Whats the difference between ionization and photoelectric smoke alarms?
A. An ionization smoke alarm contains a small amount of radioactive material. The radiation passes through an ionization chamber which is an air-filled space between two electrodes and permits a small, constant current between the electrodes. Any smoke that enters the chamber absorbs the alpha particles, which reduces the ionization and interrupts this current, setting off the alarm.Photoelectric smoke alarms operate using a light source, a light beam collimating system and a photoelectric sensor. When smoke enters the optical chamber and crosses the path of the light beam, some light is scattered by the smoke particles, directing it at the sensor and thus activating the alarm.Combination alarms feature both ionziation and photelectric technologies. Ionization sensing alarms may detect invisible fire particles, (associated with fast flaming fires), sooner than photoelectric alarms. Photoelectric sensing alarms may detect visible fire particles, (associated with slow smoldering fires),
