ASTM_D_4490_-_96_2011.pdf

Designation:D449096(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 revision,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 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 should 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 regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3D1356 Terminology Relating to Sampling and Analysis ofAtmospheres2.2 Other Document:29 CFR 1910Federal 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 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)Agiven 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 acalibration 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 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)(23)The contaminant 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 of 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.5.Significance and Use5.1 TheFederalOccupationalSafetyandHealthAdministration,in 29 CFR 1910,designates that certain gasesand vapors 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 isapplicable is presented in Annex A1.1This practice is under the jurisdiction ofASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.04 on Workplace 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 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 Regulations,Part 1910.1000 Subpart 2 and Part 1926.55Subpart D.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.4 This practice also provides for the sampling of gaseousatmospheres to be used for process control or other purposes(2,24-23).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 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