| 摘要 |
PROBLEM TO BE SOLVED: To eliminate faults and detect a concentration of carbon monoxide correctly by forming a structure so that only a gas to be detected which passes a toxication prevention gas layer comes in touch with a sensor element of a solid electrolyte type. SOLUTION: A toxication prevention gas layer can be formed of activated carbon. However, a sensor sensitivity sometimes deteriorates depending on a state of a layer of activated carbon when the gas layer is formed of the activated carbon. For preventing the sensitivity deterioration and obtaining a sufficient toxication preventive gas characteristic, supposing that a thickness of the activated carbon layer is X mm and a packing density of the activated carbon layer is Yg/cm2, the X and Y are set to satisfy 1.1<=XY<=2.6 (1<=X<=3). A toxicity gas layer of a sufficient performance is thus obtained. The activated carbon layer is preferably formed of granular activated carbon. A greatly low gas permeability may hinder a sufficient amount of a gas to be detected from being sent to a sensor element. A particle size influences less if the granular activated carbon is used. That is, an effect is attained with 50-2 meshes. |
