Improving catalytic sensors performances by electronic techniques

Antoinette Accorsi (1) , Gérard Rose (1)

1 INERIS - Institut National de l'Environnement Industriel et des Risques

Sensors used in explosimeters for the detection of explosive gases are generally catalytic. The most widespread are catalytic pellets. A metallic oxidation catalyst is heated to a sufficiently high temperature to oxidize the gas. The oxidation reaction increases the temperature of the catalyst which increases its electrical resistance, whose amplitude is proportional to the gas concentration. In the 1950s we developed a sensor of this type for the mining industry. It was based on a platinum filament and destined to detect methane, responsible for mine explosions. The filament is distinguished from the catalytic pellets by its operating temperature: 1000°C instead of 600°C, which confers on it the advantage of being relatively insensitive to fouling and catalyst poisoning. The disadvantage, however, is rapid wear, preventing it from operating permanently. The measurement technique thus involves energizing the sensor just long enough to make the measurement and then turning it off for as long as the application permits. The first instruments of this time could run for 100,000 measurements, or about 9 months at the rhythm of one measurement every 4 minutes. By improving the filament heating technique, the measurement capacity has been increased considerably: 10,000,000 measurements with the last methanemeter recently marketed, or a lifetime of 1.5 years at the practically continuous measurement rhythm of once every 5 seconds. Endowed with these performance characteristics, the platinum filament sensor is today a reliable solution for explosimetry, in particular in environments polluted with certain catalyst poisons such as sulfur-containing products, which other catalytic sensors resist poorly.

Domains: Engineering Sciences [physics]

Antoinette Accorsi, Gérard Rose. Improving catalytic sensors performances by electronic techniques. 6. Eurosensors, Oct 1992, Saint Sébastian, Spain. ⟨ineris-00971851⟩