GAS SHUT-OFF DEVICE, FLOW VARIATION DETERMINING METHOD BY THE SAME, AND CONTROLLER FOR GAS SHUT-OFF DEVICE

摘要

PROBLEM TO BE SOLVED: To enable a safe duration time shut-off at proper timing by improving a flow variation presence/absence determining method for determining the presence or absence of substantial flow variation in a normal operation or a non-use state due to forgetting of turn-off.

SOLUTION: A gas shut-off device includes a flow variation detecting section 112, a counting section 113, a flow variation presence/absence determining section 114 and a security section 116. The device thereby performs in parallel a flow variation determination processing for preventing early shut-off, a flow variation determination processing for preventing late shut-off, and a reducing-direction flow variation determination processing. In the flow variation determination processing for preventing early shut-off, the device determines on a determination condition that "flow variations equal to or greater than a flow variation minimum value occur the prescribed number of times (N times) or more. In the flow variation determination processing for preventing late shut-off, the device determines on a determination condition that "flow variation equal to or greater than an ignition flow rate minimum value occurs". In the reducing-direction flow variation determination processing, the device determines on a determination condition that "flow variations equal to or greater than a reducing-direction variation determination value occur the prescribed number of times (M times) or more within a prescribed time (X hours)."

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