GB796013A - Improvements in or relating to automatic-closure valves - Google Patents

Abstract

796,013. Valves. COAL INDUSTRY (PATENTS), Ltd. Jan. 26,1956 [Oct. 26, 1954], No. 30893/54. Class 135. A valve which closes automatically whenever the upstream or downstream pressure drops below a given value comprises a casing in which is mounted a diaphragm 5 capable of sealing the inlet 2a from the outlet 2b and a second diaphragm 4 spaced apart from and having a larger effective area than the diaphragm 5, the two diaphragms 4, 5 and a part 3 of the casing defining a control chamber 64 arranged to communicate with the upstream or downstream pressure fluid through manual control means such as the auxiliary valve 6. The diaphragms 4, 5 are clamped between casing parts 1, 3 and 2, 3 respectively and are centrally mounted on a spindle 11 with a spacer member 10, the parts being secured by a screwed sleeve 12 and a nut 13. The diaphragm and valve assembly is loaded in the closing direction by coaxial springs 15, 16 arranged between discs 17, 18. The disc 17 is provided with a screwed plug 21 having a non-circular recess filled by a wooden plug 21a to hinder access to the adjusting sleeve 12, the upper end of which has a left-hand internal thread 22 requiring a correspondingly threaded tool for adjustment purposes. The auxiliary valve is operated by the rotation of a knob 40 against the action of a torsion spring 51 secured to the casing part 3 and to the valve 6. A flange 47 on the valve 6 has a detent co-operable with a spring-loaded ball 49. The valve 6 is retained in the casing part 3 by a washer 52 and a spring clip. The casing part 1 is open to the atmosphere through passages 60 fitted with filter plugs 62. The valve inlet 2a communicates with the auxiliary valve 6 through a bore 37 fitted with a filter plug 39, an annular groove 36 and a channel 33. The outlet 2b communicates with the auxiliary valve through a bore 41 adjacent a ridge or projection 45, a filter plug 43 and a passage 34. The auxiliary valve 6 has an axial bore 30 and radial bores 31, 32 which in the position shown connect the chamber 64 to the atmosphere. To open the main valve, the valve 6 is turned to connect the bore 31 to register with the passage 33 so that inlet pressure is admitted to the chamber 64. Subsequently the valve 6 is turned so that the bore 32 is aligned with the passage 34 so that the chamber 64 is open to the outlet 2b. The valve 6 is retained in this position by the ball 49 so that if the supply pressure fails or the outlet pressure falls unduly low, e.g. due to rupture of a hose, the main valve closes and cannot re-open since no pressure can communicate with the chamber 64. The projection 45 creates a venturi effect in the passage 41.