I'm studying smoke detector, but i don't understand very well how it
works....
If i consider a photoelectric smoke detector, it shoud work in this
manner
1)a photodetector and a diode laser are present in the same chamber,
but photodetector is angulated so , if smoke is not present, radiation
emitted by laser diode isn't seen by photodiode.
2)if smoke is present, for mie scattering, a fraction of radiation is
seen by photodiode
If this is right, i don't understand data sheet...sometimes i've found
sensitivity defined as percentage of obscuration/ metres.....What does
it mean??How can i relate scattered optical intensity with
obscuration??
Thanks

l...@gmail.com wrote:
> I'm studying smoke detector, but i don't understand very well how it
> works....
> If i consider a photoelectric smoke detector, it shoud work in this
> manner
> 1)a photodetector and a diode laser are present in the same chamber,
> but photodetector is angulated so , if smoke is not present, radiation
> emitted by laser diode isn't seen by photodiode.
> 2)if smoke is present, for mie scattering, a fraction of radiation is
> seen by photodiode
> If this is right, i don't understand data sheet...sometimes i've found
> sensitivity defined as percentage of obscuration/ metres.....What does
> it mean??How can i relate scattered optical intensity with
> obscuration??
> Thanks

There are two types of photoelectric smoke detector,
transmissive, and reflective.  You've confused them,
perhaps?

James Arthur

Check the fine print on the back of your smoke detector. If it says "
Americium-241 or AM-241 "  it's radioactive, and constitutes a
potential bio-hazard. This radioactive material, which is contained
between thin layers of gold and silver foil, can be released into the
environment if the detector is tampered with, damaged due to fire,
crushed in disposal or incinerated.  While the radioactive material
inside typical ionization-type smoke detectors is not likely to break
free from its container, it nevertheless constitutes a constant very
low-level exposure. Continual low-level nuclear irritation may cause a
disturbance of life-energy functions over an area larger than
classical radiation theory predicts, via the unshieldable oranur
effect discovered by Dr. Wilhelm Reich.

The alternative to this potential health hazard is a non-radioactive,
photoelectric smoke detector which uses a tiny beam of light to detect
smoke particles. Compared with radioactive detectors that rely on
ionized air, photoelectric detectors use no atomic-radioactive
materials whatsoever. They are additionally less sensitive to humidity
and cooking smoke -- which means fewer annoying false alarms,
increased sensitivity to larger smoke particles, and faster detection
of smoldering fires, the most common and deadly of all household
fires.

Check the fine print on the back of your smoke detector. If it says "
Americium-241 or AM-241 "  it's radioactive, and constitutes a
potential bio-hazard. This radioactive material, which is contained
between thin layers of gold and silver foil, can be released into the
environment if the detector is tampered with, damaged due to fire,
crushed in disposal or incinerated.  While the radioactive material
inside typical ionization-type smoke detectors is not likely to break
free from its container, it nevertheless constitutes a constant very
low-level exposure. Continual low-level nuclear irritation may cause a
disturbance of life-energy functions over an area larger than
classical radiation theory predicts, via the unshieldable oranur
effect discovered by Dr. Wilhelm Reich.

The alternative to this potential health hazard is a non-radioactive,
photoelectric smoke detector which uses a tiny beam of light to detect
smoke particles. Compared with radioactive detectors that rely on
ionized air, photoelectric detectors use no atomic-radioactive
materials whatsoever. They are additionally less sensitive to humidity
and cooking smoke -- which means fewer annoying false alarms,
increased sensitivity to larger smoke particles, and faster detection
of smoldering fires, the most common and deadly of all household
fires.

AsianDoll

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<a...@gmail.com> skrev i meddelelsen 
news:d...@d10g2000pra.googlegroups.com...
> Check the fine print on the back of your smoke detector. If it says "
> Americium-241 or AM-241 "  it's radioactive, and constitutes a
> potential bio-hazard.

