Centrifugal pump

Centrifugal pump is used to raise water from a low level to a high level. In these pumps, external driver is an electrical motor which drives the shaft resulting in rotation and fluid flow in directions opposite to those of a turbine. The main components of a centrifugal pump are a disc with vanes and the impeller revolving in a casing. The material used for the construction of impeller is bronze, aluminium bronze and stainless steel. The dynamic pressure caused by the rotation of the blades lifts the water from a low level to a high level. If diffusers are provided in pumps, they are known as diffusion pumps. In diffusion pumps, some fixed guide blades act as diffuser. Centrifugal pumps which are provided with volute chambers are known as volute pumps. Volute chambers are straight tapered ducts wrapped around the impeller. This helps to reduce the exit velocity. Commonly used types of impellers are closed type, semi-closed type and open type. Closed and semi-closed types offer superlative performance and efficiency but are expensive. Open type are less expensive and maintenance free but its efficiency is very poor.