FILTERENHETSKONSTRUKTION INNEFATTANDE EN SPIRALLINDAD FLERLAGERBANA

• Main Authors: DWYER J L, REIMAN P A
• Format: Patent
• Language: Swedish
• Published: 31.01.1977
• Subjects: PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING

1390222 Filters MILLIPORE CORP 10 March 1972 [22 April 1971] 11219/72 Heading B1D Liquid is filtered by introducing it into housing 29 (Fig. 2) wherein it passes through a cylindrical filter element 32 formed by spirally winding, around core 21, a multilayer sheet 20 (Fig. 1) comprising a non- corrugated filter layer 6 sandwiched between two generally-flat spacer layers 4 and 5 having a high percentage of void volume, spacer layer 5 being backed by an impermeable layer 11. Some of the edges of the layers of sheet 20 are sealed by adhesive strips 10, 16, 18 as shown in Fig. 1 so that the liquid in housing 29 flows into the upper edge of spacer layer 5, passes downwards and inwards through filter layer 6, and leaves the filter element through the lower edge of spacer layer 4. The filtered liquid flows out of housing 29 through holes 37. The filter layer may be formed from cellulose acetate or cellulose nitrate, and have an average pore size as small as 0.025 micrometer. The filter layer may be laminated between two woven support layers formed with polyester fibre. Each spacer layer, which may be between 0.02 and 0.03 inches thick, may be formed by two sets of parallel plastics strands adhered to each other as shown in Fig. 5. The impermeable layer may comprise polyvinyl chloride, polyvinyl acetate, polyethylene or polypropylene. The type and amount of adhesive employed is such that adhesive penetrates into, but not through, the filter layer so that sealing on one surface of the filter layer does not result in sealing on the opposite surface. Epoxy or polyurethanebased adhesives are particularly useful for providing the desired sealing. A cylindrical filter element can also be produced by spirally winding a multi-layer sheet having more than one filter layer, more than two spacer layers, and more than one impermeable layer. Spacer layers could taper axially of the element from thick open edges. The impermeable layer may be longer than the others and thus form the cylindrical periphery of the element.