Gas detecting method and apparatus

摘要

A gas detecting method and apparatus for selectively detecting a fuel gas having methane as a main component thereof and an incomplete combustion gas having carbon monoxide as a main component thereof. A low heat capacity, hot-wire semiconductor type gas sensor used has an oxide semiconductor formed mainly of valency-controlled tin oxide and acting as a sensitive section thereof. An inactive to gas combustion, heat resistant, quadrivalent metallic oxide is mixed into the sensitive section. The sensitive section is alternately switched between a fuel gas detecting temperature and an incomplete combustion gas detecting temperature.