Positive Displacement Pumps

A positive displacement pump works by capturing a given volume of liquid at the suction of the pump, and then mechanically forcing it out of the discharge at a higher pressure. In contrast to centrifugal pumps, in which the flow is affected by downstream pressure, positive displacement pumps (within the limitations of the driver) deliver a nearly constant flow, independent of the downstream pressure. Positive displacement pumps can be categorized as reciprocating or rotary action pumps. This course describes the general characteristics of positive displacement pumps and the principles of operation of various common designs.