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Smoke/CO Alarms?

C

Caledon1297

pfm Member
Any recommendations for smoke/CO alarms - having looked at a few on Amazon, there seems to be an almost across the broad 'great, highly recommended' and 'crap, don't touch with a bargepole' extremes in the reviews?!

If they meet the relevant standards, is that all that's required, or are some better/more reliable/less prone to false alarms etc. than any others? (All that I require are good, basic, battery-powered alarms i.e. I don't need any 'fancy' features such as Wifi enabled etc.)

TIA.
 
I think the only thing to think about is whether the batteries can be replaced or are 'sealed for life' which last for at least 5 years
 
Please get one. A colleague of mine had his boiler repaired in the summer by (I won't say who!) and they've been getting monoxide poisoning ever since. now fixed, but not a good situation and life threatening..
 
Smoke detectors are EXTREMELY simple - they are activated by the particles/droplets of smoke in the air. Most do (or at least did) use a radio-active source as part of the detector (Americium?????? - you can look that one up...)

Detecting anything else is problematic because it is trying to detect a gas within a gas. I used to work in a lab where we used several low pressure gases that could, in theory, leak and asphyxiate anyone in the lab because a leak would not be at all obvious. The detectors were HORRENDOUSLY expensive and had to be checked and recalibrated as required every 6? 12? months.
 
billo said:
I think the only thing to think about is whether the batteries can be replaced or are 'sealed for life' which last for at least 5 years
Click to expand...

My existing alarm has replaceable batteries, but still has an expiry date (which was pointed out by the gas engineer at the last boiler service :oops:).
 
Vinny said:
Smoke detectors are EXTREMELY simple - they are activated by the particles/droplets of smoke in the air. Most do (or at least did) use a radio-active source as part of the detector (Americium?????? - you can look that one up...)

Detecting anything else is problematic because it is trying to detect a gas within a gas. I used to work in a lab where we used several low pressure gases that could, in theory, leak and asphyxiate anyone in the lab because a leak would not be at all obvious. The detectors were HORRENDOUSLY expensive and had to be checked and recalibrated as required every 6? 12? months.
Click to expand...

I've noticed mention of 'optical sensors' for some smoke alarms - better? unnecessary? they're all like that?

So all consumer CO alarms (that meet the relevant standards) are likely 'much of a muchness'?
 
I had one that came with the house. After a while it gave up, it was marked with a "do not use after" sticker and that date had passed. I have bought a Kidde CO detector, it lives in the room with the boiler, and it's fine. £15 I think, no problems. I also have a smoke detector, the only snag with that is that once every year or two it gives "low battery" alarm at about 2am and I have to get up and disable it. The things are dirt cheap for what they do, just get one of each.

I don't know how the CO detectors work, they may be radioactive source based. I know the smoke alarms are, as Vinny says I think it's Americium. After a while the radioactive source decays to whatever its decay products are and it won't be putting out the same radiation. A little thought and memory of A level chemistry suggests that radioactive emitters go alpha-beta-beta-alpha-beta-beta as they decay so if you are relying on one and get another it's not much good. What's a CO detector cost, a fiver? Get one and stick a new 75p battery in it every year. The fire brigades give these out and fit them for free for a good reason, they save lives.
 
Vinny said:
Most do (or at least did) use a radio-active source as part of the detector (Americium?????? - you can look that one up...).
Click to expand...
I think one of ours became depleted as once a week the whole system would trigger and would not reset.
I ended up removing the offending alarm and it's being replaced this Friday by an Alarm company . Frustratingly the Hi-spec model fitted is now obsolete and the next model does not fit the hardwired base unit!
 
Because I’m an old codger The fire Brigade came round and fitted two fire angel CO2 detectors for free. I also have First Alert CO detectors by the gas boiler and by the gas fire.
 
All detector elements will age, and hence have a useful life. In the case of smoke detectors using a radio-active source, their life is determined by the half-life of the radio-active element.
 
241-Am has a half life of 241 years. It's an alpha emitter, as you might have guessed. Alphas are going to be deflected by a smoke particle, betas probably not. Tough little buggers, betas. On that basis a smoke detector won't last a whole human lifetime, they will be significantly down after about 20 years. Given what they cost a 10-year service life isn't unreasonable.
 
Our local fire service swear by Fire Angel (and fit them free for pensioners etc.) so I got a few and they don’t go off at the slightest hint of burnt toast like the cheap jobs. A chum in France who also works in UK said he noticed that we here tend to default to the cheaper, over-sensitive jobs.
Fire Angel have a decent warranty. One of mine started the death chirp at 18 months so I returned it to Screwfix who replaced it without quibble.
 
Thanks BigL, that's what I intended to type but I typed its atomic number again. So maybe a 20 year working life.

Edit, a google to remind me how to calculate rate constant k from half life and some 30-year old A level stuff tells me that after 10 years 98% of your detector's Americium remains, after 20 years it's down to 96.8%, after 30 it's at 95%, and at 40 years it's just under 94%. You could push one of these to your entire adult life if you wanted to, but a 30 year working life and 95% efficiency is reasonable. I'd venture that the case would be falling apart 30 years in, even indoors plastics exposed to light don't last for ever.

That was interesting, if a little pointless. Keep the grey stuff moving a bit.
 
The hard wired smoke alarm in the hall goes off at the slightest provocation while grilling. Any suggestions on how to deal with this?
 
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