Plunger pump
Encyclopedia
A plunger pump is a type of positive displacement pump where the high-pressure seal is stationary and a smooth cylindrical plunger slides though the seal. This makes them different from piston pump
Piston pump
A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases.-Types:* Axial piston pump* Radial piston pump...

s and allows them to be used at high pressures. This type of pump is often used to transfer municipal and industrial sewage.

History

The invention of the plunger pump is attributed to Samuel Morland
Samuel Morland
Sir Samuel Morland, 1st Baronet , or Moreland, was a notable English academic, diplomat, spy, inventor and mathematician of the 17th century, a polymath credited with early developments in relation to computing, hydraulics and steam power.-Education:The son of Thomas Morland, the rector of...

 based on a patent of 1675.

Operation

Piston pump
Piston pump
A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases.-Types:* Axial piston pump* Radial piston pump...

s and plunger pumps are reciprocating pumps that use a plunger or piston to move media through a cylindrical chamber. The plunger or piston is actuated by a steam powered
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...

, pneumatic, hydraulic, or electric drive. Piston pumps and plunger pumps are also called well service pumps, high pressure pumps, or high viscosity pumps.

Piston pumps and plunger pumps use a cylindrical mechanism to create a reciprocating motion
Reciprocating motion
Reciprocating motion, also called reciprocation, is a repetitive up-and-down or back-and-forth motion. It is found in a wide range of mechanisms, including reciprocating engines and pumps. The two opposite motions that comprise a single reciprocation cycle are called strokes...

 along an axis, which then builds pressure in a cylinder or working barrel to force gas or fluid through the pump. The pressure in the chamber actuates the valves at both the suction and discharge points. Plunger pumps are used in applications that could range from 70 to 2070 bars. Piston pumps are used in lower pressure applications. The volume of the fluid discharged is equal to the area of the plunger or piston, multiplied by its stroke length. The overall capacity of the piston pumps and plunger pumps can be calculated with the area of the piston or plunger, the stroke length, the number of pistons or plungers and the speed of the drive. The power needed from the drive is proportional to the capacity of the pump.

Seals are an integral part of piston pumps and plunger pumps to separate the power fluid from the media that is being pumped. A stuffing box
Stuffing box
A stuffing box is an assembly which is used to house a gland seal. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements.-Boats:...

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

Piston pumps and plunger pumps have a number of components that require the choice of materials based upon wear considerations and contact with the media type
MIME
Multipurpose Internet Mail Extensions is an Internet standard that extends the format of email to support:* Text in character sets other than ASCII* Non-text attachments* Message bodies with multiple parts...

. Components may have a number of materials used including bronze, brass, steel, stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....

, iron, nickel alloy, or other material. For example, piston pumps that function in general service or oil service applications may have an iron cylinder and piston with a steel piston rod
Piston rod
In a piston engine, a piston rod joins a piston to a connecting rod.Many internal combustion engines, and in particular all current automobile engines, do not have true piston rods, and the term piston rod is often used as a synonym for connecting rod in the context of these engines.All engines...

. The plunger, discharge valves, and suction valves come in contact with the media type transferred; material choices should be considered based on the fluid transferred. In power applications where continuous duty piston pumps and plunger pumps are needed, solid ceramic plungers may be used when in contact with water and oil, but may not be the appropriate choice for use with highly acidic media types.

The difference between piston pumps and plunger pumps as compared to rotary piston
Pistonless rotary engine
A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does, but instead uses one or more rotors, sometimes called rotary pistons...

 pumps is the actual mechanism used to transfer the fluid. The piston elements moving along an axis are called axial piston pumps. Rotary piston pumps typically have an internal rotating mechanism that moves the piston.

Plunger Pump Heads up to 7.250 psig
Plunger pump heads are preferably used for simple, non-critical fluids.
For critical, abrasive, toxic or flammable fluids diaphragm pump
Diaphragm pump
A diaphragm pump is a positive displacement pump that uses a combination of the reciprocating action of a rubber, thermoplastic or teflon diaphragm and suitable non-return check valves to pump a fluid...

heads are recommended.

The principle using K 110 and K 210 plunger pump heads as an example:

The reciprocating plunger directly displaces the process fluid. As the plunger and plunger seal are wetted, high operational safety is achieved by optimal selection of plunger material and seal design.

The plunger seal selection is dependent on the fluid, pressure and temperature.

Many options are possible:
e. g. pump head K 500 with overall heating jacket and accessible valves
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