Chapter 11 - Types of Pumps

Abstract

This chapter provides information on the types of pumps commonly used in public utilities for the pumping of water, wastewater, and sludge, emphasizing details such as impellers, casings, seals, and wear rings. There are two basic groups of pumps that include kinetic and positive displacement. Kinetic pumps impart velocity and pressure to the fluid as it moves past or through the pump impeller and, subsequently, converts some of that velocity into additional pressure. Kinetic pumps are subdivided into two major groups that include centrifugal (or volute), and vertical (or turbine) pumps. In positive displacement pumps, the moving elements such as piston, plunger, rotor, lobe, and gear displace the liquid from the pump casing (or cylinder) and, at the same time, raise the pressure of the liquid. The three major groups of positive displacement pumps are reciprocating pumps, rotary pumps, and pneumatic pumps. In an overhung-impeller pump, the impeller is mounted at the end of the pump shaft in a cantilever fashion. Both bearings are arranged on the same side of the impeller. The basic components of the centrifugal pump include the impeller that increases the velocity of the liquid and raises its pressure, wear rings that control the liquid recirculation between the impeller discharge side and the inlet side, and the pump shaft, which support all radial and axial impeller forces.