GB1208035A - Methods of and apparatus for assembling an ultra-filtration membrane in a porous support tube - Google Patents

Abstract

1208035 Dialysis apparatus AMERICAN STANDARD Inc 17 May 1968 [22 May 1967] 23613/68 Heading B1X A resilient "ultra-filtration", i.e. dialysis, membrane is positioned inside a porous support tube by a method which comprises (a) forming a flat strip of resilient ultra-filtration membrane into a tube by wrapping the membrane around a resilient tubular member, (b) holding the membrane in place around the resilient tubular member while inserting the membrane and resilient tubular member into the porous support tube, (c) applying fluid pressure to the internal surface of the resilient tubular member thereby to cause the resilient tubular member to expand and move the membrane against the interior wall surface of the porous support tube, (d) releasing the fluid pressure thereby to cause the resilient tubular member to contract and (e) removing the resilient tubular member from the porous support tube and membrane. When the membrane has been wrapped around the resilient tubular member, the end portions of the membrane may be overlapped; adhesive may be applied to the overlapped end portions of the membrane thereby to form at least a temporary bond to hold the membrane in place on the resilient tubular member for insertion of the membrane and resilient tubular member into the porous support tube. The membrane may be positioned inside the porous support tube by use of apparatus comprising a resilient tubular member and means for applying fluid pressure to the internal surface of the resilient tubular member thereby to cause the resilient tubular member to expand. As illustrated in Fig.3, the apparatus comprises a resilient tubular member 10 which preferably is made of an elastomer, for example rubber, and which is secured at each end in fluid sealing relationship, for example by means of clamps 11, about an inner tubular member 12 which preferably is made of metal; the inner tubular member is closed at one end and is formed with a plurality of radial bores 14 so that fluid, for example air or water under pressure, introduced therein may be supplied to the interior of the resilient tubular member thereby to bring a membrane 16, which is positioned around the external surface of the resilient tubular member, into contact with the internal surface of a porous support tube 17 which may be made of woven reinforced glass fibre. The membrane, which may be made of cellulose acetate, polyvinyl alcohol, polyvinyl acetate, polyvinyl methyl ketone, polycaprolactam (nylon 6), ethyl cellulose, cellulose, cellulose isobutyrate, amylose triacetate, methyl carbonate or ethyl carbonate, initially is in the form of a flat strip which may be wrapped around the resilient tubular member either by use of a longitudinallysplit and hinged metal tube 18, see Figs.1 and 2 (not shown), which tube is discarded after placing the membrane, resilient tubular member and inner tubular member within the porous support tube, or by use of a structure comprising a base member which is formed with a longitudinallyextending groove for receiving the membrane and the resilient tubular member and to which are pivotally connected two cover members in each of which is formed a complementary longitudinallyextending groove, see Figs.4A and 4F (not shown). When positioned within the porous support tube, the end portions of the membrane may overlap and may be bonded together by adhesive which may be applied to the membrane as the membrane is being positioned on the resilient tubular member prior to placing the membrane and resilient tubular member within the support tube; the adhesive forms a temporary bond when the membrane is on the resilient tubular membrane, which bond is broken and reformed on transfer of the membrane to the support tube. Alternatively, the end portions of the membrane may not overlap, either the abutting ends of the membrane being sealed by a separate strip of material or the porous support tube being provided with means, for example a line of waterproof adhesive, to seal the ends of the membrane.