| 摘要 |
PURPOSE:To detect leakage securely at its early stage without malfunction by measuring the time difference when the time variation rate of pressure between adjacent pressure detection points exceeds a set value. CONSTITUTION:Pressure signals P0-Pn from detectors H0-Hn at pressure detection point K0-Kn of a pipeline are sent to a time variation rate device 5. Those pressure signals are transduced into a time variation rate signal dP/dt, which is inputted to a comparator 6 to be compared with the set value of a setter 7; when it exceeds the set value, an output signal is sent to an OR circuit 8 and an AND circuit 9. A time limit device 10 operates by the output of the OR circuit 8 and stops by the output of the AND circuit 9. The output of the time limit device 10, i.e. time difference is inputted to a comparator 11, which compares the input with the set time of a time setter 14 determined by pressure detection point distance and a pressure propagation speed; when the time ratio is nearly equal, the comparator 11 sends an output signal to an alarm 12. |
