The Method for Easy Identifying Zero Temperature Drift of Catalytic Bead Sensor

Catalytic sensors, also known as pellistors, are the most popular sensing elements measuring concentration of flammable gases in air. They are applicable in mobile and stationary instruments for indicating presence of explosive conditions in mines and other branches of industry. Among the advantages of those sensors are, for example, their linear characteristic in standard operation conditions, sensitivity to every flammable gases, lack of sensitivity toward non-flammable substances, good signal to noise ratio. However, one of their problems is fluctuation of their output signals with the change of environmental temperature. It can lead to either false alarms or lack of reactions in case of a presence of explosive conditions. To avoid such situations, the sensors are carefully selected or equipped with additional systems for compensation of the temperature drift, but identification of their thermal parameters is troublesome due to the necessity of tests performed in temperature chambers. In this paper, an alternative method of identification of the temperature dependencies is presented, based on a temperature change of the sensing element independent of ambient temperature. Physical properties of pellistors are analysed, proper dependencies are derived, and results of tests conducted on a group of the sensors are presented to show the efficiency of the method.