Pumps fall into two categories: positive displacement, kinetic (centrifugal). Their names describe the method for moving water.

 

A positive displacement pump causes water to move by trapping a fixed volume of water and then forcing (displacement) that trapped volume into the receiving pipe. Positive displacement pumps can be further classified as either rotary-type (for example the rotary lobe pump ) or reciprocating-type (for example the diaphragm pump).

A centrifugal pump causes water to move by transfering the kinetic (rotational) energy from a motor (through an impeller) into water pressure (potential energy).