GB258051A - - Google Patents

Abstract

258,051. Glenfield & Kennedy, Ltd., and Price, O. A. July 25, 1925. Vacuum relief valves.-Avacuum relief valve for use on large water mains and hydro-electric power penstocks has the inlet protected by a shroud or baffle 14 formed to present in conjunction with the valve chest a smoothly contoured annular passage in which the air accelerates to a maximum velocity so reducing to a safe limit the velocity of the air entering the valve. The valve member 1 co-operates with a seating 2 secured to the casing 3 and is carried by a spindle 5 secured to the moving cylinder 7 of a dashpot which in turn is connected by links 9 to counterweighted levers 10. The inner member 8 of the dashpot is secured to a superstructure 12 and is thin walled and only slightly less in diameter than the outer member so that in operation the drop of oil level is substantially the same in both inner and outer members. The outer member has metallic packing rings 18 and the inner member overflow openings 21. The bottom of the member 8 is fitted with a non-return valve 19 and a needle-valve 20 arranged to allow a rapid flow from the chamber 8 but only a restricted flow in the reverse direction. The annular passage in the shroud or baffle is divided up by radial ribs to prevent the entry of wind blown foreign material. In the form shown the valve member and seat have flat contacting surfaces and have their upper surfaces shaped to form a wedge-shaped groove so that should a film of ice form on said surface it cannot adhere thereto. Modifications are desscribed in which tapered seating surfaces are employed and in which the seat member is provided with drainage passages or shaped to present a substantially continuous self-draining surface.