1、Designation: D 4599 03Standard Practice forMeasuring the Concentration of Toxic Gases or VaporsUsing Length-of-Stain Dosimeters1This standard is issued under the fixed designation D 4599; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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.1. Scope1.1 This practice describes the detection and measurementof time weighted average (TWA) concentrations o
3、f toxic gasesor vapors using length-of-stain colorimetric dosimeter tubes. Alist of some of the gases and vapors that can be detected by thispractice is provided in Annex A1. This list is given as a guideand should be considered neither absolute nor complete.1.2 Length-of-stain colorimetric dosimete
4、rs work by diffu-sional sampling. The results are immediately available byvisual observation; thus no auxiliary sampling, test nor analysisequipment are needed. The dosimeters, therefore, are ex-tremely simple to use and very cost effective.1.3 This standard does not purport to address all of thesaf
5、ety 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 ASTM Standards:2D 1356 Terminology Relating to
6、Sampling and Analysis ofAtmospheres2.2 Other Document:Federal Occupational Safety and Health StandardTitle29 1910.1000 Subpart Z33. Terminology3.1 For definitions of terms used in this practice, refer toTerminology D 1356.4. Summary of Practice4.1 Length-of-stain colorimetric dosimeters consist of a
7、sealed glass tube containing a detector inside the tube (1-5).4The detector is a length of granulated material impregnatedwith a reactive chemical that is sensitive to the particular gasfor which the dosimeter is designed. To use the tube, one endis opened. The gas, if present, diffuses into the tub
8、e and reactswith the chemical reagent on the carrier material, causing thelatter to change color. Each lot of dosimeters is individuallycalibrated so that by measuring the length of stain and the timeof exposure, the TWAconcentration to which the dosimeter hasbeen exposed can be determined directly
9、and immediately.4.2 Information on the correct use of length of stain dosim-eter tubes is presented.5. Significance and Use5.1 The Federal Occupational Safety and Health Adminis-tration in 29 CFR 1910.1000 Subpart Z designates that certaingases and vapors present in work place atmospheres must becon
10、trolled so that their concentrations do not exceed specifiedlimits.5.2 This practice will provide a means for the determinationof airborne concentrations of certain gases and vapors listed in29 CFR 1910.1000.5.3 A partial list of chemicals for which this practice isapplicable is presented in Annex A
11、1 with current ThresholdLimit Values (TLV) (2) and typical measurement ranges for theselected chemicals as obtained from various manufacturersspecifications.5.4 This practice may be used for either personal or areamonitoring.6. Interferences6.1 The instructions may provide correction factors to beap
12、plied when certain interferences are present. Some common1This practice is under the jurisdiction of ASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.04 on Workplace Atmo-spheres.Current edition approved April 10, 2003. Published June 2003. Originallyapproved in
13、1986. Last previous edition approved in 1997 as D 4599 97.2For 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.3Co
14、de of Federal Regulations, available from U.S. Government Printing Office,Washington, DC 20402.4The boldface numbers in parentheses refer to the list of references appended tothis practice.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sta
15、tes.interfering gases or vapors for each dosimeter are listed in theinstruction sheets for the dosimeter provided by the manufac-turers7. Apparatus7.1 Dosimeter Tube:7.1.1 General DescriptionA length-of-stain dosimetertube consists of a glass tube containing an inert granularmaterial impregnated wit
16、h a chemical system that reacts withthe gas or vapor of interest. As a result of this reaction, theimpregnated chemical changes color. The granular material isheld in place within the glass tube by porous plugs of a suitableinert material. To protect the contents during storage, the endsof the glass
