Re: fire suppression in-flight

From: (C. Emory Tate)
Organization: BDM Federal, Inc.
Date:         09 Feb 95 18:50:03 
References:   1
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In article <airliners.1995.134@ohare.Chicago.COM>, wrote:
>I am not sure whether this question has been asked here before, but
>here I dare: with Halon being discontinued from production given
>its ozone-unfriendliness, what alternate fire suppression systems
>are being considered to replace existing technology?

Research I'm aware of is proceeding along two fronts: CF3I and
refrigerant replacements (e.g., HFCs).  Problems with CF3I
(almost as good as 1301, with no ozone depletion because it's
more unstable and I is a heavier species than the problematic Br)
include its toxicity and poorer stability in storage.  Work on
the effects of diluting it with a refrigerant replacement HFC on
its toxicity is proceeding.  The onboard systems are leaning toward
HFCs, despite their poor volumetric efficiency (like twice the
volume for the same extinguishing effect as 1301 in one case), to
avoid tox and stability problems.  The increased volume of re-
frigerants is because they have to cool and smother the fire
rather than chemically quenching it like the Halons.  Also, the
HFCs are greenhousers, but the EPA allows some in critical apps,
like onboard firefighting where available volumes are low.

C. E. Tate   snailmail:  BDM Federal, Inc.
                         1501 BDM Way, McLean, VA  22102
Stick forward and opposite rudder to stop the spin.