ASTM D8236-18

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8236 − 18
Standard Practice for
Preparing an Equilibrium Liquid/Vapor Sample of Live Crude
Oil, Condensates, or Liquid Petroleum Products Using a
Manual Piston Cylinder for Subsequent Liquid Analysis or
1
Gas Analysis
This standard is issued under the fixed designation D8236; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope nitrogen, carbon dioxide, carbon monoxide, hydrogen sulfide,
C1 to C7 hydrocarbons at levels consistent with the Test
1.1 This practice covers the preparation of an equilibrium
Method D7833 method used. The equilibrium liquid phase can
gas sample of live crude oil, condensate, or liquid petroleum
be subsequently analyzed by Test Method D8003 to obtain
products, using a Practice D8009 manual piston cylinder
paired analytical results on both the equilibrium liquid and
(MPC) as a vapor tight expansion chamber to generate an
vapor pair with a sealed sample system.
equilibrium vapor/liquid pair at a known temperature and
vapor/liquid ratio (V/L). Inert gas such as helium or argon is
1.4 Addition of the diluent gas provides a positive pressure
injected to the equilibrium vapor space of the MPC to provide
sample to allow the use of a typical RGA-type gas injection
an equilibrium vapor sample sufficiently above atmospheric
system that operates only slightly above barometric pressure.
pressure for subsequent analysis using a standard refinery gas
The preferred diluent gas shall be the same as the carrier gas
analyzer (RGA) such as described in Test Method D7833.
used in the RGA(typically helium or argon). Choice of diluent
Other gas analysis methods may be used provided they meet
or carrier gas may affect the ability to detect some inert gases
the minimum performance criteria stated in 7.4.1.
(especially O or H ) in some RGAconfigurations conforming
2 2
1.2 This practice is suitable for UN Class 3 Liquid samples
to Test Method D7833.
having vapor pressures between 0 kPa and 300 kPa at 50.0 °C,
1.5 The VLE gas generation and subsequent RGAoutput is
and 0.1:1 to 4:1 vapor/liquid ratio, spanning the nominal range
usedasascreeningmethodtoidentifygascomponentsthatcan
near bubble point (Test Method D6377 VPCr,0.1) to Test
be present in the crude oil affecting the total vapor pressure.
Methods D323 (RVP), D4953, and D5191 (V/L=4). The
The RGA output only represents the equilibrium vapor com-
temperature may vary over a wide range, provided that the
ponents present and relative to one another. Due to dilution of
cylinder is maintained at isothermal and isobaric conditions to
the VLE gas with inert gas, the RGA output does not purport
prevent condensation of equilibrium vapor upon cooling either
to accurately provide the actual vapor composition at VLE
in the cylinder or in the injection system of the Refinery Gas
Analyzer (RGA, Test Method D7833). The method is best conditions and is definitely not representative of the composi-
tion of the whole sample.
suited for preparation of an equilibrium gas/liquid pair near
ambient conditions, typical of routine daily operations in a
1.6 The values stated in SI units are to be regarded as
typical refinery quality assurance or marine terminal
standard. The values given in parentheses after SI units are
laboratory, to routinely monitor the light ends content of crude
provided for information only and are not considered standard.
oil receipts.
1.7 This standard does not purport to address all of the
1.3 This practice is suitable to prepare an equilibrium
safety concerns, if any, associated with its use. It is the
liquid/vapor sample pair in a sealed sampling system (no light
responsibility of the user of this standard to establish appro-
ends loss from either phase). The equilibrium gas phase is
priate safety, health, and environmental practices and deter-
suitable for subsequent gas analysis of both hydrocarbon and
mine the applicability of regulatory limitations prior to use.
fixed/inert gases in the sample, including: hydrogen, oxygen,
1.8 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
ization established in the Decision on Principles for the
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
Development of International Standards, Guides and Recom-
mittee D02.08 on Volatility.
mendations issued by the World Trade
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