| 摘要 |
Disclosed is an instrument wherein the pressure or flow of a fluid in a pipeline is monitored with a voltage proportional thereto being electronically differentiated to determine whether any rate of change of pressure exists, which is often indicative of a leak in the pipeline. If a rate of pressure change of a predetermined extent exists for a predetermined period of time and if a total pressure change exceeds a predetermined value, an output signal can close a valve in the pipeline or can sound an alarm. In addition, in situations where a liquid is involved, a surge develops upon a line break, that is, a large rate of instantaneous pressure drop, and such surge can also be detected and appropriate remedial measures taken. The instrument is also capable of shutting down the pipeline in instances of inordinately low or high pressure conditions.
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