1、Designation: D 4490 96 (Reapproved 2006)e1Standard Practice forMeasuring the Concentration of Toxic Gases or VaporsUsing Detector Tubes1This standard is issued under the fixed designation D 4490; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorially revised 10.2 and 10.3 in April 2006.1. Scope1.1 This practice covers the detection and
3、 measurement ofconcentrations of toxic gases or vapors using detector tubes (1,2).2A list of some of the gases and vapors that can be detectedby this practice, their 199495 TLV values recommended bythe ACGIH, and their measurement ranges are provided inAnnex A1. This list is given as a guide and sho
4、uld beconsidered neither absolute nor complete.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regu
5、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 1356 Terminology Relating to Sampling and Analysis ofAtmospheres2.2 Other Document:29 CFR 1910 Federal Occupational Safety and HealthStandard Title 2943. Terminology3.1 For definitions of terms used in this method, refer to
6、Terminology D 1356.4. Summary of Practice (3)4.1 Detector tubes may be used for either short-term sam-pling (grab sampling; 1 to 10 min typically) or long termsampling (actively or passively; 1 to 8 h) of atmospherescontaining toxic gases or vapors.4.1.1 Short-Term Sampling (Grab Sampling) (4-18)Agi
7、ven volume of air is pulled through the tube by a mechanicalpump. If the substance for which the detector tube wasdesigned is present, the indicator chemical in the tube willchange color (stain). The concentration of the gas or vapor maybe estimated by either (a) the length-of-stain compared to acal
8、ibration chart, or (b) the intensity of the color changecompared to a set of standards.4.1.2 Long-Term Active Sampling (Long-Term Tubes) (19-22)A sample is pulled through the detector tube at a slow,constant flow rate by an electrical pump. The time-weightedaverage concentration of the gas or vapor
9、is determined bycorrelating the time of sampling either with (a) the length-of-stain read directly from the calibration curve imprinted on thetube or (b) the intensity of the color change compared to a setof standards.4.1.3 Long-Term Passive Sampling (Diffusion or DosimeterTubes) (25)The contaminant
10、 molecules move into the tubeaccording to Ficks First Law of Diffusion. The driving force isthe concentration differential between the ambient air and theinside of the tube. The time-weighted average concentration ofthe gas or vapor is determined by dividing the indication on thetube by the number o
11、f hours sampled (1 to 10 h according tothe manufacturers instructions).4.2 Instructions are given for the calibration of the samplingpumps required in this practice.4.3 Information on the correct use of the detector tubes ispresented.1This practice is under the jurisdiction of ASTM Committee D22 on
12、Air Qualityand is the direct responsibility of Subcommittee D22.04 on WorkplaceAtmospheres.Current edition approved April 1, 2006. Published June 2006. Originallyapproved in 1985. Last previous edition approved in 2001 as D 4490 - 96 (2001).2The boldface numbers in parentheses refer to the list of r
13、eferences at the end ofthis practice.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Code of Federal Regulat
14、ions, Part 1910.1000 Subpart 2 and Part 1926.55Subpart D.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 The Federal Occupational Safety and Health Adminis-tration, in 29 CFR 1910, designates that certain g
15、ases andvapors must not be present in workplace atmospheres atconcentrations above specific values.5.2 This practice will provide a means for the determinationof airborne concentrations of certain gases and vapors given in29 CFR 1910.5.3 A partial list of chemicals for which this practice isapplicab
16、le is presented in Annex A1.5.4 This practice also provides for the sampling of gaseousatmospheres to be used for process control or other purposes(2, 23-25).6. Interferences (26, 27)6.1 Some common interferences for the various tubes arelisted in the instruction sheets provided by the manufacturers
17、.7. Apparatus (28-31)7.1 Detector TubeA detector tube consists of a glass tubecontaining an inert granular material that has been impregnatedwith a chemical system which reacts with the gas or vapor ofinterest. As a result of this reaction, the impregnated chemicalchanges color. The granular materia
18、l is held in place within theglass tube by porous plugs of a suitable inert material. The endsof the glass tube are flame-sealed to protect the contents duringstorage.7.2 Pump (32):7.2.1 Short-Term SamplingA mechanical, hand-operated,aspirating pump is used to draw the sample through thedetector tub
