5.1 Vapor pressure of crude oil at various vapor/liquid ratios is an important physical property for transport, storage, and refinery operations.

5.2 Vapor pressure of crude oil is important to crude oil producers, regulators, transporters and refiners for general handling, transportation, and initial refinery treatment.

5.3 The direct sample collection and subsequent, in place, vapor pressure measurement without the need for further sample handling eliminates the potential loss of light hydrocarbon material from the sample. The combination of sampling and testing may produce higher results than Test Method D323.

5.4 Chilling and air saturation of the sample prior to the vapor pressure measurement (as required in Test Method D323) is not required in this test method.

1.1 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.

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

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

1.4 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.

1.5 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).

1.6 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.

1.7 The values stated in SI units are to be regarded as standard.

1.7.1 Exception—Other units of measurement are included in this standard for ease of use in multiple jurisdictions.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.