Plunger pump
A plunger pump (plunger pump ) is a piston pump with a plunger piston . The name Plunger comes from English, where u. a. Diver / plunger , piston / piston rod , tappet , valve piston , etc. a.) means.
Instead of a piston that moves along the cylinder wall in a sealed manner, the piston rod itself represents the piston in a plunger pump. The piston rod can also have thickenings, which, however, do not extend to the cylinder wall. When the piston rod (the plunger) is immersed in the working space, the volume is displaced just like with other pistons that have a seal on the outside that is flush with the cylinder wall. In contrast to this, the cylindrical plunger is only sealed by a fixed stuffing box . The working space, in which the retracting piston displaces the water with its own volume, only has to offer space for it, but can otherwise have any shape and be integrated with an air tank , for example .
Plunger pumps are available as single and double acting (oscillating between two chambers) and as differential pumps in which the plunger has two different diameters.
functionality
The upward movement of the plunger opens the suction valve due to the suction effect and water enters the pump chamber. During the downward movement, the suction valve closes under its own weight and the pressure valve opens, whereby water is pressed into the pressure pipe.
One problem with this is the intermittent flow of water, which can lead to shocks in the pipe. The pressure air vessel converts this into a more even flow, while the enclosed air acts like a shock absorber on the water column. The suction air tank also contributes to an even flow of the water. If more water is to be pumped or the water flow is even more uniform, several plungers are used in combination. Several individual plunger pumps feed the same pressure pipe.
The individual plungers are usually driven by a common crankshaft via connecting rods and cross heads. The angular positions on the crankshaft are evenly distributed so that the pressure peaks are reached at different times; this leads to a more even pressure in the pressure pipe. The number of plungers in a pump varies depending on the design. With hydraulically driven plunger pumps there are usually two. In the case of a drive via a crankshaft, there is always an odd number in order to avoid superimposition of the load peaks in the reversal points. In practice there are three, five or seven.
Other uses of the plunger
Plungers were previously used as pistons in internal combustion engines , where the seal is located in the cylinder wall . A plunger is therefore also referred to as a piston without a piston ring .
Richard Trevithick used huge plungers in his early high-pressure steam engines, as sealing a normal working piston at increased operating pressure had initially proven to be practically impossible. A little later, advances in mechanical engineering made it possible to use normal pistons again at the same and even higher pressures.
See also
Individual evidence
- ↑ Woma high pressure pumps. Retrieved June 21, 2015 .
- ↑ Hammelmann high pressure pumps. Retrieved June 21, 2015 .