19、e during the short-term sampling. Two types ofpumps are commercially available: piston-operated andbellows-operated. The pumps have a capacity of 100 mL for afull pump stroke. By varying the number of pump strokes, thesample volume is controlled. Sampling pumps should bemaintained and calibration ch
20、ecked periodically according tothe manufacturers instructions. The pumps shall be accurate to65 % of the volume stated.7.2.2 Long-Term SamplingSmall electrical pumps havingstable low flow rates (2 to 50 mL/min), are required forlong-term sampling (2 to 8 h). Flow rates to be used with eachdetector t
21、ube are given by the manufacturers. As with themechanical pumps, the electrical pumps must be maintainedand calibrated regularly. Maintenance and calibration areperformed using the instructions supplied by the manufacturerof the pump. The pump flow rate, and, therefore, the sampledvolume, shall be a
22、ccurate to 65 % of the stated flow rate. Withthis system either area or personal monitoring can be accom-plished.7.3 AccessoriesSeveral accessories are provided with de-tector tubes for special applications:7.3.1 Reactor TubesThese are tubes that are used inconjunction with detector tubes. Some gase
23、s and vapors,because of their low reactivity, are not easily detected bydetector tubes alone. The reactor tubes consist of very powerfulchemical reactants, which break down the unreactive com-pound into other more readily detectable substances, whichstandard detector tubes can detect. Thus, the reac
24、tor tube isplaced upstream of the detector tube and the combination mustbe used for certain compounds as a detector tube system.7.3.2 Dryer TubesWater vapor interferes with the detec-tion of certain substances; therefore, dryer tubes are usedupstream of the detector tube in these cases to remove the
25、water vapor.7.3.3 PyrolyzerA pyrolyzer is a hot wire instrumentoperated by batteries. Instructions for its use and maintenanceare given in the manufacturers instruction manuals. Thepurpose of the pyrolyzer, as with reactor tubes, is to breakdown difficult-to-detect compounds into other compoundsmore
26、 easily detected. The breakdown in this case is caused byheat. The pyrolzyer is particularly useful for organic nitrogencompounds, one of the products of breakdown being nitrogendioxide, which is easily monitored.7.3.4 Remote Sampling LineWhen the sampling point isremote from the pump location, a le
27、ngth of nonreactive tubingcan be attached to the pump with the detector tube attached tothe other end of the tubing. This is useful for sampling ininaccessible or dangerous places.7.3.5 Cooling UnitThe cooling unit consists of a length ofmetal tubing through which the sampled gas is pulled. Becauseo
28、f the high thermal conductivity of the metal tubing, the hotsampling gas is cooled sufficiently so that it will not destroy theindicator in the detector tube. The cooling unit must be placedupstream from the detector tube. Cooling units are particularlyuseful when sampling flue gases.8. Reagents8.1
29、The reagents used are specific for each tube, and, todetect a specific gas, may vary from manufacturer to manufac-turer. The instruction sheets supplied by the manufacturers givethe principal chemical reaction(s) that occur(s) in the tube, thusshowing the reagent that is used to react with the gas o
30、r vaporto produce the color change.9. Sampling with Detector Tubes9.1 GeneralDetector tubes made by one manufacturermust not be used with pumps made by a different manufacturer(33). Each lot of detector tubes is calibrated at the manufac-turers plant, using their equipment. The pumps of othermanufac
31、turers have different flow characteristics that causedifferent lengths-of-stain resulting in erroneous readings.9.2 Procedure (34)The detector tube program should beconducted under the supervision of a trained professional suchas a chemist or an industrial hygienist. Carefully follow theinstruction
32、sheet of the manufacturer for the proper use of eachdetector tube. In general, the instruction sheet will include thefollowing information.9.2.1 Storage conditions.9.2.2 Shelf life.9.2.3 Chemical reaction and color change.9.2.4 Test procedure.9.2.5 Significant interferences.9.2.6 Temperature and hum
33、idity correction factors, if re-quired.9.2.7 Correction for atmospheric pressure.9.2.8 Measurement range.D 4490 96 (2006)e1210. Accuracy of Detector Tubes10.1 The Safety Equipment Institute (SEI) has a certifica-tion program for certain detector tubes used in short-termsampling. This program is simi
34、lar to the NIOSH program forevaluating and certifying detector tube performance (35, 36).Under this program the tubes are required to meet an accuracy(95 % confidence level) of 625 % between one and five timesthe SEI test concentration and 635 % at one half the testconcentration. The SEI test concen
