Defining centrifugal pumps

  26/08/2015

Defining centrifugal pumps

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Centrifugal pumps are one of the most used types of water pumps. There are various reasons which support this fact; some of them are – efficient functioning, easy to use, strong built, long life etc. They are defined as dynamic pumps which help in the displacement of fluids via a system that make use of one or more impellers. Centrifugal pumpstend to provide more flow rate and lower pressures than positive displacement pumps.

Functioning and Parts -

A centrifugal pump mainly functions with the help of kinetic energy with the help of a circular pump casing and an impeller. Significant changes take place because of two key parts of the pump, diffuser or volute and the impeller. The impeller is responsible for the conversion of driver energy into kinetic energy. The diffuser or volute is a fixed part which helps in the conversion of kinetic energy into pressure energy.

There are various parts that help in smooth functioning of the centrifugal pumps. Following are these important parts:

  • Stuffing box.
  • Packing.
  • Shaft.
  • Shaft sleeve.
  • Vane.
  • Casing.
  • Eye of the impeller.
  • Impeller.
  • Casing wear ring.
  • Discharge nozzle.

Types -

There are various types of centrifugal pumps which are based on varied elements. Let us discuss them in detail –

Number of impellers -

  • Single stage pump comprises of single impeller and it is ideal for low head service.
  • Two stage is ideal for medium head service and it comprises of two impellers.
  • Multiple stage has three or more impellers. It is an ideal choice for high head service.

Impeller suction -

  • Single suction – It is a type in which only one side of the impeller has suction cavity. It has a less complicated design, but the impeller gets subjected to elevated axial thrust imbalance as the flow is coming on one side only.
  • Double suction – This type has low NPSHR as compared to single suction. The pump is hydraulically balanced but if the suction piping is not rightly installed, it is more prone to uneven flow on the impeller’s both sides.

Volute Type -

  • Single volute – This pump has a single lip and it is quite easy to cast. It is most commonly used in low capacity pumps. Such type of pumps has higher radial loads.
  • Double volute – This type comprise of a double lip and they are positioned 180 degrees, apart which further results in balanced radial loads. The majority of the centrifugal pumps comprise of double volute design.

Advantages -

With so many advantages, centrifugal pumps are being used extensively across the globe. Following are the benefits –

  • Capable of pumping out dangerous liquids.
  • Offer utmost efficiency.
  • In the absence of drive seal, there is no leakage.
  • Reduced frictional losses.
  • Water cannot enter the motor as there is an apt gap between the motor and pump chamber.
  • Less wear and tear.
  • Noiseless functioning.

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