GB809536A - Improvements in or relating to gas shut-off valves - Google Patents

Abstract

809,536. Valves. SPERRYN & CO. Ltd May 10, 1956 [May 12, 1955], No. 13710/55. Class 135. Between the inlet and outlet chambers 4, 5, Fig. 4, is an annular seat 7 with which cooperates a closure member 8 that is secured to a rubber or oiled leather diaphragm 10, the space 12 above which is maintained at atmospheric pressure via a plug 11 whilst a weight 13 screwed on to the underside of the member 8 seats the latter by gravity when the pressure in the outlet chamber 5, acting on the diaphragm 10, is insufficient to overcome the downward pull of the weight. A passage 14, which passes through the weight 13, opens into a chamber 15 defined by a flexible frusto-conical. wall 16 having its upper edge attached to a ring 17 on the valve cover 6 whilst its lower edge is fixed to the centre of the diaphragm 10; pressure from the inlet chamber 4 is transmitted to the chamber 15 and therein exerts a downward force and diaphragm 10 which may be equal to or greater than that acting on the underside of the member 8, depending upon the ratio of the areas concerned. The member 8 can only be reopened by manually operating a spring-loaded valve to allow pressure gas to pass from the inlet to the outlet chamber and by closing cocks in the delivery side. In a modification, the weight is placed on top of the closure member. In another modification the weight is replaced by a spring disposed between the valve cover and closure member. In a further modification, the chamber 15, Fig. 8, is formed by a flexible bellows 31 and the closure member 8 is loosely guided by a depending tube 32 moving in an upstanding sleeve 33, the clearance between the tube and sleeve enabling gas to pass from the inlet chamber 4 to the chamber 15. The space 12 above the diaphragm 10 is connected through a pipe 34 to a flame failure or over-heating warning device 35 associated with the burner supplied with gas from the valve; an orifice 36 in the diaphragm 10 permits a slow escape to atmosphere via the device 35 which escape is closed upon flame failure or overheating, the resulting pressure build-up in the chamber 12 seating the member 8. The orifice 36 may be replaced by a restricted passage by-passing the diaphragm through the body of the assembly. According to the Provisional Specification the by-pass valve may be thermally controlled.