Abstract: The invention relates to a fluid treatment apparatus resulting from the stacking of plates 1 each having, on each of their two main faces, a treatment zone 3 provided with ribs 2, the two membranes being placed between the opposite faces of each adjacent plate 1 of the stack. The two membranes between each adjacent plate are held at a multiplicity of points by the ribs of adjacent plates, at least one rib, and preferably both, at each such point having at least one portion 14 of maximum height H only over a length l which is less than the total length L of that rib or the distance between maximum height portions on that rib. The apparatus is particularly useful in the medical field, especially as a haemodialyser.

Abstract: The invention relates to an apparatus comprising a stack of plates having plates of a type A and a type B alternating. Each plate has exposed channels and a semi-permeable membrane 1 turned over one of its edges 2. The membranes extend into the exposed channels 8, 8a-9, 9a to provide locations for the passage of the fluid to be treated flowing between the two superposed membranes 1 arranged between two adjacent plates A and B. Further exposed channels 13, 15, 17, 19 are used for the passage of the treating fluid flowing between the face of each plate in the exchange and/or separation zones 3, 3a of the plates A and B thereon and the adjacent membrane. If each plate A is symmetrical relative to a median plane perpendicular to one edge 2, each plate B of the stack can be considered as a plate A which has been turned through 180 degrees about a median axis perpendicular to the edge 2.

Abstract: Fluid treatment apparatus is disclosed in which a stack of flat membrane elements and support plates are enclosed and compressed by means of a casing which comprises two endplates between which the stack is arranged, the internal faces of the endplates being adapted to contact the faces of the stack which is substantially parallel to the plane of the elements, and at least two lateral plates are located with their internal surfaces in front of the lateral faces of the stack. A number of studs and cooperating recesses are provided in adajcent surfaces of each lateral plate and each endplate, whereby the lateral plates and endplates are connected together within cooperating engagement surfaces, which are disclosed as being cylindrical, of its stud and recesses, hold the endplates and lateral plates together and thus hold the stack compressed.