Membrane Filter Elements
38 Operating Manual Status: 06/2001/01
Squeezing pressure limitation
The maximum permissible squeezing pressure must be limited on the manifold in
accordance with the pressure/temperature graph for membrane filter elements with a safety
valve (see Graphs 1-10 in the Appendix).
Pressure rise
Here as well, the pressure rise is measured and regulated in accordance with Graph 13
(page 63) and 15 (page 64) in the Appendix.
For volumetric feeding pumps, the pressure rise results from the maximum possible
dewatering rate or the filter cake and the pump size.
Squeezing volume flow
From an economical standpoint, the squeeze pump is to be dimensioned so that the
multiple average value of the squeeze volume flow is available at the start of the squeeze
phase.
Discharging squeeze medium
Following squeezing, the squeeze medium must be drained out of the membrane filter
elements. Depending on the individual conditions, the medium may either drain out of the
membranes by gravity or it can be pumped out.
• If filter elements with exchangeable membranes, e.g. R, RUD or RUM types, are used,
pump out the squeeze water.
- Only in this way can it be ensured that no water is left behind the membranes.
• For the one-piece welded membrane design, it is sufficient to allow the squeeze
medium to drain off by gravity. Small amounts which may remain behind the
membranes in the squeeze chamber are normally irrelevant.
Note
Do not use pressure sources or feeding pumps which cause pressure pulsation. Poor
dewatering results and possible membrane damage may occur.
Note
The squeeze water has drained off completely when a vacuum results in the manifold
and the flow rate in the drain line is zero.
