Characterization and Identification of Super-Effective Thermal Fire Extinguishing Agents. Final Report. NGP Project 4C/1/890.
Characterization and Identification of Super-Effective
Thermal Fire Extinguishing Agents. Final Report. NGP
Project 4C/1/890.
(1059 K)
Pitts, W. M.; Yang, J. C.; Bryant, R. A.; Blevins, L.
G.; Huber, M. L.
NIST Technical Note 1440; NIST TN 1440; 138 p. July
2006.
Keywords:
fire extinguishing agents; reaction kinetics; flame
extinguishment; surface cooling; combustion; propane;
experiments; thermophysical properties; lactic acid;
halon alternatives; diffusion flames; methane;
extinction; argon; nitrogen; carbon dioxide; helium;
water vapors; dilution; heat extraction; flame fronts;
extinguishing; halon 1301
Abstract:
The use of halon 1301 for fire fighting is being phased
out due to its deleterious effects on stratospheric
ozone. This report summarizes the findings of a
three-year study designed to characterize and identify
super-effective thermal fire-fighting agents as possible
replacements for these widely used compounds. Four
distinct aspects related to the effectiveness of
potential thermal agents have been considered. First,
existing thermodynamic databases maintained by NIST have
been searched in order to identify chemical compounds
which are predicted to extract large amounts of heat
from a combustion zone. Second, two liquids that were
identified as being particularly interesting during the
database search were tested experimentally for their
extinguishing effectiveness. Third, detailed
chemical-kinetic modeling and experimental studies of
extinguishing volume fractions in simple flame systems
were employed to improve the understanding of the
effects of thermal agents on diffusion flames. Fourth,
empirical heat transfer correlations for spray cooling
of a surface were used to estimate the efficiencies of
surface cooling by thermal agents. The database searches
used two primary sources -- the Design Institute for
Physical Properties database containing 1458 compounds
from 83 family types and a smaller database, REFPROP,
containing 43 compounds which is tailored to refrigerant
applications. Additional substances were included that
are not well represented in these databases. Compounds
having high 1) heats of vaporization, 2) liquid-phase
heat capacities, and 3) total heat absorption due to
phase changes (if applicable), heating of a liquid (if
applicable), and the heating of the gas phase to
combustion temperatures were identified. The results are
reported in tables of compounds ordered in terms of
their ability to extract heat. The following
recommendations are made based on the findings of the
study: 1. The effectiveness of HFE7100 as a
fire-extinguishing agent should be tested on full-scale
simulations of aircraft fires. 2. Additional studies of
the effectiveness of fire extinguishing agents released
as liquids should be performed with a focus on
confirming and understanding their enhanced performance
relative to that expected based on simple heat
extraction. 3. Experiments should be designed and
performed with a goal of better understanding the
interactions of liquid agent droplets with heated and
reacting surfaces. Such an understanding is needed to
better predict the effectiveness of liquid agents and
could lead to improved approaches for delivering such
agents to a fire.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899