Abstract: A flexible fleece-like filter material is provided wherein in a matrix-like basic framework consisting of synthetic or natural fibres, ultra-finely fibrillated fibres and/or inert porous particles are incorporated as a filter medium, the filter medium forming, anchored in the matrix, chain structures provided with a cationic or anionic charge or possibly charged with other substances which influence the filtering properties or with immobilised cells and/or catalysts. A fleece is formed with a thickness of between 0.5 mm and 5 mm and preferably up to 2 mm, which is flexible and which can even be pleated. This filter material can be produced by a simple method without harming the environment.

Abstract: A process for the manufacture of microfiltration membranes from aromatic polyamides, of which the pore sizes are between 0.05 and 10 .mu.m. A copolymer of isophthalic acid and m-phenylenediamine is dissolved in a solvent mixture of dimethylacetamide and dimethylformamide in the presence of alkali or alkaline earth chlorides and polyethyleneglycol. This solution is produced without the addition of water and is subsequently poured out onto a smooth surface formed of chemically inert material with the formation of the membranes. The water that is required as the precipitation agent, is only added to the poured-out solution by means of the air humidity. The relative air humidity is increased from 30% to 100% during formation of the membranes.

Abstract: A filter cartridge with a filter element inserted in a receiving space formed by a central cylindrical flow pipe 32 and a peripheral wall 34 is in terms of its possibilities of use and possibilities of adaptation to filtration problems substantially improved in that the filter element consists of fleece-like filter material and in that in its radial direction it comprises mutually enclosing zones of different filtering properties. For practical purposes, these zones can follow one another without any transition or they may be constructed with filtering properties which are varied in stepwise fashion. The filter element can be formed by the combination of a pleated filter fleece with a rolled-up filter fleece, the pleated part of the filter element being optionally on the inside or the outside.

Abstract: A filter cartridge has a support structure consisting of at least one tube provided with openings over its entire length and having at least one axially yieldable annular zone to permit axial movement to compensate for axial stresses and prevent damage to the filter material supported by the structure.

Abstract: A membrane type filtering device has modules containing bundles of capillary tubular membranes. To meet various filtration problems the modules have double accesses located at the two end faces of the module housings. Connections to these accesses are made by plugging in the module ends into flow distributor heads, which can be of two types whereby the crossflow can be selectively conducted either through the internal passages of the capillary membranes or else along the outsides of the capillary membranes. Appropriate matching is achieved by exchangeable inserts and exchangeable intermediate tension plates and end tension plates.

Abstract: A microfiltration membrane is made up dissolving m-phenylenediamine-isophthalic acid polymer, a high temperature aromatic polyamide, in one or more solvents selected from the group which consists of N-methylpyrrolidone, dimethylformamide and dimethylacetamide, and the resulting solution in the presence of two or more of these solvents, a structure-loosening agent such as water or a polyhydric alcohol, is cast. After gel formation in the film the latter is washed free from solvents and dried. The microfiltration membrane has high bursting strength and a pore point of 0.05 to 10 microns and a high permeability.

Abstract: Processes for the production of filter elements based on aromatic polyamide in which a semi-finished filter element is produced from a solution of the polyamide in aprotic solvent and the polyamide is then coagulated by immersion in a liquid bath containing precipitating agent may be used for the production of filter elements with a pore size of from 0.05 .mu.m to 10 .mu.

Abstract: A microfiltration membrane is made up dissolving m-phenylenediamine-isophthalic acid copolymer, a high temperature aromatic polyamide, in one or more solvents selected from the group which consists of N-methylpyrrolidone, dimethylformamide and dimethylacetamide, and the resulting solution in the presence of two or more of these solvents, a structure-loosening agent such as water or a polyhydric alcohol, is cast. After gel formation in the film, the latter is washed free from solvents and dried. The microfiltration membrane has high bursting strength and a pore point of 0.05 to 10 microns and a high permeability.