Piston Pumps

Pump Application and Operation

What is a piston pump?

A piston pump is a type of reciprocating pump that moves and pressurizes fluid by using one or more reciprocating pistons; it is typically driven by an electric motor through a crankshaft and connecting rod.

Though there are many types, all piston pumps feature at least one piston moving in an enclosed cylinder. The piston will normally have one or more o-rings on its periphery, which seals against the cylinder as the piston moves. The piston draws liquid into the cylinder and pushes it out under pressure as the volume in the cylinder gets progressively larger and then smaller as the piston reciprocates.

Piston pumps can handle the following ranges: 
Flow rates between 5 and 700 gpm
Total head (pressure) between 50 and 5,000 psi
Horsepower between 1 and 500 hp

Piston Pump

How do they work?

Like most positive displacement pumps, they operate by using the force of the pumping mechanism to expand and contract an internal movable volume of liquid. Piston pumps can draw power from an electric motor, internal-combustion engine, or other power-source, though less advanced piston pumps may be powered by hand, wind, or flowing water. Typically, rotational motion drives the piston.

Piston pumps can have more than one piston and set of check valves. A duplex pump has two pistons and two sets of check valves, a triplex has three, and so on. It is important to check valves on either side of the pumping chamber to ensure fluid is flowing in the correct direction.

Piston pumps can also be single or double acting. Double acting pumps entail two sets of check valves and fluid on both sides of the piston. This allows the piston to complete a full pumping cycle by moving in one direction from the other; as the piston is in-taking on one side, it is exhausting on the other. Single action versions require the piston to move in both directions to complete a full pumping cycle.

Where are they used?

Piston pumps are used as hydraulic pumps to power heavy machinery, but they are also useful in smaller machines such as paint sprayers. This pump type can be upsized for use in oil production and other industrial applications. Variations of this pump type are also used in high tech and advanced industrial applications in the form of axial and radial pumps, which consist of multiple pistons arranged in a circular cylinder block.

Contributed by PumpScout staff.

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