminologyD123,TerminologyD1356,Terminol-
5. Sampling
ogy E176, and Practice E535 unless otherwise indicated.
3.2 Definitions of Terms Specific to This Standard:
5.1 More errors in analysis result from poor and incorrect
3.2.1 batch sampling—sampling over some time period in
sampling than from any other part of the measurement process.
such a way as to produce a single test sample for analysis.
It is therefore essential to devote special attention to sampling,
sample transfer, and pretreatment aspects of the analysis
procedures.
Available from National Fire Protection Association (NFPA), 1 Batterymarch
Park, Quincy, MA 02169-7471, http://www.nfpa.org.
5.2 Planning for Analysis—Definitive answers should be
Available from International Organization for Standardization (ISO), ISO
sought and provided to the following questions during the
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Geneva, Switzerland, http://www.iso.org. planning stage: (1) Why is the sampling (analysis) being
E800 − 20
performed? (2) What needs to be measured? (3) Where will as hydrogen fluoride (HF), hydrogen chloride (HCl), and
samples be taken? (4) When does one sample? (5) How are hydrogen bromide (HBr). Other species frequently determined
samples collected? are oxygen, the sulfur-oxide species sulfur dioxide (SO ) and
5.2.1 All aspects of sampling and analysis relate to the sulfurtrioxide(SO );thenitrogen-containingspecieshydrogen
fundamental reasons for performing the analysis. Analysis of cyanide(HCN),nitricoxide(NO),andnitrogendioxide(NO );
combustion products is normally performed for one of the and hydrocarbons and partially oxidized hydrocarbons.
following reasons: for research on the composition of the
5.4.2 The following potential problems must be avoided or
gases; to relate directly to flammability, smoke generation,
minimizedbyproperdesignofthesamplingsystemandchoice
toxic or irritant effects; to study mechanisms of combustion; or
of materials of construction:
for development of test equipment. The experimenter should
(1) Reaction of the gaseous products with materials used in
decide exactly what type of information the analysis must
sampling lines and test equipment that could lead to loss of
provide. The necessary detection limits, acceptable errors, and
sample and potential equipment failure;
possible or tolerable interferences must be determined.
(2) Adsorption, absorption, or condensation of gaseous
5.2.2 A representative sample must be obtained; however,
products in the sampling system or on particles trapped in the
sampling must not interfere with the test (for example, sam-
filtration system;
pling could alter the atmosphere in an animal toxicity experi-
(3) Reaction among species present in the gaseous sample;
ment or in a smoke measurement device). The size and shape
(4) Interferences caused by species in the sample, other
of the test chamber affects the possible location and number of than the product being analyzed, that respond to the analytical
sampling probes.
method.
5.2.3 Single or cumulative samples may be adequate for
5.5 Sampling Frequency—The frequency of sampling is
many requirements; however, a continuous monitor may be
based primarily on the information sought. Most requirements
desirable for the determination of concentration-time
will be met by one of the following three sampling modes:
dependence, or in the case of analysis of reactive species (for
(1) The quantity formed during the experiment is deter-
example, hydrochloric acid (HCl).
mined by collecting one time-integrated sample;
5.2.4 Collection and transport of samples must be accom-
(2) The concentration is determined at a limited number of
plished in such a way that the analyses properly reflect the
time points during the experiment;
nature and concentration of species in the combustion gas
(3) The concentration is determined either continuously or
stream. Heated sampling lines made from an inert material are
with sufficient frequency to represent it as a function of time.
often required. Direct sampling and immediate analysis are
5.5.1 The two techniques used most commonly in the past
preferable to retention of the sample for later analysis. Filtra-
have been the single, integrated sample and sampling at fixed
tionofcombustiongasespriortoanalysismaybenecessaryfor
time intervals. However, techniques for continuous analysis of
some applications, but may be totally incorrect for other cases
certain species are now readily available (CO, CO , and
(see 5.9).
