Both Halon (which was bad for the Ozone layer) and a more
environmentally friendly replacement 1,1,1,2,3,3,3-heptafluoro-propane
(manufactured under names such as HFC-227ea, FM-200, FE-227) have a
minimum concentration at which they will suppress fires, and a higher
concentration at which they become toxic. If I remember correctly, the
size of the effective, nontoxic range is not that large, and smaller for
Halon than HFC-227ea. IF the fire suppression system is properly
designed and sized for the area covered, concentrations would not be
toxic; but, I have also read such things as "possible effects of
long-term exposure to lower level concentrations of HFC-227 are not well
understood", so erring on the side of caution where possible sounds
advisable.
More importantly, if these chemicals are discharged because a fire is in
progress, chemical byproducts of the combustion itself and the
byproducts of the reaction of the fire suppressant with the fire ARE
most likely toxic and exposure should be avoided.
I don't remember how Halon functions, but my understanding of HFC-227ea
is that in contact with fire it undergoes a chemical reaction that both
absorbs heat and also consumes some oxygen at the point of the fire, and
the combination of these extinguishes the fire. I think the effective
fire suppression concentration of HFC-227 is somewhere in the 5% - 10%
range (maybe less), so at worst only 10% of the air is displaced and the
reduction in oxygen concentration in the room caused by the chemical
discharge would be relatively minor, say from 20% down to 18%.
Shane Ginnane wrote:
I can only own up to being in 2.
In neither case was I affected by the gas - I was out the door as soon as I
heard it drop.
*VERY* good incentive to get moving.
Shane ....
IBM Mainframe Discussion List <IBM-MAIN@BAMA.UA.EDU> wrote on 22/06/2005
11:23:25 AM:
Not true, I've been in 3 HALON dumps back in the days it was THE method
for
computer room FS. One must exit quickly as it will make you short of
breath
at high enough concentrations since it displaces oxygen.
I can best describe the experience as running at 10,000 feet elevation.
--
Joel C. Ewing, Fort Smith, AR [EMAIL PROTECTED]
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