Publisher Summary This chapter deals with centrifugal pump, which moves liquid by rotating one or more impellers inside a volute casing. The liquid is introduced through the casing inlet to the eye of the impeller, where it is picked up by the impeller vanes. The two pump types that are more commonly used are the American National Standards Institute (ANSI) pump and the American Petroleum Institute Standard (API) pump. Both the pumps have a radial split casing and most of the smaller pump cases employ a single volute design of the interior passages. Another design style incorporates a circular casing with a diffuser, which has the interior passages needed to transfer the velocity energy to the pressure energy prior to discharge from the casing. The impeller is secured on a shaft by which it is rotated. The pump casing is horizontally split along the axis of the shaft. Iron and bronze pumps are widely used in general service applications. Nonmetallic pumps also play a major role in the movement of chemicals. A number of plastics are used as pump linings because they offer the corrosion resistance of more expensive metals at a fraction of the cost.