Short Answer:

A centrifugal pump is a mechanical device used to move liquids by converting rotational energy into kinetic energy. This energy is supplied by an electric motor or engine, and the pump pushes fluid using a spinning impeller. It is widely used in water supply systems, agriculture, and construction sites for pumping clear water or other low-viscosity fluids.

Centrifugal pumps are classified based on several factors like the type of casing, the number of impellers, the direction of flow, and the type of impeller. Common classifications include single-stage or multi-stage, radial or axial flow, and open or closed impeller pumps.

Detailed Explanation:

Centrifugal pump

A centrifugal pump is a hydraulic machine that moves liquid by using centrifugal force. It works by spinning an impeller inside a casing filled with liquid. When the impeller rotates, it throws the liquid outward from the center to the edges, increasing its velocity. This kinetic energy is then converted into pressure energy, which allows the fluid to move through pipes to the desired location.

Centrifugal pumps are simple, durable, and suitable for moving large volumes of fluids at low pressure. They are widely used in civil engineering projects like water supply, drainage, firefighting systems, and irrigation. The key components of a centrifugal pump include the impeller, casing, shaft, bearing, and mechanical seal. The impeller is the rotating part that imparts energy to the liquid, and the casing helps in collecting and directing the liquid flow efficiently.

The working process of a centrifugal pump begins when the pump is primed and liquid fills the casing. When the motor starts, the impeller rotates and pushes the liquid towards the outer edge. Due to centrifugal force, the liquid gains high velocity. As it leaves the impeller, it enters the casing where the high-speed liquid slows down, converting its velocity into pressure, which helps move the liquid through the pipeline system.

Centrifugal pumps are preferred because of their simple construction, ease of use, and low maintenance. They are not suitable for very thick or highly viscous fluids or situations where high suction lift is required, as their performance drops in such cases.

Classification of centrifugal pumps

Centrifugal pumps can be classified in different ways depending on their construction and operation:

1. Based on Number of Impellers
   • Single-stage pump: Has one impeller. Used for low to medium head and simple applications.
   • Multi-stage pump: Has more than one impeller. Suitable for high-head applications like high-rise building water supply.
2. Based on Direction of Flow
   • Radial flow pump: Liquid flows perpendicular to the shaft. Common in most applications.
   • Axial flow pump: Liquid flows parallel to the shaft. Used for high flow, low head.
   • Mixed flow pump: Combination of radial and axial flow, used in medium head applications.
3. Based on Type of Casing
   • Volute casing: A spiral casing that converts velocity into pressure.
   • Diffuser casing: Contains guide vanes that slow down the fluid and increase pressure.
4. Based on Type of Impeller
   • Open impeller: Blades are free on both sides. Used for dirty or viscous fluids.
   • Semi-open impeller: Partially covered. Suitable for medium-thickness fluids.
   • Closed impeller: Covered on both sides. Best for clean fluids and efficient operation.

These classifications help in choosing the right pump for different civil engineering needs depending on the fluid type, required flow rate, and delivery head.

Conclusion:

A centrifugal pump is a machine that moves liquids using centrifugal force generated by a rotating impeller. It is commonly used in civil engineering for water handling tasks. Centrifugal pumps are classified based on factors like impeller count, flow direction, casing type, and impeller design. Proper classification helps engineers select the most suitable pump for each specific application, ensuring efficiency and durability in operation.