| 摘要 |
PROBLEM TO BE SOLVED: To provide a combustible gas detector which comprises two gas sensors for a low concentration range and a high concentration range, and enables to accurately detect a concentration of a combustible gas even when the combustible gas concentration is in the low concentration range and the oxygen concentration is insufficient. SOLUTION: The combustible gas detector comprises the first gas sensor and the second gas sensor whose detection target is combustible gases, and a sensor selection mechanism which selects one of the sensors to be activated. The first gas sensor comprises a catalytic combustion type gas sensor. The sensor selection mechanism is characterized by having a function which selects the second gas sensor to be activated when the oxygen concentration is lower than a predetermined reference level regardless of the combustible gas concentration, and a function which selects the first gas sensor to be activated when the combustible gas concentration is lower than a setting level, and selects the second gas sensor to be activated when the combustible gas concentration is not less than the setting level, if the oxygen concentration is not less than the predetermined reference level. COPYRIGHT: (C)2005,JPO&NCIPI
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