| 摘要 |
PROBLEM TO BE SOLVED: To enable gas cut-off at a proper timing, when a gas quantity consumed is changed, by forming this device with a flow measuring means, a cutoff valve or the like, and by changing to the lower side, the level of the quantity consumed for operating the cutoff valve at the time of an abnormality, if the gas quantity consumed is smaller than a primary setting. SOLUTION: This device comprises a gas passage 1, a flow measuring means 2, a cutoff valve 3, a cutoff valve driving circuit 4 and a control circuit 5. Usually, gas flow flowing in the gas passage 1 is measured by the flow measuring means 2 and the result is sent to the control circuit 5. It is judged whether a measured gas quantity consumed is abnormal or not, and if it is judged abnormal, an operation signal is transmitted to the cutoff valve driving circuit 4 to close the cutoff valve 3. A quantity consumed setting means 6 learning- memorizes normal gas quantity consumed by measured data from the flow measuring means 2, and if the gas quantity consumed is smaller than a primary setting, the level of the gas quantity consumed for operating the cutoff valve at the time of an abnormality is changed to the lower side.
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