| 摘要 |
<p>1381097 Valves D H SHARP 13 March 1972 [18 Feb 1971] 4914/71 Heading F2V [Also in Division G3] In a valve for shutting off flow in an oil pipeline in the event of leakage a ball 62 rests on a compressible seat 66 which is pressed against the ball by fluid pressure in the pipe-line. On leakage the pressure in the pipe-line drops, the seat moves away from the ball to allow equalization of pressure across the ball which floats upwards to close off an outlet hole and flow through the seat passes to a surge tank. A vent 71 may be provided in the seat. In a further embodiment for controlling flow from a water tank 239, the polythene seat 244 has an inlet 248 a vent 250 and an outlet 268. The seat is depressurised by moving ball 270 off its seat by lever 276. The polythene ball 264 move down on to stops 262 until the pressure differential decreases and it can float to the top of the tank. Ball valve 270 may be replaced by a pinch cock. Either of the above valve constructions may be used as valve 102 in a system for closing a float-operated gate 86 in the event of leakage in oil pipe-line 22. On leakage the seat of valve 102 collapses to allow flow from tank 122 to tank 98. The gate 86 thereby moves to closed position to shut-off the defective pipe 22.</p> |
