GB562084A - Improvements in and relating to fluid controlling valves - Google Patents

Abstract

562,084. Safety cut-off valves. SAUNDERS VALVE CO., Ltd., and SUTTON, F. March 3, 1943, No. 3526. Divided out of 559,679. [Class 135] A safety cut-off device comprises a self-closing and self-locking diaphragm valve closed and held closed upon a fall in the fluid pressure in the main conduit by a piston moving in a cylinder to which fluid has normally no access, but to which pressure is admitted by an auxiliary valve which opens under spring pressure against the pressure of fluid upon it and is locked in the open position. The main valve comprises a diaphragm 1 adapted to co-operate with a weir 3 and backed by. an annular comb 6 adapted to mesh with a comb 5 formed on the casing. The comb is screwed to a stud 19 having a head embedded in a boss on the diaphragm within a strengthening ring 21. The comb is also pinned to a rod 27 adjustably screwed to a piston 8 and secured by an eccentric set-screw 30. The piston is acted on by a spring 28 and its downward movement is limited by shoulder 25. To open the valve a push-button 56, protected by a pivoted cover 57 and padlock 58, is depressed to open an auxiliary valve 55 and increase the spring- loading on a non-return valve 49. This releases the pressure above a piston 41 and permits pressure in the main actuating chamber to raise a piston valve against the action of a spring 36 to vent the main chamber through passages 51, 53 and 48. At the same time a cam 46 moves to allow a pressure inlet valve to close under the action of a spring 34. If the push-button is now released and the main conduit is under pressure, the main valve remains open. In the event of the pressure falling below a predetermined value, the spring 36 acts through the cam to reopen the valve and admit pressure to close the main valve. A part of the cam prevents restoration of pressure alone reclosing the valve 29.