GAS SENSOR, AND COMBUSTION EQUIPMENT AND GAS ALARM WITH THE GAS SENSOR

PROBLEM TO BE SOLVED: To provide a gas sensor which surely determine that a filter portion is in a condition of filter contamination by coarse gas and a gas detection portion is under an influence of coarse gas and correctly detecting and alarming an existence of a detection object gas of a predetermined concentration. SOLUTION: The gas sensor includes a gas detection part which is sensitive to the detection object gas to change an electric resistance value, a filter part to which the coarse gas attaches, a control part which controls operation of a heating part by switching the gas detection part between a high temperature operation state and a low temperature operation state and detects an incomplete combustion gas based on the electric resistance value in the low temperature operation state, and a determination part which determines to be the condition of filter contamination of the filter part attached by the coarse gas when the control part detects a minimum value of a first electric resistance value in the high temperature operation state and a second electric resistance value immediately before changing from the high temperature operation state to the low temperature operation state and the ratio of the minimum value to the second electric resistance value is lower than a previously set prescribed determination value. COPYRIGHT: (C)2011,JPO&INPIT