Machine for imparting energy to a fluid, causing it to do work
* Centrifugal pump: Pump having a stationary element (casing) and a rotary element (impeller) fitted with vanes or blades arranged in a circular pattern around an inlet opening at the center. The casing surrounds the impeller and usually has the form of a scroll or volute
* Diaphragm pump: Type of pump in which water is drawn in and forced out of one or more chambers by a flexible diaphragm. Check valves let water into and out of each chamber
* Positive displacement pump: Has an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses. Examples of positive displacement pumps include reciprocating pumps and rotary pumps
* Reciprocating pump: A back-and-forth motion of pistons inside of cylinders provides the flow of fluid. Reciprocating pumps, like rotary pumps, operate on the positive principle. That is each stroke delivers a definite volume of liquid to the system
* Rotary pump: Pumps that deliver a constant volume of liquid regardless of the pressure they encounter. A constant volume is pumped with each rotation of the shaft and this type of pump is frequently used as a priming pump