Abstract: Process for the partial modification of porous, hydrophilitic filter membranes, of filter membranes treated in such manner and filter modules equipped with such filter membranes. When hydrophilic filter membranes are embedded in hydrophobic securing components of filter modules, the membrane filters are hydrophobized beyond the embedding area in an edge region, so that this edge region, that can no longer be wetted by water, forms an air by-pass when the filter modules are tested, rendering thus impossible that the filter modules can be tested. The novel process is intended to modify the edge regions in such a manner that, even after partial areas have been embedded in a hydrophobic polymer material, they remain porous and hydrophilic over the whole of their effective area.

Abstract: A process is described for filtration of fluids, particularly of heterodisperse fluids like beer, in which a cleaning cycle of the MF modules is always carried out when the transmembrane pressure exceeds a pre-set pressure which has been selected to be equal to the optimal trans-membrane pressure for the particular fluid to be filtered as regards its analytical appearance. In beer filtration this value is preferably set at 1.5 bar. The microfiltration facility is equipped with numerous MF modules 5, arrayed in series and parallel; with a device for cleansing the MF modules 5; and with a measuring device 3 for recording trans-membrane pressure, attached to a control device 7, which, upon attaining the pre-set trans-membrane pressure, interrupts the filtration process and starts a cleansing cycle going.

Abstract: A process is described for filtration of fluids, particularly of beverages like beer, utilizing microfiltration membrane modules operated in alternating filtering cycles and cleansing cycles, in which the cleansing cycles are always carried out when the transmembrane pressure exceeds a pre-set pressure which has been set to equal to the optimum trans-membrane pressure for the particular fluid being filtered, based on an analysis of the fluid after it has been filtered. In beer filteration, this value is preferably set at 1.5 bar. The microfiltration facility is equipped with numerous MF modules, arrayed in series and parallel; with a device for cleansing the MF modules and a measuring device for recording trans-membrane pressure that is attached to a control device which, upon attaining the pre-set trans-membrane pressure, interrupts the filtering cycle and starts a cleansing cycle.

Abstract: A multi-layer microfiltration membrane having an integrated prefiltration layer. Pursuant to a phase inversion process, several layers are successively poured out onto one another prior to phase separation of a lower layer, with the viscosity for the pour solution decreasing toward the upper layers. This produces a microporous, multi-layer, integral filtration membrane having a homogenous symmetrical pore structure for the final filtration layer and an open-pored structure for the prefiltration layer disposed therebelow. Even with small pore diameters, this membrane can be easily pleated for installation in filter cartridges without the formation of damage at the crease edges. High throughput rates are possible at a low tendency to clog.

Abstract: A filter material forming a filter layer consisting substantially exclusively of celluloses and cellulose derivatives. In addition to cellulose acetate fibers, the filter layer contains, in the form of additives, microcrystalline cellulose and microfine cellulose, or else microcrystalline cellulose only. The amount of microcrystalline cellulose can be as high as 70% of the weight of the filter layer and that of microfine cellulose up to 50% of the weight of the filter layer. Cellulose acetate fibers can be excluded if in their place, microcrystalline cellulose having particle sizes less than 10 .mu.m. are used. The manufacturing method provides for cellulose acetate fibers to be first mixed in a wet state with microfine cellulose and microcrystalline cellulose, after which differently prepared celluloses are admixed. The mash formed by mixing is formed into a fleece by means of a known felting method, and the fleece is subsequently dried.

Abstract: A module for crossflow filtration, a method of making same, and a filtration device that accommodates at least one such module, which includes at least two multilayer filter units which are stacked on top of one another and are separated from one another by a respective spacer, with the module having at least one channel for unfiltered material and at least one filtrate channel that connects the filter units. The module further includes a sealing material ring for sealingly interconnecting peripheral portions of the filter units, with at least one edge section of the filter units being spaced from the sealing material ring to form the channels for unfiltered material. The layers of each individual filter unit are fused together at least at edge sections that are not embedded in the sealing material ring which, at edge sections of the filter units that are embedded therein, has a width that is sufficient to completely accommodate the filtrate channels.

Abstract: In known membrane filter modules the sealing of the inlet of the faces of the capillary or hollow fiber membranes relative to the inlet of the stainless steel filter housing suffers from loosening of the sealing compound from the housing and from ruptures within the sealing compound due to different extension coefficients of the materials employed. With the inventive membrane filter module the safe employment of stainless steel filter housings with sealings and fluid distributing heads made of plastic is possible. At least a portion of the outer mantle surface of the end of the membrane bundle which is enclosed by a sealing compound or fused with plastic material is exposed so that the exposed outer mantle surface of the end of the membrane bundle may cooperate with sealing elements. Due to the fact that the sealing no longer acts on the stainless steel housing a simple and safe combination of the membrane filter module with the fluid distributing heads made of plastic is achieved.

Abstract: With known fluid distributing heads a change of the fluid path for a given fixedly mounted membrane filter apparatus is only possible by using special adapters, respectively, insert parts due to the varying geometry of the flow channels of the fluid distributing heads for outer, respectively, inner flow paths. The suggested fluid distributing heads specific to inner or outer flow path facilitate the use of a filter module with fluid distributing heads within a membrane filter apparatus.