oxygen (O )); while continuous analysis of other compounds
5.3 Test Systems—Many devices of various sizes can gen-
of interest have been reported.
erate “fire gases’’ for analysis. These systems include large-
5.5.2 The integrated sampling technique entails collection
scale facilities (fire situations simulated on a 1:1 scale (see
of all the products (or a continuous sample from the gas
Guide E603); large laboratory-scale tests (for example, Test
stream) into an unreactive sampling bag such as polytetrafluo-
Method E2257, NFPA 265, NFPA 286, and ISO 9705-1);
roethylene (PTFE) or polyvinyl fluoride (PVF), or polyvinyl
laboratory-scale chambers (for example, Test Method E662);
difluoride (PVDF). Alternatively, absorption of the species of
cone calorimeters (see Test Method E1354), and microcom-
interest can be captured in an appropriate solvent in an
bustion furnace or tube furnace assemblies (for example, Test
impinger for the duration of the experiment.Analyses are then
Method D7309).
performed on the contents of the bag or trapping medium.
5.3.1 Ingeneral,thecombustiondevices(testchambers)fall
Water-soluble species such as HCl or HBr have been collected
into three categories:
in solution impingers over the duration of the experiment,
(1) closed chambers (for example, Test Method E662 and
enabling analysis of the “integrated” sample. The gas flow rate
ISO 5659-2);
through the impinger and the liquid volume determine the
(2) open chambers (for example, a full-scale room burn);
buildup of acid gas in the solution (the solubility of the species
(3) flow-through systems (for example, Test Method E84).
at the given gas flow rate should be verified). The integrated
5.3.2 Differenttestchambersizesandconfigurationsrequire
sampling techniques provide either the “average” concentra-
different methods of sampling and analysis. Appropriate ana-
tion of the particular species over the duration of the test or, for
lytical procedures and equipment must be selected. In a
certain flow-through test procedures, a measure of the total
full-scalefireexperimentthesamplingfrequencyanddetection
amount of that species produced in the experiment. In this
level and accuracy may not need to be the same as in a small
latter case, a total gas flow measurement is required.
laboratory-scale experiment.
5.5.3 Continuous or frequent, periodic sampling is often
5.4 Reactivity of Fire Gases:
desirable. This limits further reaction of reactive species (such
5.4.1 Fire gases to be analyzed range from relatively inert as HCl, HBr, and HCN), and is useful for studies of time-
and volatile substances, such as carbon monoxide (CO) and dependent, cumulative effects of toxic gases (such as CO) on
carbon dioxide (CO ), to reactive hydrogen halide gases such animals.
E800 − 20
5.5.4 Samples of combustion gas can be collected sequen- 5.7.3 Probe and transfer lines should be heated to prevent
tially for subsequent instrumental analysis. An electrically lossesofsomecombustionproductssuchastotalhydrocarbons
activated multiport stream selection valve or a manifold of due to condensation and HBr, HCl, nitrogen oxide (NO ), and
x
solenoid valves can be used to sequentially divert the combus- SO due to solubility in condensed moisture (see Sections 7
tion gas into a series of gas collection devices. This collection and 9).
procedure can be automated by using a computer controlled 5.7.4 Commercially available gas syringes, evacuable glass
device. or metal containers, plastic sample bags, and sorption tubes are
5.5.5 For noncontinuous sampling of combustion gases, the often used for intermittant grab sampling.
frequency of sampling is often determined by the instrumen- 5.7.4.1 The sorption tube should be appropriate for the
tation. For example, using gas chromatography, sampling will gassestobeanalyzed.Glass-linedstainless-steelsorptiontubes
be dependent on the residence time of species in the instru- filled with glass beads coated with a strong base solution give
ment. Sampling of species at time intervals using gas syringes, excellent collection efficiency for the hydrogen halides. Glass-
plastic sampling bags, sorption tubes, or the like, with analyses lined stainless-steel tubes packed with p-2,6-
to be performed later, is not dependent on analysis time. diphenylphenylene oxide (a porous polymer that withstands
5.5.6 The volume of frequent or continuous gas samples high temperatures) are effective in the collection of hydrogen
removed must not significantly affect the concentration of cyanide, organic nitriles, and other organics generated in fires.
