EPA Method 25

1201METHOD25-DETERMINATIONOFTOTALGASEOUSNONMETHANEORGANICEMISSIONSASCARBON1.0ScopeandApplication.1.1Analytes.AnalyteCASNo.SensitivityTotalgaseousnonmethaneorganiccompounds(TGNMO)N/ADependentuponanalyticalequipment1.2Applicability.1.2.1Thismethodisapplicableforthedeterminationofvolatileorganiccompounds(VOC)(measuredastotalgaseousnonmethaneorganics(TGNMO)andreportedascarbon)instationarysourceemissions.Thismethodisnotapplicableforthedeterminationoforganicparticulatematter.1.2.2ThismethodisnottheonlymethodthatappliestothemeasurementofVOC.Costs,logistics,andotherpracticalitiesofsourcetestingmaymakeothertestmethodsmoredesirableformeasuringVOCcontentsofcertaineffluentstreams.ProperjudgmentisrequiredindeterminingthemostapplicableVOCtestmethod.Forexample,dependinguponthemolecularcompositionoftheorganicsintheeffluentstream,atotallyautomatedsemicontinuousnonmethaneorganics(NMO)analyzerinterfaceddirectlytothesourcemayyieldaccurateresults.This1202approachhastheadvantageofprovidingemissiondatasemicontinuouslyoveranextendedtimeperiod.1.2.3Directmeasurementofaneffluentwithaflameionizationdetector(FID)analyzermaybeappropriatewithpriorcharacterizationofthegasstreamandknowledgethatthedetectorrespondspredictablytotheorganiccompoundsinthestream.Ifpresent,methane(CH4)will,ofcourse,alsobemeasured.TheFIDcanbeusedunderanyofthefollowinglimitedconditions:(1)whereonlyonecompoundisknowntoexist;(2)whentheorganiccompoundsconsistofonlyhydrogenandcarbon;(3)wheretherelativepercentagesofthecompoundsareknownorcanbedetermined,andtheFIDresponsestothecompoundsareknown;(4)whereaconsistentmixtureofthecompoundsexistsbeforeandafteremissioncontrolandonlytherelativeconcentrationsaretobeassessed;or(5)wheretheFIDcanbecalibratedagainstmassstandardsofthecompoundsemitted(solventemissions,forexample).1.2.4AnotherexampleoftheuseofadirectFIDisasascreeningmethod.Ifthereisenoughinformationavailabletoprovidearoughestimateoftheanalyzeraccuracy,theFIDanalyzercanbeusedtodeterminetheVOCcontentofanuncharacterizedgasstream.Withasufficientbuffertoaccountforpossibleinaccuracies,thedirectFID1203canbeausefultooltoobtainthedesiredresultswithoutcostlyexactdetermination.1.2.5Insituationswhereaqualitative/quantitativeanalysisofaneffluentstreamisdesiredorrequired,agaschromatographicFIDsystemmayapply.However,forsourcesemittingnumerousorganics,thetimeandexpenseofthisapproachwillbeformidable.2.0SummaryofMethod.2.1Anemissionsampleiswithdrawnfromthestackataconstantratethroughaheatedfilterandachilledcondensatetrapbymeansofanevacuatedsampletank.Aftersamplingiscompleted,theTGNMOaredeterminedbyindependentlyanalyzingthecondensatetrapandsampletankfractionsandcombiningtheanalyticalresults.TheorganiccontentofthecondensatetrapfractionisdeterminedbyoxidizingtheNMOtocarbondioxide(CO2)andquantitativelycollectingintheeffluentinanevacuatedvessel;thenaportionoftheCO2isreducedtoCH4andmeasuredbyanFID.TheorganiccontentofthesampletankfractionismeasuredbyinjectingaportionofthesampleintoagaschromatographiccolumntoseparatetheNMOfromcarbonmonoxide(CO),CO2,andCH4;theNMOareoxidizedtoCO2,reducedtoCH4,andmeasuredbyanFID.Inthismanner,the1204variableresponseoftheFIDassociatedwithdifferenttypesoforganicsiseliminated.3.0Definitions.[Reserved]4.0Interferences.4.1CarbonDioxideandWaterVapor.Whencarbondioxide(CO2)andwatervaporarepresenttogetherinthestack,theycanproduceapositivebiasinthesample.ThemagnitudeofthebiasdependsontheconcentrationsofCO2andwatervapor.Asaguideline,multiplytheCO2concentration,expressedasvolumepercent,timesthewatervaporconcentration.Ifthisproductdoesnotexceed100,thebiascanbeconsideredinsignificant.Forexample,thebiasisnotsignificantforasourcehaving10percentCO2and10percentwatervapor,butitmightbesignificantforasourcehaving10percentCO2and20percentwatervapor.4.2.ParticulateMatter.Collectionoforganicparticulatematterinthecondensatetrapwouldproduceapositivebias.Afilterisincludedinthesamplingequipmenttominimizethisbias.5.0Safety.5.1Disclaimer.Thismethodmayinvolvehazardousmaterials,operations,andequipment.Thistestmethodmaynotaddressallofthesafetyproblemsassociatedwithitsuse.Itistheresponsibilityoftheuserofthistest1205methodtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortoperformingthistestmethod.6.0EquipmentandSupplies.6.1SampleCollection.Thesamplingsystemconsistsofaheatedprobe,heatedfilter,condensatetrap,flowcontrolsystem,andsampletank(seeFigure25-1).TheTGNMOsamplingequipmentcanbeconstructedfromcommerciallyavailablecomponentsandcomponentsfabricatedinamachineshop.Thefollowingequipmentisrequired:6.1.1HeatedProbe.6.4-mm(¼-in.)ODstainlesssteeltubingwithaheatingsystemcapableofmaintainingagastemperatureattheexitendofatleast129EC(265EF).Theprobeshallbeequippedwithatemperaturesensorattheexitendtomonitorthegastemperature.AsuitableprobeisshowninFigure25-1.Thenozzleisanelbowfittingattachedtothefrontendoftheprobewhilethetemperaturesensorisinsertedinthesidearmofateefittingattachedtotherearoftheprobe.Theprobeiswrappedwithasuitablelengthofhightemperatureheatingtap