Patent ID: 8522815

Claim:
A gas shutoff device, comprising: a flow rate detection section which outputs a flow rate signal in response to a gas flow rate passing through a gas passage; a flow rate calculation section which calculates a flow rate upon receiving the flow rate signal; an abnormal flow rate determination section which compares the flow rate with a previously-retained determination value upon receiving the flow rate, and outputs a valve-closing signal if abnormality exists in the comparison; a sensor abnormality determination section which outputs a valve-closing signal if the flow rate signal is in accord with a predetermined abnormal condition; a valve driving section which outputs a valve-closing drive signal as a valve driving signal upon receiving the valve-closing signal from either the abnormal flow rate determination section or the sensor abnormality determination section, and outputs a valve-opening drive signal as the valve driving signal upon receiving a valve-opening signal; a valve which opens or closes the gas passage upon receiving the valve driving signal from the valve driving section; and a valve-closing timer section which starts to time upon receiving the valve-closing drive signal from the valve driving section, and outputs the valve-opening signal when an external release input is accepted only within a predetermined setting time.