remaining species. In small test chambers and some
5.8 Sample Volume, Sampling Rate:
flowthrough systems, the volume of gas available for sampling
5.8.1 In any sampling technique, the same volume is deter-
is limited.
mined by the sensitivity of the method used for analysis, the
5.6 Sampling Sites: detection level sought, the concentration of the species to be
5.6.1 The number and the locations of sampling sites are analyzed, and the precision required for the determination.
determined by the extent of analytical information sought and 5.8.2 In continuous sampling, the sampling rate is partially
by the configuration of the test chamber. To obtain represen- determined by the desired response time. To minimize the
tative samples from an NBS smoke density chamber, intake response time, small-diameter transfer lines are used and all
ports in one study were located at three heights inside the in-line devices (for example, filters and scrubbers) are kept to
chamber. The sample streams were then combined before minimum volumes. A pressure drop may result from use of
being introduced into the analyzers. Previous experiments had small diameter sampling lines.
demonstrated that significant stratification occurred in the 5.8.3 Response time cannot be calculated exactly from
chamber during part of the test. In a full-scale bedroom fire sample line volume and gas flow rate because of the viscous
test, four gas sampling probes were used. nature of gas flow in the transfer lines and the continuous
5.6.2 Guidelines developed for the monitoring of the emis- mixing of gas in sensor compartments. Response times can be
sionofpollutants(Ref 1) canbeutilizedforthedemonstration determined experimentally by making a rapid change in gas
of the mass flow rates of combustion products through ducts. concentrations at the sampling probe inlet and determining the
Traverses across the ducts (in a steady-state experiment) with time to a given response (usually 90 % or greater).
a CO- or CO -probe can be useful for determining whether a Furthermore, all instruments have an intrinsic response time
need exists for multiple sampling sites. independent of sampling procedure.
5.8.4 Information pertaining to sampling rate and sampling
5.7 Sampling Probes:
volume is contained in Historical Refs (20) and (21).
5.7.1 Sampling probes must withstand exposure to the test
environment and must not affect the integrity of the sample 5.9 Sample Pretreatment:
with respect to the substances being analyzed. Care should be 5.9.1 Pretreatment of the sample must not affect sample
exercised in heating probes of PTFE; temperatures above integrity with respect to the species being analyzed. Pretreat-
250°C may affect their physical properties. ment is used for the following purposes:
5.7.2 Probes fabricated from PTFE, PTFE-lined stainless- (1) The removal of species that would interfere with the
steel, glass-lined stainless-steel, unlined stainless-steel, boro- performance of the detectors or would react with the species
silicate glass, or quartz tubing are frequently used for sample being analyzed, and
extraction from combustion or pyrolysis systems. Stainless (2) Chemical conversion of the species present in the
steel should not be used with combustion products containing sample to those that are detected by the sensors.
hydrogen halides since it reacts with these compounds. Glass 5.9.2 Removal of particulate matter may be required for
and quartz react with fluorides; the latter substance can be certain analyses. Particulates interfere with optical measure-
extracted with PTFE probes if the atmospheric temperature is ments; they can deposit in transfer lines and valves, possibly
low enough. If the temperature is high, an alternative sampling causing malfunctioning; and they can adsorb gases of interest
technique would be placing absorption tubes at the sampling or chemically react with sample gases.
point, housing the tubes in an ice-water bath, and trapping HF 5.9.2.1 Loosely compacted PTFE-fiber filters have been
upstream of all sampling lines and pumps. found to be useful for the removal of particulate matter. Fiber
Tenax, a trademark of Enka BV, Ressort Pantentwesen, Postfach 100149,
The boldface numbers in parentheses refer to a list of references at the end of D-5600, Wupertal, Federal Republic of Germany, available through gas chromatog-
this standard. raphy supply houses, has been found suitable for this purpose.
