GB898139A - Improved liquid flow control system - Google Patents

Abstract

898,139. Fluid-pressure servomotor-control systems; valves. BRITISH PETROLEUM CO. Ltd., and WILLIAMS, P. G. Aug. 5, 1960 [June 12, 1959], No. 20147/59. Class 135. A liquid flow control system comprising a pressure control valve 16 having an actuating mechanism 18 which is hydraulically controlled by applying a variable pressure differential thereto, the valve being connected at the downstream side thereof to a Venturi 8, means 14, 25 adapted to vary the pressure differential within the actuating mechanism of the valve and, in consequence, to reduce the flow through the Venturi when the pressure differential between the fluid in the throat of the Venturi and fluid at a pre-set pressure exceeds a given value, and means 26, operating in response to movement of the actuating mechanism of the valve, for providing control of a pump 2 connected at the up-stream side of the Venturi. The pump, which may be driven by an internal combustion engine 30, forces liquid via pipe 3, filter 4, pipe 5, flowmeter 6, valve 7, and Venturi 8, through a pipe 9. With the valve 7 open and increase in pressure in the pipe 9 causes the pressure in the pipe 25 to act on one side of a diaphragm 24 constituting the actuating mechanism 18 and thereby to open the valve 16 against a pre-set pressure on the other side of the diaphragm, fluid then being by-passed via a pipe 17. Movement of the valve 16 causes a piston valve 26 connected thereto to move and, via pipes 27, 28, piston 29, control a throttle 32 of the engie 30 and so reduce the output of the pumps When the valve 7 is closed, in order to prevent the reduced pressure in the throat of the Venturi from tending to close the valve and so cause the pump to increase speed, a piston 12 is connected across the valve 7 and actuated in response to the high pressure differential so as to open a valve 21 and thereby bleed-off the pressure in the chamber 19 above the diaphragm via pipes 20, 22. A second pipe 9a may be supplied by the pump and provided with duplicated parts as shown.