New and Improve Aerosol Suppressants Publications

Fleming, J.W., Reed, M.D., Williams, B.A., and Sheinson, R.S., “Fire Suppression by Bicarbonate
Powders: The Influence of Particle Size,” Proceedings of the Third Annual SERDP Symposium,
Washington, DC, p. 16, 1997.

Reed, M.D., Fleming, J.W., Williams, B.A., and Sheinson, R.S., “Laboratory Evaluation of Bicarbonate
Powders as Fire Suppressants,” Proceedings of the International Conference of Ozone Protection
Technologies, Baltimore, MD, pp. 333-34, 1997.

Fleming, J.W., Reed, M.D., Zegers, E.J.P., Williams, B.A., and Sheinson, R.S., “Extinction Studies of
Propane/Air Counterflow Diffusion Flames: The Effectiveness of Aerosols,” Proceedings of the 1998
Halon Options Technical Working Conference, Albuquerque, pp. 403-414, 1998.

Reed, M.D., Williams, B.A., Sheinson, R.S., and Fleming, J.W., “Behavior of Bicarbonate Powders in
Counterflow Diffusion Flames,” Proceedings of the Eastern States Section of the Combustion Institute,
Hartford, pp. 83-86, 1997.

Fleming, J.W., Reed, M.D., Zegers, E.J.P., Williams, B.A., and Sheinson, R.S., “Extinction Studies of
Propane/Air Counterflow Diffusion Flames: The Effectiveness of Aerosols,” Proceedings of the 1998
Halon Options Technical Working Conference, Albuquerque, pp. 403-414 1998.

Fuss, S.P., Dye, D.J., Williams, B.A., and Fleming, J.W., “Inhibition of Premixed Methane-Air Flames by
Water Mist,” Proceedings of the Fall Technical Meeting of the Eastern States Section of the Combustion
Institute, Raleigh, pp. 105-108 1999.

Zegers, E.J.P., Williams, B.A., Sheinson, R.S., and Fleming, J.W., “Water Mist Suppression of Non-
Premixed Counterflow Flames,” Proceedings of the Fall Technical Meeting of the Eastern States Section
of the Combustion Institute, Raleigh, pp. 109-112, 1999.

Fu, C., Sojka, P. E., and Sivathanu, Y. R., “Water Mist Impingement onto a Heated Surface,”
Proceedings of the 5th Joint ASME/JSME Joint Thermal Engineering Conference, 1999.

Fu, C., Sojka, P. E., and Sivathanu, Y. R., “On the Interaction Between Evaporating Sprays and Heated
Surfaces,” Proceedings of the 12th Annual Conference on Liquid Atomization and Spray Systems, 1999.

Sivathanu, Y., Oke, H.P., Fu, C., and Sojka, P.E., Droplet Interaction with Hot Surfaces, Annual Report
to the Strategic Environmental Research and Development Program, 1998.

Oke, H.P., Sojka, P.E., and Sivathanu, Y. R., “Flame Spread over Polymethylmethacrylate with Opposed
Air Flow,” Fire Safety Journal, submitted for publication, 1999.

Oke, H.P., “An Experimental Study of Flame Spread Over PMMA Subject to a Water Mist” M.S. Thesis
submitted to the School of Mechanical Engineering, Purdue University, November, 1999.

Rumminger, M., Reinelt, D., Babushok, V., and Linteris, G. T., "Numerical Study of the Inhibition of
Premixed and Diffusion Flames by Iron Pentacarbonyl," Combustion and Flame 116, 207-219, 1999.

Rumminger, M. D.; Reinelt, D.; Babushok, V. I.; Linteris, G. T., “Inhibition of Flames by Iron
Pentacarbonyl,” Proceedings of the 1998 Halon Options Technical Working Conference, Albuquerque,
pp.1-12, 1998,


Figure 4. Schematic of TARPF (dimensions in mm)

suppressant
aes

flow 490 ——>! reignition
straightener surface

Figure 5. Computer Simulation of a Stabilized Propane Flame in the TARPF



= A second approach directs the hot gas generator discharge from an “inert” solid propellant
across an “activated” agent bed and entrains a chemically active additive into the gas stream
and carries it to the flame zone. Activated coolant bed formulations under consideration
include granular magnesium carbonate coolant “activated” by deposits of varied levels of
potassium iodide and potassium carbonate.

Improved Suppressant Delivery Publications

Takahashi, F., Schmoll, W.J., and Belovich, V.M., “Extinction of Bluff-Body Stabilized Diffusion
Flames,” Proceedings of the Spring Technical Meeting of the Central States Section of the Combustion
Institute, Lexington, Kentucky, Paper No. 37, 1998.

Takahashi, F., Schmoll, W.J., and Belovich, V.M., “Suppression of Bluff-Body Stabilized Diffusion
Flames,” 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Cleveland, Paper No. 98-3529,
1998.

Belovich, V.M., Takahashi, F., and W.J. Schmoll, “Suppression of Fires Stabilized Behind Clutter,”
Proceedings of the Twenty-sixth International Conference on Fire Safety, Columbus, Ohio, 1998.

Takahashi, F., Schmoll, W.J., and Belovich, V.M., “Suppression of Bluff-Body Stabilized Pool Flames,”
AIAA 37th Aerospace Sciences Meeting, Reno, NV, Paper No. 99-0327, 1999.

Takahashi, F., Schmoll, W.J., and Belovich, V.M., “Stabilization and Suppression of a Diffusion Flame
Behind a Step,” Proceedings of the Joint U.S. Sections Meeting of the Combustion Institute, Washington,
DC., 1999.

Takahashi, F., Schmoll, W.J., Strader, E.A., and Belovich, V.M., “Effects of Obstruction on Fire
Suppression Efficiency,” Proceedings of the 1999 Halon Options Technical Working Conference,
Albuquerque, 1999.

Takahashi, F., and Belovich, V. M., “Suppression of Step- Stabilized Diffusion Flames in Air Vehicles,”
Proceedings of the Twenty-eighth International Conference on Fire Safety, Columbus, Ohio, 1999.

Takahashi, F., Schmoll, W. J., Strader, E., and Belovich, V. M., “Suppression of Step-Stabilized
Nonpremixed Flames,” Combustion and Flame, accepted for publication (1999).

21


I. INTRODUCTION

Halon 1301 (CF3Br) has long been the choice for fire extinguishment in most weapon systems and
mission-critical facilities. However, due to its high ozone-depletion potential, halon 1301 was banned
from production as of January 1, 1994, under the Copenhagen Amendments to the Montreal Protocol on
Substances that Deplete the Ozone Layer.

As part of its effort to eliminate its dependence on halon 1301, in FY1997 the Department of Defense
(DoD) initiated its Next Generation Fire Suppression Technology Program (NGP). The goal of the 9-
year, $46 million research program was to develop and demonstrate, by 2005, retrofitable, economically
feasible, environmentally acceptable and user-safe processes, techniques, and fluids that meet the
operational requirements currently satisfied by halon 1301 systems in aircraft, ships, land combat
vehicles, and critical mission support facilities. The results are to be specifically applicable to fielded
weapons systems. If successful, the NGP would eliminate DoD dependence on a substance no longer in
national production, minimize any readiness impacts that could result if halon 1301 use restrictions were
imposed in the future, and achieve these at greatly reduced cost.

