HYDROGEN-CHLORIDE DETECTION BY LITAO3

A pyroelectric calorimeter for the amine-hydrogen chloride (HCl) reaction has been constructed by using spun amine in thin-film form and Cr-Au electrodes on a 2.5 cm diameter, 0.4 mm thick LiTaO3 wafer, the counter (or common) electrode being of gold. The sensor is placed in a test chamber and hydrogen chloride admitted at a pressure close to atmospheric. Thermal signatures resulting from the amine-HCl interaction are observed through the gold electrodes. Concentrations of HCl in an HCl + N2 mixture ranging from thousands down to 1 ppm are used. A miniaturized thermistor immersed in the amine layer is used to confirm and calibrate the temperature variation.