Detecting a fire as early as possible is immensely important for two reasons: Firstly, ensuring personal safety is paramount, which makes it crucial to commence evacuations as quickly as possible. Secondly, the damage to the train itself should be kept to a minimum.
Very early smoke detection systems can already detect the tiniest quantities of smoke particles during the initial phase of a fire's development, before it generates open flames (know as the "pyrolysis" phase). A wide range of automatic detection equipment is in place to monitor for fire characteristics such as smoke and temperature in the protected areas. This may include air sampling smoke detectors, linear heat detectors, optical smoke detectors, heat detectors or multi-criteria detectors. There is also a wide range of input and output modules for control purposes or for receiving external alarms. These are integrated into the ring bus in combination with a detection and alarm panel.
It is essential for detectors installed in the public areas of a train to be immune to false alarms so that an alarm cannot be triggered by cigarette smoke, for example. Fire detection should also be afforded special protection from vandalism.