Designation:D5191−22StandardTestMethodforVaporPressureofPetroleumProductsandLiquidFuels(MiniMethod)1ThisstandardisissuedunderthefixeddesignationD5191;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thistestmethodcoverstheuseofautomatedvaporpressureinstrumentstodeterminethetotalvaporpressureexertedinvacuumbyair-containing,volatile,liquidpetroleumproductsandliquidfuels,includingautomotivespark-ignitionfuelswithorwithoutoxygenatesandwithethanolblendsupto85%(volumefraction)(seeNote1).Thistestmethodissuitablefortestingsampleswithboilingpointsabove0°C(32°F)thatexertavaporpressurebetween7kPaand130kPa(1.0psiand18.6psi)at37.8°C(100°F)atavapor-to-liquidratioof4:1.Measurementsaremadeonliquidsamplesizesintherangefrom1mLto10mL.Noaccountismadefordissolvedwaterinthesample.NOTE1—Theprecision(seeSection16)using1Lcontainerswasdeterminedina2003interlaboratorystudy(ILS);2theprecisionusing250mLcontainerswasdeterminedina2016ILS.3NOTE2—Samplescanalsobetestedatothervapor-to-liquidratios,temperatures,andpressures,buttheprecisionandbiasstatementsneednotapply.NOTE3—TheILSconductedin1988,1991,2003,and2016todeterminetheprecisionstatementsinTestMethodD5191didnotincludeanycrudeoilinthesamplesets.TestMethodD6377,aswellasIP481,havebeenshowntobesuitableforvaporpressuremeasurementsofcrudeoils.1.1.1Somegasoline-oxygenateblendsmayshowahazewhencooledto0°Cto1°C.Ifahazeisobservedin8.5,itshallbeindicatedinthereportingofresults.Theprecisionandbiasstatementsforhazysampleshavenotbeendetermined(seeNote15).1.2Thistestmethodissuitableforcalculationofthedryvaporpressureequivalent(DVPE)ofgasolineandgasoline-oxygenateblendsbymeansofacorrelationequation(seeEq1in14.2).ThecalculatedDVPEverycloselyapproximatesthedryvapo...
