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Re: Halon

On Sat, 25 Jul 1998, Simon Aegerter wrote:

> >Oh Gawd!!! We wouldn't want to have another sunburned penquin on our souls
> >would we?
> Unfortunately, Dale, it ain't so harmless. How about some cancerous Aussies
> to begin with? I wish it wern't true, because, as you see from my other
> posts, I love halon as a fire extinguisher.

Unfortunately, I have to agree with Simon. The ozone thing is almost 
certainly a real problem in contrast to global warming where I find the 
evidence to be almost totally speculation and propaganda. However if one 
looks at the tonnages involved, the amount of Halon that has been 
injected into the atmosphere is so much smaller than the amount of Freon 
that it can only be a very small part of the problem at worst. Therefore, 
I don't feel guilty for using a Halon extingusher. 

> >Would someone be kind enough to explain to me how something heavier than air,
> >such as Freon or Halon can get up to the level of the ozone layer to deplete
> >it?
> Easy: for the same reason water vapor (molecular weight 18) doesn't all
> stay at the surface of the earth, but is part of the mixture of Oxygen (mw
> 32) and nitrogen (mw28) and carbon dioxide (mw 44). Small- and large scale
> turbulence mixes the stuff to the molecule level and at that level, the
> rate of descent due to weight is so small that it is irrelevant compared to
> the vertival movement of the air masses.
Again, I agree with Simon. However, above the tropopause the process is 
amost exclusively that of molecular diffusion which is so slow that only 
materials that can presist for literally decades in the atmosphere 
without change are the only ones that will make it up to the ozone layer. 
There is some question whether Halon is inert enough to make it up, Freon 
certainly is. On the other hand it is certainly inert enough that the 
amount decomposition when used in fire extingushers is much to small to 
be dangerous.

> >We might have better luck getting the government to legislate natural
> >phenomenon like volcanic activity which certainly puts natural fluorocarbons
> >way up high.
> Nope, hardly any halocarbons, just halogens. But they have a hard time to
> make it up there for chemical reasons. (See what Don Royer sais).
Actually, the culprit is almost exclusively chlorine. Fluorine and bromine 
have almost no effect on the ozone. Yes both Freon and Halon do contain 
chlorine. Yes volcanic activity has been shown to cause a spike in the 
chlorine in the ozone layer and there are other natural scources as well. 
Not nearly all of the chlorine in the ozone layer is manmade.

Enough of this. Let's all get back to building airplanes

Don Royer