17、 tube are flame sealed. The calibration scale isprinted on the tube to make it easy to read the length of stainof reacted chemical.7.1.2 Stability on StorageStability on storage may varydepending on manufacturer and type of dosimeter, but mostdosimeter tubes can be stored for at least 24 months with
18、 nodeleterious effects.7.2 Tube HoldersDuring use, the dosimeter tube is held ina lightweight, plastic holder. The tube holder protects thedosimeter during use and also helps to minimize effects of aircurrents on performance. The holder has a clip that allows it tobe fastened to a collar or pocket d
19、uring personal sampling or tosome appropriate object during area sampling.8. Reagents8.1 The reagents used to impregnate the granular material inthe dosimeters are specific for each tube, and, to detect aspecific gas or vapor, may vary from manufacturer to manu-facturer. The instruction sheets suppl
20、ied by the manufacturersusually give the principal chemical reaction(s) that occur(s) inthe tube.9. Diffusional Sampling Theory9.1 Ficks First Law of Diffusion states that the mass (m) ofmaterial that diffuses is directly proportional to the diffusioncoefficient (D) of the material, the diffusional
21、cross sectionalarea (A), the concentration gradient (Dc) and the time (t), andinversely proportional to the length of the diffusion path (l).These parameters are linked by Ficks First Law of Diffusionas follows:dmdt5DADcl(1)The molecules of the contaminant reach the granular reagentlayer. At this po
22、int the chemical conversion to a coloredreaction product takes place. The increase in length of the colorzone dl is proportional to the converted mass of contaminantdm (Eq 1).dl 5dmkA(2)where:k = absorption capacity of a layer element, ng/cm3, andA = cross-sectional area of the reagent layer, cm2ass
23、umedconstant.This process, called chemisorption, has the following effectson the remaining measuring process:9.1.1 Since the gas molecules to be measured are boundchemically, they are practically no longer present in theatmosphere directly above the granular carrier material. Thus,additional sample
24、molecules are able to flow into the detectortube according to Ficks First Law of Diffusion, since theconcentration gradient Dc is maintained.9.1.2 The effect of the color zone formed in the process isthat the subsequent contaminant molecules must cover a longerdiffusion path, l, until they reach the
25、 unused reagent layer. Thismeans that the diffusion path, l, as defined in the diffusion law,is not constant, but becomes greater with progressive exposure.The transport rate dm/dt of the sample molecules decreases inthe process. The slowdown in mass transport has a direct effecton the shape of the
26、calibration curves of the indicating tubes.The mathematical correlation can be traced to Formulas 1 and2. Eliminating the contaminant mass, dm, from Eq 1 and 2 andintegrating yields:cTWA1t*0tDcdt5Sk2DtD3 l2(3)where cTWAis the time-weighted average of the time-dependent concentration, Dc. Calibration
27、 curves described bythis equation are not linear, but have the shape of a parabolawhen cTWAis plotted versus l. Accounting for an air gapbetween tube entrance and sorbent, and also transverse analyteflow (if present), modifies Eq 3 through an additive constantand also a term proportional to the stai
28、n length, l (5).9.1.3 The correlation of Eq 3 is confirmed by actualcalibration curves of diffusion tubes. The influence of theproduct resulting from the concentration c and the measuringduration t on the detector tube indication l is shown in Fig. 1.A linear correlation is obtained between the squa
29、re of thedetector tube indication and the product resulting from theconcentration and increasing time as shown by Fig. 2.9.2 Measurement RangeThe measurement range of thevarious length-of-stain dosimeters is shown in Annex A1.9.3 Air VelocityThe sampling rate of the dosimeter tubesis very slow (of t
30、he order of 0.1 cm3/min); thus the “starving”effect in static air is not significant for these devices, so that airvelocity is not critical. However, a stream of high velocity airshould not be permitted to flow directly into the open end of thetube (parallel to the axis of the tube). The tube holder
