Membrane filter plates have a chamber below the drainage surface that may be inflated. The common method used is water pressure, which is generated by pumping into the squeeze cavity to inflate the face of the plate against the filter cake. Air may also be used.
Membrane plates are used to reduce the cake moisture content or shorten the filtration cycle time. Two types of membrane plate designs are used, fixed membranes and replaceable membranes. Mixed pack membranes are the most common configuration (one recessed plate, then one membrane plate alternate in the press plate pack). The final product produces savings in the overall plate pack cost.
Membrane plates usually operate at a feed pressure of up to 7 bar and squeeze pressure up to 15 bar. Special plates can be designed to accept higher feed and squeeze pressures.
Fixed Membranes are most commonly 100% polypropylene but, thermoplastic is also available. The plate is manufactured by molding a face membrane and a core plate separately. The face membranes are then joined into the core by heat welding to form a homogeneous plate. Although this type of membrane is suitable for many designs, it has particular advantages in food applications, where the lack of joints will prevent contamination.
Replaceable Membranes use a polypropylene core, which is machined to accept the connection and seal of a rubber membrane. These faces are easily changed. EPDM thermoplastic and other compounds are used for specific conditions. Savings in operation can be achieved in difficult environments and the membrane’s superior flexibility make it the best design for many installations.
Contact us to discuss filter plate selection and whether membrane filter plates and associated options such as membrane squeeze water skids are suitable for your installation.