GB901061A - Improvements in or relating to safety valves - Google Patents

Abstract

901,061. Fluid-pressure servomotor-control systems. GESELLSCHAFT DER L. VON ROLL'SCHEN EISENWERKE A.G. Dec. 2, 1959 [Dec. 2, 1958; July 22, 1959], No. 41018/59. Class 135. A safety valve, which is operative with fluid flowing in either direction, is provided with a hollow closure member 11, Fig. 1, which controls the communication between the bores. Upon supplying highpressure fluid to the bore 35 the fluid flows via ports 8, restricted passage 33 and check-valve 31 into a chamber 22 where it acts on the outer annular face of closure member 11 and assist a spring 17 to urge the member 11 on to its seat 13. Should the fluid exceed a given value then an element 19 is displaced against an adjustable spring 20, since chamber 22 opens to the element 19 via a bore 21, whereupon fluid exhausts through passages 23 in the element 19, grooves 24 and a passage 26. The restricted passage 33 creates a pressure drop between the ports 8 and chamber 22, and the higher fluid pressure in the ports 8 acts on the surface b 2 -b 1 and unseats the member 11 to interconnect bores 35, 36. When the fluid pressure has reduced to its normal level and has been re-established in the chamber 22 the member 11 re-seats and the element 19 closes the bore 21. Upon connecting the bore 36 to the high-pressure supply, the fluid passes to chamber 21 via another check valve 32 and a restricted passage 34, the valve functioning as previously described. The loading of the spring 20 may be adjusted by a fluid-actuated piston instead of the screw 28 shown. In a modification, the outer end of the closure member 111, Fig. 2, is of reduced diameter and operates in the chamber 122 whilst element 119 is disposed on the outer side of the end cover 116 of the chamber 122. An adjustable throttle screw 134 is placed in the flow path to the chamber 122. The latter may have manually or an electromagnetically and manually operated valve connected thereto to additionally control the release of pressure-fluid therein.