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?

On Nov 11, 3:36*pm, "john east" wrote:
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?

clean it out, fit new battery, see if it behaves. I dont think theres
much else one can do with them. Except build a nuclear power plant...
google radioactive boy scout.


NT

On 11/11/2011 15:36, john east wrote:

Have an ordinary house smoke alarm. It's about twenty years old and it has

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)

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?

Definitely. Your life may depend on it.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Nov 11, 3:36*pm, "john east" wrote:
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?

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

On Fri, 11 Nov 2011 15:36:22 -0000, john east wrote:

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.

"gone off" as in full alarm or the low battery beep? See other
posts...

Or does it probably mean that I have to replace it?

FFS a good quality smoke alarm is around a tenner. What price you or
your loved ones lives?

Smoke alarms are one of the few safety devices that really do save
lives. At 20 years old don't **** about buy a decent new one, perhaps
even get the local fire service to come and do a fire safety check.
This is free and may well highlight dangers your are not aware of.
They may even fit new smoke alarms for free, though they may only do
that if there are no existing ones.

--
Cheers
Dave.

In article ,
writes:
On Nov 11, 3:36*pm, "john east" wrote:
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?
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

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.

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

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

john east wrote:

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?

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?

--
When a true genius appears in the world, you may know him by
this sign, that the dunces are all in confederacy against him.
Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting

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

On Fri, 11 Nov 2011 17:03:23 +0000, Frederick Williams wrote:

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 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.

--
Cheers
Dave.

Andrew Gabriel wrote:
In article ,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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

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).

Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.

Frederick Williams wrote:
john east wrote:
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?

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?


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 ****.

On Fri, 11 Nov 2011 18:01:52 +0000, The Natural Philosopher wrote:

Andrew Gabriel wrote:
In article ,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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

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).

Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.

the reason they use alpha emitters is because the smoke particles block
them significantly well - beta and gamma are too penetrating - the smoke
makes little difference to the radiation hitting the detector - agree with
TNP observation but its the penetrating power ( or lack of) through smoke
is the reason they use them :-)
--
(º€¢.¸(¨*€¢.¸ ¸.€¢*¨)¸.€¢Âº)
.€¢Â°€¢. Nik .€¢Â°€¢.
(¸.€¢Âº(¸.€¢Â¨* *¨€¢.¸)º€¢.¸)

Frederick Williams wrote:
john east wrote:
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?

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 come under the WEEE rules. Class 9 or mixed, depending on your
local facilities. Your local recycling centre will be able to take them.

--
Tciao for Now!

John.

On Fri, 11 Nov 2011 15:42:22 -0000, John Rumm
wrote:

On 11/11/2011 15:36, john east wrote:

Have an ordinary house smoke alarm. It's about twenty years old and it
has

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)

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?

Definitely. Your life may depend on it.


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.

--
Rod

On 11/11/2011 18:01, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article
,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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

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).

Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.

Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

SteveW

On Fri, 11 Nov 2011 22:30:49 +0000, Steve Walker wrote:

Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

Agreed, the fact they are big and heavy and get absorbed so easyly
may well make ingesting an alpha emmiter far more dangerous than a
beta or gamma emitter. Simply because those forms of ionising
radiation get do not get absorbed so easyly. If it doesn't interact,
it doesn't do any damage...

--
Cheers
Dave.

In article ,
Steve Walker writes:
On 11/11/2011 18:01, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article
,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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

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).

Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.

Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

as Alexander Litvinenko found out to his cost.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Fri, 11 Nov 2011 22:30:49 +0000, Steve Walker wrote:

On 11/11/2011 18:01, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article
,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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

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).

Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.

Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

SteveW

yes - a very common GCSE level question - which is the most dangerous type
of radiation? low penetrating power but hgh ionisation potential means
alpha is the safest outside and most dangerous inside the body,Gamma Low
ionistion potential but very penetrating - less damage but difficult to
shield from, Beta meduim penetration and medium ionisation potential -
worst of both world in effect
--
(º€¢.¸(¨*€¢.¸ ¸.€¢*¨)¸.€¢Âº)
.€¢Â°€¢. Nik .€¢Â°€¢.
(¸.€¢Âº(¸.€¢Â¨* *¨€¢.¸)º€¢.¸)

In article ,
The Natural Philosopher writes:
Frederick Williams wrote:

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?


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 ****.

Actually, the Americium 241 in them does come from nuclear power stations.
That's how it's made.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In message , John Williamson
wrote


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.


Just throw them in the bin unless you want the local council to spend
thousands on "legally" getting rid of them.
--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

On 11/11/2011 16:06, Dave Liquorice wrote:
On Fri, 11 Nov 2011 15:36:22 -0000, john east wrote:

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.

"gone off" as in full alarm or the low battery beep? See other
posts...

Or does it probably mean that I have to replace it?

FFS a good quality smoke alarm is around a tenner. What price you or
your loved ones lives?