31、 providesadditional protection from turbulence within the dosimeter.10. Sampling with Length-Of-Stain Dosimeter Tubes10.1 GeneralSince these dosimeters work by diffusion,the procedure for using them is very simple. All that isnecessary is to open one end of the dosimeter properly, placethe opened tu
32、be into its holder, and fasten the holder to anobject at a point where the sampling is to be done. Follow theinstruction sheet of the manufacturer for the proper use of eachdosimeter tube. The sampling starting time and ending timemust be recorded so that the sampling time is known. This isneeded to
33、 estimate the average concentration (TWA) over thesampling time.10.2 Determining the Concentration from the DosimeterTubeThe dosimeter tubes are calibrated in units of concen-tration 3 time, typically ppm(v) 3 hours. The average gasconcentration can be determined by the following formula:D4599032ave
34、rage concentration ppmv!# (4)5dosimeter tube reading ppmv! hoursactual sampling time hours11. Accuracy of Dosimeter Tubes (4-5)11.1 The accuracy of dosimeter tubes is generally within625 %; however, some tube types may vary from this, andspecific tube accuracy may vary from lot to lot and manufac-tu
35、rer to manufacturer. Therefore, if users want to know theaccuracy of a certain tube, they should check with themanufacturer for an accuracy statement or run their own teststo determine accuracy under their particular conditions of use.12. Keywords12.1 air monitoring; colorimetric dosimeter tubes; di
36、ffu-sional sampling; dosimeter tubes; sampling and analysis; toxicgases and vapors; workplace atmospheresFIG. 1 Dosimeter Calibration Curve Relating Length of Color Zone to Concentration 3 TimeFIG. 2 Dosimeter Calibration Curve Relating Square of Color Zone Length to Concentration 3 TimeD4599033ANNE
37、X(Mandatory Information)A1. SOME GASES AND VAPORS THAT CAN BE MEASURED BY LENGTH-OF-STAIN DOSIMETER TUBESREFERENCES(1) Pannwitz, Karl-Heinz, “Direct-Reading Diffusion Tubes,” DrgerReview, Vol 53, 1984, pp. 1014.(2) “Threshold Limit Values for Chemical Substances and PhysicalAgentsand Biological Expo
38、sure Indices, 1996,” American Conference ofGovernmental Industrial Hygienists, Cincinnati, OH, 1996.(3) Palmes, E. D., and Lindenboom, R. H., “Ohms Law, Ficks Law andDiffusion Samplers for Gases,” Analytical Chemistry, Vol 51, 1974,pp. 24002401.(4) Roberson, R. W., Matsunobu, K., Hoshino, F., and Ko
39、matsu, T.,“Per-formance Testing of Sensidyne/Gastec Dosimeter Tubes for CO, H2S,SO2and HCN,” presented at the American Industrial Hygiene Con-ference (1985).(5) Bartley, D. L., “Diffusive Samplers Using Longitudinal SorbentStrips,” American Industrial Hygiene Assoc. Journal, Vol 47, No. 8,1986, pp.
40、571577.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such righ
41、ts, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional
42、standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM
43、Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the abovea
44、ddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE A1.1 Threshold Limit Values (2)NOTE 1The measurement ranges given in the table are not for a singletube. They are the lowest and highest concentrations (over 8 h exposu
45、re)listed in the various manufacturers brochures.SubstanceTLVRTWA ValuesAMeasurement Range(ppm(v)ppm(v) mg/m3Acetic acid 10 25 0.6325Acetone 500 1187 6.3187.5Ammonia 25 17 2.5187.5Butadiene 2 4.4 1.337.5Carbon dioxide 5000 9000 62.537 500Carbon monoxide 25 29 1.3125Chlorine 0.5 1.5 0.36.3Ethanol 100
46、0 1881 1253125Ethyl acetate 400 1440 62.51250Formaldehyde C0.3BC0.37B0.132.5Hydrogen chloride C5BC7.5B1.325Hydrogen cyanide C4.7BC551.325Hydrogen peroxide 1 1.4 0.635Hydrogen sulfide 10 14 1.337.5Methyl ethyl ketone 200 590 2.575Nitrogen dioxide 3 5.6 0.125Olefin . . 12.5250Perchloroethylene 25 170 3.1187.5Sulfur dioxide 2 5.2 0.618.8Toluene 50 188 12.5250Trichloroethylene 50 269 3.1125Water vapor . . 0.6312.5 mg/lAValues for ppm(v) and mg/m3are Time-Weighted Average (TWA).BC = Ceiling limit.D4599034
