GAS DETECTING ELEMENT WITH FILTER

PURPOSE:To prevent the generation of a change in the sensitivity of SO2 which is a cause for erroneous operation, etc. of a gas leakage alarm, etc. by depositing >=1 kind of BaCl and SrCl2 on a filter. CONSTITUTION:SO2 is oxidized by the catalytic effect of active carbon in contacting with active carbon and produces H2SO4 under the addition of the moisture in air and the physically adsorbed SO2 exists therein as well. Desorption arises as well depending upon the concn. of SO2 in the atm. If >=1 kind among BaCl2, SrCl4 and CaCl2 are deposited on the filter in order to prevent such desorption and to remove the SO2, the SO2 is chemically adsorbed thereon and is fixed. The sensitivity of the gas detecting element increases accordingly and the SO2 in the atm. is adsorbed as a stable material on the filter by which the increase in the sensitivity of the detecting element is obviated. The deposition of the BaCl2, etc. on the filter is executed by a method consisting in preparing an aq. soln. contg. chloride, dipping the filter into the aq. soln., and drying the filter.