GB1299658A - Hydraulic flow-operated shut-off device - Google Patents

Abstract

1299658 Valves BENDIX CORP 11 Dec 1970 [29 Dec 1969] 59055/70 Heading F2V A valve 36 having surfaces exposed to pressures representative of the flows in the supply and delivery conduits of an hydraulic apparatus is moved against a spring 48 towards a position blocking the supply conduit when the difference between the flows, which may be due to rupture of a pipe-line, exceeds a predetermined amount. The pressures are derived from a throttle 74 in the supply conduit 78 and a throttle 96 in the return conduit 86. The pressure upstream of the throttle 74 is communicated through a restriction 66 and a passage 72 to a space 40 within the valve while that upstream of the throttle 96 is communicated to a space 46 through a passage 86 and a restriction 104, the downstream pressures acting directly on spaces 38 and 42 through passages 78 and 97. A second spring-loaded valve 54 is subjected to the pressure drop across the throttle 74 so that it opens to provide additional flow in parallel with the throttles when pressure fluctuations occur. When a single-acting piston is to be supplied, the throttles 66 and 104 reduce the speed of the valve 36 so that the piston reaches the end of its travel before the valve is closed by the difference in flow to the two sides of the piston.