Pump

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Overview

File:Wasserwerk pumpe01.jpg

An electrically driven pump (electropump) for waterworks near the Hengsteysee, Germany.

A pump is a device used to move gases, liquids or slurries. A pump moves liquids or gases from lower pressure to higher pressure, and overcomes this difference in pressure by adding energy to the system (such as a water system). A gas pump is generally called a compressor, except in very low pressure-rise applications, such as in heating, ventilating, and air-conditioning, where the operative equipment consists of fans or blowers.

Pumps work by using mechanical forces to push the material, either by physically lifting, or by the force of compression.

The earliest type of pump was the Archimedes screw, first used by Sennacherib, King of Assyria, for the water systems at the Hanging Gardens of Babylon and Nineveh in the 7th century BC, and later described in more detail by Archimedes in the 3rd century BC.^[1] In the 13th century AD, al-Jazari described and illustrated different types of pumps, including a reciprocating pump, double-action pump with suction pipes, water pump, and piston pump.^[2]^[3]

Types

File:Rotary piston pump.svg

A two-lobe pump (multiple rotor, positive displacement type)

Pumps fall into two major groups: rotodynamic pumps and positive displacement pumps. Their names describe the method for moving a fluid.

Positive displacement pumps

File:Drehkolbenpumpe.jpg

A lobe pump

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Hand-operated, reciprocating, positive displacement, water pump in Košice-Ťahanovce, Slovakia (walking beam pump).

File:Two moving spirals scroll pump.gif

Mechanism of a scroll pump

A positive displacement pump causes a liquid or gas to move by trapping a fixed amount of fluid and then forcing (displacing) that trapped volume into the discharge pipe. The periodic fluid displacement results in a direct increase in pressure. A positive displacement pump can be further classified as either

a rotary-type (for example the rotary vane),
lobe pump similar to oil pumps used in car engines, or
the Wendelkolben pump or the helical twisted Roots pump.

Roots-type pumps

The low pulsation rate and gentle performance of this Roots-type positive displacement pump is achieved due to a combination of its two 90° helical twisted rotors, and a triangular shaped sealing line configuration, both at the point of suction and at the point of discharge. This design produces a continuous and non-vorticuless flow with equal volume. High capacity industrial "air compressors" have been designed to employ this principle as well as most "superchargers" used on internal combustion engines.

Reciprocating-type pumps

Reciprocating-type pumps use a piston and cylinder arrangement with suction and discharge valves integrated into the pump. Pumps in this category range from having "simplex" one cylinder, to in some cases "quad" four cylinders or more. Most reciprocating-type pumps are "duplex" (two) or "triplex" (three) cylinder. Furthermore, they are either "single acting" independent suction and discharge strokes or "double acting" suction and discharge in both directions. The pumps can be powered by air, steam or through a belt drive from an engine or motor. This type of pump was used extensively in the early days of steam propulsion (19th century) as boiler feed water pumps. Though still used today, reciprocating pumps are typically used for pumping highly viscous fluids including concrete and heavy oils.

Compressed-air-powered double-diaphragm pumps

Another modern application of positive displacement pumps are compressed-air-powered double-diaphragm pumps, commonly called SandPiper or Wilden Pumps after their major manufacturers. They are relatively inexpensive and are used extensively for pumping water out of bunds, or pumping low volumes of reactants out of storage drums.

Kinetic Pumps

Continuous energy addition
Conversion of added energy to increase in kinetic energy (increase in velocity)
Conversion of increased velocity to increase in pressure
Conversion of Kinetic head to Pressure Head.
Meet all heads like Kinetic , Potential, and Pressure

Application

File:Dosierpumpe.gif

metering pump for gasoline and additives

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

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.

Pumps as public water supplies

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 most houses 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".

Today, hand operated village pumps are 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 opens 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 (pictured) are designed to be cheap to build and install, and easy to maintain with simple parts. It was assumed that spare parts would become available in the local market by for-profit wholesalers. However, it became clear with time that often spare parts are not available locally, because of the low profit margins for wholesalers, especially in Africa. This means that communities are often stuck without spares and cannot use their handpump anymore and have to go back to traditional and sometimes distant, polluted resources. This is unfortunate, as water projects often have put in a lot of resources to provide that community with a handpump. As a result, spare parts free handpumps are now being developed, like the Afripump.

Power source

File:Gemaal.JPG

19th century Dutch diesel pump in Rijswijk, Netherlands

Pumps have been powered by water flow (as with the noria), 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). Solar power has been used to power an electric motor, for remote locations.[2]

References

↑ Stephanie Dalley and John Peter Oleson (January 2003). "Sennacherib, Archimedes, and the Water Screw: The Context of Invention in the Ancient World", Technology and Culture 44 (1).
↑ Al-Jazari, The Book of Knowledge of Ingenious Mechanical Devices : Kitáb fí ma'rifat al-hiyal al-handasiyya, translated by P. Hill (1973). Springer.
↑ Derek de Solla Price (1975). Review of Ibn al-Razzaz al-Jazari, The Book of Knowledge of Ingenious Mechanical Devices. Technology and Culture 16 (1), p. 81.