Hazards of Smoke

Fire Alarm and Detection

Boxes on fire

The thermal and visible outputs from this flame are two examples of fire “signatures.”

Fire detection devices operate in a variety of ways. To simply say that a smoke detector activates when it senses smoke is an oversimplification of the operating principles for which it is designed. Fire detection devices (smoke detectors, heat detectors, radiant energy detectors, gas detectors) are designed to detect changes in the atmosphere produced by changes resulting from a fire. These changes are known as “fire signatures” and can be measured by various detection devices.


Chart of Signatures for Detection

Fire Signatures for Detection


For additional information, refer to National Fire Protection Association 72, National Fire Alarm Code.


Knowledge Check: Can you describe how fire signatures influence detector selection?