Metrohm 843 Pump Station with membrane pump - Manual (Page 27)

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7 Appendix
843 Pump Station with Membrane Pumps
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7 Appendix
7.1 Functioning of the membrane pump
Figure 10 Functioning of the membrane pump
1 Outlet valve 2 Inlet valve
3 Conveyor space 4 PTFE membrane
5 Eccentric
Principle
The membrane pump is located in the pump head (see Chapter 2.3, page
7). The membrane 4 made of PTFE is moved upward and downward by
means of an eccentric 5. These results in periodic volumetric changes in
the conveyor space 3. The medium to be conveyed is therefore aspirated
through the inlet valve 2 during the downstroke. The membrane presses
the medium through the outlet valve 1 back out of the conveyor space
during the upstroke.
The following properties characterize the membrane pump:
￭ Self-priming, thanks to its sophisticated membrane technology.
￭ Secure against dry-running, e.g. the pump suffers no damage if gases
are conveyed instead of liquids.
￭ Can be operated in any conceivable position.
￭ Small construction dimensions, therefore space-saving.
￭ High chemical resistance: the utilization of chemical-resistant materials
such as PTFE, PP and FFPM in the components that have contact with
the media permits the conveyance of practically all neutral and aggres-
sive media.