What is the difference between Photoelectric and Ionization Smoke Alarms?

There are two types of smoke alarms available today: Photoelectric Smoke Alarms and Ionization Smoke Alarms. Both types of alarms provide adequate protection against fire.


  • Ionization detectors respond more quickly to flaming fires with smaller combustion particles
  • Photoelectric detectors respond more quickly to smoldering fires
  • Combination smoke alarms featuring both photoelectric and ionization technology are also available.


When smoke enters a photoelectric alarm, light from a pulsating light source in reflected off the smoke particles onto a light sensor, triggering the alarm.

When smoke enters an ionization alarm, ionized air molecules attach to the smoke particles and reduce the ionizing current, triggering the alarm.


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