GB722316A - A liquid pressure relief valve device for use with liquid fuel pumping plant - Google Patents

Abstract

722,316. Fluid-pressure servomotor-control systems ; valves. STOTHERT & PITT, Ltd. Jan. 18, 1952 [March 28, 1951], No. 7238/51. Class 135. In a liquid pressure relief valve for a pumping system in which a pilot piston actuates a pump by-pass valve and is controlled by a pilot piston valve movable in response to pressure variation in the system to connect the pilot piston to one or the other of the sides of the pump, both pilot and piston valve are freely movable in their cylinders and have channels leading to the pump suction for draining liquid leaking around the pistons. The outflow from a pump is passed through fittings to a distant point where a rise in the pressure which is to be kept instant is led to a connection 33<SP>1</SP> and raises a plunger 46 abutting an adjustably spring- loaded, suction-pressure balanced piston valve 40, so that a land 48 passes liquid fuel from a pump pressure chamber P through ports 21, 26, pipe 27, passage 70<SP>1</SP> in a relief valve 70, pipe 30 and check valve 9 to a cylinder 6<SP>1</SP> where it raises a piston 1 to open a valve 3 by-passing the pump pressure chamber to the pump suction chamber S. When the pressure returns to normal the piston valve moves down to pass the liquid in the cylinder 6<SP>1</SP> via the leaky check valve 9, through ports 26, 22, to the suction chamber so that the valve 1 closes. On a sudden rise in pump pressure due to, e.g., a valve in the fittings being closed, a relief valve 74 rises to pass liquid via passage 81, 19, to the suction chamber. Further upward movement of the relief valve plunger 70 closes the passage 70<SP>1</SP> and allows pump-pressure via groove 77 and pipe 30 to raise the piston and open the valve 1. The restriction 9<SP>11</SP> makes the ball 9 act as a dashpot.