2016-04-18

Safe transport and handling of crude oil and condensate streams requires diligent monitoring of the vapor pressure of these products. Where it is not practical to have an ASTM D6377 instrument onsite such as at an oil gathering battery, trans-loading or rail-loading terminal, a field version of the method was developed as ASTM D7975. The D7975 test method utilizes the same principle of operation as the D6377 test method by expanding a sample of test fluid to a specified vapor/liquid ratio and measuring the resulting pressure. The drawback of the D7975 test method is that is does not allow for accurate temperature control of the test cell and thus results are difficult to compare to laboratory results performed using D6377 as well to operational or product specifications.

The paper provides nomographs and equations to allow easy correction of D7975 data to D6377 for field results comparison to operational or product specifications.