| 摘要 |
<p>A piping system and method having a plurality of power operated valves located substantial distance apart. The method continuously monitors pressure conditions at each valve and senses abnormal pressure conditions indicative of a line break. When such abnormal pressure conditions occur, valves on opposite sides of the break automatically close. Pressure sensing continues and if after closing certain predetermined pressure requirements are met, the valves are automatically opened. Where the system includes looped or parallel branch lines connected at their ends to upstream and downstream portions of the main lines, valves in both branch lines and also adjacent valves in the main line may close, after which all of the valves will be automatically opened, except the valves that isolate the break. Also apparatus for carrying out the method, including means for monitoring pressure conditions and means for effecting automatic closing and opening of the valve responsive to predetermined pressure conditions.</p> |
