Chapter 4 - Pump Types

Abstract

There are three major types of pumps, which are further divided into subcategories. This chapter emphasizes these subcategories of pumps, which include centrifugal pumps and positive displacement pumps. In centrifugal pumps, the rotation of a series of vanes in an impeller creates pressure. There are three main categories of centrifugal pumps: axial flow, mixed flow, and radial flow. In axial-flow pumps, the pumped fluid flows along the pump drive shaft. Mixed-flow pumps give both an axial and a radial motion to the liquid pumped. Most of the centrifugal pumps are of radial-flow type. Radial-flow pumps include end suction pumps, in-line pumps, vertical volute pumps, axially split pumps, multistaged centrifugal pumps, and vertical turbine pumps. In positive-displacement pumps, the liquid flows into a contained space, such as a cylinder, plunger, or rotor. Then, a moving piston forces the liquid out of the cylinder, thereby increasing the pressure. They are common in applications that require high discharge pressure and relatively low flow. The three types of positive displacement pumps include reciprocating pumps, rotary pumps, and special-purpose pumps.