Fire Safety Science Digital Archive

The time honored methods of fire detection have depended upon, or been derived from, the four human senses of sight, sound, touch, and smell, each of which has advantages and disadvantages determined by its characteristics. Detection by smell depends upon the remarkably sensitive response of the olfactory nerve to vapors produced by the thermal decomposition of the fuel or of nearby materials which may or may not be combustible. It has the great a advantage of being able in principle to detect a fire in its very early stages, long before it produces enough heat, light, sound, or smoke to produce a response by the other senses. This report describes the results of some preliminary experiments on the detection of combustion-produced vapors by two different kinds of "artificial noses" which have shown promising sensitivity. One depends upon the change in electrical conductivity of a thin oxide layer when it is exposed to vapors from thermal decomposition of cellulose. The other depends upon the mass spectrometric analysis of those vapors.