Designation:D4490−96(Reapproved2011)StandardPracticeforMeasuringtheConcentrationofToxicGasesorVaporsUsingDetectorTubes1ThisstandardisissuedunderthefixeddesignationD4490;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversthedetectionandmeasurementofconcentrationsoftoxicgasesorvaporsusingdetectortubes(1,2).2Alistofsomeofthegasesandvaporsthatcanbedetectedbythispractice,their1994–95TLVvaluesrecommendedbytheACGIH,andtheirmeasurementrangesareprovidedinAnnexA1.Thislistisgivenasaguideandshouldbeconsideredneitherabsolutenorcomplete.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:3D1356TerminologyRelatingtoSamplingandAnalysisofAtmospheres2.2OtherDocument:29CFR1910FederalOccupationalSafetyandHealthStandardTitle2943.Terminology3.1Fordefinitionsoftermsusedinthismethod,refertoTerminologyD1356.4.SummaryofPractice(3)4.1Detectortubesmaybeusedforeithershort-termsam-pling(grabsampling;1to10mintypically)orlongtermsampling(activelyorpassively;1to8h)ofatmospherescontainingtoxicgasesorvapors.4.1.1Short-TermSampling(GrabSampling)(4-18)—Agivenvolumeofairispulledthroughthetubebyamechanicalpump.Ifthesubstanceforwhichthedetectortubewasdesignedispresent,theindicatorchemicalinthetubewillchangecolor(stain).Theconcentrationofthegasorvapormaybeestimatedbyeither(a)thelength-of-staincomparedtoacalibrationchart,or(b)theintensityofthecolorchangecomparedtoasetofstandards.4.1.2Long-TermActiveSampling(Long-TermTubes)(19-22)—Asampleispulledthroughthedetectortubeataslow,constantflowratebyanelectricalpump.Thetime-weightedaverageconcentrationoft...
