Have an ordinary house smoke alarm. It's about twenty years old and it has recently gone off in the middle of the night for two days running and for no apparent reason.
I've heard that it might need a vacuum cleaner applied to it. Is there likely any truth in that, or is there anything else i might usefully do?
Or does it probably mean that I have to replace it?
Assuming it is an ionisation style detector, then just throw it away and install a new one.
These things have a maximum useful life of around 10 years. (modern alarms are marked with an expiry date)
Definitely. Your life may depend on it.
There has been some discussion here before, based on half-lives, as to whether the expiry date is absolute, or just a guideline for people who don't test them. Mine are 20 years old and still detect my burning the toast, so I suppose they're OK. They do beep when the battery is low. This is exacerbated by lower temperatures, as when the heating goes off at night. Was the "false alarm" just a slow series of low- battery beeps or a full-blown screech?
Chris
The 10 year live is because you can't clean the ionisation chamber, and sticky dirt will eventually short out the ionisation current flow, causing the alarm to go off.
Don't even think about taking the ionisation chamber apart to clean it (too risky given the radioactive source in it). Just chuck it out and buy a new one.
If I may piggyback...
Since these things contain radio isotopes, may they be thrown in the dustbin, or does one need to take special care when disposing of them?
They are designed to be binnable (even when new)
S
They contain a tiny (0.3 micro grams) amount of Americium 241 principally an alpha emitter. Alpha particles are big (a Helium-4 nucleus) and don't travel very far, even in air, before being absorbed. A sheet of paper will stop them.
Having said that you don't want to ingest an alpha emitter and have it lodge somewhere. It will damage tissue, in it's immediate vicinity, over a period of time.
I've not heard of special collection or disposal facilities for smoke detectors in the UK. But then I haven't been looking.
If they came from a nuclear power station, they would need to be disposed of with men in leads suits and breathing aopparatus.
Since they don't, basically no one gives a s*it.
They come under the WEEE rules. Class 9 or mixed, depending on your local facilities. Your local recycling centre will be able to take them.
Too true - not worth the, umm, candle.
Given the long life batteries - that is, no cost or effort replacing every so often - you might even save some money.
Actually, the Americium 241 in them does come from nuclear power stations. That's how it's made.
In message , John Williamson wrote
Just throw them in the bin unless you want the local council to spend thousands on "legally" getting rid of them.
Well there seem to be two kinds, ones with radiation hazard stickers and ones without,both seem to give false alarms at times. I think the former can decay so they just don't work at all once the radiation reduces to the point where nothing gets ionised.
Brian
Most of the time the Fire service will probably fit you one for nothing if you ask for a free fire inspection. I guess this makes sense from their point of view as a smoke alarm saves lives and gives early warnings. Bit worried though to note that the ones they fit are merely stuck somewhere with sticky pads, but I was told this was fine as by the time the sticky failed due to heating, you would probably have been dead anyway. Brian
Yup, Optical and Ionization types typically. (you can also get heat alarms for traditionally smoky rooms)
If its using Americium 241 as a source then that has a half life of over
400 years, so probably not too much to worry about. I think ingress of crap into the detection chamber is more of a problem.
yep.
anything that blocks that will cause an alarm
in our case, even a steamy bathroom..
In message , john east writes
Is it battery or mains powered? Batteries go slightly higher resistance when cold. If I don't keep an eye on the battery indicator my pager goes off in the early hours when its battery is nearly flat, I put this down to the cold.
If battery then try changing it and see if it still does it.
>
Hmph, I bought some and the duracell battery lasted for a month. I tried lithium super long lasting ones and they lasted 4 months.
Can't this be cleaned then?
Everything sets the pesky things of, which is why I removed them all.
Why would I want to be warned of a fire right next to me anyway? The only alarm I have now is in my indoor aviary (well the detector is, the sounder is in the house) so I know if the parrots are on fire.
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