GB867123A - Manual operating means for piston operated valves - Google Patents

Abstract

867,123. Valves. ACF INDUSTRIES Inc. Dec. 15, 1958 [Dec. 18, 1957], No. 40306/58. Class 135. In a rising stem valve comprising a piston- and-cylinder operator and manual operating means including screw-threaded engagement between the valve stem and the rod of the operator, means are provided to resist movement of the operator rod toward the valve housing, whereby on rotation of the operator rod, the valve stem may be moved relatively to the operator rod to effect manual positioning of the valve closure member. As shown in Fig. 1, a two-part valve gate 26 is movable between removable seat members 22, 24 in a valve housing 10. The valve stem 30 is screw-threadedly attached to the rod 50 of the piston 46 of a piston-and-cylinder actuator 12 and, as shown, pressure liquid admitted above the piston moves the valve gate to its open position and compresses a spring 58. In the event of failure in pressure liquid supply the valve automati. cally " fails-safe " in its closed position under the action of the spring 58 whence the piston 46 moves to abut the top cylinder cover. To reopen the valve prior to the restoration of the pressure liquid supply the hand wheel 56 may be rotated and since the rod 50 and piston 46 are held against further upward movement the valve stem 30 moves downwardly to open the valve. The port through the valve gate may be sited in the lower part of the gate in which case the valve is closed by the pressure liquid and opened by the spring. In another embodiment, the spring 58 is omitted and pressure liquid is admitted to above and below the piston to both open and close the valve. The rod 50 is replaced by a rod 51, Fig. 4, having a screw-threaded extension 53 engageable with a nut 65 securing a hand wheel 59 on the rod 51. If, on failure of pressure liquid supply, it is necessary to operate the valve, the hand wheel 59 is rotated to disengage the rod 51 from the stem 30 and raise the piston 46 into abutment with the top cover. The hand wheel 59 is then reversed and locked in its new position by the nut 65 (see Fig. 5), whence further rotation of the hand wheel raises the stem 30 and hence the valve member. Specification 390,711 is referred to.