Prior DoD efforts had identified viable, near-term halon alternatives for a wide variety of weapon system
applications. These alternatives typically require weights and volumes that are double or triple that of
halon 1301 for equivalent effectiveness. While they can be accommodated in new system designs, they
pose a significant problem to existing weapon systems because of form, fit, and function constraints.
Given the current extensions of in-service lives of fielded weapon systems, this problem could ultimately
require DoD program managers to expend large amounts of funding and time for fire suppression system
redesign and reconfiguration.

The potential fire locations for which alternatives to halon 1301 are sought include aircraft engine
nacelles, dry bays, cargo bays, and fuel tanks; ground vehicle crew compartments; and shipboard
machinery spaces and storage compartments. [Figure 1] These locations vary in size, shape and
occupancy; the fuels are solids, vapors and liquids (pools and sprays); and the suppression times range
from about 0.1 s to 100s. The hazards to be avoided include harm to people, thermal damage, post-fire
corrosion, loss of visibility, and overpressure. Successful candidates must thus do well in: fire
suppression efficiency and reignition quenching, ODP, GWP, atmospheric lifetime, suppressant residue
level, electrical conductivity, metals non-corrosivity and polymeric materials compatibility, long-term
storage stability, low toxicity of the chemical and its combustion and decomposition products, speed of
dispersion, safety and occupational health requirements. To be cost-effective, the suppressant and
storage/delivery system must be of light weight and low volume, as well as compatible with the host
designs of existing platforms.


Rumminger, M.D. and Linteris, G.T., "Particle Measurements in Fe(CO)s-Inhibited Flames," N/ST
Annual Conference on Fire Research, Rockville MD, Nov. 2-5, 1998.

Rumminger, M.D. and Linteris, G.T., “The Role of Particles in Flame Inhibition by Iron Pentacarbonyl,”
Proceedings of the 1999 Halon Options Technical Working Conference, Albuquerque, 1999.

Rumminger, M.D. and Linteris, G.T., “Particle Measurements in Flames Inhibited by Iron
Pentacarbonyl,” Joint Meeting of the United States Sections of the Combustion Institute, Washington,
D.C., March 1999.

Linteris, G.T. and Rumminger, M.D., “Flame Inhibition by Ferrocene, Carbon Dioxide, and
Trifluoromethane Blends: Synergistic and Anti-synergistic Effects,” 1999 Fall Technical Meeting,
Eastern States Section of the Combustion Institute, 1999.

Rumminger, M.D. and Linteris, G.T., “Numerical Modeling of Inhibition of Counterflow Diffusion
Flames by Iron Pentacarbonyl,” Proceedings of the Sixth International Symposium on Fire Safety
Science, in press, 2000.

Rumminger, M.D. and Linteris, G.T., “Inhibition of Premixed Carbon Monoxide-Hydrogen-Oxygen-
Nitrogen Flames by Iron Pentacarbonyl,” Combustion and Flame, accepted for publication, 1999.

Linteris, G.T. and Rumminger, M.D., “Premixed Carbon Monoxide/Nitrous Oxide/Hydrogen Flames:
Measured and Calculated Burning Velocities with and without Fe(CO);,” Combustion and Flame,
submitted for publication, 1999.

Rumminger, M.D. and Linteris, G.T. “An Experimental Study of the Role of Particles in Flame Inhibition
by Iron Pentacarbonyl,” Combustion and Flame, submitted for publication, 1999.
1999,

Linteris, G.T. and Rumminger, M.D., “Flame Inhibition by Thermal and Catalytic Blends: Synergistic
and Antagonistic Effects,” Proceedings of the Twenty-eighth Symposium (International) on Combustion,
The Combustion Institute, Pittsburgh, submitted for publication, 1999.


Figure 13. Framework for Quantifying Benefits

Identify
, Document pected Fut
| Current } - waters lex ruturd
Environment / Environment |
~ 44
‘ Survey for |
| Benefits of New
| Environment |
a J
eee
| Categorize |
| Benefits |
i ____}
i oo 1 —
Who Is the What Part of th Probability of When Will the
{
| Beneficiary of Organization is i Benefit Benefit Be
the Benefit Benefiing | Occurring Realized

| Change In Opportunities to]
| Mission Move Up
(Performance | Probability

Viability of New Suppressant Technologies Publications

McNesby, K.L., Skaggs, R.R., Miziolek, A.E., Clay, M., Hoke, S., and Miser, C.S., “Diode Laser-Based
Measurements of Hydrogen Fluoride Gas During Chemical Suppression of Fires,” App. Phys. B 67, 443-
447, 1998.

Skaggs, R.R., Daniel, R.G., Miziolek, A.W., McNesby, K.L., Herud, C., Bolt, W.R., and Horton, D.,
“Diode Laser Measurements Of HF Concentrations Produced From Heptane/Air Pan Fires Extinguished
By FE-36, FM-200, FE-36 Plus APP, Or FM-200 Plus APP,” Applied Spectroscopy, accepted for
publication 1999.

Williamson, C.K., McNesby, K.L., Daniel, R.G., and Miziolek, A.W., “Laser-Induced Breakdown
Spectroscopy for Real-Time Detection of Halon Alternative Agents," Analytical Chemistry 70, 1186-
1191, 1998.

McNesby, K.L., Skaggs, R.R., Miziolek, A.W., Daniel, R.G., and Miser, C.S., “Near-Infrared Tunable
Laser Diagnostics In Laboratory Scale Flames,” Proceedings of Laser Applications To Chemical and
Environmental Analysis Topical Meeting, p. 203, 1998.

24


temperature at five locations, void fraction at the end of the pipe, and mass flow rate out of
the discharge vessel are recorded.

A principal reason for the historic overdesign of halon 1301 systems was to overwhelm the impedance of
suppressant distribution by the extensive clutter in the space. NGP engineers are quantifying these
penalties for different fuels (methane, ethane, JP-8), fire suppressants (halon-1301, HFC-125, nitrogen)
and bluff body shapes (step, baffle, J-flange). These results will both quantify the potential gains from
redesigned distribution systems and assist in screening for the effectiveness of candidate suppressants.

An NGP mode] based on a well-stirred reactor describes the rate of agent entrainment into the
tecirculation zone. It relates the free stream agent concentration and injection period to the critical
concentration needed for extinguishment and a characteristic mixing time for entrainment into the
recirculation zone. Figure 10 shows that this model captures the normalized agent mole fraction at
extinction as a function of agent injection period for a range of flow conditions, agents, and clutter

shapes.

Figure 10. | Calculated and Measured Normalized Extinction Concentrations as a
Function of Normalized Agent Residence Time

: : t roe
ee (by Fuel Us tw |
ae “SS stare SA
f ° 74 023
fee 2 71 OM ¥ Methane 10.8 0.15
Sep 84 7.1 23 9 Ethane 7.1 0,23
Sup 64 K B & Ethane 10.8 0.15
dhange 64 21
sfanje 6407.1 0.23 J
S45
x
Extinction
Pa 4
ae 0s No Extinction 4
0 mn A ni 4 ° \ A Lottie tte)
0 2 8 10 oO 2 4 6 8 10 12 414
AY ep BU Teg

Based on these results, a fire suppression system should be designed to provide a critical concentration of
agent for a period at least three or four times the characteristic mixing time of the system.

