Agent Stability Under Storage.
Agent Stability Under Storage.
(4675 K)
Harris, R. H., Jr.
NIST SP 890; Volume 1; Section 7; November 1995.
Fire Suppression System Performance of Alternative
Agents in Aircraft Engine and Dry Bay Laboratory
Simulations. Volume 1. Section 7, Gann, R. G.,
Editor(s), 249-406 pp, 1995.
Available from:
National Technical Information Service
Order number: PB96-117775
Keywords:
fire suppression; aircraft engines; nacelle fires;
simulation; storage stability; FT-IR; copper;
degradation; halon 1301; halon alternatives;
unimolecular decomposition
Abstract:
Significant losses in fire suppression effectiveness and
increases in toxicity are possible if a fire
extinguishing agent degrades during multi-year storage.
Halon 1301 is known to be stable in metal containers for
many years, and any trace degradation products do not
affect its fire suppression effectiveness. For
candidate replacement agents, comparable data are
needed, reflecting the storage conditions of elevated
temperature and pressure. The storage environment
fosters conditions which may have an adverse effect on
the stability of halon replacements. Stored chemicals
may engage in oxidation-reduction reactions, hydrolysis,
and other corrosive interactions with metal cylinders.
They are also subject to unimolecular decomposition and
attack by reactive impurities in the agent. Water and
oxygen, for example, will sorb to surfaces of cylinders
and transfer lines and can never be completely excluded.
These sources of instability, along with the possibility
of catalytic interactions with the cylinder walls, can
promote the evolution of undersirable products and a
concomitant loss of fire suppression effectiveness.
Toxicity and corrosiveness are particularly important
concerns with respect to halogenated compounds, due to
the tendency to librate hydrogen halide in the process
of degradation. This report gives the details of the
test procedure and a comparison of agent absorbance band
areas from low concentration spectra. Also, presented
are a comparison of absorbance bands in high density
spectra for impurities present in the agents or produced
as a result of degradation. These data provide a
quantification of any degradation of the agents during
long-term storage.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899