How is smoke detector works

The other type of commonly used detection technology is called photoelectric. This technology works by detecting light that is reflected off particles from a light beam inside the sensing chamber. When no particles are present in the sensing chamber, the light from the beam does not strike the light detector, indicating all clear. When there are particles present and the amount of light registered by the light detector reaches a certain threshold level, the alarm sounds.

Ionization-based alarms tend to detect small black soot particles from flaming fires more quickly because they are produced in greater numbers and take away more current from between the plates. Photoelectric detectors tend to be more sensitive to particles that are larger in size and white or light-colored, and thus more reflective, like those emitted by smoldering fires. The NFPA advises that people have both ionization and photoelectric units in their homes.

And dual-sensor alarms that combine both technologies are also available. As important as smoke alarms are for protecting your family and your property, many times they can be a nuisance. Sometimes something as simple as turning on a toaster can set them off. So as with many safety measures, smoke detectors have a trade-off. They can be made sensitive enough to detect almost any smoke.

This one consists of a printed circuit board see the article Inside a Remote Control for an explanation of printed circuit boards , an ionization chamber the silver cylinder toward the top right in the following picture and an electronic horn the brass cylinder toward the bottom right in the following picture :. The ionization chamber is an aluminum can containing the ionization source. You can see that the can has slots in it to allow air flow.

The can itself acts as the negative plate of the ionization chamber. Underneath the can is a ceramic holder that contains the positive plate of the ionization chamber. For more information on smoke detectors and related topics, check out the links on the next page. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Home Improvement.

Home DIY. Household Safety. How Smoke Detectors Work. Do you know how they work? Photoelectric Detectors " ". It's a pretty big smoke detector. It is not very sensitive. Did You Know? Ionization Detectors: Ionizing Radiation Ionization smoke detectors use an ionization chamber and a source of ionizing radiation to detect smoke.

Ionization Detectors: Ionization Chamber " ". Inside an Ionization Smoke Detector " ". Why does smoke come from a fire? Create a personalised content profile. Measure ad performance.

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Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels. Facebook Facebook Twitter Twitter. Featured Video. Cite this Article Format. Helmenstine, Anne Marie, Ph. How Do Smoke Detectors Work?