Volute pump

A volute pump is a single-stage centrifugal pump whose casing forms a spiral volute that collects flow leaving the impeller and converts velocity into pressure as the cross-section widens toward the discharge. It is the common workhorse for sea water cooling, fresh water, fire, and general service duties, handling moderate head at moderate to high flow. The volute replaces the diffuser vanes of a multi-stage pump with a simpler curved passage, which is cheaper and tolerant of varying flow. Performance follows the affinity laws: flow scales with speed, head with the square of speed, and power with the cube.