Patent GB-642180-A (GB)
Title: Improvements in and connected with filters
IPC: B01D29/39
Filed: 1948-01-07
Abstract: 642,180. Filters; purifying water. MARTIN, M. J. Jan. 7, 1948, No. 532. Convention date, Feb. 27, 1947. [Class 46] A-filter element comprises a body or former having a surface; formed) with a plurality of substantially straight grooves which in cross-section converge inwardly from the surface, and a filler member  arranged longitudinally within each of the grooves, the grooves communicating inwardly of the filler members with filtrate discharge openings. As shown in Figs. 1, 3 and 4. the element comprises a tubular former 14 having longitudinal grooves, 21 of inwardly convergent shape in cross-section along its outer surface, the internal surface being counterbored in sections to a diameter greater than that at the base of the grooves 21, disjointed narrow slits 23 being thus formed at the inner extremities of the grooves 21 between the end portions and intermediate portions 24 of the former 14. The external diameter of the end portions is reduced leaving tapered abutments 22<SP>1</SP> at the ends of the ribs 22 so that a length of flexible filler member 25 may be laid along the grooves, up and down alternately, the ends being tied at 26. The filler members may comprise cords, wires, elastic threads or the like of metal, or textile fibres, twisted, plaited or braided, or in the form of close helical windings. Single lengths may be used. The members may also comprise rods in which case they are retained at the inner extremities of the grooves 21 by elastic bands at the top and bottom of the element beyond the abutments 22<SP>1</SP>. In each case the arrangement is such that the filler members bear against the opposite sides of the grooves. End plugs 27, 30, retaining caps 28, 32, and an outlet pipe 15 are provided. A tensionadjusting member, round projections on which the flexible filler members are arranged, may be provided at one end, adjustable longitudinally by a screw-operated device. When the element is mounted in a casing 10, Fig. 1, a mixture of filter air with water may be introduced before screwing on a cap 12, and the liquid to be filtered passes in through a pipe 19 to an annular space 18 and then through holes under inclined deflector lugs 20 which give it a swirling motion. For cleansing, the cap 12 is removed, and the element, with its attached tube 15, which slides out of the block 11, is also removed from the top. The tube 15 is then replaced in the block 11 from the underside, as shown in dotted lines, and cap 12 replaced. When clean liquid is passed through tube 19 and into the casing 10 the pressure acting outwards forces the filler member in each groove outwardly, against its natural tension, or, (in the case of rods), against the elastic retaining bands. The invention may be applied to flat formers, two of which may comprise a hollow leaf for inward filtration, three such leaves being mounted in a single casing with a common outlet pipe. Units of the type shown in Fig. 4 may be mounted as at 51, Fig. 1:1, for distributing liquid to a sand filter, or water-softener, similar units; being used at 47 to prevent escape of filtering material. On backwashing such a filter, the elements 51 permit escape of " floc " but not of filtering material. Fig. 12 shows an application to a rotary filter drum having, separate peripheral compartments 53, each provided with a filtrate outlet pipe 54. The outer face of each compartment 54 is formed by an arcuate plate 55 having longitudinally-extending grooves 21: each accommodating a filler member 25.