| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas shut-off device capable of determining and notifying an abnormality and even when the influence of a reverberation signal caused from variation inherent to ultrasonic-wave transceiver.SOLUTION: The gas shut-off device includes: a flow rate calculation section 7 that calculates the flow rate of a gas based on a propagation time measured by a flow rate measurement section 4; a flow rate storage 8 that stores the flow rate value calculated by the flow rate calculation section 7; a gas estimation section 9 that estimates the type of the gas measured by the flow rate measurement section 4 based on the propagation time; an abnormality detection section 10 that determines as abnormal when the gas estimation section 9 determines that the gas is not a fuel gas but the air, and when the flow rate value stored in the flow rate storage 8 is out of a predetermined range in the forward and the backward directions exceeding a predetermined times; an error detection selecting section 11 that selects whether the function of the abnormality detection section 10 is valid or invalid; and an alarm section 12 that displays an alarm when determined as abnormal. |