NGP research is developing new types of solid propellant gas generators (SPGGs) that have high flame
suppression efficiency, yet little negative impact on the environment or the weapons system. The first of
these formulations are aimed at both reducing SPGG combustion temperatures and increasing flame
suppression.

= One approach directs a rapid gas generator exhaust discharge of additive-enhanced propellant
formulations into a flame zone. Two formulations are being considered:
= 5-amino tetrazole(5-AT) and potassium perchlorate (KP), with an elastomeric binder,
with and without decabromodiphenyl ether, added as a chemically active flame inhibitor
= Potassium carbonate or nitrate.

20



Cc. NEW AND IMPROVED AEROSOL SUPPRESSANTS

Nearly all suppressants of interest emerge from pressurized storage containers as liquids or powders,
along with a gaseous component. The properties of the aerosol (a) determine its transport effectiveness to
the fire, (b) the magnitude of its effect on the flames, (c) its ability to quench condensed-phase fuels, and
(d) its impact on preventing reignition. The values of the aerosol properties that optimize each of these
may be uniform for the four impacts or may be in conflict. This section deals with the latter three of these
impacts.

NGP studies of water droplets injected into propane/air and methane/air counterflow non-premixed
flames have identified the optimal droplet diameter ranges for suppression effectiveness. Droplets with
diameters $18 Hm completely evaporated before reaching the stagnation plane at every strain rate
measured. A significant number of droplets with diameters >30 Hm survived in most propane/air flames.
Droplets larger than 42 #m were much less efficient at suppression.

* These water mist concentrations approach the predicted limit based on comparison of the physical
effect of water mist's sensible enthalpy and heat of vaporization to gaseous thermal agents.

For the droplet sizes and flame strain rates measured, extinction effectiveness appears to correlate
with the degree of evaporation. Thus, for water aerosols, if all of the water droplets can evaporate
in or near the flame, water is as effective as halon 1301 on a mass basis.

Droplet diameter variation was found to have a minimal impact on flame spread rate across a PMMA
surface. The rate decreased almost linearly with the mass of water incident on the surface (Figure 7).

Figure 7. Variation in Flame Spread with Liquid Loading. The open symbols were
obtained with 0.3 mm PMMA, and the closed symbols were obtained with 0.64 mm PMMA
sheet. The symbol shapes correspond to different air velocities.

root ;
L 0.60 m/s
B 1.00¢ 0.94 mis J
© s 1.21 mis
Gb t 1.50 m/s
@ 0.75 5 j
a [ a
iL c ]
B 0.50F 4
N [ 4
Bas’ ne
6 0.25 + . . 4
z [ a
0,00 Ce tt
0 20 40 60 80 10

Liquid loading (g/min/m?)

15


Acute inhalation toxicity testing: OK = tested, with no perceived effects; Y = tested, with some effects on the test
animals; N = not tested

Table 2. Tropodegradable Bromofluoro-Amines

ccoD Compound Formula Boiling

Ext. Conc.
‘Dee point °C) (vol, 2)
1392 Bis(trifluoromethyl)-2-bromo-1,2,2- N(CF3)x(CHFCF)Br) 72 (24)57*
trifluoroethyl amine
1393 Bis(trifluoromethyl)-2-bromo-I,,1,2- N(CF3)(CF,CFHBr) 2 (2.4)t0*
trifluoroethy! amine
1398 Bis(trifluoromethy!)-2-bromo-2- N(CF;),(CH,CF,Br) 80 (2.4)**

fluoroethylamine

. Results of a 60/40 blend of CCODs 1392 and 1393
had () reflect values considered to be upper bounds on extinguishment

New Flame Suppression Chemistry Publications

Babushok, V.I., Tsang, W., Linteris, G.T., and Reinelt, “Chemical Limits to Flame Inhibition,”
Combustion and Flame 115, 551-560, 1998.

Noto, T., Babushok, V.I., Hamins, A., and Tsang, W., “Inhibition Effectiveness of Halogenated
Compounds,‘ Combustion and Flame 112, 147-160, 1998.

Skaggs, R.R., McNesby, K.L., Daniel, R.G., Homan, B. and Miziolek, A.W., “Spectroscopic Studies Of
Low Pressure Opposed Flow Methane/Air Flames Inhibited By Fe(CO);, CF;Br, Or N2 ,” Combustion
Science and Technology, accepted for publication, 1999

Skaggs, R.R., Daniel, R.G., Miziolek, A.W., and McNesby, K.L., “Spectroscopic Studies Of Inhibited
Opposed Flow Propane/Air Flames,” Proceedings of 1999 Joint Meeting of the United States Sections of
the Combustion Institute, Washington, DC, 1999.

Skaggs, R.R, Daniel, R.G., Miziolek, A.W., McNesby, K.L., Babushok, V.L, Tsang, W., and Smooke,
M_D., “Spectroscopic Studies Of Inhibited Opposed Flow Propane/Air Flames” Proceedings of 1999
Halon Options Technical Working Conference, pp. 117-131, Albuquerque, 1999.

Fisher, E.M., Williams, B.A., and Fleming, J.W., “Determination of the Strain in Counterflow Diffusion
Flames From Flow Conditions,” Proceedings of the Eastern States Section of the Combustion Institute,
pp. 191-194, 1997.

Williams, B.A. and Fleming, J.W., “Suppression Mechanisms of Alkali Metal Compounds,” Proceedings
of the 1999 Halon Options Technical Working Conference, pp. 157-169, Albuquerque, 1999.

Davis, M.P., Fleming, J.W., Williams, B.A., and Ladouceur, H.D., “Flow Field Considerations for
Counter Flow Burners, ” Proceedings of the Fall Technical Meeting of the Eastern States Section of the
Combustion Institute, pp. 200-203, 1999.


I. TECHNICAL PROGRESS

A. NEW FLAME SUPPRESSION CHEMISTRY

The NGP is continuing the search for new chemicals that perform as well as CF;Br, but without the
environmental limitation. The research follows two directions: (a) learning more about how different
chemicals effect suppression, then looking for optimal analogs and (b) identifying the best chemicals
from the various families of chemicals. The principal desirable properties guiding the search are:

¢ Fire suppression efficiency at least comparable to halon 1301 and certainly higher than the HFCs.

© Short atmospheric lifetime (current preference of the order of a month), to keep ozone depletion,
global warming and any future unidentified contamination issues to a minimum.

¢ Low toxicity relative to the concentration needed for suppression.

¢ Boiling point sufficiently low that for gaseous agents, an extinguishing concentration can be
achieved within a specified time following discharge. An approximate upper limit is 80 °C, but
slow evaporation may reduce this significantly for some chemicals.

Current NGP research has built on results from the prior years of the Program and findings of pre-NGP
research to evolve a model for how fire suppressant additives quench flames. Flame propagation relies on
fast reactions of the free radical pool (OH radicals and O and H atoms) with fuel molecules. In
uninhibited flames, these three reactive species are in equilibrium with each other, but at concentrations
well above equilibrium with their surroundings.

