Newtonian liquid

As per DIN 1342, the Newtonian liquid is defined as an isotropic, purely viscous liquid (see Viscosity), whose behaviour is subject to Newton's law of viscosity:

In fundamental terms, dynamic viscosity (η) depends only upon temperature.

Examples of Newtonian liquids are water and mineral oils from distillates that are handled by conventional centrifugal pumps.

Non-Newtonian liquids include sewage sludges and fine-grained mineral sludges (solids transport of sand, coal or ore) but also oils if their temperature is nearing the solidification point.

Pumping a non-Newtonian liquid by means of centrifugal pumps is sometimes only possible or efficient if the fluid handled has been heated. Such fluids' flow characteristics (see Pulp pumping)have an influence on pressure losses in the piping as well as the selection of centrifugal pumps.