jjfa
Mechanical
- Apr 13, 2004
- 9
I would like to know the equivalence between API grade and cP or cStoke viscosity.
Thanks a lot
Thanks a lot
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Equivalence
- Thread starter jjfa
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API gravity is an indictation of specific gravity relative to pure water.
SG(oil) = 141.5/(131.5+API Gravity)
The current Petroleum Engineer's Handbook by Bradley has a chart to go from oil specific gravity to kinematic viscosity (centistokes). Earlier versions went from API to viscosity, but the whole "degree API" always got confused with a temperature correction.
David Simpson, PE
MuleShoe Engineering
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
SG(oil) = 141.5/(131.5+API Gravity)
The current Petroleum Engineer's Handbook by Bradley has a chart to go from oil specific gravity to kinematic viscosity (centistokes). Earlier versions went from API to viscosity, but the whole "degree API" always got confused with a temperature correction.
David Simpson, PE
MuleShoe Engineering
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
cSt is kinematic viscosity and is in mm2/sec
This is correlated to the dynamic viscosity by multiplying with the density and correcting for units.
cP=0.001 Pa*sec=0.001 kg/(m*sec)
So if you have that water has a vicosity of 1 cSt and a density of 1000 kg/m3 then:
1cSt= 1*1000/1000000 = 0.001 Pa*sec = 1cP
Best regards
Morten
This is correlated to the dynamic viscosity by multiplying with the density and correcting for units.
cP=0.001 Pa*sec=0.001 kg/(m*sec)
So if you have that water has a vicosity of 1 cSt and a density of 1000 kg/m3 then:
1cSt= 1*1000/1000000 = 0.001 Pa*sec = 1cP
Best regards
Morten
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