In the context of the NGP, flame suppressant additives can be viewed in three categories:

Halon-like suppressants. Globally, these suppress flames at about 3 percent by volume. The
active species, such as a bromine atom, catalytically reduces the radical pool to a near-
equilibrium level. The increased heat capacity from the additive reduces the flame temperature,
further reducing the flame propagation reaction rates to the point where they can no longer
sustain combustion. The chain length of the Br catalytic cycle has been estimated as about 7.

Super suppressants. These compounds contain a highly reactive entity, such as a metal or
phosphorus atom. They are as much as two orders of magnitude more efficient than Br atoms at
bringing the radical pool closer to equilibrium level, and thus are seen as highly efficient reducers
of premixed flame velocity. However, a mass fraction similar to the halon-like chemicals is
needed to reduce the flame temperature and thus the flame propagation kinetics to non-
combustion-sustaining rates. The extinguishing concentrations thus appear to be only modestly
lower than the halon-like chemicals, perhaps of the order of 1 percent.

Thermal (non-catalytic) suppressants. These chemicals operate mainly by absorbing flame heat
into multiple sensible heat modes, e.g., vibronic absorption and endothermic phase changes.
Gaseous compounds have been identified that can increase the thermal bath to quenching levels
as low as 6 percent by mass. Adding the heat of vaporization can reduce this to below 2 percent
by mass.

Thus, it appears that all these categories contain chemicals that are comparable to halon 1301 in
suppression efficiency. Conversely, it remains to be seen whether it is possible to effect flame
suppression at levels well below the halon efficiency (without blowing the flame out). This discussion
also suggests that there may be a non-linear relationship between the chemical (catalytic) and thermal
contributions of a suppressant.


Figure 1. NGP Research on Retrofitable Fire Suppression Technologies

Applications
Managers

On Bey

=
==

Fee Tank

The NGP has just completed its third year of research, having expended about 23 percent of the planned
resources. Support from the NGP comes from DoD funding and cost sharing from the participating
laboratories. To date, most of the DoD support has come from the Strategic Environmental Research and
Development Program (SERDP), with additional support from the Army Tank and Automotive
Command (TACOM).

The following Section highlights the new knowledge gained from the NGP research and the progress
made towards the NGP Goal. Additional information on the strategy and status of the NGP can be found
at the NGP web site: www.dtic. mil/ngp/.


Droplet diameter and velocity measurements from a mono-disperse spray onto a hot plate showed that
buoyancy had a significant impact on the droplet velocities and diameters. The droplet velocity slows to
half the injection velocity causing the faster and cooler droplets to collide and coalesce with the droplets
in front of them near the surface of the hot plate. Therefore, it is important to model coalescence in fire
suppressions scenarios. Further study of this phenomenon with non-evaporaling droplets is in progress.

The NGP has developed a two-color planar pyrometer which can measure the surface temperatures of
smoldering and charring surfaces. This equipment will be used to obtain surface temperatures for a
charring fire under the influence of a spray mist.

It is important to know the conditions under which fine droplet sprays can suppress the fireballs
experienced in aircraft dry bay and ground vehicle crew compartment fires. Calculations for fine sprays
(diameters <50 1m) indicate nominally complete evaporation near the flame front. Thus, for these small
droplets, other parameters such as the droplet transport time to the fireball should be considered.

It is possible to encapsulate a practical mass of a suppressant onto an inert host for transport to the fire. A
large weight fraction of Fe(CO); can be absorbed into zeolites (33 %) and acrogels (up to 200%).

Further, thermogravimetric analysis showed that at 250 °C a large fraction of the Fe(CO); is desorbed.
Flame tests will allow assessment of whether the agent can be liberated in the time available in a flame.

* Some matrix materials (i.e., zeolites) can exacerbate the pyrophoricity of Fe(CQ)s, likely due
to reaction with residual absorbed water. However, ferrocene has been shown to be as
effective as Fe(CO)s (Figure 8) and is less toxic and pyrophoric.

= Combining iron compounds with HFCs is not an effective combination because stable iron-

halogen species act as sinks for active gas-phase iron compounds,

Figure 8. Comparison of Premixed CH,/O,/N2 Flame Inhibited by Ferrocene and
Fe(CO)s

1 —
Tin = 963 K
“a
a 210
08 4,
5
Aa
8 “ve
> 06 ae
2 a
: af,
€ aae
é mo Kee Fe(CO)s
N04
‘s Fee
E
2
02
0 T
° 200 400

Ferrocene or Fe(CO)s Mole Fraction (ppm)
16


combustion modifiers offer significant improvement over iron-containing compounds. A chemical
kinetic mechanism was assembled to examine the inhibition of these compounds. The calculations
indicate no difference between the two Mn-containing chemicals. The reaction pathway is similar to the
iron-containing compounds, with the Mn-containing compounds being 5-7 times less efficient at reducing
burning velocity. Thus, further mechanistic investigation of these compounds is unwarranted.

Research continues on tropodegradable bromocarbons, bromine-containing compounds that are readily

degraded in the lower atmosphere. For instance, bromoalkenes are expected to have atmospheric

lifetimes of just a few days. Ten tropodegradable bromofluoro-alkenes and three bromofluoroamines
were successfully synthesized or acquired from commercial and academic sources (Table 1). Upper
limits of extinguishing concentrations were obtained using the NMERI 5/8-scale cup-bumer, generally
below 4%(v/v). Working with the Advanced Agent Working Group, acute inhalation toxicity “limit”
tests of 8 of the tropodegradable bromofluoro-alkenes were performed at the Lovelace Respiratory
Research Institute. For 4 of the tested compounds (#s 707, 873, 903, and 1116), rats exposed for 30
minutes to 5% (v/v) concentration survived and showed no aftereffects. These results substantially
contributed to NGP predictive models for the acute inhalation toxicity of bromofluoro-alkenes, and
additional bromofluoro-alkenes have now been identified for future work. Table 2 shows initial results
for the 3 bromofluoro-amines.

Table 1. Tropodegradable Bromofluoro-Alkenes Acquired for Testing

CCOD Boiling Ext. Conc.
Ip! Compound Formuta point °C) | (vol.%) | airconc.’ Toxicity’

707 1-Bromo-3,3,3- CF;CH=CHBr 40 3.57 30°C OK
trifluoropropene

872 3-Bromo-3,3- CBrF,CH=CH; 42 45 -30 °C Y
difluoropropene

873 2-Bromo-3,3,3- CF;CBr=CH; 34 2.6 35°C OK
trifluoropropene

903 4-Bromo-3,3,4,4- CF,BrCF,CH=CH) 54 35 -15°C OK
tetrafluorobutene

1116 2-Bromo-3,3,4,4,4- CF,CF,CBr=CH; 56 (3.8) -15°C OK
pentafluorobutene

1358 2-Bromo-3,3,4,4,5,5,5- CF;CF,CF,CBr=CH, 78 (3.7) Y
heptafluoropentene

1359 2-Bromo-3-trifluoromethyl- ) CF,;CF(CF;)CBr=CH 78 (3.3) -10°C Y
3,4,4,4-tetrafluorobutene

1360 2-Bromo-3- CF;CF(OCF;)CBr=CH, 75 (3.8) -10°C Y
trifluoromethoxy-3,4,4,4-
tetrafluorobutene

1391 1-Bromo-2-trifluoromethyl- | (CF3),C=CHBr 63 (2.6) 15°C N
3,3,3-trifluoropropene

1413 1-Bromo-4,4,4,3,3- CF,CF,CH=CHBr 58 GB.1) 15°C N
pentafluorobutene

NMERI Chemical Compound Options Database ID
() represent values that should be considered an upper limit for extinguishment
Predicted lowest application temperature assuming 5% extinguishing concentration, based on a calculation employing

Trouton’s Constant



E. VIABILITY OF NEW SUPPRESSANT TECHNOLOGIES

The success of new NGP technologies requires (1) that the laboratory research replicate the suppression
phenomena in real-scale fires and (2) that the NGP be able to demonstrate that candidate fire suppression
methods are quenching flames as they would under the threats experienced in the field. Meeting both of
these needs entails improved instrumentation in the test articles already owned by the Military

Department laboratories.

