Plunger Type Pump and Motor

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PLUNGER TYPE PUMP AND

MOTOR

By: JOSEPH CHANDY

11MS32


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PLUNGER TYPE PUMP

It is a positive displacementpump, ie it causes a fluid tomove by trapping a fixedamount of it and then forcing(displacing) that trappedvolume into the discharge pipe.In plunger pump the high-pressure seal is stationary and asmooth cylindrical plungerslides though the seal. This

makes them different frompiston pumps and allows themto be used at high pressures. Itdevelops pressure upto30,000psi


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OPERATION

plunger pumps use a cylindrical mechanism to create a reciprocatingmotion along an axis, which then builds pressure in a cylinder or workingbarrel to force gas or fluid through the pump.

Plunger pumps are used in applications that could range from 70 to 2070bars.

The volume of the fluid discharged is equal to the area of the plunger orpiston, multiplied by its stroke length. The overall capacity of the pistonpumps and plunger pumps can be calculated with the area of the piston orplunger, the stroke length, the number of pistons or plungers and thespeed of the drive. The power needed from the drive is proportional tothe capacity of the pump.

Seals are an integral part of piston pumps and plunger pumps to separatethe power fluid from the media that is being pumped.

A stuffing box or packing is used to seal the joint between the vesselwhere the media is transferred and the plunger or piston. A stuffing boxmay be composed of bushings, packing or seal rings, and a gland.


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CAPACITY/ DISCHARGE

The capacity (Q) of a single acting piston or

plunger pump is proportional to its displacement

(D) per unit time. The displacement is the

calculated capacity of the pump, assuming 100%

hydraulic efficiency, and is proportional to the

cross sectional area of the piston (A), the length

of its stroke (s), the number of cylinders (n), andthe pumps speed in rpm.

D = A x s x n / Rev


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POWER

The power required to drive a Plunger pump is quitestraight forward. It is simply proportional to pressureand capacity. In brake horsepower it is:

bhp = (Q X P) / (1714 X ME) where 1714 is the bhp conversion factor and ME is

mechanical efficiency. Mechanical efficiency is thepercentage of the driver power that is not lost in thepumps power frame and other reciprocating parts. Themechanical efficiency of a piston or plunger pumpranges between 80 and 95% depending upon speed,size, and construction.


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PV plus Noise reduction Pulsations

Primary cause pulsation

Pulsating internal forces

4 or 5 pistons under pressure, varies with piston frequency (225 Hz @ 1500

rpm)

Eg. PV046: At 350 bar, the force per piston is 8000N, which means force

pulsating from 32 to 40kN at 225Hz. For PV270 the force per piston is26500N.

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ADVANTAGES

Wide pressure range, can reach high pressuresand the pressure can be controlled without animpact on the rate of flow.

Plunger pumps have a continous rate ofdischarge.

Pressure changes and discharge rate haveminimal effect on performance. Piston pumps canmaneuver viscous fluids.

Efficiency, volumetric efficiency is 95% of the totalefficiency of about 90%.

Variable discharge.


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DISADVANTAGES

Piston pumps cost more per unit to run compared tocentrifugal and roller pumps.

The mechanical parts are prone to wear, so themaintenance costs can be high.

The valves must be resistant to abrasives for largesolids to pass through.

Piston pumps are heavy due to their large size and theweight of the crankshaft that drives the pump.

Not suitable for flammable fluids due to internalrubbing parts.

Vibration generation and dynamic balancing difficult.


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USES

Fuel(Variable feed) injectors

Oil lubrication pumps

Industrial water jets Fuel feed pumps

Air compressors


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THANK YOU

Documents

Plunger Type Pump and Motor