Presentation Pump

7/29/2019 Presentation Pump

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PUMP

Pump is a device that moves liquids and

gases. Pumps are used in a variety of

machines and other devices, including home

heating systems, refrigerators, oil wells and

water wells, and turbojet and automobile

engines.Most pumps are made of steel orcast iron. Gas pumps are also called

compressors, fans, or blowers..


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TYPES OF PUMP

CENTRIFUGAL OR ROTOR DYNAMIC

POSITIVE DISPLACEMENT

Table 4.3.1 Classification of Pumps


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ROTO DYNAMICDynamic pumps maintain a steady

flow of fluid


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ROTO DYNAMIC OR CENTRIFUGAL

Can further be classified as :End suction pumps

In-line pumpsDouble suction pumps

Vertical multistage pumps

Horizontal multistage pumps

Submersible pumps

Self-priming pumps

Axial-flow pumps


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The main advantage of an AFP is that it caneasily be adjusted to run at peak efficiencyat

low-flow/high-pressure and high-flow/low-pressure by changing the pitch on thepropeller (some models only).These pumps have the smallest of thedimensions among many of theconventional pumps and are more suited for

low heads and higher discharges.

Axial-flow pump
http://en.wikipedia.org/wiki/Efficient_energy_usehttp://en.wikipedia.org/wiki/Blade_pitchhttp://en.wikipedia.org/wiki/Blade_pitchhttp://en.wikipedia.org/wiki/Efficient_energy_use


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General components of a CentrifugalPump

Cut-away of a pump showing volutecasing


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DiffuserThe purpose of the diffuser is to increasethe efficiency of the centrifugal pump byallowing a more gradual expansion and less

turbulent area for the liquid to reduce invelocity.This increase in flow area causes a reductionin flow velocity, converting kinetic energyinto flow pressure


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.

Wearing rings

To minimize the cost of pump maintenance, many centrifugal pumps are

designed with wearing rings which are replaceable rings that attached to theimpeller and/or the pump casing to allow a small running clearancebetween the impeller and the pump casing without causing wear of theactual impeller or pump casing material.


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One of the simplest types of shaft seal is the stuffingbox which is cylindrical space in the pump casingsurrounding the shaft.The packing rings are held in

place by a gland which is in turn, held in place bystuds with adjusting nuts. As the adjusting nuts aretightened, they move the gland in and compress thepacking. This axial compression causes the packing

to expand radially, forming a tight seal between therotating shaft and the inside wall of the stuffing box.


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POSITIVE DISPLACEMENT


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Different between rotary and

reciprocating pump

Reciprocating pumps are those which causethe fluid to move using one or more

oscillating pistons, plungers or membranes(diaphragms).

Rotary pumps are pumps that move fluidusing the principles of rotation.


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RECIPROCATING PUMPS

Typical reciprocatingpumps areplunger pumps

diaphragm pumps


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PLUNGER PUMPSPlunger pumps comprise of a cylinder with areciprocating plunger in it. In the head of the cylinderthe suction and discharge valves are mounted. In the

suction stroke the plunger retracts and the suctionvalves opens causing suction of fluid into the cylinder.In the forward stroke the plunger push the liquid outthe discharge valve.


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pumps the plunger pressurizes

hydraulic oil which is used to flexa diaphragm in the pumpingcylinder. Diaphragm valves are

used to pump hazardous andtoxic fluids.

Diaphragm pump


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Rotary pumps


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TYPE OF PUMPSInternal Gear. Internal gear pumps carry fluid between the gear teeth fromthe inlet to outlet ports. The outer gear (rotor) drives the inner or idler gear on

a stationary pin. The gears create voids as they come out of mesh and liquidflows into the cavities. As the gears come back into mesh, the volume isreduced and the liquid is forced out of the discharge port. The crescentprevents liquid from flowing backwards from the outlet to the inlet port.


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Flexible Member. This principle is similarto the Vane principle except the vanes flexrather than slide. The fluid pumping andsealing action depends on the elasticity ofthe flexible members. The flexible members

may be a tube, a vane, or a liner. shows aflexible vane pump.

Lobe. Fluid is carried between the rotorteeth and the pumping chamber. The rotorsurfaces create continuous sealing. Bothgears are driven and are synchronized bytiming gears. Rotors include bi-wing, tri-lobe, and multi-lobe configurations. is a tri-lobe pump.


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External Gear. External gear pumps also use gears whichcome in and out of mesh. As the teeth come out of mesh,liquid flows into the pump and is carried between the teethand the casing to the discharge side of the pump. Theteeth come back into mesh and the liquid is forced out thedischarge port. External gear pumps rotate two identical

gears against each other. Both gears are on a shaft withbearings on either side of the gears.

Vane. The vanes - blades, buckets, rollers, orslippers - work with a cam to draw fluid into andforce it out of the pump chamber. The vanes maybe in either the rotor or stator. The vane-in rotorpumps may be made with constant or variabledisplacement pumping elements. shows a slidingvane pump.


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Circumferential Piston. Fluid iscarried from inlet to outlet in spacesbetween piston surfaces. Rotors mustbe timed by separate means, and eachrotor may have one or more pistonelements.

Screw pumps carry fluid in the spaces between the screwthreads. The fluid is displaced axially as the screws mesh.Single screw pumps are commonly called progressive cavitypumps. They have a rotor with external threads and a stator

with internal threads. The rotor threads are eccentric to theaxis of rotation.Multiple screw pumps have multiple external screw threads.These pumps may be timed or untimed.


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VANE PUMP


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Lobe Pumps


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INTERNAL GEAR PUMP


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EXTERNAL GEAR PUMP

CAVITATIONS


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Suction Cavitations occurs when the pump suction is under a low pressure/high

vacuum condition where the liquid turn into a vapor at the eye of the pump impeller.This vapor is carried over to the discharge side of the pump where it no longer seesvacuum and is compressed back into liquid by the discharge pressure. Thisimploding action occurs violently and attacks the face of the impeller. An impellerthat has been operating under a suction cavitations condition has large chunks ofmaterial removed from its face causing premature failure of the pump.

Discharge Cavitations occurs when the pump discharge isextremely high. It normally occurs in a pump that is running atless than 10% of its best efficiency point. The high dischargepressure causes the majority of the fluid to circulate inside the

pump instead of being allowed to flow out the discharge. Asthe liquid flows around the impeller it must pass through thesmall clearance between the impeller and the pump cutwaterat extremely high velocity. This velocity causes a vacuum todevelop at the cutwater similar to what occurs in a venturi and

turns the liquid into vapor

CAVITATIONS

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