smoke alarms

[ronald]

Do smoke alarms get more sensitive as they get older? Mine is about 18 years old. It still works in fact I just put a new battery in it a month ago.

My wife has a steam generator iron and if she does not open all the windows in the room she is using it the alarm will go off, most annoying as she has stopped ironing now. At least I'll get a cup of coffee.The alarm is in the hall, not where she is ironing, but we have a vent above the door which does not help.

It is pouring with rain just now and the humidity is quite high so I think because of that and also the high temperature that is what is making it go off.

When I think about it the alarm seems to go off more now than it did before.

Anyway I would buy a new alarm but if the new one is going to go off when there is steam instead of smoke there is no point. So is there a specific type of smoke alarm that is less sensitive to steam or all they all basically the same?

Ron

[Phil L]

We've had mains operated ones that go off when the bathroom door opens after a hot shower, so probably yes.

If I were you I'd buy a couple of new ones, they're cheap as chips nowadays, and you may get lucky WRT the steam thing.

[ARWadsworth]

Smoke alarms usually have a "replace by date" on them. This is usually about

10 years after the manufacturing date.

An 18 year old smoke alarm may be no use in the event of a fire.

Adam

[Graham.]

But you don't tell us what type you have now.

18 years ago IIRC most of them were of the radioactive type using the radioisotope Americium-241, which has a half-life of 432 years. So after 18 years its radioactivity would have decayed by about 3% so if anything you would expect a slight decrease in its ionisation capability with a corresponding decrease in sensitivity.

[Graham.]

Sorry. Those figures are total arse-gravy, I didn't read the wiki I was quoting from properly.

[Andrew Gabriel]

Ionisation detectors have a rated life of 10 years. The reason is that dirt build-up in the detector will affect sensitivity (in either direction) and it can't be cleaned or serviced.

Small droplets of condensed moisture in the air will behave just like smoke particles in both ionisation and optical smoke detectors.

Optical may be lightly better in this respect, but certainly not proof against triggering by steam.

[Roger Mills]

You could try cleaning it out! They work by measuring the opacity of the air passing through them - smoke (and steam) passing a lot less light than fresh air. When they get full of grot and dead flies etc., they can think they're seeing smoke when they're not.

If you *do* buy a new one, get one with a silencing button[1] so that - if it does go off erroneously - you can easily silence it.

I recently needed to replace the smoke alarm in my caravan. Frying the breakfast or toasting bread in a caravan is guaranteed to set off the alarm - so it's important to have one with a silencing button. Amazingly, none of the ones sold by my local caravan dealer had such a button - but Argos came to the rescue.

[1] All alarms have a Test button - but the silencing button is an extra one which silences it for a few minutes. If the smoke - or whatever - is still there after a few minutes, it starts sounding again

[The Medway Handyman]

Don't know where you are, but Kent Fire Brigade will install smake alarms for nothing.

be worth check your local brigade.

[Pete Verdon]

Mine is handy in that it can be used preemptively. So if I'm frying a steak (which is guaranteed to set off the alarm outside the kitchen door) I press the button before I start and get 15 minutes' grace to make as much smoke as I like before it will go off.

Pete

[Dave]

Lancashire fire brigade are the same.

Next door had a kitchen fire that did a fair bit of damage to the fittings in the kitchen and blackened the rest of the house.

When the fire service were satisfied about the safety of the house they fitted smoke alarms to it and came round to our house to do the same.

Once they have done this, you go on a register they keep and they will come back and change them at the recommended period.

Makes sense, as it takes a lot more money putting fires out than fitting smoke alarms.

Dave

[The Medway Handyman]

>>> Might be worth check your local brigade.

Absolutely. We apparently have one of the lowest fire death rates because the fire brigade & building regs are so pro active.

[Dave]

snip

>>>>> Might be worth check your local brigade.

I forgot to mention, about 2 weeks later we got a visit from the FB again. They were doing a survey about fire awareness. Itold them I had been trained for cotton fires by Oldham FB and again by Lancashire FB and finally by BAe systems in the control of aircraft fires. After asking a few questions, he turne round and said we had one of the lowest risks of fire that he had seen in a long while. Neither of us smokes, we dont have a chip pan, no open fires and only one box of matches that are kept in a little used drawer etc.

Dave

[Matty F]

would have decayed by about 2.68%. So, not very much effect on the smoke alarm sensitivity.

18 years of dust would have a much bigger effect.