| 摘要 |
PURPOSE:To prevent a ratio of combustion production gas in the air from entering a hazard range, by a method wherein, when a power outage occurs, the feed of gas is automatically stopped before it attains a limit amount or a limit time in a condition in which an air exhaust device remains to be brought to a stop. CONSTITUTION:When the supply of a power to a trouble discriminating circuit 62 is stopped, after the potential of an output terminal (d) is increased to a potential (o) at an abnormal time, a lag, during which an output command signal is provided, is determined based on an accumulating amount of the flow of gas instead of a time. When the supply of a power is stopped, only when a given amount set to less than a hazardous leak amount flows, the supply of gas is shut off, and thereby this method is more reasonable than a method employing a time. |
