Description
The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress and its measurements are performed using viscometers or rheometers. Rheometer is used for those fluids which cannot be defined by a single value of viscosity and therefore require more parameters to be set and measured than is the case for a viscometer. Classic viscometers are simple glass capillary devices while modern automatic machines use falling ball, oscillating piston, vibrating plate, rotational or other measurement method and perform calculations providing user with processed data.