E800 − 20
filter thimbles of PTFE have been used in sampling probes. In and hydrocarbons should be heated to prevent condensation
that system, filter medium was also contained in a chamber and reduce adsorption.
where several sample streams were combined prior to analysis.
5.10.4 Quantitative sample transfer requires flow rate deter-
5.9.2.2 Glass-fiber filters can be used with many types of mination. Rotameters and orifice-type meters are generally
gaseous samples; however, they cannot be used for samples useful in combustion gas analysis.
containing HF. Cellulosic filters should be used with caution
5.11 System Maintenance:
because of their reactivity toward a variety of substances.
5.11.1 Preventive maintenance is essential for analysis sys-
5.9.2.3 Filtersmustbeheatedtothesametemperatureasthe
temsinwhichthegasstreamscontainreactiveandcondensable
sampling probe and sample transfer lines to minimize adsorp-
components.
tion and condensation in the filtration media.
5.11.2 In addition to normal instrument maintenance, the
5.9.2.4 In some circumstances, filtering material should not
following preventive steps are recommended:
be present before the analysis point. An example is the
5.11.2.1 Filters should be examined and replaced before
measurement of acid gases using a liquid impinger as the
they become heavily loaded with particulate matter. Some
trapping and analysis medium. A filter before the impinger
filters should be replaced after each experiment.
would remove acid gases by adsorption onto liquids and
5.11.2.2 The inside surfaces of gas transfer lines, valves,
particulates on the filter. Care must be taken that the impinger
and pumping devices should be examined and cleaned peri-
does not clog with particulates, and that oils or particles in the
odically. Deposits should be removed with appropriate sol-
impinger liquid do not interfere with analysis.
vents.
5.9.3 Some analyzers require the removal of water vapor
5.11.2.3 Rotameters should be examined to ascertain that
from the sampling line for proper operation or for valid data
the floats are moving freely. The rotameter tubes and the floats
analysis purposes. Water vapor can be removed by a cold trap,
should be periodically cleaned with appropriate solvents.
by absorbent media, or by selective permeability media.
5.9.3.1 A cold trap will remove any gases, such as the acid
6. Analytical Methods for Carbon Monoxide, Carbon
gases, that are soluble in water. The vapor pressure at the
Dioxide, Oxygen, and Nitrogen
temperature of the cold trap of any gas to be measured must
also be considered. Due to these factors, this technique is 6.1 The gases carbon monoxide (CO), carbon dioxide
(CO ), oxygen (O ), and nitrogen (N ) will be considered as a
generally limited to use in O , CO, and CO analysis systems.
2 2 2 2 2
group, since several of the analytical methods to be discussed
5.9.3.2 The low capacity of most absorbent media generally
can be applied to more than one of them, sometimes simulta-
limits the application of this technique to second stage
neously. The techniques to be described are gas
desiccation, following a cold trap.Water vapor as well as other
chromatography, infrared spectrophotometry, and “other meth-
gases, especially water soluble ones can also be removed.
ods’’ including electrochemistry.
Conversion of NO to NO has been observed. Due to these
considerations, the absorbent media technique is generally
6.2 Gas Chromatography:
limited to use in O , CO, and CO analysis systems.
2 2
6.2.1 General Description—Gas chromatography is an ideal
5.9.3.3 The performance of selective permeability driers in
batch method for analyzing nonreactive gases in combustion
removing or not removing classes of compounds present in the
products. These gases can be separated on columns with solid
sample stream has been studied. Water and, in general, water
stationary phases operated isothermally and detected using
soluble hydrocarbons are removed. Many inorganic gases, CO,
thermal conductivity (TC) detectors. Some of the column
CO , and others, are not removed.
configurations and alternative detectors are described below.
