Facts about the ASTM D6377 Standard Test Method
The ASTM D6377 test method measures the vapor pressure of crude oil. This expansion method is used for automated vapor pressure instruments to determine the vapor pressure exerted in vacuum of crude oils. It can be used either for live crude oil, which has to be sampled under pressure, or dead crude oil which does not include gases.
The marking live crude oil is used for crude oils in pressurized systems that will result in actual boiling of the sample when brought to normal atmospheric pressure at room temperature.
The marking dead crude oil is used for crude oils that will not result in actual boiling of the sample when exposed to normal atmospheric pressure at room temperature.
With this method, the vapor pressure determined at a vapor-liquid ratio of 4:1 of crude oil is measured at 37.8°C. The operator can decide between vapor-liquid ratios from 4:1 to 0.02:1. (Andreas Schwarzmann, R&D)
The results measured with ASTM D6377 can be correlated with ASTM D323. With ASTM D6377, the chilling of the sample prior to the measurement is not required. The test method can also be applied in online applications which can not perfom air saturation procedures prior to the measurement. The method is suitable for testing samples that exert a vapor pressure between 25 and 180 kPa at 37.8°C at vapor-liquid ratios from 4:1 to 0.02:1. Above that, it allows the determination of vapor pressure for crude oil samples having pour points above 0°C.
RVPE = A x VPCR4 (37.8°C)
A = 0.834 (for samples in pressurized floating piston cylinders)
A = 0.915 (for samples in nonpressurized 1-L sample containers)