Patent GB-258027-A (GB)
Title: Improved automatic self-closing valve
IPC: F16K17/26
Filed: 1925-06-27
Abstract: 258,027. Glenfield & Kennedy, Ltd., and Price, O. A. June 27, 1925. Valves controlled by pilot or relay valves.-An automatic self-closing hydraulic valve of the kind comprising a plunger movable axially in the main conduit in the vicinity of a zone of less cross sectional area than the main channel has the plunger subject on its rear face to the reaction of the flowing stream 4 and provided with a piston member forming a partition between front and rear chambers, supplied with conduit pressure under the control of an auxiliary valve actuated by changes in the flow conditions in the main conduit. In the form shown in Fig. 4 the plunger 1 has a flange 9 forming the piston and slides in a two part casing 2, 3 arranged axially in an outer casing 4, 5 so as to leave an annular water way 13. The plunger has a valve face adapted to co-operate with a corresponding seat on the part 5 and in the open position of the valve the flange engages a stop 8 on the part 2 so that the plunger and inner casing form an approximately stream line body coaxial with the water way. The chambers 10, 11 on each side of the piston are connected by pipes 14, 15 to the casing of auxiliary piston valve 16 loaded by weights 17 and actuated by a piston 18 subject on one side to the pressure in the full bore conduit and in the other to the pressure in the restricted part 12 of the conduit transmitted through a pipe 20. Under normal conditions the lower pressure from the conduit 12 is maintained in the chamber 10 and the higher pressure from the conduit 13 in the chamber 11. In the event of an abnormal outflow the pilot valve is raised to reverse these connections. The conduit 23 may be connected to atmosphere instead of to conduit 12. The chamber 11 may be permanently connected to the conduit 13 and the pilot valve arranged as a weighted piston valve or flap valve so as to connect the chamber 10 alternately to the conduits 12, 13 in which case the reaction of the flowing stream acting on the exposed rear end of the plunger is relied on to close the valve. To retard the closing movement a cock 25 may be fitted on the pipe 15 and connected by linkage mechanism to the main plunger and arranged to throttle progressively the exhaust from the chamber 11 as the valve moves to its closed position. The linkage may also operate an indicator. A serrated flange may also be formed on the piston adapted to engage a flange on the part 3 so as to form a buffer chamber. Cocks 31 may be fitted on the conduits 14, 15 to enable the main valve to be actuated bv hand. Fig. 8 shows two valves arranged back to back so that abnormal flow in either direction closes the conduit. Both valves are controlled by a common weighted flap or piston auxiliary valve 16. The full bore connections 36, 36<a> are connected to the control valve and chambers 10, 10<a> through a flap valve 37 so that the higher pressure is transmitted while the restricted bore connections are connected to the control valve through a pair of coupled flap valves so that the lower pressure is transmitted. In all forms the exposed area at the back of the plunger may be made either greater or less in area than the front end.