1、Designation: D4490 96 (Reapproved 2011)Standard Practice forMeasuring the Concentration of Toxic Gases or VaporsUsing Detector Tubes1This standard is issued under the fixed designation D4490; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the detection and measurement ofconcentrations of toxic gases or vapors usin
3、g 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 should beconsidered neither absolute nor complete.1.2 This sta
4、ndard 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 regulatory limitations prior to use.2. Referenced Documents2.1
5、ASTM Standards:3D1356 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 toTerminology D1356.4. Summary of Practice (3)4.1 Detector tub
6、es 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)Agiven volume of air is pulled through the tube by a mechanicalp
7、ump. 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 acalibration chart, or (b) the intensity of the color changecompa
8、red 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 is determined bycorrelating the time of sampling either with
9、(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 molecules move into the tubeaccording to Ficks First Law of
10、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 of hours sampled (1 to 10 h according tothe manufacturers inst
11、ructions).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.5. Significance and Use5.1 The Federal Occupational Safety and Health Adminis-tration, in 29 CFR 1910, designates that certain
12、gases 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 isapplica
13、ble 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).1This practice is under the jurisdiction of ASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.04 on Workp
14、lace Air Quality.Current edition approved Oct. 1, 2011. Published October 2011. Originallyapproved in 1985. Last previous edition approved in 2006 as D4490 - 96 (2006)1.DOI: 10.1520/D4490-96R11.2The boldface numbers in parentheses refer to the list of references at the end ofthis practice.3For refer
15、enced 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 Regulations, Part 1910.1000 Subpart 2 and Part 1926.55
16、Subpart D.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Interferences (26, 27)6.1 Some common interferences for the various tubes arelisted in the instruction sheets provided by the manufacturers.7. Apparatus (28-31)7.1 Detector
17、 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 material is held in place within theglas
18、s 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 tube during the short-term sampling.
19、 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 checked periodically according toth
20、e 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 tube are given by the manufacturer
21、s. 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 accurate to 65 % of the stated flo
22、w 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 gases and vapors,because of their low
23、 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 reactor tube isplaced upstream of the
24、 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 thewater vapor.7.3.3 PyrolyzerA pyro
25、lyzer 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 easily detected. The breakdown i
26、n 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 length of nonreactive tubingcan be
27、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. Becauseof the high thermal conductivity o
28、f 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 The reagents used are specific fo
29、r 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 or vaporto produce the color chang
30、e.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 othermanufacturers have different flow charac
31、teristics 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 sheet of the manufacturer for the
32、 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 humidity correction factors, if re-q
33、uired.9.2.7 Correction for atmospheric pressure.9.2.8 Measurement range.10. 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 similar to the NIOSH program forevaluating and certifyin
34、g 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 concentration is chosen as theThreshold Limit Value as def
35、ined by the American Conferenceof Governmental Industrial Hygienists for the test gas or vapor(37). The calculation of tube accuracy is based on a set ofD4490 96 (2011)2statistical procedures (38) and provides an estimate of accuracyunder actual use conditions. The SEI Certified Equipment Listshould
36、 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 gases and vapors not coveredby the SEI p
37、rogram, 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 the tube manufactureror run his own t
38、ests 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 detector tube in sampling aspecific
39、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, several different indicating chemistriesf
40、or 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 vapor;workplace atmospheresANNEX(Man
41、datory 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) unless otherwise indicated.D4490 96 (20
42、11)3TABLE A1.1 Non-Exclusive List of Compounds Measurable by Detector TubesD4490 96 (2011)4TABLE A1.1 ContinuedREFERENCES(1) Air Sampling Instruments by the American Conference of Govern-mental Hygienists, 4th ed., 1972.(2) American Industrial HygieneAssociation: Direct Reading Colorimet-ric Indicat
43、or 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, Air Sam-pling Instruments for Evaluation of
44、 Atmospheric Contaminants, fourthed., American Conference of Governmental Industrial Hygienists,1972.(5) Ketcham, N. H., “Practical Experience with Routine Use of FieldIndicators,” American Industrial Hygiene Association Journal,Vol23, p. 127, 1962.(6) Linch, A. L. and H. Pfaff, “Carbon MonoxideEval
45、uation 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 OccupationalHealth, New York, NY, 1960.(8) Ringold,
46、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, R. L., “Methods for Detecting and Determi
47、ning CarbonMonoxide,” Bureau of Mines Bulletin 557, 1955.(11) Ingram, W. T., “PersonalAir Pollution Monitoring Devices,” Ameri-can Industrial Hygiene Association Journal, Vol 25, p. 298, 1964.(12) Linch, A. L., Evaluation of Ambient Air Quality by PersonnelMonitoring, CRC Press Inc., 1974.(13) Sheph
48、erd, 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. 380383, 1955.(15) Shepherd, G. M., “Colorimet
49、ric 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 ofPittsburgh, Pittsburgh, PA, 1982.(19) Jentzch, D.
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