What is a Piston Pump?
A piston pump is a specific form of reciprocating pump characterized by a high pressure seal that moves in tandem with the piston itself. These pumps are versatile, serving both to transport liquids and to compress gases, and they can be adjusted to operate effectively across a broad range of pressures.
Notably, achieving high pressure performance does not significantly affect the flow rate, making piston pumps suitable for demanding applications.
One of the advantages of piston pumps is their capacity to handle not just standard fluids but also viscous substances and mixtures containing solids.
The pump operates using a piston cup and an oscillating mechanism; during the downward stroke, a pressure difference draws fluid into the pump chamber, and the subsequent upward stroke expels the fluid for use.
Piston pumps are commonly chosen in situations that demand steady, high pressure delivery, such as water supply systems or irrigation setups, where consistent performance is critical.
How Does a Piston Pump Work?
The operation of a piston pump closely resembles that of other positive displacement pumps, as both types rely on mechanical force generated by the pumping mechanism to move liquid by increasing its volume. These pumps typically draw power from external sources.
Structurally, piston pumps feature multiple pistons along with corresponding control components. For example, a duplex pump is equipped with two pistons and two control devices, whereas a triplex pump uses three pistons and three control devices.
It’s crucial to regularly inspect the control devices on each side of the pump to verify that the liquid is flowing correctly in both directions.
Piston pumps are available in single acting and double acting configurations. Double acting models include two sets of control devices and accommodate liquid at both ends of the piston.
This design allows the pump to complete a full cycle by enabling the flow of liquid alternately from one side to the other.
As the piston moves in one direction, it draws in fluid, and as it reverses, it discharges on the opposite side. In single acting versions, the pump relies on one way movement, requiring a complete cycle to achieve bidirectional flow.
Types of Piston Pumps
These pumps are classified into different types namely lift pump, force pump, axial pump, and radial piston pump. From these pumps, lift and force pumps can operate manually otherwise with the help of an engine.
1. Lift Piston Pump
In this pump design, the upward movement of the piston draws fluid into the lower section of the cylinder with the assistance of a valve, which serves as the control device.
When the piston moves downward, the fluid passes through additional control devices these are integrated into the piston itself and enters the upper section of the cylinder. On the following upward stroke, the fluid from the upper section is expelled through a spout.
2. Force Pump
In this pump design, fluid is drawn into the cylinder through an inlet valve during the piston’s upward stroke. When the piston moves downward, the fluid is then pushed out through an exit valve into the outlet tube.
3. Axial Piston Pump
This pump operates as a positive displacement (PD) pump and features multiple pistons arranged in a circular pattern within a tube block. The block itself rotates around its central axis, which is connected to a main shaft that, in turn, drives the pistons responsible for the pumping action.
Such pumps are versatile in their applications; they are commonly found as automotive air conditioning compressors, used as standalone pumps, or even serve as hydraulic motors in various systems.
4. Radial Piston Pump
This type of hydraulic pump operates with its pistons arranged radially, expanding outward in a symmetrical pattern around the drive shaft. Unlike the axial piston pump, where the pistons move along the axis, here the movement occurs along a radial track, resulting in a distinct operational mechanism.
Differences Between Piston and Plunger Pumps
Below is a table outlining the differences between piston and plunger pumps:
| Piston Pumps | Plunger Pumps |
| High pressure seal reciprocates with the piston in the cylinder. | High pressure seal is stationary. Plunger slides through seal allowing the pump to be used at higher pressures. |
| Inlet design pressure of 8.5psi to 40psi (0.58 bar to 2.8 bar). | Inlet design pressure of 60-70psi (4-5 bar). |
| Best suited to short duty cycles unless a larger pump operates slowly. | Okay for continuous operation when ran slowly. |
| Inlet values are mechanically actuated. | Requires flooded suction or higher inlet pressure supplied by a booster pump. |
| Output pressure 100-1200psi (6.9 bar to 83 bar). | Output pressure 100 to 10,000psi (6.9 bar to 700 bar). |
Applications of Piston Pumps
This type of hydraulic pump operates with its pistons arranged radially, expanding outward in a symmetrical pattern around the drive shaft. Unlike the axial piston pump, where the pistons move along the axis, here the movement occurs along a radial track, resulting in a distinct operational mechanism.
Advantages of Piston Pumps
The advantages of a piston pump mainly include the following.
- The range of pressure is wide
- Force can be managed without moving flow rate.
- The rate of flow and Pressure changes has a small outcome on the act.
- Skilled in moving of thick fluids, slurries, as well as abrasives with good control device design.
Disadvantages of Piston Pumps
The disadvantages of piston pumps mainly include the following.
- Maintenance cost, & operating is high usually bulky and heavy
- They handle only lesser flow rates
- Flow is Pulsating
FAQs
What is another name for piston pump?
A reciprocating pump is a class of positive displacement pumps that includes the piston pump, plunger pump, and diaphragm pump. Well maintained, reciprocating pumps can last for decades.
How reliable is a piston pump?
Low Maintenance: With their simple design and fewer moving parts compared to other pump types, piston pumps require minimal maintenance. This means less downtime for servicing and repairs, allowing farmers to focus more on their core farming activities.
Is piston pump a rotary pump?
Rotary piston pumps work by a piston sliding back and forth along a rotors groove drawing liquid into the inlet. Two directly driven pistons move reciprocally in cylinders, with the piston drawing back towards the centre of the pump when at the pump inlet causing fluid to be drawn into the inlet.
What is the difference between a piston pump and a regular pump?
While both pumps need hydraulic fluid to generate mechanical power, a piston pump uses a piston to move liquid throughout the pump valves, while a gear pump uses cogs to move fluid throughout the pump.
What is the difference between a plunger pump and a piston pump?
Unlike a piston that fits tightly inside the cylinder, a plunger fits loosely. The plunger creates negative and positive water pressure inside the cylinder as it moves up and down.
What is a piston pump used for?
Piston pumps can be used to move liquids or compress gases. They can operate over a wide range of pressures. High pressure operation can be achieved without adversely affecting flow rate. Piston pumps can also deal with viscous media and media containing solid particles.