ASTM_D_8236_-_18.pdf

Designation:D823618Standard Practice forPreparing an Equilibrium Liquid/Vapor Sample of Live CrudeOil,Condensates,or Liquid Petroleum Products Using aManual Piston Cylinder for Subsequent Liquid Analysis orGas Analysis1This standard is issued under the fixed designation D8236;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the preparation of an equilibriumgas sample of live crude oil,condensate,or liquid petroleumproducts,using a Practice D8009 manual piston cylinder(MPC)as a vapor tight expansion chamber to generate anequilibrium vapor/liquid pair at a known temperature andvapor/liquid ratio(V/L).Inert gas such as helium or argon isinjected to the equilibrium vapor space of the MPC to providean equilibrium vapor sample sufficiently above atmosphericpressure for subsequent analysis using a standard refinery gasanalyzer(RGA)such as described in Test Method D7833.Other gas analysis methods may be used provided they meetthe minimum performance criteria stated in 7.4.1.1.2 This practice is suitable for UN Class 3 Liquid sampleshaving vapor pressures between 0 kPa and 300 kPa at 50.0 C,and 0.1:1 to 4:1 vapor/liquid ratio,spanning the nominal rangenear bubble point(Test Method D6377 VPCr,0.1)to TestMethods D323(RVP),D4953,and D5191(V/L=4).Thetemperature may vary over a wide range,provided that thecylinder is maintained at isothermal and isobaric conditions toprevent condensation of equilibrium vapor upon cooling eitherin the cylinder or in the injection system of the Refinery GasAnalyzer(RGA,Test Method D7833).The method is bestsuited for preparation of an equilibrium gas/liquid pair nearambient conditions,typical of routine daily operations in atypical refinery quality assurance or marine terminallaboratory,to routinely monitor the light ends content of crudeoil receipts.1.3 This practice is suitable to prepare an equilibriumliquid/vapor sample pair in a sealed sampling system(no lightends loss from either phase).The equilibrium gas phase issuitable for subsequent gas analysis of both hydrocarbon andfixed/inert gases in the sample,including:hydrogen,oxygen,nitrogen,carbon dioxide,carbon monoxide,hydrogen sulfide,C1 to C7 hydrocarbons at levels consistent with the TestMethod D7833 method used.The equilibrium liquid phase canbe subsequently analyzed by Test Method D8003 to obtainpaired analytical results on both the equilibrium liquid andvapor pair with a sealed sample system.1.4 Addition of the diluent gas provides a positive pressuresample to allow the use of a typical RGA-type gas injectionsystem that operates only slightly above barometric pressure.The preferred diluent gas shall be the same as the carrier gasused in the RGA(typically helium or argon).Choice of diluentor carrier gas may affect the ability to detect some inert gases(especially O2or H2)in some RGA configurations conformingto Test Method D7833.1.5 The VLE gas generation and subsequent RGA output isused as a screening method to identify gas components that canbe present in the crude oil affecting the total vapor pressure.The RGA output only represents the equilibrium vapor com-ponents present and relative to one another.Due to dilution ofthe VLE gas with inert gas,the RGA output does not purportto accurately provide the actual vapor composition at VLEconditions and is definitely not representative of the composi-tion of the whole sample.1.6 The values stated in SI units are to be regarded asstandard.The values given in parentheses after SI units areprovided for information only and are not considered standard.1.7 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.08 on Volatility.Current edition approved Dec.15,2018.Published February 2019.DOI:10.1520/D8236-18.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Stan