WHAT IS A CENTRIFUGAL PUMP AND HOW DO THEY WORK?

What is a centrifugal pump and how do they work? A centrifugal pump is essentially quite a simple machine. An impeller rotates at speed within a casing so creating a centrifugal force on the liquid. Discharged through a port on the periphery of the casing. It follows that the faster the impeller rotates then the greater the centrifugal force is created and the higher pressure, or head, the pump can produce.

The work of the pump designer is centred around creating this centrifugal force in the most efficient way. So, producing the desired flow rate and discharge pressure at the minimum of power input and there are many factors that can influence this. The design of the impeller is critical and there are basically two main influences to keep in mind. Firstly, the depth of the impeller vane influences the flow rate. The deeper the vane then the greater volume of liquid the impeller can move with each revolution. And, secondly, the diameter of the impeller directly impacts upon the pressure it can develop. So a larger diameter means that the outer tip of the impeller rotates much faster per revolution than a smaller diameter therefore generating a greater centrifugal force and a higher pressure.

Of course, there are many other factors to be taken into account, not least specific details of the liquid to be pumped. Does it contain solids? What temperature is the liquid? What is the specific gravity (SG is the weight of a liquid as compared to water)? All these, as well as other, factors will impact upon the design consideration.

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