A pump is a mechanical device. used to move fluid, such as gas, liquid or slurry.



Pumps operate by displacing a volume by a physical or mechanical action.

Pumps alone do not create pressure. Pumps only displace fluid, causing a flow. Adding resistance to the flow causes pressure.

Pumps fall into two main groups: positive displacement and rotodynamic. Their names describe their method for moving a fluid.

Pump efficiency can be defined as the ratio of the power imparted on the fluid by the pump in relation to the power supplied to drive the pump.

Pump efficiency is an important aspect and pumps ought to be regularly tested. Thermodynamic pump testing is one method of Pump efficiency testing.

Pumps are commonly rated by the following criteria: horsepower, flow rate, outlet pressure in feet / metres of head, inlet suction in suction feet / metres of head. The head is the number of feet or metres the pump can raise or lower a column of water at atmospheric pressure.

Engineers often use a quantity termed the 'specific speed' to identify initially the most suitable pump type for a particular combination of flow rate and head.

A Positive displacement pump causes fluid to move by trapping a fixed amount of it then forcing (displacing) that trapped volume into the discharge pipe. A positive displacement pump can be further classified according to the mechanism used to move the fluid, Rotary-type, (e.g., the lobe, external gear, internal gear, screw, shuttle block, flexible vane or sliding vane, helical twisted roots e.g. the Wendelkolben or liquid ring vacuum pump) or Reciprocating-type, e.g., the piston or diaphragm pump.)

Pumps are used for a variety of purposes. Early applications includes the use of the windmill or watermill to pump water. Today, pumps are used for irrigation, water supply, gasoline supply,air conditioning systems, refrigeration (usually called a compressor), chemical movement,sewage movement, flood control / relief, marine services, etc.

Because of the wide variety of applications, pumps have a variety of shapes and sizes: from large to very small, from handling gas to handling liquid, from high to low pressure, and from high to low volume.

Liquid / slurry pumps can lose prime and this will require the pump to be primed by adding liquid to the pump and inlet pipes to get the pump started. Loss of "prime" is due to ingestion of air into the pump. The clearances and displacement ratios in pumps used for liquids and other more viscus fluids cannot displace the air due to its lower density.

One sort of pump once common worldwide was a hand-powered water pump over a water well where people could work it to extract water, before communities had individual water supplies. From this came the expression "parish pump" for "the sort of matter chattered about by people when they meet when they go to get water", "matter of only local interest". However water from pitcher pumps are more prone to contamination since it is drawn directly from the soil and thus doesn't undergo filtration, this may cause gastrointestinal related diseases.

Today, hand operated village pumps are still considered the most sustainable low cost option for safe water supply in resource poor settings, often in rural areas in developing countries. A hand pump may open access to deeper groundwater that is often not polluted and also improves the safety of a well by protecting the water source from contaminated buckets. Pumps like the Afridev pump are designed to be cheap to build / install, and easy to maintain with simple parts. However, scarcity of spare parts for these type of pumps in some regions of Africa may diminish their use for these areas.

Rotary-type pumps include the Gear pump, Progressing cavity pump, Roots-type pumps, Peristaltic pumps

Reciprocating-type pumps include the Compressed-air-powered double-diaphragm pumps

Rotodynamic pumps (or dynamic pumps) include the centrifugal pump, Radial flow pumps, Axial flow pumps, Mixed flow pumps and Eductor-jet pumps.

Types of Multiphase Pumps include Helico-Axial (Centrifugal), Twin Screw (Positive Displacement), Progressive Cavity (Positive Displacement)

And Electric Submersible Pumps (Centrifugal).

A hydraulic ram is a water pump powered by hydropower