5.9.4 Some analyses require chemical conversion of species
6.2.2 Apparatus and Procedures:
to that detected by the analytical sensors (for example, reduc-
6.2.2.1 Apparatus requirements are modest. A basic gas
tion of chlorine to chloride). Most chemical conversions are
chromatograph with standard temperature controls and thermal
performed within the detector (for example, reduction of NO
conductivity detector can be used. A gas sampling valve is a
to NO (see Section 9)).
very useful accessory. Temperature programming, automated
5.10 Sample Transfer:
valve operation, electronic integration, etc., are convenient but
5.10.1 Sample transfer is usually effected by pumping not necessary.
devices. Sample integrity must be retained during transfer. 6.2.2.2 Complete separation of all of these gases normally
Materials suitable for sample probes and pretreatment devices
requires the use of two columns—a molecular sieve, which
are usable for transfer lines. For certain applications, stainless separates O,N , and CO but irreversibly absorbs CO at
2 2 2
steel (no exposure to acid gases) and glass (no exposure to HF)
normal operating temperatures; and a porous polymer column
can be used. which readily separates CO and CO from air but does not
5.10.2 The internal surfaces of the pumps must be inert to resolve O and N . The two columns have been used together,
2 2
the substances being transferred. Interior parts coated with in various configurations and with column-switching valves, to
PTFE are commonly used. In the transfer of acid gases, the achieve complete separation of the gases.
impingers or scrubbers used for the adsorption of these species
6.2.2.3 An arrangement, using dual columns and a column-
should precede the pumps in the sample transfer system. switching valve, has been successfully used to analyze O,N ,
2 2
5.10.3 To retain sample integrity, transfer lines leading to CO, and CO gases. Total analysis time was approximately 15
analyzersfornitrogenoxides,hydrogenhalides,sulfurdioxide, min.
E800 − 20
6.2.2.4 Concentric single columns, consisting of an inner magnitude of the interference is highly dependent on the
and an outer column of different packing, are also available. specific instrument and on the relative concentrations of the
These will separate O,N , CO, and CO in a single pass. The gases.
2 2 2
use of such columns eliminates the column-switching valve
6.3.3.2 The major interferences found are of CO for CO
required in the dual-column arrangement; however, their use to
and vice versa. For most applications, CO interference with
date has been limited.
CO analysis is minor. The interference of CO with a CO
2 2
6.2.2.5 The sensitivity of the gas chromatographic method measurement can be reduced (if necessary) by incorporating a
trap (for example, soda-lime or granular lithium hydroxide
depends on sample size, the type of detector, and temperature
and filament current for TC detectors. Thermal conductivity (LiOH)) to remove CO from the sample stream before
reaching the analyzer.
detector filaments will deteriorate if large air samples are
repeatedly measured at high current. These gases can be
6.3.3.3 Water vapor seriously interferes with CO and CO
measured at concentrations as low as 0.05 %. analysis; a moisture trap in-line can reduce this interference
6.2.2.6 Lower concentrations of CO can be detected by (see 5.9.3). Smoke particulates must be filtered out (see 5.9.2).
converting CO to methane (CH ) by catalytic hydrogenation. 6.3.3.4 The instrument readings will be affected by the total
The CH is then detected, using a flame ionization detector gas pressure in the measuring cell. This arrangement is usually
(FID). adequate if the measuring cell is vented to ambient conditions.
6.2.3 Advantages and Disadvantages:
6.4 Other Methods:
6.2.3.1 The major limitation of gas chromatography for
6.4.1 General Description—Electrochemical techniques are
monitoring combustion products is its inherent restriction to
available for measuring CO and O , but not for CO . Such
2 2
batch sampling, since each analysis requires several minutes to
devices are usually designed for air pollution or stack gas
complete. Therefore, only a limited number of points can be
monitoring.Astandard technique for CO involves oxidation in
obtained during a test. However, samples can be collected,
an electrolytic cell. Techniques for measuring oxygen include
intermittently during a run, in suitable gas-tight containers (for
galvanic cells, polarographic analyzers, and paramagnetic
example, syringes with close-off valves or gas sampling bags)
analyzers.
and the contents analyzed at a later time. The relative nonre-
6.4.2 Advantages and Disadvantages—Allofthesemethods
activity of these gases allows them to be stored for extended
can be accurate and specific, but have slower response than the
periods of time before analysis.
