ASTM D3162-21

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D3162 − 12 (Reapproved 2020) D3162 − 21
Standard Test Method for
Carbon Monoxide in the Atmosphere (Continuous
Measurement by Nondispersive Infrared Spectrometry)
This standard is issued under the fixed designation D3162; 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
1.1 This test method is applicable to the determination of the carbon monoxide (CO) concentration of the atmosphere between 0.6
3 3
mg/m (0.5 ppm(v)) and 115 mg/m (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/m (0.5 ppm(v)) carbon monoxide in air.
1.3 The values stated in SI units are to be regarded as standard. The values and units in parentheses are provided for information
only and are not considered standard.
1.4 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. See Section 9 for additional precautions.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
D1357 Practice for Planning the Sampling of the Ambient Atmosphere
D1914 Practice for Conversion Units and Factors Relating to Sampling and Analysis of Atmospheres
D3249 Practice for General Ambient Air Analyzer Procedures
D3631 Test Methods for Measuring Surface Atmospheric Pressure
E1 Specification for ASTM Liquid-in-Glass Thermometers
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
(Withdrawn 2009)
This test method is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.03 on Ambient Atmospheres
and Source Emissions.
Current edition approved Sept. 1, 2020Nov. 1, 2021. Published September 2020May 2022. Originally approved in 1973. Last previous edition approved in 20122020 as
D3162 – 12.D3162 – 12 (2020). DOI: 10.1520/D3162-12R20.10.1520/D3162-21.
The boldface numbers in parentheses refer to the list of references at the end of the standard.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3162 − 21
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D1356 and Practice D3249.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 fall time, n—the time interval between initial response and 90 % of final response after a step decrease in input
concentrations.
4. Summary of Test Method
4.1 An atmospheric sample is introduced into a sample conditioning system and then into a nondispersive infrared spectrometer
(NDIR). The spectrometer measures the absorption by CO at 4.7 μm using either a single path monitor capable of distinguishing
between sample and reference gases, or two parallel infrared beams through a sample and a reference cell and a selective detector.
The detector signal is conducted to an amplifier control section, and the analyzer output measured on a meter and recording system
(2).
4.1.1 Some instruments use gas filter correlation to compare the IR absorption spectrum between the measured gas and other gases
present in the gas being sampled, in a single sample cell. These instruments utilizeuse a concentrated sample of CO as a filter for
the IR transmitted through the sample cell to produce a beam that cannot be further attenuated by the CO in the sample, and thus
produces the reference beam. The broadband radiation that passes through the sample cell and the CO filter is filtered again by
a narrow-band-pass filter that allows only the CO-sensitive portion of the band to pass to the detector. The removal of wavelengths
sensitive to other gases reduces interferences.
4.2 The concentration of CO in the sample is determined from a calibration curve prepared using standard calibration gases.
5. Significance and Use
5.1 Determination of carbon monoxide is essential to evaluation of many air pollution complexes. concerns and pollution control
strategies. This test method derives significance from providing such determination.
5.2 Carbon monoxide is formed in the process of incomplete combustion of hydrocarbon fuels, and is a constituent of the exhaust
of gasoline engines. The Environmental Protection Agency (EPA) has set primary and secondary air quality standards for CO that
are designed to protect the public health and welfare (3, 4).
5.3 This test method is suitable for measurements appropriate for the purposes noted in 5.1 and 5.2.
6. Interferences
6.1 Degree of interference varies among individual instruments. Consult manufacturer’s specifications for the particular analyzer
to determine whether interferences render the instrument unsuitable for the proposed use.
6.2 The primary interferent is water vapor. With no interferents are water vapor and carbon dioxide. Without correction, the error
may be as high as 11 mg CO/m map edit n (10 (10 ppm(v)) (5).
6.2.1 Water vapor interference can be minimized by using one of the following steps:
6.2.1.1 Passing the air sample through silica gel or similar drying agent.
6.2.1.2 Maintaining constant humidity in the sample and calibration gases by refrigeration.
6.2.1.3 Saturating the air sample and calibration gases to maintain constant humidity.
6.2.1.4 Using narrow-band optical filters in combination with some of the above measures.
6.2.1.5 Where a sample is dried or humidified a volume correction may be necessary.
D3162 − 21
6.2.1.6 Gas correlation spectrometers minimize interferences and use a narrow-band-pass filter to ensure measuring only the
CO-sensitive IR wavelengths.
6.3 Interference may be caused by carbon dioxide (CO ). The effect of CO interference at concentrations normally present in
2 2
3 3
ambient air is minimal; that is, 1350 mg (750 ppm(v)) CO /m may give a response equivalent to 0.6 mg CO/m (0.5 ppm(v)) (5).