35、tration is chosen as theThreshold Limit Value as defined by the American Conferenceof Governmental Industrial Hygienists for the test gas or vapor(37). The calculation of tube accuracy is based on a set ofstatistical procedures (38) and provides an estimate of accuracyunder actual use conditions. Th
36、e SEI Certified Equipment Listshould be consulted for the listing of approved units.10.2 In general, the accuracy of any detector tube dependson the construction and chemistry of the tube along with theactual composition of the test atmosphere and the conditionsunder which the tube is read. For gase
37、s and vapors not coveredby the SEI program, detector tubes may or may not meet theaccuracy requirements of the previous paragraph (39, 40).There is also some variation in accuracy between manufactur-ers tubes designed to detect a specific compound. Thereforethe user should verify the accuracy with t
38、he tube manufactureror run his own tests to determine accuracy (41-43). It must beemphasized that a correct estimate of accuracy can only bedone by qualified operators and with careful attention to thegeneration and verification of test gas or vapor concentrations(44).10.3 Because the accuracy of a
39、detector tube in sampling aspecific compound depends on the cross-sensitivity of the tubeto other gases or vapors present in the test atmosphere, themanufacturer should be consulted for information on cross-sensitivity effects for the specific chemistry employed in theirtube. Quite frequently, sever
40、al different indicating chemistriesfor a specific compound are available. Proper choice ofindicating chemistry can minimize the effect of a co-contaminant in the test atmosphere.11. Keywords11.1 air monitoring; detector tubes; dosimeter sampling;grab sampling; sampling and analysis; toxic gases and
41、vapor;workplace atmospheresANNEX(Mandatory Information)A1. SOME COMPOUNDS THAT CAN BE MEASURED BY DETECTOR TUBESA1.1 The measurement ranges shown in Table A1.1 are notfor a single tube. They are for the lowest and highestconcentrations listed in manufacturers brochures. Values aregiven in ppm(v) unl
42、ess otherwise indicated.D 4490 96 (2006)e13TABLE A1.1 Non-Exclusive List of Compounds Measurable by Detector TubesD 4490 96 (2006)e14TABLE A1.1 ContinuedREFERENCES(1) Air Sampling Instruments by the American Conference of Governmen-tal Hygienists, 4th ed., 1972.(2) American Industrial Hygiene Associ
43、ation: Direct Reading Colorimet-ric Indicator Tubes, 1st ed., 1976.(3) Collings, A. J., “Performance Standard for Detector Tube Units Usedto Monitor Gases and Vapors in Working Areas,” Pure and AppliedChemistry, Vol 54, pp. 17631767, 1982.(4) Saltzman, B. E., Direct Reading Colorimetric Indicators,
44、Air SamplingInstruments for Evaluation of Atmospheric Contaminants, fourth ed.,American Conference of Governmental Industrial Hygienists, 1972.(5) Ketcham, N. H., “Practical Experience with Routine Use of FieldIndicators,” American Industrial Hygiene Association Journal, Vol 23,p. 127, 1962.(6) Linc
45、h, A. L. and H. Pfaff, “Carbon MonoxideEvaluation of Expo-sure Potential by Personnel Monitor Surveys,” American IndustrialHygiene Association Journal, Vol 32, p. 745, 1971.(7) Kitagawa, T: “The Rapid Measurement of Toxic Gases and Vapors,”Transactions of the 13th International Congress on Occupatio
46、nalHealth, New York, NY, 1960.(8) Ringold, A., Goldsmith, J. R., Helwig, H. L., Finn, R., and F. Scheute,“Estimating Recent Carbon Monoxide Exposures, A Rapid Method,Archives of Environmental Health” Vol 5, p. 38, 1963.(9) Leichnitz, K.,“ Detector Tube Measuring Techniques,” Ecomed, 1983.(10) Beatty
47、, R. L., “Methods for Detecting and Determining CarbonMonoxide,” Bureau of Mines Bulletin 557, 1955.(11) Ingram, W. T., “Personal Air Pollution Monitoring Devices,” Ameri-can Industrial Hygiene Association Journal, Vol 25, p. 298, 1964.(12) Linch, A. L., Evaluation of Ambient Air Quality by Personne
48、lMonitoring, CRC Press Inc., 1974.(13) Shepherd, M.,“ Rapid Determination of Small Amounts of CarbonMonoxide,” Analytical Chemistry Vol 19, pp. 7781, 1947.(14) Shepherd, M., Schuhmann, S., and M. V. Kilday, “Determination ofCarbon Monoxide in Air Pollution Studies,” Analytical ChemistryVol 27, pp. 3
49、80383, 1955.(15) Shepherd, G. M., “Colorimetric Gas Detection,” U.S. Patent No.2 487 077, 1949.(16) McConnaughey, P. W., “Article for the Determination of CarbonMonoxide,” U.S. Patent No. 3 507 623, April 21, 1970.(17) Littlefield, J. B., Yant, W. P., and L. B. Berger, “A Detector forQuantitative Estimation of Low Concentrations of Hydrogen Sul-fide,” Department of the Interior, U.S. Bureau of Mines Report, Vol3276, 1935.(18) Underhill, Dwight W., “New Developments in Dosimetry,” Depart-ment of Industrial Environmental Health Science, University ofPittsbu
