Plunger & Piston pumps
Plunger pumps, also often just called piston pump by layman, belong to the group of oscillating positive displacement pumps - one of the oldest pump types. The displacers in plunger pumps are moved/pressed by crankshafts which is integral to the pump and the pump has one or more cylinders. The displacer of this pump is called “plunger”. In contrast to piston pumps the plunger “dives” through a fixed seal into a sealed off working space, displacing the fluid. The seal in piston pumps is oscillating with the displacer (= piston) in the same time. Check valves in the inlet and outlet ports of the cylinder make sure that the fluid is being pushed/pressed in the right direction. At least one plunger dives in its cylinder on each crankshaft’s rotation and gets withdrawn once taken back by the crankshaft. The plunger diving into the cylinder changes displaces a volume of fluid and, whilst withdrawing it draws in a volume of fluid i.e. the pump is pumping. In order to keep the pulsation of the pumped fluid as low as possible, an odd number of cylinders is used.
Plunger pumps / piston pumps are suitable for high pressure & high flow rates
As the dynamic high-pressure seal of the plunger pump is not attached to the moving plunger body, but to the housing of the pump, complex sealing systems are possible. The sealing system design is critical, and these designs have countless variations. Thus, a plunger pump can be adapted to many various fluids and environments. The pump’s housing and inner parts can be produced out of nearly any material. By the correct material choice, it is possible to pump abrasive, corrosive, hot, cold, viscous, toxic and flammable fluids – even under highest pressures. In this case, elaborate leakage monitoring and almost any barrier fluids can be used. If a fluid has a high vapour pressure, a plunger pump can also pump this by increasing the charge pressure of the plunger pump. Even sterilizable designs of plunger pumps are possible for any pressure level. For potentially explosive environments, it is possible to construct plunger pumps which are explosion proof.
Because the oscillating plungers are powered by force by a crankshaft, it is possible to overcome the highest flow resistance. That is why a plunger pump can also be used in processes with highest pressures, if the driving motor/power unit is strong enough.
The crankshaft, which powers the plunger, is usually rotated by a slower rotational speed than that of common prime movers. This is why most of the plunger pumps have an integrated gear reduction. Only very small pumps up to 45kw are powered by external v-belt-drives. For very large pumps tend to have no integrated gear reductions but use an external gearbox between the pump and its drive.
Because plunger pumps belong to the oscillating positive displacement pumps, the flow rate for a given pump depends only on the rotational speed of the pump’s crankshaft. The characteristic line of the delivery rate is nearly linear and directly proportional to the crankshaft speed. As a result, dosing tasks can be performed just as well as speed-dependent pressure control – up to many thousand bar operating pressure.
Due to the design, plunger pumps work with efficiencies of more than 90%! This makes their use interesting wherever energy saveing is a priority. The high energy density – or small size – of plunger pumps fascilitates their installation enormously.
Due to its many advantages, a plunger pump is often an economically viable alternative to previously used solutions.
Range of applications for plunger pumps / piston pumps:
- High-Pressure Cleaning
- Water Hydraulics
- Oil Hydraulics
- Process Technology
- Metering Systems
- Hydraulic Pressure Testing
- Energy Saving Fluid Transportation
- Drilling Service
- Water Injection
- Waterjet Cutting
Benefits of plunger pumps / piston pumps:
- configurable for almost any fluid
- linear performance curve
- capable of pumping against highest pressures
- highest possible efficiency
- small size
- low energy consumption
- high flow rate at high pressure
Delivery characteristics of plunger pumps / piston pumps:
- Operating Pressure: up to 3500bar
- Flow rate: up to 4000l/min
- Temperature: up 200°C
- Viscosity: up to 2000mPas
- Inlet pressure/ Suction pressure: atmospheric up to 1000bar
Plunger pump with Diesel engine
Plunger pump with electric engine