As mentioned in the introduction, gas detection for fire warning has become an area
of major interest in the last few years especially for the early detection of slowly burning
smouldering fires. A photoacoustic detector can be used to detect carbon dioxide or hydrocarbons such as methane. In case of carbon dioxide there is almost no cross interference with other gases which might cause false alarms. Fig. 3 shows the
carbon monoxide, carbon dioxide and methane concentrations in a standard TF2 test
fire using smouldering wood.