= _NGP researchers are complementing prior instrumentation advances by developing a time-
resolved (10 ms), multi-point, fieldable, fiber-coupled, near-infrared tunable diode laser-
based sensor for measurement and detection of combustible mixtures of oxygen and
hydrocarbon fuels (heptane and JP-8) before, during and after the fire suppression event of
250 ms duration. Detection of fuel and oxygen concentration is especially important after the
suppression event in order to predict the possibility of reignition. Two separate lasers, one to
detect each species, are combined to produce the probe beam. Initial tests of this system have
shown that detection of fuel and oxygen at the anticipated levels is feasible (Figure 11).

Figure 11.
K, and the Calculated Absorbance Spectrum of O2

H20

0.007 5

JP-8

0.005 +
0.003 |

H2O0

0.001,
0.001 ©
0.003 =
0.005 -

0.007
1270 1370 1470 1570 1670 1770 1870 1970

Wavelength (nanometers)

Absorbance

3.00E-02 |
2.50E-02 +

2.00E-02 |

1,.50E-02

Absorbance

1.00E-02 ;

§.00E-03

Lo

0.00E+00 —

Wavelength (nanometers)

759° «759.5 «760 7605 761 7615 762 762.5

22

Measured Near-infrared Absorbance in the Region Near JP-8 Vapor at 355

JP-8 vapor, 10 cm path length
355K, 4cm"t resolution,
256 scans.

O,, 1m path length,
296K, calculated using
HITRAN database.


NISTIR 6479

Next Generation Fire Suppression
Technology Program
FY 1999 Annual Report

Richard G. Gann

1007-1061

NUST CENTENNTAL ®&

NUT

National Institute of Standards and Technology
Technology Administration, U.S. Department of Commerce


B. SUPPRESSANT SCREENING TESTS

As planned, the NGP research to develop a set of efficient, accurate screening tests for new suppressant
chemicals is drawing to a close, with completion expected in FY2000. Protocols for progressive
evaluation of compounds for environmental impact, toxicity, and materials compatibility have been
completed and published. Evaluation of inhalation toxicity using a human pharmacokinetic model and a
test for fire suppression efficiency of gases and liquid aerosols are nearly complete. Significant progress
has been made on a method for screening the effectiveness of a suppressant in transient release.

The Dispersed Liquid Agent Screen (DLAS) is now in steady use both to obtain suppression efficiency
data on candidate suppressant fluids and as a research tool. A final report, including full documentation
of the apparatus and its use, has been published. Two modifications have been made to the apparatus to
enhance its operation. The apparatus is also suitable for evaluating powder agents when a powder delivery
system is integrated into the current system.

= The test section has been modified to minimize the corrosive damage from the HF generated
by fluorinated suppressants.

= The suppressant sprays from the nebulizer have been characterized using a Phase Doppler
Particle Analyzer. This is because the suppressant performance may depend on the droplet
size, and different fluids may produce different droplet diameter distributions under the same
nebulizer conditions. For several fluids of widely varying density, viscosity and surface
tension (water, 30 % and 45 % potassium lactate by mass, and 1000 mg/L and 2000 mg/L
sodium dodecyl sulfate), the differences in the average droplet size were found to be within
+15% (Figure 2). The effect of this variation in droplet size was found to affect the blow-off
velocity (a measure of extinction efficiency) by under +15% (Figure 3). These variances are
well within useful tolerance for a screen apparatus. The standard operating protocol uses a
reference delivery rate based on these results.

Figure 2. Effect of Fluid and Fluid Flow on Droplet Size

32

© Distilled water
30 © 1000 mg/l Sodium Dodecyl Sulfate | 2
vy 30% K-lactate °
~ y 2000 mg/l SDS ’
E os mw 45% K-lactate :
s
3
ry &
E26 e z
3 °
Pa 3 v
S v
@ 2 . ° .
ra 8 .
3 ;
Zz 22
an iM 3
20 °
18 1

0.2 03 04 O5 0.6 O7 0.8 09 1.0
Volumetric flow rate (ml/min)


Fleming, J.W., “Chemical Fire Suppressants: How Can We Replace Halon?,” Proceedings of the Fall
Technical Meeting of the Eastern States Section of the Combustion Institute, pp. 16-23, Raleigh, NC,
1999.

Williams, B.A. and Flaming, J.W., “Factors Influencing Chemical Flame Suppression,” Combustion and
Flame, submitted for publication (1999).

Pitts, W.M. and Blevins, L.G., “An Investigation of Extinguishment by Thermal Agents Using Detailed
Chemical Modeling of Opposed Flow Diffusion Flames, ” Proceedings of the 1999 Halon Options
Technical Working Conference, pp. 146-156, Albuquerque, 1999.

Pitts, W.M., Yang, J.C., Huber, M.L., and Blevins, L.G., “Characterization and Identification of Super-
Effective Thermal Fire Extinguishing Agents—First Annual Report,” National Institute of Standards and
Technology Internal Report, NISTIR 6414, 58 p., 1999.

Tapscott, R.E and Mather, J.D., “Tropodegradable Fluorocarbon Replacements for Ozone Depleting and
Global Warming Chemicals, Proceedings of the International Conference on Fluorine Chemistry °99,
Tokyo, 1999.

Tapscott, R.E. and Mather, J.D., “Tropodegradable Fluorocarbon Replacements for Ozone Depleting and
Global Warming Chemicals,” Journal of Fluorine Chemistry, submitted for publication, 1999.

Tapscott, R.E., and Mather, J.D., “Research on Main Group Element Compounds and Tropodegradable
Halocarbons as Halon Substitutes,” Proceedings, Fire Suppression and Detection Research Application
Symposium, Orlando, National Fire Protection Research Foundation, 1999.

Mather, JD., and Tapscott, R.E., “Next-Generation Fire Suppression Technology Program:
NMERI/CGET Projects Overview,” Proceedings of the 1998 Halon Options Technical Working
Conference, Albuquerque, 1998.

Tapscott, R.E., and Olivares-Sooley, M.G., “A Decision Tree for Global Environmental Impact
Screening,” Proceedings of the1998 Halon Options Technical Working Conference, Albuquerque, 1998.

Tapscott, R.E., and Mather, J.D., “Research on Main Group Element Compounds and Tropodegradable
Halocarbons as Halon Substitutes,” Proceedings, Fire Suppression and Detection Research Application
Symposium, pp. 190-195, Fire Protection Research Foundation, 1999.

