| 摘要 |
PURPOSE:To detect the leakage from a tank with high sensitivity by determining the rate of change in the level of the liquid stored in said tank. CONSTITUTION:The level 1 of the liquid stored in a storage tank 1 is inputted as an analog signal X to a leakage detector 8 by a level converter 6. On condition that a transfer pump 3 is held stopped and contacts 7 are off, the detector 8 monitores the signal X, detects the decrease of the signal X with time and generates an alarm to the outside. The signal X is operated of a change rate signal DELTAx in a change rate operator 8a, and said signal is inputted to setter 8b. When the signal is lower than the set signal k, a relay 8c is operated to generate an alarm output to the outside. The setter 8b is so constituted that its operation is prohibited by a tracking signal T while the contacts 7 are held closed. |