IR methods previously described. Accurate measurement of
6.2.3.2 The gradual build-up of organic pyrolysis and com-
oxygen concentration with a paramagnetic analyzer requires
bustion products in the analytical columns may result in
compensation for the effects of measuring cell pressure.
eventual degradation of performance. When this occurs, col-
umns can be purged overnight at elevated temperatures or
7. Analytical Methods for Hydrogen Halides
back-flushed; however, after a long period of use, it may be
7.1 General Comments:
necessary to replace the column.
7.1.1 The analysis of the hydrogen halide gases (hydrogen
6.3 Infrared Analysis:
fluoride (HF), hydrogen chloride (HCl), and hydrogen bromide
6.3.1 General Description:
(HBr)) in combustion atmospheres has always been considered
6.3.1.1 Infrared (IR) methods are useful for continuously
difficult, due primarily to the highly reactive nature of these
monitoring the concentration of CO or CO in fire gases.
2 species. The gases must be analyzed immediately or converted
Symmetric diatomic molecules, such as oxygen and nitrogen,
to a stable form to be analyzed at a later time (for example,
cannot be detected because they are infrared inactive.
dissolved aqueous solution in an impinger). The reactivity of
6.3.1.2 Infrared analysis is based on absorption of radiation these gases has led most workers to limit the length of
at specific wavelengths when the species of interest is present.
sampling lines and to ensure that these lines are both heated
By varying the length of the sample cell, gas concentrations and prepared from an inert material such as PTFE or glass, as
from a few parts per million up to 100 % can be analyzed.
described in 5.7. Instead of in-line pumps, gas samples are
generally pulled into the analytical device using a vacuum
6.3.2 Apparatus and Procedures:
source.
6.3.2.1 A standard (dispersive) infrared spectrophotometer
7.1.2 The techniques used for the quantitative detection of
can be used to measure CO or CO by operating with the
hydrogen halides (HX) can be classified into three broad
monochromator fixed at a particular wavelength; or a conven-
categories: (1) “proton-detection devices,’’ in which the HX is
tional infrared spectrum of the gas mixture can be obtained.
dissociated in solution and the activity of the hydrated proton
6.3.2.2 A nondispersive infrared (NDIR) analyzer continu-
is analyzed (for example, pH, conductometric); (2) “anion
ously monitors a single wavelength or wavelength band. Such
detector devices,’’ in which the HX is dissociated in solution
instruments are often less expensive than dispersive instru-
and the anion is analyzed (for example, ion-selective electrode,
ments; however, they are restricted to a particular wavelength
titrimetry, and ion chromatography); and (3) “hydrogen halide
or chemical species. (See Test Method D3612.)
detection devices,’’ in which the intact molecule is analyzed
6.3.3 Advantages and Disadvantages:
(for example, infrared and gas chromatography). These will be
6.3.3.1 Interferences can occur in infrared analyses when
discussed in the following sections.
absorption bands of other components in the sample overlap
the absorption band of the compound being analyzed. The 7.2 Proton Detection Devices:
E800 − 20
7.2.1 General Description—One of the simplest ways to in combustion gas samples. The ultraviolet (UV) detector for
measure the concentration of acid gases in a combustion ion chromatography is sensitive to all anions. With indirect
environment is to draw a portion of the gases into an aqueous photometric chromatography light-absorbing eluent anions
solvent and measure the pH of the resulting solution, using a enable the sample anions to appear as negative peaks in the
conventional pH electrode as described in Test Methods absorbance record.
D1293. This technique is not specific to any particular species 7.3.2.3 A variety of methods involving titration of the
(see below); therefore, this approach can only be used as a
hydrogen halides in municipal drinking water have been
general indicator of acid gases.Another approach involves the developedbuthavenotbeenextensivelyappliedtotheanalysis
measurement in the change of conductance of a solution in
of combustion gases.
which sample gases have been dissolved.
