[[Image:centrifugal pump icon.png|right|80px]][[Image:centrifugal pump.jpg|thumb|right|300px200px|General components of a Centrifugal Pump. Photo: [http://www.maintenanceworld.com/articles/engresource/centrifugalpumps.pdf The Chemical Engineers’ Resource Page]]][[Image:CentrifugalPump.jpg|thumb|right|300px200px|Centrifugal pump. <br> Photo: WHO.]]__NOTOC__<small-title />
The essential components of a centrifugal pump are the fast-rotating impeller and the casing. Water flows into the centre “eye” of the impeller, where centrifugal force pushes the water outwards, to the casing. The kinetic energy of the water is partly converted to useful pressure that forces the water into the delivery pipe. Water leaving the central eye of the impeller creates a suction, which draws water from the source into the pump. An impeller and the matching section of the casing is called a “stage”.
Several stages can be combined with a single shaft to increase the overall pressure (multiple-stage pump). The water passes through the successive stages, with an increase in pressure at each stage. Multiple-stage centrifugal pumps are normally used when water has to be pumped to a significant height (200 m or more). For deep-well applications, the centrifugal pump and electrical engine are housed in a single unit. When the unit is to be located under the water level, a submersible pump will be required.
===Suitable conditions===
One limitation of a centrifugal pump is that the suction height cannot be higher than about 7 m above the water level. To overcome this limitation, and make it possible to place the pump above the suction limit, some pumps inject a jet stream of water into the suction pipe inlet. The kinetic energy of the injected water is partly converted into extra pressure, which helps to lift the water above the suction limit of the pump.
Centrifugal pumps are not energy-efficient, especially in the smaller size ranges (that are most common for rural water supply applications). Centrifugal pumps are still used for solar pumping but as electronics have become cheaper and more sophisticated, progressive cavity pumps have become more common. It is not unusual for a centrifugal pump to be found to be oversized, having been poorly selected for its intended duty. This causes a significant waste of energy. In general, centrifugal pumps with inverters and AC motors have efficiencies of 20 to 40%.
===Construction, operations and maintenance===
'''Head range''': Typically, 4–50 m per stage, with multiple-stage pumps to 200 m and more.<br>
'''Yield''': Varies widely, according to many options available in the market.<br>
— the main limitations of a centrifugal pump are its cost, the need to ensure a reliable supply of electricity or fuel, and the need for skilled technicians to maintain and repair the pump.<br>
===Costs===
Highly dependent on the power rating and quality of the pump.
==Field experiences== ==Manuals, videos, and links== =Acknowledgements=Acknowledgements==* Brikke, François, and Bredero, Maarten. [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CC0QFjAB&url=http%3A%2F%2Fwww.who.int%2Fwater_sanitation_health%2Fhygiene%2Fom%2Flinkingintro/water_sanitation_health/hygiene/om/linkingintro.pdf&ei=cwJpT-zaO-OiiQKCst2rBw&usg=AFQjCNEWOQhTgF3a7lzhuw5OA2KmbVGxcA&sig2=Rt2EURUyGVqDcwFg6p0xAw Linking technology choice with operation and maintenance in the context of community water supply and sanitation: A reference document for planners and project staff]. World Health Organization and IRC Water and Sanitation Centre. Geneva, Switzerland 2003.* [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CGgQFjAB&url=http%3A%2F%2Fartplatformartplatform.unicef.org%2Fwash%2FUNICEF_WASH_Technology_web/wash/UNICEF_WASH_Technology_web.pdf&ei=o2apT83fOKWhiAKFg7zkAg&usg=AFQjCNGKCfJz4oZ-8k2bQ3sulhgHRLV4EQ&sig2=hJsl_JqK0Dc3su6NRXyXcA WASH Technology Information Packages – for UNICEF WASH Programme and Supply Personnel.] UNICEF, 2010.
