ASTM D3162-94(2000)e1
(Test Method)Standard Test Method for Carbon Monoxide in the Atmosphere (Continuous Measurement by Nondispersive Infrared Spectrometry)
Standard Test Method for Carbon Monoxide in the Atmosphere (Continuous Measurement by Nondispersive Infrared Spectrometry)
SCOPE
1.1 This test method is applicable to the determination of the carbon monoxide (CO) concentration of the atmosphere between 0.6 mg/m3 (0.5ppm(v)) and 115 mg/m3 (100 ppm(v)). The measuring principle is based on the absorption of infrared radiation by CO in the 4.7 µm region (1).
1.2 The test method has a limit of detection of about 0.6 mg/m3 (0.5 ppm(v)) carbon monoxide in air.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See section 9 for additional precautions.
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e1
Designation:D3162–94(Reapproved2000)
Standard Test Method for
Carbon Monoxide in the Atmosphere (Continuous
Measurement by Nondispersive Infrared Spectrometry)
This standard is issued under the fixed designation D 3162; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Editorial corrections were made throughout in September 2000.
1. Scope Methods forAnalysis and Testing of Industrial Chemicals
1.1 This test method is applicable to the determination of
3. Terminology
the carbon monoxide (CO) concentration of the atmosphere
3 3
3.1 Definitions:
between0.6mg/m (0.5ppm(v))and115mg/m (100ppm(v)).
3.1.1 For definitions of terms used in this test method, refer
The measuring principle is based on the absorption of infrared
2 to Terminology D 1356 and Practice D 3249.
radiation by CO in the 4.7 µm region (1).
3.2 Definitions of Terms Specific to This Standard:
1.2 The test method has a limit of detection of about 0.6
3.2.1 fall time—the time interval between initial response
mg/m (0.5 ppm(v)) carbon monoxide in air.
and 90 % of final response after a step decrease in input
1.3 This standard does not purport to address all of the
concentrations.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 An atmospheric sample is introduced into a sample
bility of regulatory limitations prior to use. See Section 9 for
conditioning system and then into a nondispersive infrared
additional precautions.
spectrometer (NDIR). The spectrometer measures the absorp-
tionbyCOat4.7µmusingtwoparallelinfraredbeamsthrough
2. Referenced Documents
a sample and a reference cell and a selective detector. The
2.1 ASTM Standards:
detectorsignalisconductedtoanamplifiercontrolsection,and
D 1356 Terminology Relating to Sampling and Analysis of
3 the analyzer output measured on a meter and recording system
Atmospheres
(2).
D 1357 Practice for Planning the Sampling of the Ambient
3 4.1.1 Some instruments use gas filter correlation to compare
Atmosphere
the IR absorption spectrum between the measured gas and
D 1914 Practice for Conversion Units and Factors Relating
3 othergasespresentinthegasbeingsampled,inasinglesample
to Sampling and Analysis of Atmospheres
cell. These instruments utilize a concentrated sample of CO as
D 3249 Practice for General Ambient Air Analyzer Proce-
3 a filter for the IR transmitted through the sample cell to
dures
produce a beam that cannot be further attenuated by the CO in
D 3631 Test Methods for Measuring Surface Atmospheric
3 the sample, and thus produces the reference beam. The
Pressure
broadbandradiationthatpassesthroughthesamplecellandthe
E 1 Specification for ASTM Thermometers
CO filter is filtered again by a narrow-band-pass filter that
E 180 Practice for Determining the Precision of ASTM
allows only the CO-sensitive portion of the band to pass to the
detector. The removal of wavelengths sensitive to other gases
reduces interferences.
This test method is under the jurisdiction of ASTM Committee D22 on
Sampling andAnalysis ofAtmospheres, and is the direct responsibility of Subcom-
4.2 The concentration of CO in the sample is determined
mittee D 22.03 on Ambient Atmospheres and Source Emissions.
from a calibration curve prepared using standard calibration
Current edition approved June 15, 1994. Published August 1994. Originally
gases.
published as D 3162 – 73T. Last previous edition D 3162 – 91.
The boldface numbers in parentheses refer to the list of references at the end of
the standard.
Annual Book of ASTM Standards, Vol 11.03.
4 5
Annual Book of ASTM Standards, Vol 14.03. Annual Book of ASTM Standards, Vol 15.05.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3162
5. Significance and Use 6.2.1.4 Using narrow-band optical filters in combination
with some of the above measures.
5.1 Determination of carbon monoxide is essential to evalu-
ation of many air pollution complexes. This test method 6.2.1.5 Where sample is dried or humidified a volume
derives significance from providing such determination. correction may be necessary.
5.2 Carbon monoxide is formed in the process of incom-
6.2.1.6 Gas correlation spectrometers minimize interfer-
plete combustion of hydrocarbon fuels, and is a constituent of
ences and use a narrow-band-pass filter to ensure measuring
the exhaust of gasoline engines. The Environmental Protection
only the CO-sensitive IR wavelengths.
Agency (EPA) has set primary and secondary air quality
6.3 Interference may be caused by carbon dioxide (CO ).
standards for CO that are designed to protect the public health
The effect of CO interference at concentrations normally
and welfare (3, 4).
present in ambient air is minimal; that is, 1350 mg (750
5.3 This test method is suitable for measurements appropri-
ppm(v)) CO /m may give a response equivalent to 0.6 mg
ate for the purposes noted in 5.1 and 5.2. 3
CO/m (0.5 ppm(v)) (5).
