I read this [https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/smoke-detectors.html](https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/smoke-detectors.html) but I need help 😛
In: 3
There’s two types of smoke detectors, Ionisation and Optical.
Ionisation smoke detectors have a small slightly radioactive substance between two electrodes. The radioactivity crates ions in the air, which can transport a tiny amount of current between the electrodes. If smoke enters the detector, it displaces the air and the ions, and the amount of current drops. A sensor detects that drop in current and triggers the alarm
In optical sensors, there’s a small led or laser diode enclosed in a light tight, but not air tight, compartment. It regularly pulses light towards a photoreceptor, which picks it up. If smoke enters the chamber, it partially blocks and scatters the light and the photocell detects less of it, and again the fire alarm is triggered.
Optical fire alarms are significantly less prone to false alarms, but can trigger slightly later, since they rely on smoke with a lot of soot, and a clean burning flame produces only clear fumes, however, in a real world scenario, any uncontained fire inside a residential home will almost immediately begin burning _something_ that doesn’t burn cleanly, and produce the black smoke necessary to trip the alarm, so the downside is really not that relevant, and the reduced chance of false alarms means you’re less likely to turn of the alarm because it’s annoying you whilst you’re cooking or having a hot shower, an forget to turn it back on again
Here’s a good [Video ](https://youtu.be/DuAeaIcAXtg) about smoke detectors
Latest Answers