On Wed, 11 Feb 2009 05:06:20 -0600, firstname.lastname@example.org wrote:
The atomic number of C is 6, and the weight is about 12.
The atomic number of O is 8, and the weight is about 16.
(The same number of neutrons as protons. Same number of electrons too
but they weigh very little.
So the weight of a CO molecule is about 28.
The atomic number of N is 7, and the weight is about 14.
So the weight of an N2 molecule is about 28. N2 is about 78% of air
The atomic number of 0 is still8, and the weight is about 16.
So the weight of O2 is about 32. 02 is about 21% of the air, which
added to the N2 is about 99% of the air.
There are small amounts of other gases in the air. I never knew or
forget the details. OK, I looked and it's almost 1% argon, 0.038% CO2.
So the oxygen is a little heavier than the N2 and CO, and the CO is
about the same as the nitrogen which is most of the air.
But I do vaguely recall that they are right, the various gases mix
quite a bit with each other, probably because they are gases.
I have a combination CO-plus-flammable-gas (not smoke) detector. Its
instructions were to mount high in rooms where natural gas is being
used, low if propane is being used (which should be news to nobody in
this group). It says that CO mixes uniformly in air and that CO
detection is equal no matter the mounting height.
And do not buy anything but a digital readout. If threshold level is 500, I
want to know if it is at 450. Screamer units only go off if there is a lot
of CO. I want to know if there is, say, a level that is 30% of safe, and I
want to find out why that lower level is even present.
imo, ymmv, and all that crap
Combo units are a compromise. They're better than nothing at all, but
fall short of the standards I've set in protecting my own family. If I
won't use them in my own home, it stands to reason I wouldn't use them
in someone elses.
Agreed. I don't know if anyone else already explained the drawbacks of
combined smoke and CO detectors but I'll put in my $0.02 on the subject.
There is a different response protocol for smoke from CO detection. If a
smoke detector goes off in a private residence the usual response is to make
sure the family is safe, then check for an actual fire. If no fire is
detected it's probably safe to go back inside. If a CO detector goes off the
family needs to exit the premises immediately and **stay out** until the fire
department clears the premises. Unlike fire, CO cannot be detected by human
senses. It's colorless and odorless, yet can be lethal even at low doses if
exposure continues over time.
There is (or at least there should be) a different protocol for a monitored
system as well. When we received fire alarm signals on private residences we
called the premises to notify the residents of the alarm. If no one answered
we would send the fire department. For CO we called the department first.
Then we would call the premises. We would not cancel the FD even if the
resident assured us they were OK. Twice this resulted in lived being saved
when clients didn't realize there was a problem.
Certainly gases mix. Some mathematician once computed that with every breath
we take, there's at least one molecule of Nitrogen that was in the last
breath exhaled by Julius Caeser.
On a similar note, you can create water by burning Hydrogen in an Oxygen
environment. This reaction yields "fresh" water.
All other water is "used" water.
CO is measured in PPM (parts per million) in comparison to air. What
kills is not necessarily the PPM's. Exposure time is also a factor.
For example: You may tolerate 100 PPM forever, but you may die withing
a few minutes if exposed to 50,000 PPM.
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