ASTM D4490-96(2006)e1
(Practice)Standard Practice for Measuring the Concentration of Toxic Gases or Vapors Using Detector Tubes
Standard Practice for Measuring the Concentration of Toxic Gases or Vapors Using Detector Tubes
SIGNIFICANCE AND USE
The Federal Occupational Safety and Health Administration, in 29 CFR 1910, designates that certain gases and vapors must not be present in workplace atmospheres at concentrations above specific values.
This practice will provide a means for the determination of airborne concentrations of certain gases and vapors given in 29 CFR 1910.
A partial list of chemicals for which this practice is applicable is presented in Annex A1.
This practice also provides for the sampling of gaseous atmospheres to be used for process control or other purposes (2, 23-25).
SCOPE
1.1 This practice covers the detection and measurement of concentrations of toxic gases or vapors using detector tubes (1, 2) recommended by the ACGIH, and their measurement ranges are provided in . This list is given as a guide and should be considered neither absolute nor complete.
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.
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Designation:D4490–96 (Reapproved 2006)
Standard Practice for
Measuring the Concentration of Toxic Gases or Vapors
Using Detector Tubes
This standard is issued under the fixed designation D4490; 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.
´ NOTE—Editorially revised 10.2 and 10.3 in April 2006.
1. Scope sampling (actively or passively; 1 to 8 h) of atmospheres
containing toxic gases or vapors.
1.1 This practice covers the detection and measurement of
4.1.1 Short-Term Sampling (Grab Sampling) (4-18)—A
concentrations of toxic gases or vapors using detector tubes (1,
2 given volume of air is pulled through the tube by a mechanical
2). Alist of some of the gases and vapors that can be detected
pump. If the substance for which the detector tube was
by this practice, their 1994–95 TLV values recommended by
designed is present, the indicator chemical in the tube will
the ACGIH, and their measurement ranges are provided in
changecolor(stain).Theconcentrationofthegasorvapormay
Annex A1. This list is given as a guide and should be
be estimated by either (a) the length-of-stain compared to a
considered neither absolute nor complete.
calibration chart, or (b) the intensity of the color change
1.2 This standard does not purport to address all of the
compared to a set of standards.
safety concerns, if any, associated with its use. It is the
4.1.2 Long-Term Active Sampling (Long-Term Tubes) (19-
responsibility of the user of this standard to establish appro-
22)—A sample is pulled through the detector tube at a slow,
priate safety and health practices and determine the applica-
constant flow rate by an electrical pump. The time-weighted
bility of regulatory limitations prior to use.
average concentration of the gas or vapor is determined by
2. Referenced Documents
correlating the time of sampling either with (a) the length-of-
stain read directly from the calibration curve imprinted on the
2.1 ASTM Standards:
tube or (b) the intensity of the color change compared to a set
D1356 Terminology Relating to Sampling and Analysis of
of standards.
Atmospheres
4.1.3 Long-Term Passive Sampling (Diffusion or Dosimeter
2.2 Other Document:
Tubes) (25)—The contaminant molecules move into the tube
29 CFR 1910 Federal Occupational Safety and Health
accordingtoFick’sFirstLawofDiffusion.Thedrivingforceis
Standard Title 29
the concentration differential between the ambient air and the
3. Terminology
inside of the tube. The time-weighted average concentration of
thegasorvaporisdeterminedbydividingtheindicationonthe
3.1 For definitions of terms used in this method, refer to
tube by the number of hours sampled (1 to 10 h according to
Terminology D1356.
the manufacturers’ instructions).
4. Summary of Practice (3)
4.2 Instructions are given for the calibration of the sampling
pumps required in this practice.
4.1 Detector tubes may be used for either short-term sam-
4.3 Information on the correct use of the detector tubes is
pling (grab sampling; 1 to 10 min typically) or long term
presented.
This practice is under the jurisdiction ofASTM Committee D22 onAir Quality
5. Significance and Use
andisthedirectresponsibilityofSubcommitteeD22.04onWorkplaceAtmospheres.
5.1 The Federal Occupational Safety and Health Adminis-
Current edition approved April 1, 2006. Published June 2006. Originally
approved in 1985. Last previous edition approved in 2001 as D4490 - 96 (2001). tration, in 29 CFR 1910, designates that certain gases and
DOI: 10.1520/D4490-96R06E01.
vapors must not be present in workplace atmospheres at
The boldface numbers in parentheses refer to the list of references at the end of
concentrations above specific values.
this practice.
5.2 This practice will provide a means for the determination
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
of airborne concentrations of certain gases and vapors given in
Standards volume information, refer to the standard’s Document Summary page on
29 CFR 1910.
the ASTM website.
4 5.3 A partial list of chemicals for which this practice is
Code of Federal Regulations, Part 1910.1000 Subpart 2 and Part 1926.55
applicable is presented in Annex A1.
Subpart D.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D4490–96 (2006)
5.4 This practice also provides for the sampling of gaseous more easily detected. The breakdown in this case is caused by
atmospheres to be used for process control or other purposes heat. The pyrolzyer is particularly useful for organic nitrogen
(2, 23-25). compounds, one of the products of breakdown being nitrogen
dioxide, which is easily monitored.
