GB762219A - Improvements in or relating to pressure responsive valve - Google Patents

Abstract

762,219. Fluid-pressure servomotor-control systems. OTIS ENGINEERING CORPORATION. April 5, 1954 [July 17, 1953], No. 9884/54. Class 135. A pressure responsive valve comprises a body with a flow passage therethrough, a valve seat in the passage, a valve carried by a piston, the latter forming part of a variable volume control chamber which decreases in volume as the valve closes on to its seat, and a restricted passage for admitting fluid to the control chamber; and the ratio of the volumes of the control chamber for the seated and fully unseated positions of the valve is approximately 2 or more. The solid valve head 9 is carried by a tubular member 9a which also carries a piston 11, the latter travelling in a chamber formed in a sleeve 7 which is provided with an inturned abutment forming the valve seat 10. The valve is shown in the closed position, and to open it, a needle valve (not shown) situated in a by-pass passage leading from the inlet conduit 6 to the chamber control 13 at the back of piston 11 is opened temporarily to allow inlet fluid to act on the piston and so push the valve forward off of its seat. After the valve has been opened, fluid can flow from the inlet 6, through openings 9c in the tube, and through the tube to the downstream conduit 8. Fluid can also flow from the tube through a restricted aperture 39 into the chamber 13 and so maintain inlet pressure in that chamber to keep the valve open. Should a predetermined high or loss pressure develop in the fluid passing through the valve, one of two relief valves 47, 48 will open and chamber 13 will be vented, and the inlet fluid acting on the valve will close it to shut off flow along the conduits 6, 8. The valve is loaded to the open position by a spring 56. Tube 9a is packed where it passes through the end of sleeve 7 by a sealing ring 24 with backing rings 25. The piston is packed in a similar manner.