Designation:D3238−17aStandardTestMethodforCalculationofCarbonDistributionandStructuralGroupAnalysisofPetroleumOilsbythen-d-MMethod1ThisstandardisissuedunderthefixeddesignationD3238;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodcoversthecalculationofthecarbondistributionandringcontent(Note1)ofolefin-freepetroleumoilsfrommeasurementsofrefractiveindex,density,andmolecularweight(n-d-M).2Thistestmethodshouldnotbeappliedtooilswhosecompositionsareoutsidethefollowingranges:1.1.1Intermsofcarbondistribution—upto75%carbonatomsinringstructure;percentageinaromaticringsnotlargerthan1.5timesthepercentageinnaphthenicrings.1.1.2Intermsofringcontent—uptofourringspermoleculewithnotmorethanhalfofthemaromatic.Acorrectionmustbeappliedforoilscontainingsignificantquantitiesofsulfur.NOTE1—Thecompositionofcomplexpetroleumfractionsisoftenexpressedintermsoftheproportionsofaromaticrings(RA),naphthenerings(RN),andparaffinchains(CP)thatwouldcompriseahypotheticalmeanmolecule.Alternatively,thecompositionmaybeexpressedintermsofacarbondistribution,thatis,thepercentageofthetotalnumberofcarbonatomsthatarepresentinaromaticringstructures(%CA),naphtheneringstructures(%CN),andparaffinchains(%Cp).1.2ThevaluesstatedinSIunitsaretoberegardedasthestandard.1.2.1Exception—Thevaluesinparenthesesareforinforma-tiononly.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.4Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInternationalStandards,GuidesandRecom-mendat...
