GB668451A - Fluid flow and pressure control valve - Google Patents

Abstract

668,451. Fluid-actuated valves. SHELL REFINING & MARKETING CO., Ltd. April 28, 1950, No. 10529/50. Class 135. A pressure regulating valve for limiting the fluid pressure at a delivery point in a pipe line, and applicable, e.g. to aircraft fuelling equipment, comprises a valve member 3 coacting with a seat inclined, e.g. at 45 degrees, to the direction of flow, and having upstream and downstream stems 4, 5 each provided with a balancing diaphragm 7, 8 whose area is substantially equal to that of the valve member. The diaphragm 8 is subject to a pneumatic control pressure in a chamber 10, valves 18, 19 and a pressure gauge 20 facilitating adjustment of the pressure, whilst the diaphragm 7 is exposed on its lower face to the pressure at the delivery point. This pressure is transmitted through a damping ball valve 14 which permits free flow towards the diaphragm but a restricted flow in the opposite direction. In a modificaticn, pistons are used in place of the diaphragms and an adjustable spring load takes the place of the pneumatic control pressure. Also, the delivery pressure acts on a smaller piston which abuts the piston on the upstream stem, and the ball valve 14 is replaced by an adjustable needle valve. In a further modification, the loading spring acts on a plunger which has a hydraulic link with a portion of the piston on the upstream stem, the arrangement being such that the spring receives a lesser deflection than the piston. Instead of the diaphragm or piston on the downstream stem being loaded by air pressure or by a spring, it may be subjected to fluid pressure derived from a point upstream of the valve.