Patent GB-729436-A (GB)
Title: Improvements in filter bed agitation
IPC: B01D24/20
Filed: 1951-11-27
Abstract: 729,436. Gravity-sand filters. MOORE, R. P. Nov. 27, 1951 [Dec. 8, 1950 ; May 5, 1951; July 12, 1951], No. 27781/51. Class 46. [Also in Group XXIX] In apparatus for agitating a filter bed prior to or during backflushing, comprising a wheeled tubular structure carrying jet-forming devices 11, fig. 1, 1a a hydraulic cylinder 18 fixed within a channel member 17 attached to the main tube 1, and a stationary piston 19, Fig. 4, within the cylinder 18 rigid with piston rods 24 which guide the cylinder and are attached as by brackets 28, 29 to the filter tank 2, water under pressure is led alternately to the two sides of the piston 19 to move the cylinder 18 and structure to and fro, a valve 32 controlling the supply of water being actuated at the end of each traverse to reverse the direction of travel. The main tube 1 which is transverse. to the tank carries wheels at its flanged ends which run on paths or tracks at the sides of the tank 2. Water supplied to the tube 1 by means of a flexible hose attached at one end to the tank 2, passes through a central tube 6 and longitudinal pipes 8 to a pair of transverse pipes 10 carrying the jet-forming devices 11 which are directed vertically downwards. The four-way valve 32 is connected to each end of the cylinder 18 by pipes 33, 34, to the main pipe 1, and to a discharge pipe 36, the latter having a pre-set valve therein to regulate the rate of discharge of water and thus the speed of the carriage or structure. At the end of each traverse one end or the other of a movable trip rod 45, which is slidable in guides 46 carried by brackets 38, 38a, contacts a stop plate 47 fixed to the end wall of the tank 2 or the upper end of bracket 29. One of a pair of truncated conical members 51 secured to rod 45 thereupon moves a bell-crank lever 52, Fig. 5, about its axis 53 against the action of a spring 55 to release a roller 62 carried by a bolt 63 on lever 52 from an arcuate recess 61 in a trip plate 43. The trip-plate 43 is thus released for rotation by a lever 60 under the action of one of a pair of tension springs 69 connected at their inner ends by chains 70 to the lever 60 and at their outer ends by collars 71 on the trip rod 45. The trip plate 43, which is limited in its rotation by an arcuate recess 64 and co-operating pin 66, is attached to the stem 55 of the plug of valve 32 and the consequent rotation of the latter reverses the connections to the cylinder 18 and hence its direction of travel. A leak port and discharge pipe 41 are provided for each end of the cylinder 18, and an air inlet non-return valve 42 is fitted in each inlet pipe 33, 34 to permit automatic drainage of the cylinder 18 and pipes 33, 34 when not operating. In the modification shown in Fig. 9, the structure is of box formation having two main transverse tubular members 72 running on wheels 75, a pair of vertical feed pipes 76 depending from each member 72 and supporting, and feeding water to, longitudinal pipes 78 which latter are rigid with distributing pipes 81. A third and central distributing pipe 84 is also provided. The channel member 90 is connected by brackets 89 to the tubes 72. The main tubes 72 and the supporting structure is moved to and fro in the same manner as tube 1 of the first embodiment.