6. Interferences (26, 27)
7.3.4 Remote Sampling Line—When the sampling point is
6.1 Some common interferences for the various tubes are
remote from the pump location, a length of nonreactive tubing
listed in the instruction sheets provided by the manufacturers.
can be attached to the pump with the detector tube attached to
the other end of the tubing. This is useful for sampling in
7. Apparatus (28-31)
inaccessible or dangerous places.
7.1 Detector Tube—Adetector tube consists of a glass tube
7.3.5 CoolingUnit—Thecoolingunitconsistsofalengthof
containinganinertgranularmaterialthathasbeenimpregnated
metal tubing through which the sampled gas is pulled. Because
with a chemical system which reacts with the gas or vapor of
of the high thermal conductivity of the metal tubing, the hot
interest. As a result of this reaction, the impregnated chemical
samplinggasiscooledsufficientlysothatitwillnotdestroythe
changes color.The granular material is held in place within the
indicator in the detector tube. The cooling unit must be placed
glasstubebyporousplugsofasuitableinertmaterial.Theends
upstream from the detector tube. Cooling units are particularly
of the glass tube are flame-sealed to protect the contents during
useful when sampling flue gases.
storage.
7.2 Pump (32):
8. Reagents
7.2.1 Short-Term Sampling—A mechanical, hand-operated,
8.1 The reagents used are specific for each tube, and, to
aspirating pump is used to draw the sample through the
detect a specific gas, may vary from manufacturer to manufac-
detector tube during the short-term sampling. Two types of
turer.Theinstructionsheetssuppliedbythemanufacturersgive
pumps are commercially available: piston-operated and
theprincipalchemicalreaction(s)thatoccur(s)inthetube,thus
bellows-operated. The pumps have a capacity of 100 mL for a
showing the reagent that is used to react with the gas or vapor
full pump stroke. By varying the number of pump strokes, the
to produce the color change.
sample volume is controlled. Sampling pumps should be
maintained and calibration checked periodically according to
9. Sampling with Detector Tubes
themanufacturer’sinstructions.Thepumpsshallbeaccurateto
9.1 General—Detector tubes made by one manufacturer
65 % of the volume stated.
must not be used with pumps made by a different manufacturer
7.2.2 Long-Term Sampling—Small electrical pumps having
(33). Each lot of detector tubes is calibrated at the manufac-
stable low flow rates (2 to 50 mL/min), are required for
turer’s plant, using their equipment. The pumps of other
long-term sampling (2 to 8 h). Flow rates to be used with each
manufacturers have different flow characteristics that cause
detector tube are given by the manufacturers. As with the
different lengths-of-stain resulting in erroneous readings.
mechanical pumps, the electrical pumps must be maintained
9.2 Procedure (34)—The detector tube program should be
and calibrated regularly. Maintenance and calibration are
conducted under the supervision of a trained professional such
performed using the instructions supplied by the manufacturer
as a chemist or an industrial hygienist. Carefully follow the
of the pump. The pump flow rate, and, therefore, the sampled
instruction sheet of the manufacturer for the proper use of each
volume, shall be accurate to 65 % of the stated flow rate.With
detector tube. In general, the instruction sheet will include the
this system either area or personal monitoring can be accom-
following information.
plished.
9.2.1 Storage conditions.
7.3 Accessories—Several accessories are provided with de-
9.2.2 Shelf life.
tector tubes for special applications:
9.2.3 Chemical reaction and color change.
7.3.1 Reactor Tubes—These are tubes that are used in
9.2.4 Test procedure.
conjunction with detector tubes. Some gases and vapors,
9.2.5 Significant interferences.
because of their low reactivity, are not easily detected by
9.2.6 Temperature and humidity correction factors, if re-
detectortubesalone.Thereactortubesconsistofverypowerful
quired.
chemical reactants, which break down the unreactive com-
9.2.7 Correction for atmospheric pressure.
pound into other more readily detectable substances, which
9.2.8 Measurement range.
standard detector tubes can detect. Thus, the reactor tube is
placed upstream of the detector tube and the combination must
10. Accuracy of Detector Tubes
be used for certain compounds as a detector tube system.
7.3.2 Dryer Tubes—Water vapor interferes with the detec- 10.1 The Safety Equipment Institute (SEI) has a certifica-
tion of certain substances; therefore, dryer tubes are used tion program for certain detector tubes used in short-term
upstream of the detector tube in these cases to remove the sampling. This program is similar to the NIOSH program for
water vapor. evaluating and certifying detector tube performance (35, 36).
7.3.3 Pyrolyzer—A pyrolyzer is a hot wire instrument Under this program the tubes are required to meet an accuracy
operated by batteries. Instructions for its use and maintenance (95 % confidence level) of 625 % between one and five times
are given in the manufacturers’ instruction manuals. The the SEI test concentration and 635 % at one half the test
purpose of the pyrolyzer, as with reactor tubes
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