Designation:D5191−15StandardTestMethodforVaporPressureofPetroleumProducts(MiniMethod)1ThisstandardisissuedunderthefixeddesignationD5191;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thistestmethodcoverstheuseofautomatedvaporpressureinstrumentstodeterminethetotalvaporpressureexertedinvacuumbyair-containing,volatile,liquidpetroleumproducts,includingautomotivespark-ignitionfuelswithorwithoutoxygenates(seeNote1).Thistestmethodissuitablefortestingsampleswithboilingpointsabove0°C(32°F)thatexertavaporpressurebetween7kPaand130kPa(1.0psiand18.6psi)at37.8°C(100°F)atavapor-to-liquidratioof4:1.Measurementsaremadeonliquidsamplesizesintherangefrom1mLto10mL.Noaccountismadefordissolvedwaterinthesample.NOTE1—Aninterlaboratorystudywasconductedin2008involving11differentlaboratoriessubmitting15datasetsand15differentsamplesofethanol-fuelblendscontaining25volume%,50volume%,and75volume%ethanol.Theresultsindicatedthattherepeatabilitylimitsofthesesamplesarewithinthepublishedrepeatabilityofthistestmethod.onthisbasis,itcanbeconcludedthatD5191isapplicabletoethanol-fuelblendssuchasEd75andEd85(SpecificationD5798)andotherethanol-fuelblendswithgreaterthan10v%ethanol.SeeASTMRR:D02–1694filedwithASTMforsupportingdata.2NOTE2—Samplescanalsobetestedatothervapor-to-liquidratios,temperatures,andpressures,buttheprecisionandbiasstatementsneednotapply.NOTE3—Theinterlaboratorystudiesconductedin1988,1991,and2003todeterminetheprecisionstatementsinTestMethodD5191didnotincludeanycrudeoilinthesamplesets.TestMethodD6377,aswellasIP481,havebeenshowntobesuitableforvaporpressuremeasurementsofcrudeoils.1.1.1Somegasoline-oxygenateblendsmayshowahazewhencooledto0°Cto1°C.Ifahazeisobservedin8.5,itshallbeindicatedintherepor...
