Short Answer:

A centrifugal pump is a hydraulic machine that converts mechanical energy from a motor into kinetic energy and then into pressure energy of a fluid. It works on the principle of centrifugal force. When the impeller of the pump rotates, it throws the liquid outward from the center towards the periphery, thereby increasing its velocity and pressure.

Centrifugal pumps are widely used for pumping water, chemicals, and other fluids in industries, power plants, and irrigation systems. They are simple in construction, easy to maintain, and suitable for large discharge with low heads.

Detailed Explanation :

Centrifugal Pump

A centrifugal pump is one of the most commonly used types of pumps in mechanical and civil engineering applications. It is a dynamic pump that operates on the principle of centrifugal action, where the mechanical energy from an external source such as an electric motor or engine is converted into the energy of the fluid. The main purpose of this pump is to increase the pressure and velocity of a liquid to move it from one place to another efficiently.

Principle of Operation

The working principle of a centrifugal pump is based on centrifugal force. When the impeller of the pump rotates, the liquid inside the pump casing is forced outward due to the centrifugal action. This outward movement of liquid from the impeller eye (center) to its periphery causes a low-pressure region at the center. Due to this low pressure, more liquid enters the impeller from the suction pipe. As the liquid moves outward, it gains both velocity and pressure energy. This energy is then converted into useful pressure energy in the volute casing before the liquid is discharged through the delivery pipe.

Main Components of Centrifugal Pump

1. Impeller: It is a rotating part that imparts velocity to the liquid. The impeller may be open, semi-open, or closed type depending on the fluid and application.
2. Casing: It surrounds the impeller and guides the fluid from the impeller to the delivery pipe. The casing is usually spiral-shaped (volute type) to gradually increase the area and reduce velocity while increasing pressure.
3. Suction Pipe: It is used to draw the liquid from the sump and deliver it to the impeller eye.
4. Delivery Pipe: It carries the liquid from the casing to the required height or location.
5. Shaft and Bearings: The shaft transmits the mechanical power from the motor to the impeller, while bearings support smooth rotation.
6. Priming Arrangement: Since centrifugal pumps cannot suck air, priming is necessary to fill the casing and suction line with liquid before starting the pump.

Working Process

When the pump starts, the impeller rotates at high speed. The liquid inside the impeller experiences a centrifugal force that throws it outward, causing an increase in both velocity and pressure. As the liquid moves out, the pressure at the impeller eye decreases, allowing more liquid to enter from the suction pipe. The kinetic energy gained by the liquid is converted into pressure energy in the casing, and the liquid is discharged through the delivery pipe.

Types of Centrifugal Pumps

Centrifugal pumps can be classified based on several criteria:

• Based on Flow Direction:
  • Radial flow pump
  • Axial flow pump
  • Mixed flow pump
• Based on Number of Impellers:
  • Single-stage pump (one impeller)
  • Multistage pump (two or more impellers)
• Based on Casing Design:
  • Volute type
  • Diffuser type

Applications of Centrifugal Pump

Centrifugal pumps are used in a wide range of applications such as:

• Domestic water supply systems
• Irrigation and agriculture
• Cooling water circulation in power plants
• Chemical and food industries
• Drainage and sewage systems

Advantages of Centrifugal Pump

1. Simple design and easy operation
2. Suitable for large discharge and low head applications
3. Smooth and continuous flow of liquid
4. Low maintenance cost
5. Compact size and reliable performance

Disadvantages of Centrifugal Pump

1. Not suitable for high head and low discharge applications
2. Priming is necessary before operation
3. Efficiency decreases when operated away from the designed conditions
4. Cannot handle very viscous liquids effectively

Conclusion:

A centrifugal pump is an efficient hydraulic machine that converts mechanical energy into pressure energy using the action of centrifugal force. Its simple design, continuous discharge, and reliability make it the most popular type of pump used in domestic, industrial, and agricultural sectors. Understanding its working, components, and operation principles helps in efficient use and maintenance of this essential fluid handling device.