Detection of decomposed compounds from an early stage fire by an adsorption/combustion-type sensor

A low heat capacity catalytic combustion type sensor has been developed with a Pd-Al2O3 catalyst using micromachining technology and a screen-printing technique. A higher heat of combustion than contact catalytic combustion reactions was observed using a detection method with intermittent adsorption and combustion of volatile organic compounds on a catalyst surface [T. Sasahara, H. Ishihara, K. Toyada, T. Sunayama, S. Uematsu, T. Ozawa, K. Ogino, M. Egashira, A gas sensor for volatile organic compounds based on adsorption and combustion, Chem. Sensors 18B (2002) 157–159; T. Sasahara, H. Ishihara, K. Toyada, T. Sunayama, S. Uematsu, T. Ozawa, K. Ogino, M. Egashira, Detection of volatile organic compounds by a catalytic combustion sensor under pulse heating operation, Electrochemistry 71 (2003) 457–462]. In order to verify fire detection capability of this sensor, measurements of the sensorʹs characteristics and an analysis of decomposed compounds were carried out. Our results show that many kinds of organic compounds are emitted early in the smoke of a fire. The output of our sensor indicates a high sensitivity to low concentrations of these gases. For these reasons, we conclude that the detection of these gases by an absorption combustion type sensor is a useful method to detect a fire in its early stages through smoke detection.