6. Interferences
6.4 Hydrocarbons at concentrations normally found in the
ambient air do not ordinarily interfere; that is, 325 mg
6.1 Degree of interference varies among individual instru-
methane/m (500 ppm(v)) may give a response equivalent to
ments. Consult manufacturer’s specifications for the particular
0.6 mg CO/m (0.5 ppm(v)) (5).
analyzer to determine whether interferences render the instru-
ment unsuitable for the proposed use.
6.2 The primary interferent is water vapor. With no correc- 7. Apparatus
tion, the error may be as high as 11 mg CO/m map edit n (10
7.1 NDIR Carbon Monoxide in Air Analyzer, complete with
ppm(v)) (5).
voltagetransformer,analyzersection,amplifier/controlsection,
6.2.1 Water vapor interference can be minimized by using
meter, and recording system. Analyzer must meet or exceed
one of the following steps:
performance specifications described in Annex A1.
6.2.1.1 Passing the air sample through silica gel or similar
7.2 Sample Conditioning System, consisting of pump, flow
drying agent.
control valve, pressure relief valve, flowmeter, filter, and
6.2.1.2 Maintaining constant humidity in the sample and
moisture control.
calibration gases by refrigeration.
6.2.1.3 Saturating the air sample and calibration gases to 7.3 A typical sampling and analyzer system is described in
Fig. 1.
maintain constant humidity.
FIG. 1 Carbon Monoxide Monitoring System Flow Chart
D3162
7.4 Thermometer— ASTM Thermometer 33C meeting the 11.2.2 Zero and Span Calibration—A zero and span cali-
requirementsofSpecificationE 1willmeettherequirementsof bration is required before and after each sampling period, or, if
most applications. the analyzer is used continuously, daily.
7.5 Barograph or Barometer, capable of measuring atmo- 11.3 Sample Cell Pressure Gage—The sample cell pressure
sphericpressureto 60.6kPa(5torr).SeeTestMethodD 3631. gage shall be calibrated in accordance with Annex A2, as
follows:
8. Reagents and Materials 11.3.1 When the analyzer is purchased.
11.3.2 At 6-month intervals.
8.1 Zero Gas—A pressurized cylinder of pure nitrogen
11.3.3 When the gage shows a change larger than 6.9 kPa (1
containing less than 0.1 mg/m CO (0.09 ppm(v)) and having
psi) during a sampling period in which the flow rate did not
a regulated flow supply.
3 3
change more than 60.014 m /h (0.5 ft /h).
8.2 Up-Scale Span Gas—Apressurized cylinder containing
a span gas mixture consisting of CO in air corresponding to
12. Procedure
80 % of full scale. A regulated flow system must be provided.
12.1 After proper calibration has been established, check all
8.3 Calibration Gases—Pressured cylinders with regulated
analyzer system operating parameters and set the sample flow
flow control are required. These should contain concentrations
rate.
of CO in air corresponding to the instrument operating range.
12.2 When the analyzer output has stabilized, take the
In order to establish a calibration curve, nitrogen with CO in
recorder readout and determine the concentration of CO
amounts of 10, 20, 40, and 80 % of full scale are needed.
directly from the calibration curve in ppm(v).
8.4 CalibrationCertificate—Thespanandcalibrationgases
12.3 Perform the operational checks described inAnnexA4
shouldbecertifiedtobebetween 62 %ofthestatedvalue,and
daily, or during each sampling period (7).
be supplied in high-pressure cylinders with inside surfaces of a
chromium-molybdenum alloy of low iron content. Replace-
13. Calculation
ment cylinder should be verified by procedures in Annex A3.
13.1 To convert ppm(v) to mg/m , refer to Practice D 1914.
9. Precautions
14. Precision and Bias
9.1 Operate analyzer system in nonexplosive areas unless
equipment is explosion-proof. NOTE 1—The precision statements are based on an interlaboratory
study conducted by Southwest Research Institute, Houston, Tex., in 1972
9.2 The handling and storage of compressed gas cylinders,
on 3 samples of carbon monoxide in dry air.Three master cylinders of gas
and the installation and use of the analyzer shall follow
containing nominal concentrations of 8, 30, and 53 mg/m were prepared
Practice D 3249. Cylinders shall not be exposed to direct
and subsamples in high-pressure cylinders were submitted to the collabo-
sunlight.
rating laboratories. Each subsample was analyzed in triplicate and the
9.3 Maintain the same sample cell pressure during sampling
analyses replicated on 2 more days for a total of 810 determinations. The
and calibration. Use the same sample pump.
resultsfromthe15laboratorieswereevaluatedbytheproceduredescribed
in Practice E 180.
10. Sampling
14.1 Precision: (6)
10.1 General—For planning sampling programs, refer to 14.1.1 Triplicate Analysis—Report the carbon monoxide
(CO) content to 0.1 mg/m . Triplicate runs (Note 2) with a
Practices D 1357 and D 3249.
10.2 When sampling the outside ambient atmosphere from range of 0.6 mg/m are acceptable for averaging (95 % confi-
dence level).
an enclosure, a sampling line or probe shall be utilized. It shall
extend at least1m(3ft) from the enclosure, and shall be
NOTE 2—Duplicate runs that agree within 0.5 mg/m are acceptable for
protected against the entry of precipitation.
averaging (95 % confidence level).
10.3 Since the analyzer may be temperature-sensitive, it
14.1.2 Repeatability (Single Analyst)—The standard devia-
shall be placed in an enclosure with atmosphere control so the
tion of the mean (each the average of triplicate determinations)
temperature rema
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