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Plunger Pump Basic Theory (1/11)

A reciprocating positive displacement pump is one in which a piston displaces a given volume at each stroke.

Example:

A cylindrical solid (e.g. piston) has displaced its volume from the large container to the small container.Volume B (displaced fluid) is equal to the piston volume A

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Plunger Pump Basic Theory (2/11)

All reciprocating pumps have a fluid handlingportion commonly called: Liquid end

That has displacing solid called: Plunger or piston

A container to hold the liquid called: Liquid cylinder

A suction valve to admit fluid from the suction pipe into the liquid cylinder.

A discharge check valve to admit flow from the liquid cylinder into the discharge pipe.

Packing to seal the joint between the plunger (piston) and the liquid cylinder preventing liquid leaking out of the cylinder and xxx from leaking into the cylinder

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Plunger Pump Basic Theory (3/11)

Suction stroke

Plunger moved up

Pressure in cylinder reduced

When pressure becomes less than that in the suction pipe

Single acting pump

Suction valves opens

Liquid flows into cylinder and fills the volume being vacated by up works movement of the piston

Discharge valve is closed by high pressure in the discharge pipe

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Plunger Pump Basic Theory (4/11)

Discharge stroke

Single acting pump

Plunger moves down causes an increase in

Pressure of the liquid contained thein

Pressure becomes immediately higher than suction pressure

Causes to close suction valve

Further plunger movement further rise of liquid pressure

When equal to that in discharge pipe discharge valves opens

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Plunger Pump Basic Theory (5/11)

Discharge stroke

Single acting pump

Liquid flows into discharge pipe

Volume =>equal to plunger displacement less small losses

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Plunger Pump Basic Theory (6/11)

Double acting pump

Two suction and

two discharge valves

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Plunger Pump Basic Theory (7/11)

• Liquid end

• Crank - and throw device

- Driven by motor

electrical

Diesel engine(Combuston engine)

• Drive gearinternal

external

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Plunger Pump Theory (8/11)

This type of pump is used when:

Dependability is of prime importance even when the pump is operated continuously for long periods an where the pressure is very high.

Cast liquid end plunger pumps are used for low and moderate pressure

Forged liquid end plunger pumps are used for high pressure

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Plunger Pump Theory (9/11)

Liquid cylinder

Commonly made out of forged steel

Stuffing boxes and valves chambers

Are usually integral with the cylinder

Plunger

Are made by a number of materials.

Plunger must be hard and smooth as possible to reduce friction and to resist wear by the plunger - packing.

Hardened chrome alloy steels and steel coated with hard metal alloy or ceramics are must commonly used.

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Plunger Pump Theory (10/11)

Stuffing box

Vary widely depending upon service conditions

- soft square packing- solid molded rings of square- V lip or U lip

Oil and grease can be integrated into a lantern between stuffing box ring to reduce friction and reduce packing and plunger wear.

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Plunger Pump Theory (11/11)

• Very feasible machine

• Can operate at any point of pressure and flow within the limitations of the particular design.

• The maximum speed of a particular design is primarily limited by the frequency with which the valves will open and close smoothly

• The pump will operate against any pressure imposed upon it by the system it by the system it is serving.

• Maximum pressure rating of a particular design is determinant by the strength of the liquid end.

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Thank you for your attention !

Plunger Pump Theory