Positive displacement pumps trap a volume of fluid and discharge it. They are capable of forcing the flow against very high discharge pressure. Positive displacement pumps may be of a rotating design. However, most are of a reciprocating design.

Rotating positive displacement pumps include; gear pumps, hose pumps, screw pumps, progressive cavity pumps, rotary lobe pumps, rotary vane pumps, and sliding vane pumps.

Reciprocating positive displacement pumps include; diaphragm pumps, piston pumps, and plunger pumps.

Positive displacement pumps are often used in metering applications where either the rpms or the stroke frequency or the stroke length are controlled to provide a specific flow rate.