7.3.2.4 Collection tubes containing dry soda lime have
7.2.2 Apparatus and Procedures: proven to be useful for sampling HCl from combustion
7.2.2.1 Two approaches have been described which use a atmospheres. The test atmosphere is sampled over a time
microelectrolytic conductivity detector originally developed period, such as 3 or 5 min, but the interval can be shortened if
the concentration of HCl is high. Consecutive samples can be
for use in gas chromatography. In the approach described by
Herrington, filtered gases were continually pumped into the obtained in order to provide a concentration/time plot. The
conductance cell and continuously monitored. Hileman chloride is extracted from the soda lime by water and is
sampled gases through an 8-port gas-sampling valve, followed analyzed by titration.
by discrete analysis using the conductance cell. The analysis
7.3.2.5 AcontinuousanalyzerforHClhasbeendescribed.It
time for a given sample was approximately 30 s. employs readily available commercial“ stat’’ titration equip-
7.2.2.2 For pH measurement, a research-quality pH meter ment.ThemethodmonitorsHClconcentrationbycontinuously
should be employed. titrating chloride ion in an impinger with silver nitrate
7.2.3 Advantages and Disadvantages: (AgNO ).
7.2.3.1 Simple pH measurement is prone to interferences 7.3.3 Advantages and Disadvantages:
from any other gases that can generate or remove protons on 7.3.3.1 Ion selective electrodes avoid many of the problems
dissolving in water (that is, CO ,SO ,SO , HCN, NO ).Thus, encountered in other HX analyses, since they are ion specific.
2 2 3 2
the pH electrode is best used to obtain a value of total acid gas Anion interferences such as cyanide and sulfide can be
concentration. minimized with proper consideration of the interfering species.
7.2.3.2 Many of the interference problems encountered in Cyanide and sulfide degrade the electrode membrane, slowing
theresponseandreducingtheaccuracy.Slightcorrosioneffects
using pH electrodes are eliminated by using a nonaqueous
electrolyte in the conductometric procedures. The conducto- on the electrode can be removed by repolishing. Bromide
interferes with the chloride ion electrode; however, chloride
metric apparatus can be used as a continuous monitor of the
hydrogen halide gas; however, frequent calibration is recom- does not interfere with the bromide ion electrode, except at
very high concentrations of chloride.
mended.
7.3.3.2 Ion chromatography may be particularly useful
7.3 Anion Detection Devices:
when strong interference from anions causes other techniques
7.3.1 General Description—Ion-selective electrodes (for
to fail. However, this technique has the disadvantage of being
fluoride, chloride, or bromide) can be used for the analysis of
noncontinuous.
hydrogen halides as described in Practice D512, Test Methods
7.3.3.3 Collection tubes containing dry soda lime can often
D1179, and Test Method D1246. These types of analyses can
be used to sample from locations which would be difficult to
be conducted in either a continuous mode or a batch mode. Ion
sample from using solution absorbers or other techniques.
chromatography described in Test Method D4327 and titration
They are compact and easy to handle and have high absorption
procedures are also available for halide ion analysis.
efficiency.Caremustbetakentoavoidbreakthroughduetotoo
7.3.2 Apparatus and Procedures:
highgas-flowrateorhighHClconcentrationorthetendencyto
7.3.2.1 Combustiongasesmaybecontinuouslybubbledinto
plug up in extremely smokey atmospheres.
a solution containing an ion-selective electrode and the anion
7.3.3.4 There are insufficient data to accurately describe the
concentration measured while it is constantly increasing. The
advantages and disadvantages of the “stat’’ titration method;
rate of production of hydrogen halide is determined by
however, it has the potential to be a versatile continuous
differentiating the concentration-versus-time curve. A batch
method for HCl with few problems from smoke particulates or
analysis may involve obtaining a gas sample in a syringe
liquids and requiring no calibration gases. Its disadvantages
containing the dissolving solution or a single time-integrated
include interferences from other halide and cyanide gases and
sample in an impinger solution.
efficiency of absorption of the HCl.
