| 摘要 |
PURPOSE:To prevent an erroneous alarm caused by H2 and alcohol, by comparing outputs of two combustible gas detection elements having different characteristics mainly composed of a metallic oxide semiconductor and varying an action level of an alarm device. CONSTITUTION:An output to H2 of the first detection element S1 mainly composed of a metallic oxide semiconductor is larger than that to alcohol or CH4 shown by figureIand the output of the second detection element S2 to alcohol or H2 is larger than that to CH4 shown by figure II. In the case where the output of the element S1 is larger than that of the element S2 to more than a certain degree (where the gas is nearly CH4 gas), an output level for activating an alarm device is made to a low level L and an alarm is given when it has exceeded this level. In case where the output of the element S1 is smaller than that of the element S2 in some degree (where the gas is nearly alcohol) or both outputs are nearly the same (where the gas concentration is low or the gas is H2), the output level of the element S1 is made to a high level H and the alarm is given when it has exceeded this level H. |
