| 摘要 |
<p>1529556 Testing pipe-lines for leaks LEDEEN FLOW CONTROL SYSTEMS 25 Aug 1977 [30 Aug 1976] 35754/77 Heading G1S [Also in Division C3] A pipe-line pressure drop monitoring system comprises means 28 for producing an actuating signal in response to each decrease in pressure of a given increment, means 46 activated by this signal to produce an energizing signal for a predetermined period, and means 50 conditioned by the energizing signal to produce an output signal if energized for a time longer than the said predetermined period. The output signal may act to close a valve 76 in the pipe-line. The pressure in the pipe-line upstream of the valve 76 is supplied to both ends 30, 32 of valve 28, which is biased by spring 33 to close port 27. If the pipe-line pressure falls by a given increment the pressure at end 30 will fall (the pressure at end 32 being held by check-valve 34) and a pressure signal will be passed by the valve 28; this acts via conduit 41 to open the check-valve 34 and allow the valve 28 to close, to terminate the pressure signal, and also acts to open valve 46 and allow a pressure signal to pass from conduit 58 via conduit 60 to the valve 50, which opens only after a time determined by timer 53. When the signal from valve 28 ceases timer 47 holds the valve 46 open for a predetermined period which is shorter than the time set by timer 53, so that the valve 50 does not open; however if the pipe-line pressure is falling at such a rate that a further signal is passed by the valve 28 before the end of the period set by the timer 47, the signal from the valve 46 to the valve 50 will be continuous, and the valve 50 will open, actuating valve 68 to close the valve 76. Two parallel systems with different set times may be provided, Fig. 4 (not shown). The actuating fluid is normally gas from the pipe-line, but if the pipeline is conveying liquid a separate gas source (118) may be provided, Fig. 5 (not shown).</p> |
