A centrifugal pump uses a mechanical force to transport fluid by converting the fluid into a flow pressure force using a centrifugal force acting on it. Rotational power usually comes from the engine or electric motor. A centrifugal pump is a simple machine used in many industries and in everyday applications to move fluid from the lower head to the upper head. In 1475, the Italian engineer Francisco Di Giorgio Martini described the clay cultivator as a centrifugal pump. But the original centrifugal pumps were not invented until the 17th century. Dennis Poppin then built a centrifugal pump using straight wines.
Centrifugal pumps are widely used in the chemical industry to move viscous liquids easily. Also, it is less expensive than other pumping equipment. In short, it is an excellent machine for efficient work in a wide variety of applications.
Working principle of Centrifugal Pump:
This pump works on the basic principle of change of angular momentum. It states that the change of the angular momentum of a rotating particle is equal to the applied force. This means that when a certain agency fluid is rotated with the help of an external agency, i.e., a turbine or electric motor or external force, a centrifugal force acts on it, which changes further under pressure.
Some part of the energy converts in the fluid kinetic energy. The fluid enters axially through the eye of the casing, gets trapped in the impeller blade. The fluid achieves both velocity and pressure as it passes through the impeller. The donut-shaped diffuser or scroll of the cover, slows down the flow and further increases the pressure. In essence, the kinetic energy of the impeller in a centrifugal pump is converted into the compressive force of the fluid, which is used to raise it to a certain height. Due to the centrifugal force acting on the water or liquid, it is raised to a certain height. Hence these pumps are called centrifugal pumps.
Major components of Centrifugal Pump
Various major components of a centrifugal pump:
This is the main part of the centrifugal pump. This gives centrifugal acceleration to the fluid. The stimulus again has its subtypes.
2) Closed impeller:
The closed impeller has vans with cover plates on either side. It is mostly used in obtaining pure water.
3) Semi-open impeller:
It has only the base plate and no crown plate. It is comfortable with liquid-charged debris.
It uses to rotate the impeller. It designs to transmit incoming torque during the start and operation of impellers and other rotating components.
5) Shaft sleeves:
Sleeve centrifugal pumps prevent the shaft from corrosion and leakage points. Care should be taken not to close the arms at one end.
This is the airtight path that surrounds the impeller. The casing designs so that the kinetic energy of the water discharge from the outlet of the impeller can convert into a pressure force before leaving the casing and entering the distribution pipe.
Three types of casings are commonly used in centrifugal pumps and they are:
(I) Voltage casings: This is a spiral type casing in which the flow field gradually increases. Increasing the area of flow reduces the velocity and increases the pressure of the liquid flowing through the casing.
(ii) Vortex casing: In a vortex casing, a circular chamber inserts between the impeller and the casing. This is done to prevent loss of energy due to the formation of AD. The capacity of vortex casing is higher than that of solvent casing.
(iii) Cover with guide blade: In this cover, there is an array of guide blades around the impeller. The guide blades are mounted in a ring called a diffuser. The design of the guide vans means that the water coming out of the impeller enters the guide without any shock. The area of the guide van increases; This helps to reduce the velocity of the liquid and increase its pressure. Following the guide blades, water passes through the surrounding mantle. In most cases, the casing is centered with the impeller.
8) Suction pipe:
The lower end of the suction pipe submerges in water, it must be lifted up and the other end connects to the inlet of the centrifugal pump. Strainer and foot valve at the lower end of the suction pipe. These valves help remove debris such as leaves and sand from the water and allow water to flow upwards in a row.
9) Delivery pipe
It connects to the outlet of a pipe pump and the other end connects to the required height at which water is to be transported.
Working of Centrifugal Pump
- When the electric motor starts turning, it also turns the actuator. The rotation of the inductor creates suction on the suction pipe.
- From the trigger eye, due to the centrifugal force acting on the water, the water begins to move radially outwards and towards the outside of the casing.
- When the impeller moves at high speed, it also rotates the water around it in the mantle.
- Now make the outlet of the pump, the water goes to the desired place through the delivery pipe.
What is priming and why is it necessary?
Priming is the most basic and first step in the work of centrifugal pumps. Priming is the process of filling the casing, suction pipe and delivery pipe to the delivery valve before starting the pump. This is because these pumps cannot pump air without steam. Priming is done to remove air from the pump.
If air is not removed from the pump, a small negative pressure will be created on the suction pipe and it will not suck water from the sump. Therefore, it is advisable to fill the pump with water before starting.
Priming methods are classified into four types, namely manual, with vacuum pumps, with jet pumps and with separators.
- Normal operation.
- Low first cost and maintenance.
- There is minimal stress on the casing.
- Impeller and shaft only moving parts.
- Quiet operation.
- Wide range of pressure, flow and capacity.
- Use small floor space in different locations.
- No leakage problem in centrifugal pumps.
- These are capable of pumping hazardous and sensitive fluids.
- There is also no heat transfer problem as there is enough space between the motor and the chamber.
- They do not lose strength due to friction and they are very flexible in construction and easy to maintain.
- These pumps have high efficiency than reciprocating pumps.
- The magnetic resonance in the centrifuge pump loses less energy.
- Due to the particle attractive nature of the magnetic drive, the risk of pipe clogging may arise.
- Vibrations from the surrounding environment can damage these pumps.
- There is always a risk of cavitation.