A pump is a device used to move fluids, such as gases, liquids or slurries. A pump displaces a volume by physical or mechanical action. One common misconception about pumps is the thought that they create pressure. Pumps alone do not create pressure; they only displace fluid, causing a flow. Adding resistance to flow causes pressure.
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, suction pump, and piston pump.
In Indian mythology, Lord Krishna playfully splashed colors on Gopees using a "Pichkaaree", which was, and is even now, a reciprocating hand pump. Hence historically "Pichkaaree" should be recognized as the first pump ever devised.
Types
Pumps fall into two major groups: positive displacement pumps and rotodynamic pumps . Their names describe the method for moving a fluid.
Positive displacement pumps
A lobe pump
Hand-operated, reciprocating, positive displacement, water pump in Košice-Ťahanovce, Slovakia (walking beam pump).
Mechanism of a scroll pump
A positive displacement pump causes a 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 as either
* a rotary-type, for example, the lobe, external gear, internal gear, screw, shuttle block,
flexible vane or sliding vane pumps,
* the Wendelkolben pump or the helical twisted Roots pump.
* the liquid ring vacuum pump
Gear pump
This uses two meshed gears rotating in a closely fitted casing. Fluid is pumped around the outer periphery by being trapped in the tooth spaces. It does not travel back on the meshed part, since the teach mesh closely in the centre. Widely used on car engine oil pumps.
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. Run on compressed air these pumps are intrinsically safe by design, although all manufacturers offer ATEX certified models to comply with industry regulation. Commonly seen in all areas of industry from shipping to process, SandPiper, Wilden Pumps or ARO are generally the larger of the brands. They are relatively inexpensive and can be used for almost any duty from pumping water out of bunds, to pumping hydrochloric acid from secure storage (dependant on how the pump is manufactured - elastomers / body construction). Suction is normally limited to roughly 6m although heads can be almost unlimited
Positive displacement pumps
A lobe pump
Hand-operated, reciprocating, positive displacement, water pump in Košice-Ťahanovce, Slovakia (walking beam pump).
Mechanism of a scroll pump
A positive displacement pump causes a 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 as either
* a rotary-type, for example, the lobe, external gear, internal gear, screw, shuttle block,
flexible vane or sliding vane pumps,
* the Wendelkolben pump or the helical twisted Roots pump.
* the liquid ring vacuum pump
Gear pump
This uses two meshed gears rotating in a closely fitted casing. Fluid is pumped around the outer periphery by being trapped in the tooth spaces. It does not travel back on the meshed part, since the teach mesh closely in the centre. Widely used on car engine oil pumps.
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. Run on compressed air these pumps are intrinsically safe by design, although all manufacturers offer ATEX certified models to comply with industry regulation. Commonly seen in all areas of industry from shipping to process, SandPiper, Wilden Pumps or ARO are generally the larger of the brands. They are relatively inexpensive and can be used for almost any duty from pumping water out of bunds, to pumping hydrochloric acid from secure storage (dependant on how the pump is manufactured - elastomers / body construction). Suction is normally limited to roughly 6m although heads can be almost unlimited
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ReplyDeleteI read another article recently that talked about the idea of positive displacement pumps being around for thousands of years. Obviously it wouldn't have been the same as it is today, but that was interesting to me. Thanks for giving us more information parakkrama!
ReplyDeleteLiquid ring pumps can be single or multi-stage. Typically a multi-stage pump will have up to two compression stages on a common shaft. In vacuum service, the attainable pressure reduction is limited by the vapour pressure of the ring-liquid. As the vacuum generated approaches the vapour pressure of the ring-liquid, the increasing volume of vapor released from the ring-liquid diminishes the remaining vacuum capacity. The efficiency of the system declines as a result.
ReplyDeleteMultistage water pump India are made to meet the requirements of most HVAC, OEM and Industrial applications that need water and other heat transfer liquids to be carried at pressures. These pumps are preferable for handling clean water and fluids which are not chemically bellicose to the pump components. These pumps have features like Flat absorption curves at high distribution rates, intercepting motor overloading even during prolonged use.
ReplyDelete