API for Crude at standard condition

[engmsh]

i ask if the pressure have create effect at API value for crude oil as do temperature?
also if crude oil have API=33 at 33.3 psi and 70 F temp.
what this API will be at at 14.7 psi and 60 F temp (standard condition)

 

[CJKruger]

By definition API density is based on 60F.

 

[dcasto]

If the crude oil has a vapour pressure greater than atmosphere, then the gravity is measured at 60F and at bubble point. Even Propane has an API gravity even though there is not such thing as liquid propane at 60F and 14.696 psia.

 

[jmw]

The Manual of Petroelum Measurement Standards details both the temperature and pressure effects on density.
API comes from density at reference conditions so if your starting point is density measured at line temperature and pressure, then you need to apply these correction before you can convert to API degrees.

JMW

http://www.ViscoAnalyser.com

 

[engmsh]

but i think that the pressure don't have great effect on density because of liquid low compressibility

 

[whammett]

Engmsh is correct, and increased pressure shouldnt matter, but avoid sub-atmospheric pressures (<14.7psia).


Will Chevron Corp.

 

[engmsh]

i don't have The Manual of Petroleum Measurement Standards
can any one check this conversion for me in it

rude oil have API=33 at 33.3 psi and 70 F temp.
what this API will be at at 14.7 psi and 60 F temp (standard condition)

 

[Domz]

API temperature and pressure Volume Correction Factor standard, Chapter 11.1 (Adjunct to ASTM D 1250-04 and IP 200/04) is the latest version available to calculate VCF and density conversion

In Your Case you should use Section 11.1.6.3 which gives the method to convert Volume and Density from Observed Condition to Alternate Condition. (standard condition means 60 DegF & 0 PSI)

Obs density: 33 API
Obs Pr = 33.3 Psi
obs Temp = 70 DegF

Alt Pr = 14.7 Psi
Alt Temp = 60 DegF

Result
Alt density = 32.26 API