ABSTRACT

There are three main categories of pump: (a) reciprocating, (b) rotary, and (c) rotodynamic. The first two operate on the principle of positive displacement - that is to say they discharge, apart from any leakage, a definite quantity of fluid irrespective of the head pumped against. Rotodynamic is the title given to the third category because a rotating element, known as an impeller, imparts velocity to a liquid and generates pressure. An outer fixed casing, shaft, and driving motor complete the pump unit.