Patent GB-544136-A (GB)
Title: Improvements in or relating to the filtering and like treatment of fluids
IPC: B01D35/26
Filed: 1940-07-25
Abstract: 544,136. Filters. PINCHIN, JOHNSON & CO., Ltd., FORREST, W. J., and BROWN, C. H. July 25, 1940, No. 12145. Addition to 531,079. [Class 46] [Also in Group XXVIII] In filtering or straining apparatus comprising a filtrate chamber containing a reciprocating plunger, which is coaxial and connected with the plunger of a reciprocating pump whose chamber is in axial communication with the filtrate chamber, with valves operating to permit the pump to aid in drawing filtrate through the filtering-medium while part of the filtrate is being forced back through the filtering-medium to clean it and another part is being forced by the pump to discharge, as described in the parent Specification, one or both of of the plungers are arranged to serve as valves or the valves are arranged so that the pump draws the filtrate intermittently. Fig. 1 shows a filter element 1 and pump cylinder 3 with plungers 2, 4 respectively on a rod 17. The plungers have tubular hubs 56 which are a sliding fit in a tube 14, which connects the cylinder with the interior of the filter element, and with sockets 12, 13 at the opposite ends of the element and cylinder. With the plungers in the position shown, the filtrate passes from the interior of the element through the tube 14 and away from the pump cylinder through non-return valve 22, 23. The plungers are reciprocated by a crank 18 connected to the rod 17. As they move downward, the lower end of the hub 5 enters the socket 12 and that of the hub 6 enters the pipe 14. Filtrate below the plunger 2. is forced outwards to cleanse the element and that below the plunger 4 is discharged through the valve 22. The liquid continues to filter through the element above the plunger 2 and is passed through the tube 14 and hub 6 to the pump cylinder above the plunger 4. When the plungers are moved in the opposite direction, the element above the plunger 2 is cleansed and filtrate above the plunger 4 is discharged through the valve 23. The parts 14, 13 may be fitted with non-return valves 24, 25. As shown in Fig. 2, the plunger 4 is attached to a hollow rod 30 and has a depending tube 29 to which the plunger 2 is attached by means of a rod 42. The tube 29 and rod 30 have apertures 31, 32 controlled by a sleeve' 32a on a rod 33 reciprocated by a cam 38 on the shaft of the crank 18. Fig. 3 shows modified apparatus in which the hollow plunger rod 43 has apertures 46, 47 above and below the plunger 2, controlled by a sleeve valve 48 on a rod 33, and apertures 45 below the plunger 4 controlled by a sleeve or collar 49 on the rod. The plunger 4 only draws filtrate from element 1 during its upward movement, while forcing filtrate above it to discharge. During its downward movement the filtrate below the plungers passes through a non-return valve 44a in the plunger to the space above it. With this arrangement the sleeve valve 48 may be arranged to leave both apertures 46, 47 open during the upward movement of the plungers, cleansing of the element taking place only during their downward movement. Instead of providing the non-return valve 44a in the plunger a discharge outlet with non-return valve may be provided at the lower end of the pump chamber.