How Do Smoke Detectors Work?

Learn how smoke detectors work; it could mean our lives!

Smoke detectors hang on the wall unnoticed most of the time. We assume it will respond if it is ever needed to warn of fire. It saves many thousands of lives each year. It is a very important, though somewhat ignored, item consequently, we should take time to understand how it functions. Armed with knowledge we can then, choose the best one for our home.

In newly built homes smoke detectors are required to be hard wired 120 volt systems, with battery operated detectors as backups. In existing homes battery operated units are allowed and work well if maintained in good working order. This takes the diligence of a concerned homeowner.

How do smoke detectors work?

Photoelectric unit is initiated into responding by smoke that splits the beam of light emitted by the unit. This unit is less likely to react to false alarms such as fumes from cooking; but will respond to slow burning fires as in upholstery.



Ionization units actually sends forth a small amount of radiation and when smoke blocks the emitted radiation it is detected by a sensor thus sending out the alarm. This unit will react to fires that burn swiftly as paper, wood, and oil.

There are types of detectors that combine both of these attributes, forming a more complete warning system.

You may choose alarms with varied features, such as a light in the unit that will light your path of escape. This feature is available in battery operated models. There are those units that plug into a receptacle with a safety device that locks it into the plug in. However, the receptacle must not be one that is controlled by an on and off switch. Others have a light letting you know if the unit is working; shining a light on the sensor can test others. Some will "beep" when the battery is low.

Each floor of your home including the basement should have a smoke detector. Each stair well should have one at the top and in each hallway that leads to bedrooms. Wall mounted units should be 4-12 inches from the ceiling. Ceiling mounted models should be at least 4 inches from a wall.

Test your smoke detectors at least one time per month. Most have test buttons, however if not use a candle and let the smoke enter the alarm.

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