Working principle of centrifugal pump

Centrifugal pumps is a hydraulic machines which convert the mechanical energy into a hydraulic energy are called Pump. The hydraulic energy is in the form of pressure energy. If the mechanical energy is converted into a pressure energy by means of centrifugal force acting on the fluid, The hydraulic machine is called centrifugal pump.


  • Different parts of centrifugal pump:-
  1. Impeller.
  2. Casing.
  3. Suction pipe.
  4. Delivery pipe.
            These are the different parts of centrifugal pump, by which mechanical energy is converted into a hydraulic energy.

  • Impeller:- The rotating part of  a centrifugal pump is called Impeller. It consists of series of backward curved vanes. The impeller is mounted on a shaft is connected to the shaft of an electric motor.

  • Casing:- The casing of a centrifugal pump is look like of casing of reaction turbine. It is an air tight passage surrounding the impeller and is designed in such a way that the kinetic energy of the water discharged at the outlet of the impeller is converted into pressure energy before the water leaves the casing and enters the delivery pipe.
                     In centrifugal pumps there are mainly three types of casing is used:-
  1. Volute casing.
  2. Vortex casing.
  3. Guide blade casing.
  • Volute casing:- This casing is used for surrounding the impeller. It is of  spiral type in which area of flow increase gradually. The increase in area of flow decrease the velocity of flow. The decrease in velocity increases the pressure of the water flowing through the casing. It has been observed that in case of volute casing, The efficiency of the pump increases slightly as a large amount of energy is lost due to the formation of eddies in this type of casing.



  • Vortex and Guide blade casing:- If the circular chamber is introduced between the casing and the impeller than this type of casing is called vortex casing. By introducing the circular chamber, The loss of energy due to the formation of eddies is reduced to a considerable extent. Thus the efficiency of the pump is more than the efficiency when only volute casing is provided. While in guide blade casing the impeller is surrounded by a series of guide blades mounted on a ring which is known as diffuser. The guide vanes are designed in such a way that the water from the impeller enters the guide vanes without stock. also area guide vanes increases, Thus reducing the velocity of flow through guide vanes and consequently increasing the pressure of the water. The water from the guide vanes than passes through the surrounding casing which is in most of the cases concentric with the impeller.

  • Suction pipe:- A pipe whose one end is connected to the inlet of the pump and other end dips into water in a sump is known as suction pipe. A foot valve which is a non-return valve or one-way type of valve is fitted at the lower end of the suction pipe. The foot valve opens only in the upward direction.

  • Delivery Pipe:- A pipe whose one end is connected to the outlet of the pump and other end delivers the water at required height is known as delivery pipe.

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