A machine for moving a fluid or gas from one place to another; commonly used to move fluids, often water, through pipes. The earliest recorded mechanical pumps (square-pallet chain pumps) were in 1st-c BC China. The simplest pump, which uses the pressure of the air, can lift water through a height of only c.10 m/33 ft. More complex pumps provide mains water for the home, and circulate water to cool car engines. Pressure pumps are used to blow up bicycle tyres and footballs. Evacuation pumps suck air from sealed containers to make a partial vacuum. The heart is also a type of pump, moving blood through the veins in the body.
The earliest pump was described by Archimedes in the 3rd century BC and is known as the Archimedes screw pump.
Types
Pumps fall into two major groups: rotodynamic pumps and positive displacement pumps.
Rotodynamic pumps
Rotodynamic pumps are rotary machines. Rotodynamic pumps are divided into three types: centrifugal pumps, peripheral pumps and special pumps.
Peripheral pumps give energy to the fluid via a vane wheel impeller. They are also called side-channel pumps or regenerative turbine pumps.
The special type of rotodynamic pump includes jet pumps, gas lift pumps and electromagnetic pumps. A eductor-jet pump is special type of pump without moving parts that uses the kinetic energy of a fluid to increase the pressure of a second fluid.
Positive displacement pumps
A positive displacement pump causes a fluid to move by trapping a fixed volume of water and then forcing (displacing) that trapped volume into the discharge pipe. Positive displacement pumps can be further classified as either rotary-type (for example the rotary vane pump) or reciprocating-type (for example the diaphragm pump).
Because of the wide variety of applications, pumps have a plethora of shapes and sizes: from very large to very small, from handling gas to handling liquid, from high pressure to low pressure, and from high volume to low volume.
Power source
Pumps may be powered by an internal combustion engine, electric motor, manually (as with the hand pump used for pumping groundwater, called walking beam pump), or by wind power (common for irrigation).
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