6.4 Hydrocarbons at concentrations normally found in the ambient air do not ordinarily interfere; that is, 325 mg methane/m (500
ppm(v)) may give a response equivalent to 0.6 mg CO/m (0.5 ppm(v)) (5).
7. Apparatus
7.1 NDIR Carbon Monoxide in Air Analyzer, complete with voltage transformer, analyzer section, amplifier/control section, meter,
and recording system. Analyzer must meet or exceed performance specifications described in Annex A1.
7.2 Sample Conditioning System, consisting of pump, flow control valve, pressure relief valve, flowmeter, filter, and moisture
control.
7.3 A typical sampling and analyzer system is described in Fig. 1.
7.4 Thermometer—Temperature measuring devices such as RTDs (Resistance Temperature Devices), thermistors and organic
liquid-in-glass thermometers meeting the requirements of specific applications may be used. Thermometers meeting the
requirements of Specification E1 are suitable for most applications of this test method.
7.5 Barograph or Barometer, capable of measuring atmospheric pressure to 60.6 kPa (5 torr). See Test Methods D3631.
FIG. 1 Dual Path Carbon Monoxide Monitoring System Flow Chart
D3162 − 21
8. Reagents and Materials
8.1 Zero Gas—A pressurized cylinder of pure nitrogen containing less than 0.1 mg/m CO (0.09 ppm(v)) and having a regulated
flow supply.
8.2 Up-Scale Span Gas—A pressurized cylinder containing a span gas mixture consisting of CO in air or nitrogen corresponding
to 80 % of full scale. A regulated flow system must be provided.
8.3 Calibration Gases—Pressured cylinders with regulated flow control are required. These should contain concentrations of CO
in air or nitrogen corresponding to the instrument operating range. In order to establish a calibration curve, zero air from an air
cleanup panel or generator, certified zero air cylinder, or nitrogen with CO in amounts of 10, 20, 40, and 80 % 0, 10 to 20, 40 to
60, and 80 to 100 % of full scale are needed.
8.4 Calibration Certificate—The span and calibration gases should be certified to be between 62 % of the stated value, and be
supplied in high-pressure cylinders with inside surfaces of a chromium-molybdenum alloy of low iron content. Replacement
cylindercontent, or aluminum cylinders internally coated. Replacement cylinders should be verified by procedures in Annex A3.
9. Precautions
9.1 Operate analyzer system in nonexplosive areas unless equipment is explosion-proof.
9.2 The handling and storage of compressed gas cylinders, and the installation and use of the analyzer shall follow Practice D3249.
Cylinders shall not be exposed to direct sunlight.
9.3 Maintain the same sample cell pressure during sampling and calibration. Use the same sample pump.
10. Sampling
10.1 General—For planning sampling programs, refer to Practices D1357 and D3249.
10.2 When sampling the outside ambient atmosphere from an enclosure, a sampling line or probe shall be utilized. It shall extend
at least 1 m [3 ft](3 ft) from the enclosure,enclosure and shall be protected against the entry of precipitation.
10.3 Since the analyzer may be temperature-sensitive, it shall be placed in an enclosure with atmosphere control so the
temperature remains constant within 63°C [65°F].63 °C (65 °F).
10.4 Record the temperature and pressure of the atmosphere sample.
11. Calibration and Standardization
11.1 For calibration procedures, refer to Annex A2.
11.2 Frequency of Calibration:
11.2.1 Multipoint Calibration—A multipoint calibration is required when:
11.2.1.1 The analyzer is first purchased.
11.2.1.2 The analyzer has had maintenance that could affect its response characteristics.
11.2.1.3 When the analyzer shows drift in excess of specifications as determined when the zero and span calibration is performed
(see 11.2.2).
11.2.2 Zero and Span Calibration—A zero and span calibration is required before and after each sampling period, or, if the
analyzer is used continuously, daily.
D3162 − 21
11.3 Sample Cell Pressure Gauge—The sample cell pressure gauge shall be calibrated in accordance with Annex A2, as follows:
11.3.1 When the analyzer is purchased.
11.3.2 At 6-month intervals.intervals, by performance of a three point check. If results indicate the monitor has drifted, then
perform a full multipoint calibration.
11.3.3 When the gauge shows a change larger than 6.9 kPa [1 psi](1 psi) during a sampling period in which the flow rate did not
3 3
change more than 60.014 m /h [0.5(0.5 ft /h]/h).
12. Procedure
12.1 After proper calibration has been established, check all analyzer system operating parameters and set the sample flow rate.
12.2 When the analyzer output has stabilized, take the recorder readout and determine the concentration of CO directly from the
calibration curve in ppm(v).
12.3 Perform the operational checks described in Annex A4 daily, or during each sampl
...