Smoke alarms are one of the few safety devices that really do save
lives. At 20 years old don't **** about buy a decent new one, perhaps
even get the local fire service to come and do a fire safety check.
This is free and may well highlight dangers your are not aware of.
They may even fit new smoke alarms for free, though they may only do
that if there are no existing ones.

Certainly Kent Fire Brigade fit them free.

--
Dave - The Medway Handyman www.medwayhandyman.co.uk

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

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"NT" wrote in message
...
On Nov 11, 3:36 pm, "john east" wrote:
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?

clean it out, fit new battery, see if it behaves. I dont think theres
much else one can do with them. Except build a nuclear power plant...
google radioactive boy scout.


NT

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

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"polygonum" wrote in message
news
On Fri, 11 Nov 2011 15:42:22 -0000, John Rumm
wrote:

On 11/11/2011 15:36, john east wrote:

Have an ordinary house smoke alarm. It's about twenty years old and it
has

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)

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?

Definitely. Your life may depend on it.


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.

--
Rod

Steve Walker wrote:
On 11/11/2011 18:01, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article
,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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

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).

Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.

Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.


But the point is they do NOT remain there. In the gut there is no
absorbtion.

lungs will typically cough out stuff UNLESS you are a heavy smoker

If you lave a cut unwashed you are a bloody fool as well


SteveW

Dave Liquorice wrote:
On Fri, 11 Nov 2011 22:30:49 +0000, Steve Walker wrote:

Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

Agreed, the fact they are big and heavy and get absorbed so easyly

They don't get absorbed easily. Not smoke alarm emitters

"If consumed, americium is excreted within a few days and only 0.05% is
absorbed in the blood. From there, roughly 45% of it goes to the liver
and 45% to the bones, and the remaining 10% is excreted. The uptake to
the liver depends on the individual and increases with age. In the
bones, americium is first deposited over cortical and trabecular
surfaces and slowly redistributes over the bone with time. The
biological half-life of 241Am is 50 years in the bones and 20 years in
the liver, whereas in the gonads (testicles and ovaries) it remains
permanently; in all these organs, americium promotes formation of cancer
cells as a result of its radioactivity.[17][104][105]"

So it is very low absorption.

Agreed if you ate a hundred smoke alarms you MIGHT end up with a cancer
in ten years.


may well make ingesting an alpha emmiter far more dangerous than a
beta or gamma emitter. Simply because those forms of ionising
radiation get do not get absorbed so easyly. If it doesn't interact,
it doesn't do any damage...

Andrew Gabriel wrote:
In article ,
Steve Walker writes:
On 11/11/2011 18:01, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article
,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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
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).
Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.
Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

as Alexander Litvinenko found out to his cost.

That was polonium. A COMPLETELY different material, with a very short
half life, so intensely radioactive, and its also poisonous.

Polonium is a daughter product of radon, which is a product of natural
uranium decay. It is heavily implicated in lung cancer.

Ghostrecon wrote:
On Fri, 11 Nov 2011 22:30:49 +0000, Steve Walker wrote:

On 11/11/2011 18:01, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article
,
writes:
On Nov 11, 3:36 pm, "john east" wrote:
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?
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
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).
Yes, if you take that apart and swallowed it, you might JUST end up with
a small burn on your anus.

If you took it apart and smoked it, you MIGHT end up with lung cancer.
If you mamaged bnot to cough for several minths.

There is a reason why they use alpha emitters. Because they wont even go
thorough a sheet of cigarette paper, let alone your skin.
Alpha emitters are very safe, even safe to handle - as you say, alpha
particles are stopped incredibly easily. However, they are NOT safe if
swallowed, inhaled or they enter the body through a cut, as there they
can remain for lengthy periods, irradiating a small area - alpha is
actually highly damaging.

SteveW

yes - a very common GCSE level question - which is the most dangerous type
of radiation? low penetrating power but hgh ionisation potential means
alpha is the safest outside and most dangerous inside the body,Gamma Low
ionistion potential but very penetrating - less damage but difficult to
shield from, Beta meduim penetration and medium ionisation potential -
worst of both world in effect

However what is far more relevant is the propensity of the body to
absorb the material, and its half life and intensity.

Americium is almost completely harmless.

On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to the point
where nothing gets ionised.

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.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to the
point
where nothing gets ionised.

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
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?

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.


--
Bill

On Sat, 12 Nov 2011 09:54:26 +0000, The Natural Philosopher wrote:

Agreed, the fact they are big and heavy and get absorbed so easyly

They don't get absorbed easily. Not smoke alarm emitters

"They" in the context was alpha particles rather than lumps of
americium.

"If consumed, americium is excreted within a few days and only 0.05% is
absorbed in the blood.

Fair enough but what if you breath it in and lodges deep in a lung...

--
Cheers
Dave.

On Fri, 11 Nov 2011 20:44:33 -0000, polygonum wrote:

On Fri, 11 Nov 2011 15:42:22 -0000, John Rumm
wrote:

On 11/11/2011 15:36, john east wrote:

Have an ordinary house smoke alarm. It's about twenty years old and it
has

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)

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?

