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| Centrifugal pumps |
CENTRIFUGAL PUMP
Centrifugal pumps are the most preferred pumping devices in the hydraulic world.
A Pump is generally used to induce flow or raise the pressure of a liquid. The working principle of centrifugal pumps involves imparting energy to the liquid by means of a centrifugal force developed by the rotation of an impeller that has several blades or vanes.
Main parts of centrifugal pumps are
- impeller
- casing
- Mechanical seal or stuffing box
- Shaft and
- bearing housing
The impeller is always immerse in water. when the impeller is made to rotate it makes the fluid surrounding is also rotate. this imparts centrifugal force to the water particles and water moves radially out. since rotational mechanical energy is transferred to the fluids at discharge side of the impeller, both pressure and kinetic energy water will rise, at the suction side water is getting displaced.
So the negative pressure will be induced at the eye of the impeller. such a low pressure help sucking freshwater stream into the system again and this process continues.
Impeller is fitted inside the casing so the water moving out will be collected inside it, and will move in the same direction of rotation of impeller to the discharge nozzle.
Casing has got increasing area along the flow direction. Such increasing the area will help in accommodating newly added water stream and will also help in reducing exit flow velocity. reducing in flow velocity will result increase in static pressure.
A shaft is used to connect between the impeller and motor. Since water pressure inside the casing is huge. proper seal arrangement is important in arresting.water leakage through the shaft casing clearance mechanical seal for stuffing box based mechanism is used for the purpose. Is mounted on bearings but the suction side of impeller it is not advisable to fix a bearing. Since it will block the flow so bearing have to be fitted at the other end. This means impeller is mounted like a cantilever.
For high flow rate pumps a bearing housing with cooling oil is necessary for improving the life of bearings.
Applications of centrifugal pump
Centrifugal pumps are commonly used for pumping water, solvents, organics, oils, acids, bases and any 'thin' liquids in both industrial, agricultural and domestic applications. In fact, there is a design of centrifugal pump suitable for virtually any application involving low viscosity fluids.
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