| 摘要 |
<p>A pipeline break detection system wherein a rate timing device is activated in response to a predetermined pressure drop in the pipeline to direct a signal and activate the on-delay cycle of an energy-blocking device, such as a relay switch in an electric circuit. The timing device then commences an off-delay cycle, and if such cycle continues to completion, it cancels the countdown of the on-delay relay. However, if the pipeline experiences a further like pressure drop, before the timing device completes its cycle, it will be recharged and remain activated to keep the on-delay relay actuated. If the pipeline pressure fails to level off to allow the rate timer relay to close, and the on-delay relay is thus enabled to complete its timed cycle, the relay closes to deliver an electrical signal.</p> |
