Designation:D7493−14StandardTestMethodforOnlineMeasurementofSulfurCompoundsinNaturalGasandGaseousFuelsbyGasChromatographandElectrochemicalDetection1ThisstandardisissuedunderthefixeddesignationD7493;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodisforon-linemeasurementofvolatilesulfur-containingcompoundsingaseousfuelsbygaschroma-tography(GC)andelectrochemical(EC)detection.Thistestmethodisapplicabletohydrogensulfide,C1toC4mercaptans,sulfidesandtetrahydrothiophene(THT).1.1.1Carbonylsulfide(COS)isnotcoveredinthistestmethod.1.1.2Thedetectionrangeforsulfurcompoundsisapproxi-matelyfrom0.1to100ppmv(mL/m3)or0.1to100mg/m3.Thedetectionrangemayvarydependingonthesampleinjectionvolume,chromatographicpeakseparationandthesensitivitytothespecificECdetector.1.2ThistestmethoddescribesaGC-ECmethodemployingpackedGCcolumnsandaspecificdetectorfornaturalgasandothergaseousfuelcomposedofmainlylight(C4andsmaller)hydrocarbons.AlternativeGCcolumns,detectordesignsandinstrumentparametersmaybeused,providedthatchromato-graphicseparation,qualitycontrolandmeasurementobjectivesneededtocomplywithuser,orregulatorneedsorboth,areachieved.1.3Thistestmethoddoesnotintendtoidentifyandmeasureallindividualsulfurspecies,andismainlyemployedformonitoringnaturallyoccurringreducedsulfurcompoundscommonlyfoundinnaturalgasandfuelgasesoremployedasanodorantinthesegases.1.4Thetestmethodistypicallyemployedinrepetitiveorcontinuouson-linemonitoringofsulfurcomponentsinnaturalgasandfuelgasesusingasinglesulfurcalibrationstandard.NeedforamultipointcalibrationcurveorqualitycontrolprocedurescanbesatisfiedbymakinguseofproceduresdelineatedinTestMethodsD5504,D5623,D6228,D6968,ISO19739,orGPA2199.1.5ThetestmethodcanbeusedformeasurementofallsulfurcompoundslistedinTable1inairorothergaseousmatrices,provid...