Mather, J.D., and Tapscott, R.E., “Tropodegradable Halocarbons and Main Group Element Compounds,”
Proceedings of the 1999 Halon Options Technical Working Conference, Albuquerque, 1999.

Brabson, G. D., Garcia, M.M., Heinonen, E.W., Juarez, G., Mather, J.D., and Tapscott, R.E., Main Group
Compounds as Extinguishants, NMERI Report No. 98/8/33380, U. S. Department of Defense, Strategic
Environmental Research and Development Program, in preparation.


NGP research has produced new findings on several promising suppressant chemicals:

= Aqueous lactic acid had previously been identified as a particularly effective thermal agent
due to its high heat of vaporization. Calculated boiling points and latent heats of vaporization
for the full range of lactic acid fraction in water show that both are nonlinear functions of
water mole fraction. This suggests that certain mixtures may be particularly effective at
extracting heat from a flame zone.

= Last year, methoxy-nonafluorobutane (HFE-7100, H3COC,F,) was shown to be an efficient
thermally active suppressant. New calculations of critical point data and ideal gas heat
capacities, along with manufacturer’s values for boiling and freezing points, vapor pressure,
and liquid density have been added to the computer program PROFISSY (Properties of Fire
Suppressant Systems). These can be used to predict the agent storage and discharge
properties when pressurized with nitrogen.

Using the Dispersed Liquid Agent Screen (DLAS, see discussion of Screening Tests below),
the extinguishing concentration for HFE-7100 was determined to be 0.12 mass fraction and
0.016 mole fraction. Unpublished cup burner values from the New Mexico Engineering
Research Institute and a 3M patent are 0.36 and 0.061 for gaseous HFE-7100, respectively.
Thus, there is a significant advantage in getting the ether aerosol to the flame zone.

For reference, the propane cup burner mass and mole fraction values for halon 1301 are 0.17
and 0.04, respectively.

Calculated values of the maximum flame temperature at extinction were obtained as a function of strain
rate for several thermal suppressants (nitrogen, carbon dioxide, argon and helium). Experimental values
of flame extinguishment concentrations of thermal agents could be predicted using a maximum flame
temperature at extinction of 1550 K.

Extinguishing concentrations for these thermal agents were obtained using co-flowing methane and
propane diffusion flames and compared with predictions from a detailed chemical kinetic modeling study
from last year. The experimental extinguishing concentrations are considerably lower than predicted for
an opposed flow burner, but the values are related by a constant value. The experimental extinguishing
concentrations for the propane flame are considerably higher than for the methane flame. At the present
time it is unclear why this should be so. Detailed chemical kinetic modeling of opposed-flow laminar
diffusion flames, to be completed shortly, should provide additional insight.

Work has begun on developing a set of quantitative structure-activity relationships for compound
volatility. These would be used in conjunction with values of agent discharge rates and the known
dimensions of and thermal conditions in the fire compartment to determine whether compounds having a
specified chemical structure can be expected to put out the fire in the required time frame (e.g., on the
order 0.5 s in the case of an engine nacelle fire).

Previous research had shown that small amounts (ca. 10“ mole percent) of Fe(CO); are near the ideal
limit at reducing premixed flame velocities. However, at higher concentrations the agent becomes less
efficient, as the active iron species condense to form relatively inactive particles. Ferrocene, a decidedly
less toxic iron-containing compound, produced nearly identical results, indicating that varying the binding
state of the iron in the agent will not alter the flame suppression behavior.

Current research is examining two Mn-containing compounds, MMT (methylcyclopentadienyl
manganese tricarbonyl) and monomanganese pentacarbonyl, to determine whether these known


D. IMPROVED SUPPRESSANT DELIVERY

The complement to identifying new suppressants is improving the efficiency of getting the suppressant to
the site of the fire. This comprises storage and discharge technology, transport through any distribution
piping and transport once the agent has been dispensed from the storage/distribution hardware.

Replacement fluids must function within the existing distribution plumbing. Replacing the piping is a
major cost in retrofit and is to be avoided. Therefore one has to know how a new, multi-phase chemical
will behave in a long run of bent pipe.

Figure 9.

The new computer code for prediction of two-phase fire suppressant flows during discharge,
begun last year, is now nominally complete. The user can select water, halon 1301, CO,
HFC-227ea or HFC-125 as the suppressant. The software tracks both the fluid and nitrogen
as a pressurizing gas. Figure 9 compares the vessel pressure calculations with published data
(Elliott et al., “Flow of Nitrogen-Pressurized Halon 1301 in Fire Extinguishing Systems,”
JPL Publication 84-62, 1984). The code is portable to a variety of commonly used operating
systems. A tutorial and workshop on the code is being planned for spring, 2000.

Comparison of Calculated Supply Vessel pressure with Experimental Data

6.0 s aoe a
50 f With N2 Ratease
ey © Data (Eltiott et al)
~_No N2 Release

4.0
&
i 3.0
oa

1.0

acy)

Time (@)

Advanced instrumentation for the facility to verify these suppressant flow and discharge
predictions has been installed. Measurement capabilities include instantaneous mass flow of
fluid during transient discharge from the source vessel (using a differential pressure
transducer), fluid temperatures along the discharge pipe (using film thermocouples with
response times on the order of milliseconds), and void fraction (using a capacitance sensing
probe). Numerous test data have been collected using HFC-227ea, During a test run
transient measurements of local pressure at five different locations in the system, local

19


Skaggs, R.R., Daniel, R.G., Miziolek, A.W., McNesby, K.L., Herud, C. Bolt, W.R., and Horton D.,
“Diode Laser Measurements of HF Concentrations From Heptane/Air Pan Fires Extinguished by FE-36
And FE-36 Plus Ammonium Polyphosphate,” 1998 Proceedings of the International Society for Optical
Engineering: Photonics East, in press, 1999.

MeNesby, K.L., Skaggs, R.R., Miziolek, A.W., and McLaren, I.A., “Diode Laser-Based Detector for Fast
Detection of Binary Gas Mixtures,” Proceedings of the 1999 Halon Options Technical Working
Conference, Albuquerque, 1999.

McNesby, K.L., Skaggs, R.R., Miziolek, A.W., Clay, M., Hoke, S., and Miser, C.S., “Diode Laser-Based
Measurements Of Hydrogen Fluoride Gas During Chemical Suppression Of Fires,” ARL-TR -1785, 1998.

Skaggs, R.R., Daniel, R.G., Miziolek, A.W., McNesby, K.L., Herud, C., Bolt, W.R., and Horton, D.,
“Diode Laser Measurements of HF Concentrations from Heptane/Air Pan Fires Extinguished by FE-36
And FE-36 Plus Ammonium Polyphosphate,” ARL-TR, submitted 1998.

Skaggs, R.R., Daniel, R.G., Miziolek, A.W., McNesby, K.L., Herud, C., Bolt, W.R., and Horton, D.,
“Diode Laser Measurements Of HF Concentrations Produced from Heptane/Air Pan Fires Extinguished
By FE-36, FM-200, FE-36 Plus APP, or FM-200 Plus APP,” Proceedings of the 1998 JANNAF
Combustion Meeting, Tucson, in press, 2000.

