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[pdender]

can you explain the difference between the two procedures (ASTM 323 vs. D6377 ) for Reid Vapor Pressure simulated by Prode Properties ?

I have a copy of D323 starndard but I know little of D6377 (I read that it has been approved by US EPA as alternative test method for measuring vapour pressure of crude oils)

does Prode Properties simulate the D6377 procedure or simply return the true vapor pressure of mixture ?

 

[serra]

with D6377 vapor pressure is (normally) determined (as for D323) at a vapor-liquid ratio of 4:1 (37.8 C) , chilling of the sample prior to the measurement is not required : crude oil is collected in a pressurized chamber to keep the volatiles inside.
values from ASTM D6377 can be correlated with ASTM D323 (there are several papers discussing the details),

Prode Properties can simulate both ASTM D323 and ASTM D6377 with the method StrRVP() in library,
see operating manual for details (http://www.prode.com/docs/pppman.pdf)

for mixtures the calculated values are different from the True Vapor Pressure calculated with the method PfPF() or equivalent (i.e. the Excel macros =LfPF(stream,p,lf) or = PfPF(stream,p,pf,pt) etc.) again, see the manual for details...

 

of course , for crude oil, you need a good estimate of the different fractions before to proceed (see characterization procedures)