Definitely. Your life may depend on it.


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.

Hmph, I bought some and the duracell battery lasted for a month. I tried lithium super long lasting ones and they lasted 4 months.

--
http://petersparrots.com
http://petersphotos.com

It is OK to let your mind go blank, but please turn off the sound.

On Sat, 12 Nov 2011 13:34:25 -0000, John Rumm wrote:

On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to the point
where nothing gets ionised.

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.

Can't this be cleaned then?


--
http://petersparrots.com
http://petersphotos.com

Bills travel through the mail at twice the speed of cheques.

On Sat, 12 Nov 2011 13:35:29 -0000, The Natural Philosopher wrote:

John Rumm wrote:
On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to the
point
where nothing gets ionised.

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..

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.

--
http://petersparrots.com
http://petersphotos.com

A conscience just costs you money.

On Fri, 11 Nov 2011 15:55:16 -0000, wrote:

On Nov 11, 3:36 pm, "john east" wrote:
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?

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?

I had one which used the same beep for both! When the battery went flat it sounded continuously. Pretty stupid really, as if you were out it would be too dead to make a noise by the time you got back.


--
http://petersparrots.com
http://petersphotos.com

You are the only person I know that has ever had a brain tumour removed from their arse.

Dave Liquorice wrote:
On Sat, 12 Nov 2011 09:54:26 +0000, The Natural Philosopher wrote:

Agreed, the fact they are big and heavy and get absorbed so easyly
They don't get absorbed easily. Not smoke alarm emitters

"They" in the context was alpha particles rather than lumps of
americium.

"If consumed, americium is excreted within a few days and only 0.05% is
absorbed in the blood.

Fair enough but what if you breath it in and lodges deep in a lung...


that what cilia and phlegm are fort.

Lieutenant Scott wrote:
On Sat, 12 Nov 2011 13:34:25 -0000, John Rumm
wrote:

On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to
the point
where nothing gets ionised.

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.

Can't this be cleaned then?


Sure. compressed air or similar.

Lieutenant Scott wrote:
On Sat, 12 Nov 2011 13:35:29 -0000, The Natural Philosopher
wrote:

John Rumm wrote:
On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to the
point
where nothing gets ionised.

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..

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.


In my case no, only two things set them off. Falsely. fat frying and
visible 'steam'.

But they don't exist in the kitchen or bathroom, so that's a matter of
keeping the door closed.

I was deeply grateful they DID go off when a log rolled out of the
unattended fire into the hearth...

And, as fire officer in my business years ago, and as someone who has
watched his brother in law's house burn to the ground, fought by a
friends who happens to be the part time fire chief, there is no way I
am taking mine out, even if it did NOT invalidate my house insurance.

On Sun, 13 Nov 2011 11:23:45 -0000, The Natural Philosopher wrote:

Lieutenant Scott wrote:
On Sat, 12 Nov 2011 13:35:29 -0000, The Natural Philosopher
wrote:

John Rumm wrote:
On 12/11/2011 09:25, Brian Gaff wrote:
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

Yup, Optical and Ionization types typically. (you can also get heat
alarms for traditionally smoky rooms)

decay so they just don't work at all once the radiation reduces to the
point
where nothing gets ionised.

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..

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.


In my case no, only two things set them off. Falsely. fat frying and
visible 'steam'.

But they don't exist in the kitchen or bathroom, so that's a matter of
keeping the door closed.

Keeping the door closed is a hassle.

I was deeply grateful they DID go off when a log rolled out of the
unattended fire into the hearth...

Good reason for not having unattended fires. It's why I use gas central heating. If that wasn't here I'd get a gas tank or use electricity. Flames in your house is BAD.

And, as fire officer in my business years ago, and as someone who has
watched his brother in law's house burn to the ground, fought by a
friends who happens to be the part time fire chief, there is no way I
am taking mine out, even if it did NOT invalidate my house insurance.

Oh. House insurance? Didn't think they had such as clause.

--
http://petersparrots.com
http://petersphotos.com

A woman storms into her boss's office with this complaint:
"All the other women in the office are suing you for sexual harassment.
"Since you haven't sexually harassed me, I'm suing you for discrimination."

On 13/11/2011 10:32, Lieutenant Scott wrote:
On Fri, 11 Nov 2011 20:44:33 -0000, polygonum
wrote:

On Fri, 11 Nov 2011 15:42:22 -0000, John Rumm
wrote:

On 11/11/2011 15:36, john east wrote:

Have an ordinary house smoke alarm. It's about twenty years old and it
has

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)

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?

Definitely. Your life may depend on it.


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.

Hmph, I bought some and the duracell battery lasted for a month. I tried
lithium super long lasting ones and they lasted 4 months.

Something wrong with the alarm then...

Personally I use mains powered interlinked ones, saves worrying about
batteries etc.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/