How do smoke detectors work?
Question:yesterday, i lit a piece of paper on fire (but put it out immediately). Surprinsingly, there was quite a bit of smoke. Luckily it was in the bathroom so i just kept the door closed, in fear of setting of the detectors.
my question is, do smoke detectors like.. detect the smell of smoke? or just smoke..
the other day my science teacher lit a match on fire like.. 5 feet away from the detector and it didnt go off either..
Answers:
There are basically two types of smoke detectors on the market today.
One type is called "ionization". This type of detector reacts chemically to products of combustion that become airborne from a fire. Positively charged ions from a fire can reach a smoke detector long before you even see visible smoke. So ionization detectors are favourable to use where early detection of a fire is desired.
The down side to these detectors is they can mistake a pot boiling on a stove, or steam from a shower as a fire. Plus they are highly sensitive, & as they get older after awhile become too sensitive to be of any use to anybody because they go off so much that somebody just disconnects them.
Where ionization detectors are needed it is best to change them out for newer ones every so often, depending on how expensive they were to start with. The cheaper ones that cost only 5 or 6 bucks really ought to be changed once every year.
(most people don't realize this)
The other type of detector is the "photo-electric" type of detector. These work by having smoke fill up the detection chamber where the smoke will block a tiny beam of light from the photovoltaic cell inside the detection chamber.
These detectors are good in environments where a lot of cooking may be going on like in a house. They will detect visible smoke from a fire, but not go off so much that they annoy the people inside.
The down side of these detectors is that they take longer to detect a fire because they need visible smoke. Plus as they age dust & dirt gets into the detection chamber, & makes them overly sensitive as well. A lot of people make the mistake of making renovations in their homes, & generate a lot of dust in the process, but leave the smoke detectors exposed to this unusually dusty environment, & then wonder why their smoke detectors are going off all of the time after that.
So in short, ionization type of detectors in a manner of speaking DO react to the smell of smoke because they generate an alarm after a chemical reaction is produced in their detection chamber.
But the photo-electric type reacts by "seeing" the smoke when smoke enters the detection chamber.
Here's a trade secret: Keep your smoke detectors clean, & free from dust & dirt, & change your detectors completely if they are more than 5 years old.
There are two types of detectors, some employ both methods in a single box. One is products of combustion, this detects the output from a fire, I'm not sure what it is but it is not carbon monoxide because you need a different kind of box for that. The other type used is particulate, this is visible smoke.
when the smoke rises up to the ceiling the smoke goes into the smoke detector and it goes off with a beep.
they work by sensing smoke tho a radioactive isotope and as the smoke "passe's' thro the Field it triggers a alarm if you will notice on the label it says 'contains radioactive material' at least they use to any way
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