GAS SHUTOFF DEVICE, FLOW VARIATION DETERMINING METHOD BY THE SAME, AND CONTROLLER FOR GAS SHUTOFF DEVICE

摘要

PROBLEM TO BE SOLVED: To shut off a gas for a safe duration time at a proper timing by improving a method of determining the presence or absence of flow variation by determining the presence or absence of actual flow variation in a normal operation or a non-use state in such a state that the gas is left in a turned-on state.

SOLUTION: A flow variation determination processing for preventing early shutoff, a flow variation determination processing for preventing late shutoff, and a reducing-direction flow variation determination processing are performed in parallel by a flow variation detecting section 112, a counting section 113, a flow variation presence/absence determining section 114 and a security section 116. In the flow variation determination processing for preventing early shutoff, the determination is performed under a determination condition that "flow variations of a flow variation minimum value or more occur by a prescribed number of times (N times) or more. In the flow variation determination processing for preventing late shutoff, the determination is performed under a determination condition that "flow variation of an ignition flow rate minimum value or more occurs". In the reducing-direction flow variation determination processing, the determination is performed under a determination condition that "flow variations of a reducing-direction variation determination value or more occur by a prescribed number of times (M times) or more within a prescribed time (X hours)".

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