Can one actually poison anyone with the contents (all the ones they sell 
here are suddently photo-electric)? 

"Frithiof Jensen" <f...@diespammerdie.jensen.tdcadsl.dk> wrote in 
message news:492474de$0$56788$e...@dtext02.news.tele.dk...
> Can one actually poison anyone with the contents (all the ones they sell 
> here are suddently photo-electric)?

Not without lots of effort to concentrate it.  See, e.g., 
http://www.world-nuclear.org/info/inf57.html

Probably on the same order of difficulty as poisoning people by getting them 
to eat enough apples that the cyanide kills them: Pretty much impossible. 

In article <492474de$0$56788$e...@dtext02.news.tele.dk>,
Frithiof Jensen <f...@diespammerdie.jensen.tdcadsl.dk> wrote:

>> Check the fine print on the back of your smoke detector. If it says "
>> Americium-241 or AM-241 "  it's radioactive, and constitutes a
>> potential bio-hazard.
>
>Can one actually poison anyone with the contents (all the ones they sell 
>here are suddently photo-electric)? 

See http://www.epa.gov/rpdweb00/radionuclides/americium.html for one
writeup on the issues.

According to the EPA:

-  There are some potential health risks which can occur from ingestion
   of AM-241.  It's a long-lived radioisotope, and if ingested will
   expose the tissues containing it to radiation (gamma and alpha) for
   years.  The EPA doesn't mention specific chemical (as opposed to
   radiation) hazards.
   
-  Most of the AM-241 in the environment comes from nuclear-weapons
   testing back in the 1950s and 1960s.
   
-  Ionization-type smoke detectors contain a small amount of AM-241.
   Don't disassemble them, attempt to remove the AM-241 emitter, or
   burn them in your fireplace.
   
-  The amount of AM-241 in smoke detectors is so small that the NRC
   exempts individuals purchasing smoke detectors from licensing
   requirements, including disposal requirements.  According to the
   NRC it's legal to dispose of single household smoke detectors in
   the trash, without special handing.  [Some states have regulations
   which forbid disposing of any electronic equipment in the trash,
   including batteries.  I don't know whether these regs apply to
   smoke detectors.]

-- 
Dave Platt <d...@radagast.org>                                   AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

On Tue, 18 Nov 2008 20:48:13 -0800, asiandollno1 wrote:

> Continual low-level nuclear irritation may cause a disturbance of
> life-energy functions over an area larger than classical radiation theory
> predicts, via the unshieldable oranur effect discovered by Dr. Wilhelm
> Reich.

Americium 241 emits alphas, which unless you swallow it or inject it
into your bloodstream, are fairly innocuous - a layer of epidermis
stops them.

But, "life-energy"? "unshieldable oranur effect"?

Gimme a break.

Thanks,
Rich

On Wed, 19 Nov 2008 21:19:43 +0100, Frithiof Jensen wrote:
> <a...@gmail.com> skrev i meddelelsen
> news:d...@d10g2000pra.googlegroups.com...
>> Check the fine print on the back of your smoke detector. If it says "
>> Americium-241 or AM-241 "  it's radioactive, and constitutes a potential
>> bio-hazard.
> 
> Can one actually poison anyone with the contents (all the ones they sell
> here are suddently photo-electric)?

Sure! Dissolve some in mercury, and give them an IV. >:->

Cheers!
Rich

asiandollno1@ gmail.com wrote:
>Check the fine print on the back of your smoke detector.
>If it says " Americium-241 or AM-241 " it's radioactive,
>
Commonly called an "ionization detector".
It is best at sniffing the particulates that arise from open flames.
They are the type more likely to false-alarm
due to cooking fumes, hair spray, and such.

>The alternative to this potential health hazard is a non-radioactive,
>photoelectric smoke detector
>
These are best for smoldering fires that produce visible smoke.
and are orders of magnitude less likely to give a false alarm.

If you want the fastest notification of danger, you by a device
that has both an ionization detector and a photoelectric detector.