Bennett, M.V., “Use of the Department of Defense Operational Requirements-Based Casualty
Assessment (ORCA) Software System to Determine Occupant Response to Fire and the Extinguishment
Process,” Human Behavior in Fire, Proceedings of the First International Symposium, Belfast, Northern
Ireland, 1998.

Bennett, M.V., “Relative Benefit Assessment Of Fire Protection System Changes,” Proceedings of the
1999 Halon Options Technical Working Conference, Albuquerque, 1999.

F. IMPROVED FUEL TANK INERTION

Research in this area has been limited. There are only two aircraft that currently use halon 1301 to inert
fuel task when entering combat, the F-16 and the F-117. The Air Force is considering the use of CF3I for
this application. Should this decision be positive, then alternative technologies for fuel tank inerting will
not be an NGP task.

NGP staff have begun a project to assess current status of alternate systems that had in prior decades
shown promise for fuel tank inerting. Tasks underway include assessment of in-flight fuel tank operating
environments and identification of whom to consult in gathering information about these alternate
systems.

25


Mh

TABLE OF CONTENTS

INTRODUCTION .....

TECHINCAL PROGRESS ..

NEW FLAME SUPPRESSION CHEMISTRY.
SUPPRESSANT SCREENING TESTS .......ceseeserseeneoeeeereeneceeesseeaseneersneeneneee 9
NEW AND IMPROVED AEROSOL SUPPRESSANTS ......ssscserereeseteesereeneeees 15

IMPROVED SUPPRESSANT DELIVERY .....

VIABILITY OF NEW SUPPRESSANT TECHNOLOGIES ....

TM mo 9 @ >

IMPROVED FUEL TANK INERTION

WHAT'S LIES AHEAD? .


Figure 6. Monte Carlo simulations of humans exposed to halon 1301. The simulation
lines represent the mean + 2 standard deviations resulting from 1000 Monte Carlo
simulations. The horizontal line at 25.7 mg/L represents the lowest arterial blood
concentration measured at 5 minutes in a group of 6 dogs exposed to halon 1301 at the
cardiac sensitization LOAEL of 7.5%.

ae
3 a EXPOSURE
= CONC
‘4 8.0%
3 s mn 7.5%

3]
E wend 7.0%
9 fe 65%

2 ceeararmmnannrennneenrrennnerennmnneernneccvonnnd 65%
S 4
5 ——~| 6.0%
8

5.5%

Ze
Be
mR
FI
ey Halon 1301
5 6

rs
4 T T T T

0.0 1.0 2.0 3.0 40 5.0
MINUTES

The development of a physiologically based pharmacokinetic (PBPK) model of a human system to
describe the short-term inhalation of volatile halogenated hydrocarbons is nearing completion. This model
incorporates a breath-by-breath description of respiration and follows the inhaled suppressant to the
bloodstream. Use of the model has also been demonstrated for both retrospective examination of prior
exposures and prospective examination based on known potential exposure scenarios or on known
targeted endpoints.

= One important use of the model is the prediction of safe exposure duration for a given agent used
at a known extinguishing concentration. Figure 6 and Table 7 show the results of a Monte Carlo
simulation for halon 1301. Similar tables were prepared for CF3I, HFC-125, HFC-227ea, and
HFC-236fa. Extension of the model to other suppressants requires:

= Partition coefficients, i.e., solubility of the chemical into blood and other body tissues
Metabolic rate, the rate at which chemical is broken down by the body

LOAEL for cardiac sensitization measured in beagle dogs or other endpoint

Arterial blood concentrations measured in beagle dogs exposed at the LOAEL concentration
(without epinephrine challenge). (Data should be collected over a ten minute period, with the
five minute data point being the most critical)


Yang, J.C., Donnelly, M.K., Prive, N.C., and Grosshandler, W.L., “An Apparatus for Screening Fire
Suppression Efficiency of Dispersed Liquid Agents,” Fire Safety Journal, submitted for publication,
1999.

Grosshandler, W.L., Hamins, A., McGrattan , K.B., Charagundla, R., Presser, C., "Suppression Of A
Non-Premixed Flame Behind A Step," Proceedings of the 28th International Symposium on Combustion,
submitted for publication, 2000.

Grosshandler, W.L., Donnelly, M., Charagundla, R., and Presser, C., "Suppressant Performance in a
Baffle-stabilized Pool Fire," Proceedings of the 1999 Halon Options Technical Working Conference,
Albuquerque, 1999.

Grosshandler, W.L., Hamins, A., McGrattan, K.B., and Presser, C., "Transient Agent, Recirculating Pool
Fire (TARPF) Suppression Screen," in Beall, K, ed., Annual Conference on Fire Research: Book of
Abstract, NISTIR 6242, National Institute of Standards and Technology, Gaithersburg, MD, 1998.

Vinegar, A., Jepson, G., Cisneros, M., Rubenstein, R., and Brock, W. “Setting Safe Exposure Limits for
Halon Replacement Chemicals Using Physiologically-based Pharmacokinetic Modeling,” Inhalation
Toxicology, in preparation.

Nyden, M.R. and Skaggs, S.R., “Screening Methods for Agent Compatibility with People, Materials, and
the Environment,” NISTIR 6323, National Institute of Standards and Technology, 1999.

Orkin, V.L., Villenave, E., Huie, R.E., and Kurylo, M.J., “Atmospheric Lifetimes and Global Warming
Potentials of Hydrofluoroethers: Reactivity Toward OH, UV Spectra, and IR Absorption Cross Sections,”
J. Phys. Chem. A, in press, 1999.

Louis, F., Gonzalez, C., Huie, R.E., and Kurylo, M.J., “An ab Initio Study of the Reaction of
Halomethanes with the Hydroxy! Radical. Part 1: CH2Br,” J. Phys Chem. A, in press, 1999.

Louis, F., Gonzalez, C., Orkin, V., Huie, R.E., and Kurylo, M.J., “An ab Initio Study of the Reaction of
Halomethanes with the Hydroxyl Radical, Part 2: CH,F,, CF,FCl, CH2FBr, CH:Ch, CH.CIBr, CH3F,
CH;Cl, and CH3Br; Reactivities and Infrared Radiative Forcings,” J. Phys Chem. A, submitted for
publication, 1999.



eg Haake Reems Somer

FY1999 ANNUAL REPORT

Next Generation Fire Suppression

Technology Program
[PP-1059]

Richard G. Gann
Technical Program Manager
January 31, 2000


Research is also continuing on developing an instrument for measuring agent concentration with a 10 ms
time response, fast enough for quantification of the transient agent concentration during the suppression
of the fastest fires involving military systems. Tests of a second-generation version of the Differential
Infrared Agent Concentration Sensor (DIRRACS-2) (Figure 12) showed that the device is able 10 follow
HEFC-125 discharges with acceptable signal-to-noise ratio (improved by a factor of 20) and time response
(improved by a factor of 10), ‘The next in the development of the DIRRACS-2 will be the assembly
of two portable units to be deployed in the field.

