Patent ID: 8373539
Filing Date: 2013-02-12
Classification: F23K,G01F,G05D,Y10T

Abstract:
1. A gas cutoff apparatus that monitors operating conditions of a plurality of gas appliances connected to portions of a pipe extending from a gas meter and that cuts off a gas supply at the time of occurrence of an abnormality, the gas meter including: a flow detection unit that measures a gas flow quantity; a flow computing unit that computes a flow quantity value from a detected value of the flow detection unit; an average flow computing unit that obtains an average flow quantity value by averaging instantaneous flow quantity values computed by the flow computing unit; a flow storage unit that stores the average flow quantity value obtained by the average flow computing unit; a flow change determination unit that determines presence of a flow change from the value obtained by the average flow computing unit and a value stored in the flow storage unit when a flow change is larger than a predetermined change value; a flow registration unit that registers a flow quantity corresponding to the flow change when the flow change determination unit has determined an incremental change and that deletes a registered flow quantity close to the flow quantity corresponding to the flow change when the flow change determination unit has determined a decremental change; a flow memory unit that stores a flow quantity registered in the flow registration unit; a flow change correction memory unit that, in a case where a plurality of flow quantities registered in the flow registration unit when the flow change determination unit has determined presence of a change are deleted and where only the maximum flow quantity is registered, determines whether or not a sum of the registered flow quantities deleted in the past and an average flow fall within a predetermined range; a determination period unit that, when the plurality of flow quantities recorded in the past and the average flow are determined to have undergone no flow change for a predetermined time period by an output signal from the flow change correction memory unit, deletes and performs re-registration of the plurality of flow quantities in the flow memory unit and the registered flow quantity; a monitoring value memory unit that memorizes a determination value for monitoring an abnormality in an operating state; an abnormality determination unit that compares the flow quantity value in the flow registration unit with the determination value of the monitoring value memory unit, thereby determining presence or absence of an abnormality; and an operating time correction unit that outputs an operating time correction signal to the abnormality determination unit when the determination period unit has performed re-registration; and a cutoff unit that cuts off a gas supply when the abnormality determination unit has made an abnormality determination.