ASTM International

Standard Test Method for Determination of Vapor Pressure of Crude Oil: VPCRx-F(Tm°C) (Manual Expansion Field Method)
 N D7975

Annotation

This test method covers the use of manual vapor pressure instruments to determine the vapor pressure of crude oils exerted in a vacuum. This test method is suitable for testing samples that exert a vapor pressure between 25 kPa and 180 kPa at 37.8 °C at vapor/liquid ratios from 4:1 to 0.25:1 (X = 4 to 0.25, see 3.2.4).

NOTE 1—This test method is suitable for the determination of the vapor pressure of crude oils at temperatures from 0 °C to 60 °C and pressures up to 500 kPa, but the precision and bias statements (see Section 15) may not be applicable.

This test method is meant primarily for use under field conditions for immediate evaluation of vapor pressure for storage, transport, or operational uses.

This test method is not intended for use in custody transfer applications. Test Method D6377 shall be used for custody transfer applications.

This test method provides a reasonable confirmation for the presence of light ends in the source material given that the partial pressure of low boiling components contribute significantly to total vapor pressure.

This test method allows both sample collection and subsequent vapor pressure measurement of crude oil samples directly from the sample source. The collected sample may also be transferred to an automated vapor pressure instrument such as used for Test Method D6377. The field test apparatus is suitable for transportation provided suitable over-pack is used to meet the regulations for the transportation of dangerous goods in the transportation jurisdiction(s).

This test method allows the determination of vapor pressure for crude oil samples having pour points below 0 °C and flow at the sampling conditions to allow inlet to the apparatus.