GAS DETECTION ELEMENT WITH FILTER

PURPOSE:To stabilize a gas detection element for a long period of time, by using a filter material containing activated carbon and o-toluidine as the filter for removing the substance obstructing the detection capacity of a gas sensor. CONSTITUTION:A cap shaped filter 2 is provided to the upper part of a gas detection element 1 and a gas sensor 5 and an explosion-proof net 6 are arranged in said filter 2 while a sensitive layer 5a comprising a semiconductor, a catalyst 5b and a heater 8 are provided in the gas sensor 5. As the filter 2, a filter material containing porous activated alumina and o-toluidine is used. Activated alumina has effect for adsorbing and removing SO2 and NO2 while o-toluidine has effect for adsorbing and removing NO2. Because activated alumina and o-toluidine are contained in the filter material, the substance obstructing the detection capacity is removed and the gas detection element can be made stable and highly reliable for a long period of time.