Europump European Association of Pump Manufacturers

There are two principal classifications of pump, defined by their fundamental mode of operation. These are dynamic pumps and displacement pumps.

Less familiar types with more limited usage include ejectors, pulsators, gas lift pumps, hydraulic elevators and various miscellaneous types difficult to classify.

Note that both positive displacement (PD) and centrifugal (CP) pumps are broad descriptions.

Positive displacement pumps break down into reciprocating and rotary pumps, each type available in a range of configurations. For rotary pumps, the key element is a rotor which may be designed as an impeller, vane or screw. Displacement pumps include many other types apart from reciprocating and rotary units e.g., bucket, scoop, wheel, ejectors, pulsators etc. Note, however, that some types are neither displacement nor turbo machines in characteristics, in which case sub-classification is more of academic than practical interest.

A displacement pump causes a fluid to move by trapping a fixed amount of it and then forcing (displacing) that trapped volume into the discharge pipe. In a dynamic pump by contrast, kinetic energy is added to the fluid by increasing the flow velocity. This increase in energy is converted to a gain in potential energy (pressure) when the velocity is reduced before or as the flow exits the pump into the discharge pipe. Accordingly, pumps can be divided into dynamic or displacement categories.