7.3.2.2 Ion chromatographic methods permit separation of
7.4 Hydrogen Halide Detection Devices:
anionswithsubsequentconductivitymeasurementoftheeluted
7.4.1 Hydrogen halides can be analyzed with gas
species. The carbonate anion and various organic acids are
interferences for chloride with the conductivity detector if they chromatography, however, this is not commonly used because
of difficulties with corrosion and poor analysis caused by
are not well separated chromatographically. The silver/silver
problems with poorly formed peaks.
chloride (Ag/AgCl) detector is specific for chloride and bro-
mide with a very low sensitivity for carbonate and other 7.4.2 The gas filter-correlation analysis technique has been
anions. The fluoride detector is a specific detector for fluoride developed for a number of gases. Commercial instruments for
E800 − 20
HCl are available. The technique also lends itself to in situ summarized in Test Method D6888. Alternative determinative
measurements, specifically, a beam passed across an exhaust steps are available (for example, colorimetry and ion-selective
stack section. A commercial instrument suitable for full-scale electrode), but they may be more suspectible to interferences
stack measurements is available. Gas-filter correlation analyz- (for example, aldehydes, ketones, sulfide, thiocyanate, and
ers can be designed to minimize the problem of instrument
sulfur dioxide) (Ref 3). Sample pretreatment and distillation
drift. Care must be taken to avoid precipitating the HCl as an described in Test Methods D2036 may be used to overcome
aerosol; limited measurements indicate that this is unlikely if
some of these interferences. The methods described in D2036
the relative humidity in the measuring system is kept below 70 were not validated specifically for fire smoke effluent samples;
to 80 %.
therefore, it is the responsibility of the user to demonstrate
precision and recovery for each sample matrix that is burned.
8. Analytical Methods for Hydrogen Cyanide
8.1.4.2 Results from a single impinger produce a single,
averageconcentrationforthedurationoftheexperiment,while
8.1 Several analytical approaches can be used to measure
multiple impingers, required to develop a concentration-time
hydrogen cyanide (HCN).
profile, entail additional time and equipment.
8.1.1 Direct measurements of HCN can be made with
Fourier transform infrared (FTIR) spectroscopy. For more
9. Analytical Methods for Nitrogen Oxides, Sulfur
information on the determination of gaseous compounds by
Oxides, and Carbonyl Sulfide
FTIRspectroscopy,seeTestMethodD6348.Standardgascells
can be used; however, longer path length, nondispersive
9.1 Oxides of nitrogen include nitric oxide (NO) and nitro-
infrared instruments are better suited for low concentrations.
gen dioxide (NO ). Fire gases contain mostly NO; NO
2 2
Gas filter correlation techniques have also been proven useful
formation is usually a secondary oxidation process. Sulfur
for HCN analysis (see 7.4.2).
oxides include sulfur dioxide (SO ) and sulfur trioxide (SO ),
2 3
8.1.2 Advantages and Disadvantages:
the former being the more prevalent in fire gases generated
8.1.2.1 This technique offers a means for continuous analy-
from sulfur-containing materials.
sis of HCN in the gas phase, if interferences can be accounted
9.2 Nitrogen Oxides:
for or eliminated. Potential interferences to infrared determi-
9.2.1 Chemiluminescence:
nation of HCN are acetylene, propane, and water vapor.
8.1.3 HCN in fire smoke can also be collected with im-
9.2.1.1 General Description—Chemiluminescence is the
pingers (sometimes referred to as bubblers) as described in
principle of operation of several process analyzers for nitrogen
Practice D7295. A known volume of gaseous sample is
oxides. Either NO or total nitrogen oxide content (NO ) can be
x
bubbled through an impinger containing 0.1–M sodium hy-
measure
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