GB704370A - Improvements in or relating to pressure responsive valves - Google Patents

Abstract

704,370. Fluid-pressure servomotor-control systems. OTIS, H. C. Nov. 6, 1951 [Nov. 17, 1950], No. 25942/51. Class 135 A safety valve 9, Fig. 1, e.g. for a well-head 1, comprises a body 12, Fig. 3, with an inlet 13 and outlet 15, a tubular member 22 slidable in the body and carrying a closure member 16 tor co-operation with a seat 17 and a pressureresponsive member 29 which forms, with the member 22 and a seal 23, a chamber supplied with line fluid through an orifice 37 and adapted to be vented when a predetermined high or low pressure is reached in the chamber to cause member 16 to be seated. The closure member is held in open position by the pressure in the chamber plus a spring 44, and the chamber communicates with pilot valves connected to pipes 40, 41, Fig. 4, one opening at a predetermined high pressure and the other at a predetermined low pressure. Should either valve open due, e.g. to a blockage or leakage, respectively, in the outlet, inlet pressure seats the member 16, orifice 37 being then positioned downstream of seal 23 to prevent a continuous bleed of fluid through the open pilot valve. To move the member 16 to open position the open pilot valve is closed, and inlet pressure admitted to the chamber by opening a valve 46, which is closed once member 16 is unseated. In another arrangement, the orifice 37 is omitted and pressure fluid is supplied to the chamber through a line 71, Fig. 5, from a point 50 downstream of a throttle 10 connected to the outlet of the valve. When the closure member 57 is unseated, the pressure fluid passes through orifices 75, 76 to both sides of the pressure responsive member 77, but when one of the pilot valves opens, inlet pressure commences to move the member 57 towards its seat, and causes a ring 72 to cut off the orifices 75 whereby the pressure acting through orifices 76 aids in seating the closure member. U.S.A. Specification 2,566,772 is referred to.