Centrifugal Pumps: Working, Types and Advantages
Centrifugal pumps are the most common type of pumps used in power generation plants, agriculture, industry, municipal, petroleum and other industries. They are used to transport fluids by converting rotational kinetic energy to the hydrodynamic energy of the fluid flow. The common uses of these pumps include water, sewage and petrochemical pumping.
The working of centrifugal pumps is very simple. There is an impeller at the heart of the system with a series of curved vanes inside the shroud plates. The impeller always remains immersed in the water. When the impeller is made to rotate, the surrounding fluid also rotates, which imparts centrifugal force to the water particles, and water moves out. The pressure and the kinetic energy of the water rises as at the discharge side of the impeller the rotational mechanical energy is transferred to the fluid. The water is getting displaced to the suction side, causing negative pressure to be induced at the eye. This low pressure helps to suck fresh water into the system again and this process continues. For almost all farm machinery and equipment, service is the key and its no different for a smooth working centrifugal pump.
Centrifugal pumps can be grouped into several types on the basis of different criteria like design, construction, applications and service.
Based on number of Impellers:
- Single stage- The Pump has only one impeller
- Two-stage- The pump has two impellers, for medium head service
- Multi-stage- Three or more impellers for high head service
Based on Impeller Suction:
- Single Suction
- Double Suction
Based on type of Volute:
- Single Volute
- Double Volute
Based on Shaft connection to Driver:
- Close Coupled- They do not require coupling alignment as a C-face or JM motor is bolted directly to the pump.
- Long-Coupled– They include a coupling between the coupling between pump shaft and the motor shaft. Their motors are readily available and the bearings are protected from seal leaks.
Based on Bearing Support
- Between bearing
Based on Shaft Orientation
The main advantages of centrifugal pumps include:
- Simple in construction
- Can be made in a wide range of materials
- Gives a steady delivery
- Much smaller than other pumps of equal capacity
- Can easily handle liquids containing high proportions of suspended solids
- Low maintenance cost
- No valves
- High speed operation
Centrifugal pumps are widely used because of their design simplicity, high efficiency, ease of use and maintenance, wide range of capacity and smooth flow rate.