A mechanical device used to transport fluids by way of an enclosed impeller rotating at high speed. This commonly used device involves the fluid being fed in at the centre or eye of the impeller and thrown out in a roughly radial direction by centrifugal action. The large increase in kinetic energy that results is converted into pressure energy at the pump outlet by using either an expanding volute chamber or a diffuser. The latter is more efficient but more expensive. There are considerable variations in impeller design, but almost all have blades, which are curved, usually backwards to the direction of rotation. This arrangement provides the most stable flow characteristic. The head developed depends not only on the size and rotational speed of the pump, but also on the volumetric flow rate.

Centrifugal pumps are suitable for handling fluids with a wide range of properties including fluids with suspended solids. They are also capable of operating when the delivery line is blocked. They have low capital and maintenance costs, and easy fabrication in a wide range of corrosion-resistant materials. However, they have an inability to develop high heads unless multiple stages are used. They are also not self-priming. The pump must therefore be full at the point of start-up, which is achieved either manually, or requires ancillary equipment. They have a high efficiency over only a limited range of conditions and are not particularly suitable for highly viscous fluids. They are also prone to cavitation in which the pressure of the fluid falls below the vapour pressure resulting in the formation of bubbles of vapour which collapse with a violent effect within the pump at a region of high pressure. This results in noise, vibration, and eventually damage to the impeller. It is avoided by ensuring that the available net positive suction head exceeds the required net positive suction head.