Introduction to pumps

A pump is a mechanical device that uses pressure or suction to move or raise liquids or gases or force air into inflatable objects like tires. There are many types of pumps, but they are generally classified into two main groups based on the technique used to move the substance, which include centrifugal pump and positive displacement pump. Each pump is designed to serve a particular application, and pumps can be used to serve a wide range of uses including, pumping water, filtering and aerating ponds, injecting fuel and oil or circulating cooling water in car engines, pumping natural gas and oil, etc.

General Classifications and Types

Pumps are classified according to the method of displacement, which include positive displacement pumps and centrifugal pumps, and further classified into vertical type, horizontal type, submersible type, air operated diaphragm, hydraulic diaphragm, piston and many more according to their design.

Positive Displacement Pumps

A positive displacement pump moves fluids by trapping a certain amount and displacing (forcing) the trapped fluid into a discharge pipe. This type of pump uses an expanding space on the suction section and a contracting space on the release section. Some general types of positive displacement pumps include the rotary-type positive displacement pump, the reciprocating-type pump, and the linear-type pump.  Rotary-type pumps are further classified into gear pumps, screw pumps and rotary vane pumps. Some typical reciprocating-type pumps include the plunger pump, diaphragm pump, piston pump and radial piston pump.

Centrifugal Pumps

Centrifugal pump design is different from the positive displacement pump. The main part of the pump is the impeller. When the impeller spins, pressure increases at the center of the impeller which is known as the impeller eye. To run the pump, there is a minimum fluid level required (NPSHr), else the fluid will not be transferred. The fluid from the impeller is accelerated and exits towards the right angles of the shaft. These pumps are commonly used in all industry especially the high flow low pressure applications.

Others Type of Pumps

The other types of pumps are generally classified under both centrifugal and positive displacement type. For different applications, different shape and sizes are created to fit the applications. For example, the submersible pumps. Submersible pump is a type of centrifugal pump, it transfer the liquid via impeller. But the casing design is water proof, it can be submerge into the water together with the motor.

General Uses

Pumps are used for a wide range of domestic as well as industrial applications that include water supply, irrigation, gasoline supply, refrigeration, sewage movement, marine services, swimming pools, flood control, chemical movement, etc.