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Fire & Water - Cleanup & Restoration

Understanding Fire Alarms

7/20/2022 (Permalink)

Fire Alarms; Ionization Vs. Photoelectric

There are two types of fire alarms: Ionization and Photoelectric.
Ionization fire alarms are more reactive towards blazing fires with large flames. A tiny amount of radioactive material is positioned between two plates that are electrically charged. This ionizes the air around it, causing a small current to exist between both plates. Once smoke from the fire enters the detector chamber, there is a disruption of the flow of ions, causing a reduced current flow. This lack of current flow triggers the alarm to sound.
Photoelectric alarms are more reactive to smoldering, long-lasting fires. A light source in the detection chamber is angled to point away from the sensor, to not receive any light When smoke enters the detection chamber, the light is reflected and dispersed onto the sensor which then triggers the alarm.
Combined alarms are available, or a combination of both alarms is recommended to provide maximum protection from both fast flaming fires and slower smoldering fires in both the home and the workplace.
Maintenance of fire alarms is straightforward:

  • Once per month – test the batteries by holding the button for a minimum of five seconds. If they are working it will beep.
  • Every six months – Use a vacuum cleaner to remove dust. Keeping the alarm free of particles will prevent false alarms and allows for easy access of smoke to the detection chamber and sensor.
  • Every twelve months – Replace the batteries if they are lead or alkaline.
  • Every ten years – All smoke alarms should be replaced with new ones, or earlier if this is recommended by the smoke alarm manufacturer.

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