OT Don't read this (was Re: Altair MBL source)

[Allison]

>
>Subject: Re: OT Don't read this (was Re: Altair MBL source)
>   From: shoppa_classiccmp at trailing-edge.com
>   Date: Mon, 02 May 2005 13:12:33 -0400
>     To: cctalk at classiccmp.org
>
>> Apparently the whole area gets flooded with halon (sp?) to quickly absorb
>> any oxygen from the air, so if you hang about ......
>
>"Absorb any oxygen" is a bit harsh.  Halon is pretty good at stopping
>things from burning but it doesn't make it impossible to breathe.  It's
>not the most healthy thing to breathe but in the 80's and earlier a
>very common demo of halon extinguishers had the salesman in a halon filled
>booth, demonstrating how all fires go out, while happily breathing the
>stuff.
>
>Now, CO2 oxygen-displacement extinguishers, that's a different story.
>
>Tim.

Halon does not absob Oxygen.  It is an Oxygen displacement that is
also heavier than air.  In a closed room if enough is introduced 
under pressure (typically) it will push out all air (Oxygen too)
leaving an unbreathable and incombustable mix.  Because computer 
rooms are largely closed any major air displacement is dangerous
for the users inside.

A bunch of years back I was working at a pharmaceutical plant doing
controls.  While I was in a HEPA closed filling room some dolt fired 
up a Freon (R12) system used to pressurize the containers without 
checking to see if the lines were properly capped. Those 75GPM 
pumps were pushing liquid Freon that initially I thought was Glycol
for cooling.  It took only a few seconds for the Freon to vaporize 
and reduce the breathable air to nil by displacement. In the few 
seconds it took to evaluate what's going on and get out I was 
quite hypoxic.  My boss was extremely upset with the dolt.  I spent
many months after that doing lockout/tagout training and used 
that case as the what can happen.

Halon and Freon are similar in that they are "non toxic",
incombustable and generally electronics friendly in the gas form.
But life is only supported by Oxygen, anything else while not toxic
is not breathable without causing hypoxia.


Allison