HOW DO FIRE ALARMS WORK?

Fire alarm is a safety device which gives warning of a fire before it spreads. Most fire alarms work on the principle of detecting heat, smoke or flame. Heat detectors sense the rise in temperature due to fire and trigger an alarm by either melting a low fusion alloy or bending a bimetallic strip. In the smoke detectors, a beam of light falling on the photocell is interrupted by smoke particles triggering the alarm. Flame detectors usually detect infra -red radiation given off by flames to set off an alarm.