A centrifugal pump is a machine containing a set of mechanical components that enable operation, including the pump shaft supported by bearings, a sealing mechanism to prevent leakage, structural components to support stresses, and wear surfaces for repairs.
A centrifugal pump uses rotation to impart velocity to a liquid, with the impeller being the hydraulic component that rotates to impart speed to the fluid.
It converts speed into flow with the help of a housing, which absorbs the velocity from the impeller and directs the liquid to the discharge point.
A centrifugal pump consists of three main components:
The impeller rapidly spins to impart speed to the liquid, similar to a ship's propeller. Centrifugal force pushes the fluid from the impeller’s center out to its circumference, creating high-speed liquid flow. Different types of impellers exist, such as those discussed in our article Basic Pump Components.
The pump casing converts the velocity from the rotating impeller into controlled flow, directing it out through the pressure point. The most common type is the spiral casing, resembling a snail shell, which expands to build pressure. The impeller's position relative to the casing, such as the cutwater, impacts fluid pressure and flow.
A centrifugal pump needs to be combined with other devices to form a pump unit, typically consisting of a pump and a motor. Most common systems use an electric motor, but other engines like natural gas or steam turbines are also used. The impeller is often mounted on the motor shaft in a direct coupled pump unit, while frame-mounted end suction pumps offer another design option.