Figure 12. | Concentration of HFC-125 During and After 250 ms Releases in the
Transient Application Recirculating Pool Fire (TARPF) Facility

1,01 T T T T

T r r
1,00 ie
if
x
0990 Fx 3
anes
ES ri
S 0900 F x ¢
, $e
2 os f* $ Concentration J
x waet
a
tae
2 osc f x 4
Z \ :
s 0.950 f 4
~11 mis air flow
0940 Ff Chopping: 2 kHz q
Higher Sampling: 128 kHz
Concentration
0.930 n 4 1 1 4 1
0.90 0.10 0.20 9.30 0.40 0.50 0.60 0.70 0.00

Time, s

There are a large number of contributing factors that must be considered when making a decision to
retrofit a fire suppression system (or not). These include both objective cost factors and subjective value
factors. Accordingly, the NGP is developing a methodology to quantify a fire suppression technology by
its total, life c cost and to enable superimposing On this a subjective value system,

The data gathering for and formation of the baseline (halon 1301) case has been completed, as has the
structuring of the cost benefit analysis process. The latter provides a framework for evaluating a range of
weapons systems, taking financial and technical variables into consideration. Figure 13 displays a
framework for qualifying benefits. Expert Choice will be the methodology for evaluating benefits.


NISTIR 6479

Next Generation Fire Suppression
Technology Program
FY 1999 Annual Report

Richard G. Gann

Building and Fire Research Laboratory

August 2000

PS

rates of TM
U.S. Department of Commerce

Norman Y. Mineta, Secretary

Technology Administration
Dr. Cheryl L. Shavers, Under Secretary of Commerce for Technology

National Institute of Standards and Technology
Raymond G. Kammer, Director


Ill. WHAT LIES AHEAD?

The planned support for the NGP has been reset to a 9-year, $20 M effort, of which two thirds has been
committed through FY2000. This change necessitates a new NGP goal, which is:

“Develop and demonstrate, by 2005, technology for economically feasible, environmentally
acceptable and user-safe processes, techniques, and fluids that meet the operational requirements
currently satisfied by halon 1301 systems in aircraft.”

The focus on aircraft stems from the reliance of the aircraft survivability engineering teams from all three
Military Services on NGP research to meet their fire suppression needs. Thus, the updated program:

= addresses the predominant fires occurring in aircraft dry bays and engine nacelles;

= — does not include fuel tank inerting since the Air Force is in the final stages of evaluating CF3I for
this use;

= focuses resources on identifying and examining promising chemicals and precepts for their
effective storage, dispersion and distribution; and

* pertains to both current and planned platforms.

Over the next two years, the NGP will deliver the following, building on NGP research to date:

© analysis of the world of useful chemicals, identification of the best places to look for alternative
suppressants, and a first set of “best looks;”

* a suite of screening tests and guidance for their use;

© amethod for determining and comparing the total life-cycle costs of new fire suppression
technologies; and

« definition of what diagnostic information is needed to characterize the outcome (beyond flames
out or not) of real-scale tests so that program managers have confidence in the program
“products” they are considering.

From that point forward, the NGP will produce:

= specific chemicals that meet the requirements in the goal statement,

= verified precepts for improved suppressant delivery, and

= validated modeling to guide the selection of optimal dispensing conditions, nozzle locations, etc.
for the variety of nacelle and dry bay configurations, but

= limited toxicity testing and full-scale experiments.

Throughout the research, the NGP Technical Coordinating Committee will continue to maintain
close contact with the aircraft survivability engineers and platform managers in the Military
Departments. As appropriate research questions arise, they will become candidates for NGP
investigation.

26


Figure 3. Effect of Fiuid and Fiuid Flow on Flame Extinction Effectiveness

240

za04

200 8 @ g
— 180 i] 8
o a 9
— 160 a
2 °° §
B 140 $ v

120 v |
S

100 | ——____--
$ @ No agent
z 80 © Water

y¥ 60% K-acetate
M 601} 9 30%Nal
© Skim milk
40 Q 30% K-lactate
20 | |_% 80% Kiactate |
0 -
0.0 0.2 04 06 0.8 1.0
Flow rate (mi/min)

The screening tool for the effectiveness of suppressants that are impulsively discharged is well on its way
to completion. The following analyses of the Transient Application, Recirculating Pool Fire (TARPF)
agent effectiveness screen (Figure 4) have been completed:

= The effectiveness of CF;Br in suppressing an aerodynamically stabilized propane pool fire
was compared to that of N. The resulting suppression concentrations scale with the
corresponding cup burner values.

= Direct numerical simulation of the flow over various obstacles in the TARPF has been
conducted to help interpret the experimental results and extend them to other conditions.
Figure 5 shows three snapshots of a simulation of a propane flame stabilized behind a 25 mm
high baffle. The first image shows the flame before injection of the agent (nitrogen). The
second image shows how the flame is distorted in a vortex as the speed upstream roughly
doubles due to the agent injection. The third image shows the flame restabilizing after the
agent has been injected. In this case, the flame is not extinguished.

= Discussions with suppliers of solid propellant gas generators (SPGG) have lead to the design
of an SPGG agent injection system that should accommodate safely 1 to 100 g of propellant.
Preliminary tests of SPGGs have been successful.


Table 3. Time for Safe Human Exposure at Stated Concentrations for Halon 1301

Halon 1301 concentration Time in Minutes Based on LOAEL in Dogs of 7.5%
%vNV PPM
5.5 55,000 5.00 “|
= 6.0 60,000 500 sd
65 65,000 1.33 _
7.0 70,000 0.59 |
75 75,000 ~ 0.42 7
8.0 80,000 ~~ 0.35 ~

Three publications were found that presented data on releases of Halon 1211 and/or Halon 1301 in
aircraft. Model calculations of inhalation hazard have been performed using these data.

The NGP research to develop a computational screening tool for a suppressant’s atmospheric lifetime and
infrared absorption is continuing.

= The calculated rate constants for the reaction of OH with halomethanes are in good
agreement with their experimental counterparts, establishing the viability of ab initio
calculations as the basis of a screening tool.

= Calculations for the reactions of OH with several fluoroethanes and the ethers derived from
them have reproduced the experimental trends, with predictions in absolute reactivity within a
factor of three. Calculations are being extended to ethers with several carbons and containing
fluorine along with one or more bromine atoms.

Suppressant Screening Test Publications

Yang, J.C., Donnelly, M.K., Prive, N., and Grosshandler, W.L., “An Apparatus for Evaluating Liquid Fire
Suppressants,” Proceedings of the 1998 Halon Options Technical Working Conference, Albuquerque,
1998.

Yang, J.C., Donnelly, M.K., Prive, N.C., and Grosshandler, W.L., “Fire Suppression Efficiency Screening
using a Counterflow Cylindrical Burner,” Proceedings of the 5" ASME/JSME Joint Thermal Engineering
Conference, San Diego, 1999.

Yang, J.C., Prive, N.C., Donnelly, M.K., Grosshandler, W.L., “Recent Results from the Dispersed Liquid
Agent Fire Suppression Screen,” Proceedings of the 1999 Halon Options Technical Working Conference,
Albuquerque, 1999

Yang, J.C., Donnelly, M-K., Prive, N.C., and Grosshandler, W.L., “On the Design of an Apparatus for
Screening Liquid Fire Suppressants, ” Proceedings of the 8" International Fire Science and Engineering
Conference, Edinburgh, Scotland, 1999

Yang, J.C., Donnelly, M.K., Prive, N.C., and Grosshandler, W.L., “Dispersed Liquid Agent Fire
Suppression Screen Apparatus,” NISTIR 6319, National Institute of Standards and Technology, 1999.