Fire Detection

Ionization smoke alarms are generally more responsive to flaming fires.

Ionization smoke alarms have a tiny amount of radioactive material located between two electrically charged plates, which ionizes the air that causes current to flow between these plates. If smoke enters the chamber, it disrupts the ions and reduces the current to activate the alarm. 

Click on this link to NFPA Image

Photoelectric smoke alarms are typically more responsive to fires that start with a long period of “smoldering”.  

Photoelectric alarms have a light source that aims into a sensing chamber at an angle away from the sensor. Smoke enters the chamber. It reflects light onto the sensor that triggers the alarm. 

For best protection, it is recommended both technologies be used. Combination alarms that include both technologies are available. Click on this link to NFPA image