parker PAVC piston pump

Single stage pump – When a casing contains only one revolving impeller, it is called a single stage pump.

Double/multi-stage pump – When a casing contains two or more revolving impellers, it is called a double or multi-stage pump.

In biology, many different types of chemical and bio-mechanical pumps have evolved, and biomimicry is sometimes used in developing new types of mechanical pumps.