Gas sensors made of Me/SnO2 catalysts have been tested. Their sensivit
y and selectivity to CO born in the air, bearing various concentration
s of CO2, CH4, NO and H2O have been determined. Sensor made of 1% Pt/S
nO2 catalyst shows very high sensitivity to CO. This sensor has been t
ested in exhaust gases from water heaters. High stability of measureme
nts has been confirmed only for the continuous work of gas burner.