GB693489A - Filters - Google Patents

Abstract

693,489. Filters. VOKES, Ltd. Feb. 12, 1951 [Feb. 24, 1950], No. 4878/50. Class 46 [Also in Group XXVIII] Cylindrical filter elements are formed by compressing fibrous material on to a permeable inner cylinder in one or more layers and maintaining it in compression with permeable and flexible wrapping material preferably in the form of a continuous length. The ends of the filter material in the element thus formed are sealed to the cylinder. A perforated cylinder 3, Figs 2 and 4, having end caps 14 is supported by a pair of mandrels 1, Fig. 2, in a framework, Fig. 1, and has secured to it the end, preferably tapered, of a. length of wrapping material 5 carried on a cylinder 4, Fig. 1, supported by a pair of mandrels 2. A constant tension is applied to the material 5 by weights 6 acting on the mandrels to provide preferably equal loading on the roll 5 and cylinder 3. Fibrous filter medium may thus be fed from a roll 10 with little effort between the material 5 and the cylinder 3 as the latter is rotated. The degree of compression of the filter medium 10 by the wrapping material 5 is governed by the choice of the weights 6. When sufficient of the medium 10 has been rolled on to the cylinder 3 to enclose it wholly in one layer or more, any remaining filter medium is pulled off, and a further quantity of wrapping material wound on to the cylinder. Just before this operation is completed a strip of thermoplastic tape is laid across the wrapping and when this has been taken into the element heat and compression are applied to bring about complete adhesion between adjacent layers of the wrapping. Means such as the weights 6 maintain tension in the material 5 during this sealing operation to prevent unrolling of the element during sealing. The tapering of the inner end of the wrapping 5 and the length of the tapered portion are both chosen to ensure that at least one complete roll of the filter medium 10 is applied to the cylinder and is thus in direct contact with the flanges of the end caps 14 before the width of the wrapping is the same as the length of the cylinder 3. The ends of the formed element are further compressed and sealed on to the cap flanges by tensioned metal strip 15 applied by a strapping machine. One end cap is provided with an inlet or outlet. In a modification of the apparatus the mandrels 1, 2 loaded by friction clutches driven by an electric motor instead by weights 6, and the filter medium 10 is in the form of a loose heap which can be fed in by hand or by a rotary comb driven by the motor