3P PRINZ Pompe 3P M Series, Instruction & Maintenance Manual

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CH.6 DESCRIPTION OF THE PUMPS
6.2 WORKING PRINCIPLE OF THE HOLLOW DISK PUMP
In Figure 6.2, the dashed area represents the suction liquid, while the blank area represents the
liquid to be pushed, or othwerise the volume to be filled during the suction (depending on the
rotation direction).
The hollow disk is pivoted eccentrically to the pump shuft and it is guided by the diaphragm that
separates the suction port from the supply port.
The axis rotation will cause the disk to oscillate and to adhere either with the internal
circumferential area of the pump casing either with the eccentric end of the shaft and the
diaphragm, thus creating two separate leak-tight chambers.
Figure 6.2 shows the four sequential positions of the hollow disk and highlights how the impeller
moves and how the volume changes progressively from the suction torwards the supply, either
on the external and on the internal part of the disk.
Between the shaft and the disk pin, there is an elastic device that allows the disk itself to
overcome, without inconveniences, the passage of solid particles of dimensions dependant to
the type of pump, and that eventually are in suspension inside the pumped fluid; in addition, it
allows a self-recover of eventual wear-out effects and allows the pump to be scarcely sensitive to
expansions caused by high temperature variations.
In a more detailed way, the working principle can be explained as below:
The axis, while rotating, causes the impeller (or oscillating hollow disk) to roll, adhering along one
of its generatrix to the internal surface and pheriferal to the fixed pump body.
This creates a depression in the suction, suctioning fluid into the pump and it pushes to the
supply the liquid enclosed inside the pump itself, please refer to Figulre 6.2 in its working
sequences, while the pump is fill with fluid and begins one new turn.
The internal left side of the impeller is full with suction liquid, while in the right internal side and
in all the external part of the impeller there will be supply fluid.
The liquid that is external to the impeller is pushed through the supply port, while the pump
suctions fluid from the inlet port, creating a depression that can reach, in optimal rotationg
speed and supply pressure conditions, 7/8 meters of water column.
It should be highlighted that what happens in the external part of the impeller, happens also in
the internal hollow part of the impeller itself. In other wordk the impeller, during its rotation-
oscillation, creates two volumes, one external and one internal.
While on the right side the fluid is being expelled on the external part of the impeller, the left
part of the body and all the internal of the impeller are fill with suctioned fluid.
Also the fluid contained internally to the impeller is pushed to the supply side together with the
last residues of the fluid external to it.
After these sequences, the impeller comes back to the position from which it started and there
will be a new cycle.
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