Centrifugal Pumps

Centrifugal pumps are used widely in the paper, irrigation, flood control and petroleum industries as well as for the cooling of nuclear reactors. They are also used extensively for work with ordinary fluids. Centrifugal pumps operate on the principle of using kinetic energy to move fluids, thus transforming velocity into pressure. These pumps are relatively compact and their output is generally steady and non-pulsating.

Centrifugal pumps are also popular because of for their smooth and quiet operation, along with their low operating costs and dependability. There are generally reliable because they are simply designed and have very few moving parts. Of course the fewer parts a device has means the less chance there is of something going wrong with it.

There are only three basic components of centrifugal pumps which are the inlet duct, the impeller, and the volute. When liquid enters the inlet duct it meets the rotating impeller. The rotational energy of this impeller is then transferred to the liquid and forces it outwards using the principle of centrifugal force. The fast moving liquid then enters the cone shaped volute chamber. When the liquid passes through the small end of the volute it expands in volume and slows down its rate of flow. The velocity energy of the liquid is then transformed into pressure energy which produces a suction effect which helps to draw more liquid into the pump in the direction of the flow. The physical processes help to drive the pump, but it still takes more energy to start and operate the pump as it isn’t a perpetual motion device.

There are three basic types of centrifugal pumps which are classified on the basis of flow. These are radial flow, mixed flow and axial flow. Radial flow pumps are where the entire pressure is made up from the centrifugal force. Mixed flow centrifugal pumps create pressure through the action of the impeller and the centrifugal force of the liquid. Axial flow occurs because of the force of the impeller only.

The blades and the encasing used in a centrifugal pump need to be very strong to withstand high pressure and they should also be corrosion resistant. The basic design of the pump may alter due to its use. Some pumps are made to be used with strong acids and corrosive chemicals. Centrifugal pumps are constructed of materials such as plastic and stainless steel. These pumps are designed to operate in vertical, horizontal, and submergible environments.

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