Automatic Detection

Components of a fire consist of:

• • Smoke (particulate and aerosol)
  • Heat
  • Light Radiation

Fire detection devices are built to detect the presence of one or a combination of the above components. While all components are necessary for causing a fire, all components may not be present at a detectable threshold. These devices use detectors that detect the elements that may be present in a fire for ambient conditions. It is important to realize that non-fire components that are similar to those that may cause a fire might exist in the same ambient conditions and these could cause unfavorable false alarm conditions.

Devices used for fire detection include smoke detectors, thermal detectors, flame detectors, fire-gas detectors, and other devices.

• Smoke detectors sense visible or invisible particles of combustion generated by burning, smoldering or the incipient stage of combustion. These devices fall into two categories — photoelectric and ionization.
• Thermal detectors sense high temperature or the temperature rise caused by a fire.
• Flame detectors sense the radiation produced by a fire.
• Fire-gas detectors sense the gases produced by a fire.
• Other detectors sense phenomena other than smoke, thermal, flame, or fire-gas to detect a fire.