GB1177276A - Improvements in Valves - Google Patents

Abstract

1,177,276. Valves. WHEATON BRASS WORKS. 6 Feb., 1967 [7 March, 1966], No. 5602/67. Heading F2V. In a flow control valve, flow from an inlet to an outlet is controlled by a piston 41 the position of which, with respect to its seat, being governed by a shuttle valve 35, a manuallyoperable pilot valve 36, a Venturi tube 32, disposed between the shuttle and pilot valves, a pressure regulator 30 and an auxiliary control valve 27. Depression of pilot lever 37 shuts pilot valve inlet A and opens outlet B with the result that fluid which maintains the shuttle valve piston seated is drained through ducts 69, 70, chamber 65 and line 66, which line opens towards the downstream direction of the valves. A corresponding line 60, opening towards the upstream direction and disposed in the valve inlet, serves to replenish fluid which has flowed out from the Venturi 32 through the now open shuttle valve 35, chamber 65 and line 66, the flow through the Venturi drawing in fluid from line 33 and so creating a vacuum in chamber 58 thereby permitting fluid pressure in the inlet line to raise piston 41 from its seat to initiate flow from the inlet to the outlet. Upon retracting pilot lever 37, pilot inlet A is opened and outlet B closed with the result that fluid from line 60 flows through inlet A, line 69 and acts on the shuttle piston to seat it. With the flow to line 66 closed off, fluid from line 60 flows through the Venturi and into line 33 wherefrom it passes through the pressure regulator 30 to chamber 58. Upon the chamber pressure reaching 80% of the fluid pressure at the inlet, the regulator automatically closes and a slower flow of fluid to the chamber takes place through valve 27, this arrangement serving to build up pressure in chamber 58 but in such a way that piston 41 is moved towards its seat initially at a rapid rate but slowly immediately prior to seating, so ensuring gentle seating. Valve 27 is arranged to allow rapid flow from the chamber 58 but only a slow flow in the opposite direction. A solenoidoperated valve (38, Fig. 3, not shown), having ports connected in parallel with those of pilot valve 36, is provided to permit electrical as opposed to manual, actuation of the system controlling the position of piston 41.