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 pumpHand-operated, reciprocating, positive displacement, water pump in
Košice-
Ťahanovce,
Slovakia (walking beam pump).
Mechanism of a
scroll pumpA 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
Main article:
Gear pumpThis 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.
Progressing cavity pump
Widely used for pumping difficult materials such as sewage sludges, contaminated with large particles, this pumps consists of a spiral shaped rotor, about 10 times as long as its width. This can be visualised as a central core of diameter x, with typical a curved spiral wound around of thickness half x, although of course in reality it is made from one casting. This shaft fits inside a heavy duty rubber sleeve, of wall thickness typically x also. As the shaft rotates, fluid is gradually forced up the rubber sleeve. Such pumps can develop very high pressure at quite low volumes.
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
Main article:
Reciprocating pumpReciprocating-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.
Rotary peristaltic pump
Peristaltic pump
Main article:
Peristaltic pumpA peristaltic pump is a type of positive displacement pump used for pumping a variety of
fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A
rotor with a number of "rollers", "shoes" or "wipers" attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes (or "occludes") thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ("restitution") fluid flow is induced to the pump. This process is called
peristalsis and used in many biological systems such as the
gastrointestinal tract.
Kinetic pumps
A centrifugal pump uses a spinning "impeller" which has backward swept arms
This section may require
cleanup to meet Wikipedia's
quality standards. Please
improve this section if you can. (September 2008)
These types of pumps have a number of characteristics:
Continuous energy
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
Centrifugal pump
Main article:
centrifugal pump.
A centrifugal pump is a rotodynamic pump that uses a rotating
impeller to increase the pressure of a fluid. Centrifugal pumps are commonly used to move liquids through a piping system. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or
volute chamber, from where it exits into the downstream piping system. Centrifugal pumps are used for large discharge through smaller
Eductor-jet pump
Main article:
Eductor-jet pumpThis uses a jet, often of steam, to create a low pressure. This low pressure sucks in fluid and propels it into a higher pressure region.
