Smoke detectors are essential because they provide an early warning of a fire and therefore occupants can evacuate the building immediately because of the early warning.
Smoke detectors detect most fires much more rapidly than heat detectors. They automatically detect a fire by sensing smoke particles. The smoke particles may be visible or invisible to the human eye.
Common Smoke Detectors
Most smoke detectors work either by optical detection (photoelectric) or by physical process (ionization) .
Anatomy of a typical smoke detector
Analyze particles in the air. When the it senses abnormal conditions, the system actives the alarm.
Uses light sensors to detect the presence of smoke
Heat detectors are available in two general types: rate-of-rise and fixed temperature.
Rate-of-rise heat detectors activate the alarm when the room temperature increases at a rapid rate.
Fixed-temperature heat detectors activate the alarm when the detector components melts at a set temperature. Some need to be replaced after they have activated an alarm.