ElectricalHow Do Smoke Detectors Work?

A smoke detector is one of those things you hope you’ll never need, but that you’ll be thankful for if you ever do! But how do these devices work? It’s first important to realize that there are two different types of smoke detectors. There is the ionization detector, which houses an ionization chamber with two plates and a source of ionization radiation. The other type of smoke detector is a photoelectric detector, commonly referred to as an optical detector. These aim a light into a sensing chamber at an angle away from the sensor.


Ionization smoke detectors house a small amount of radioactive material between two electrically charged plates, which ionize the air and causes current to flow between the plates. The smoke detector’s battery sends a voltage to the plates, charging one positive and the other negative. If smoke enters the detector, then it disrupts the flow of ions. Therefore, the flow of current is reduced and the alarm is activated. This type of smoke detector is generally more responsive to flaming fires.


Have you ever walked into a store to hear a bell go off, but don’t see a bell? The store likely has a photo beam detector, or a light. When you cross this beam of light, you block it. The photodetector senses the lack of light and triggers a bell. This is essentially how a photoelectric smoke detector works, except that the light and sensor are positioned at 90-degree angles to one another, so that it won’t take an excessive amount of smoke for the alarm to go off. This type of smoke detector is generally more responsive to fires that begin with a long period of smoldering, called a smoldering fire.

Dual sensor detectors are recommended, as they include both ionization and photoelectric sensors. These are most capable of adequately alerting homeowners of either a smoldering fire or a fire with active flames. In an emergency, you need to be able to rely on your smoke detector. Remember to keep your detector well maintained, and replace the batteries as needed, should the detector you choose rely on batteries alone.

Contact G&S Heating Cooling & Electric today for professional smoke detector installation in Everett, WA.



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