Help with Base oil viscosity on grease

AI Thread Summary
Base oil viscosity in grease is measured in centistokes (cSt) and is equivalent to mm²/s, as both represent kinematic viscosity. The term "Stokes" refers to the original unit of measurement, with 1 Stokes equal to 1 cm²/s and 1 centistoke being 1/100 of a Stokes. The discussion clarifies that there is no difference between a grease rated at 200 cSt and 200 mm²/s; they are simply different expressions of the same measurement. Additionally, the kinematic viscosity of water at approximately 20°C is about 1 mm²/s, which helps contextualize these values. Understanding these units is crucial for accurately assessing grease performance.
sid_raptor
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hi all
can someone explain me the units of Base oil viscosity of grease?
for example is there a difference between grease rated at 200cSt and 200 mm2/s
if so then what is the meaning of cSt and what does it stand for?

thanks
 
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They are the same units for kinematic viscosity. The unit of viscosity in the centimeter-gram-second system was called the Stokes (after the physicist who first studied it, discovered Stokes' Law, etc).

1 Stokes = 1 cm2/sec
1 centistoke = 1/100 Stokes = 1 mm2/sec

The SI unit for kinematic viscosity doesn't have any special name.

FWIW the kinematic viscosity of water at about 20C is 1 mm^2/sec, which may explain why values are usually given in mm^2/sec not m^2/sec (which is the basic SI unit).
 
so cSt is centistokes then? lol why did i not think of that!
thanks for your help mate! much appreciated!
 
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