What is a Centrifugal Pump

Centrifugal pump flows the water or any liquid at a greater speed. Typical example of a Centrifugal pump is a common water pumping machine which fetches the water from underground water tanks and uploads the water into water tanks at the roof.

Centrifugal pump is a machine which uses rotation to impose velocity to a liquid.

Basic Procedure of Centrifugal Pump

To understand the working of centrifugal pump, we can think of an electric motor which rotates a fan that fetches and flows the water.

Mechanical Working of a Centrifugal Pump

Mechanically speaking, in a centrifugal pump, as the motor is running, following procedure is taking place.

  • A motor is attached with the motor shaft.
  • Motor shaft is attached with the pump shaft through coupling.
  • Pump Shaft is attached to the Impeller (with a sealing mechanism)
  • Pump shaft is rotating and is continuously fetching and throwing water

The Main Parts of a Centrifugal Pump

There are a few components that almost every centrifugal pump has in common. These components include

  • Motor Shaft
  • Coupling
  • Pump Shaft
  • Impeller

Motor Shaft

Motor Shaft is attached with the motor and is rotated as the motor runs.


Coupling is a joining mechanism of two shafts. The main purpose of the coupling is to synchronize the rotation of two shafts.There are several types of coupling (Disc, star and rubber bush coupling etc). It is usually made of cast iron or mild steel.

Pump Shaft

Pump shaft is attached with Motor shaft through coupling. Pump shaft is also attached with Pump body through bearings.


Every Centrifugal pump has an Impeller. The Impeller is concealed in the pump body and is mounted on the shaft. The impeller is similar to a fan. There are two major types of impellers (Open type and Closed Type).

Open Type Impellers are typically used for thick liquid (garbage etc) or with the liquid that contains chunks of solids whereas the Closed type impellers are mostly used for thin liquid (Water, Juices, Milk etc).

Open Type Impeller

These impellers are open from both ends. The blade collects the thick material from one side and deliver it on the other side. These type of impellers are less effective on thin liquid as they continue to rotate idle.

Closed Type Impeller

The closed type impeller receive water or thin liquid from the front and delivers from the side. This type of impellers are suitable and mostly used for liquids which contain no thick chunks. These type of impellers are not suitable for garbage or liquid with solid chunks as the objects may trap in the impeller.

Apart from these main parts, there are several other parts that are very essential and are used    in a basic centrifugal pump.

Other Important Parts of a Centrifugal Pump

Pump Casing

Pump casing is simply a sea shell shaped object made of cast iron. Main purpose of the pump casing is to encapsulate the impeller and flow the water through its inlet and outlet.

Sealing Mechanism

There is a sealing mechanism in the centrifugal pump which prevents liquid leakage from the pump casing.

There are three main parts of this sealing mechanism, Back plate (Hub plate), Packing Gland and Filling Material.

The Back plate is placed inside of the pump casing, the gland is outside of pump casing and filling material is between these two. The main shaft (pump shaft) is going through the center of this arrangement.

About Zaighum Shah 57 Articles
Zaighum Shah is a mechanical engineer having more than 20 years of experience. Zaighum is specializing in product development in Sugar Mill industries. Zaighum has gone through all phases of mechanical engineering and it’s practical implementation. Zaighum has been solving most complex problems, designing new systems and improving existing models and systems.

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