HIGH SHEAR MIXERS

High shear mixers are used in industry to produce standard mixtures of ingredients that do not naturally mix. When the total fluid is composed of two or more liquids, the final result is an emulsion; when composed of a solid and a liquid, it is termed a suspension and when a gas is dispersed throughout a liquid, the result is a Lysol. Each class may or may not be homogenized, depending on the amount of input energy.

To achieve a standard mix, the technique of equilibrium mixing is used. A target characteristic is identified, such that once the mixed product has acquired that characteristic, it will not change significantly thereafter, no matter how long the product is processed.

Fluid undergoes shear when one area of fluid travels with a different velocity relative to an adjacent area. A high-shear mixer uses a rotating impeller or high-speed rotor, or a series of such impellers or inline rotors, usually powered by an electric motor, to "work" the fluid, creating flow and shear. The tip velocity, or speed of the fluid at the outside diameter of the rotor, will be higher than the velocity at the centre of the rotor, and it is this velocity difference that creates shear.