Viscosity Definitions

Absolute Viscosity:

the force required to move a unit plane surface over another plane surface at unit velocity when surfaces are separated by a layer of fluid of unit thickness.

Unit of Absolute Viscosity in the metric system:

poise and centipoise1 poise = 1 gram / (cm) (sec) and1 centipoise = 1/100 poise

Unit of Absolute Viscosity in the English system:

slugs / (ft) (sec);1 slug / (ft) (sec) = 1 / 0.002089 poise

Kinematic Viscosity:

the absolute viscosity divided by density.

Unit of Kinematic Viscosity in the metric system and commonly used in the countries using the English system:

stoke and centistoke;

1 stoke = 1 poise / density (gm / mL)

1 centistoke = 1/100 stoke

Other units of Kinematic Viscosity in the English system, the most practical unit for making calculations is ft² / sec; 1 ft² / sec = 92903 centistoke and 1 centistoke = 1.076 x 10-5 ft² / sec