GB827293A - Control of liquid supply pressure - Google Patents

Abstract

827,293. Fluid-pressure servomotor-control systems; valves. ZWICKY Ltd. March 22, 1957 [March 22, 1956], No. 9012/56. Class 135. A device for maintaining a substantially constant pressure of liquid in a delivery conduit irrespective of variations in demand and applicable, e.g. to a fuel distribution system on an aerodrome, comprises a variable orifice valve 3 in the conduit, a circuit 7 extending from a point upstream of the valve to a point downstream thereof and including a constriction 17, an hydraulic servomotor 4, 5 subject to the pressure in the circuit upstream of the constriction acting to open the valve and to the pressure downstream of the constriction tending to close the valve, and a diaphragm actuated valve 14 controlling egress from the circuit 7 in response to the pressure downstream of the valve 3. As shown, the inlet to the circuit 7 includes a stabilizing valve 11 controlled by a diaphragm 12 subject to the pressure downstream of the valve 11 acting in the valve-closing direction against a spring 13. In a modification, the diaphragms 4, 5 are replaced by differential pistons without spring loading, and a tapered gate is employed instead of the double beat valve 3. For cases in which the delivery point is remote from the valve the pressure that acts on the diaphragm of the valve 14 is taken from the throat of a Venturi on the delivery side of the main valve 3. A construction of tapered gate valve suitable for the main valve comprises plates 31, 32 pivoted together at 33 and having a lost-motion connection with the valve stem 37 on which is mounted a bracket having rollers 41 for pressing the plates against seats 34, 35.