ON THE SUITABILITY OF CF,BR AS A BENCHMARK 

FOR REPLACEMENT FIRE SLJPPRESSANTS 

Bradley A. Williams and James W. Fleming 

Naval Research Laboratory 

ABSTRACT 

We investigate the rationale for the use of CF,Br as a reference standard for alternative fire suppresants. Stating 

efficiencies of alternative agents on a relative basis to that of CF,Br is well founded from an engineering standpoint, 

but less so from a mechanistic standpoint. The behavior of CF,Br is, in several significant respects, atypical of fire 

suppressants, which act by catalytic scavenging of flame radicals. In particular, saturation effects, dependence of 

inhibition efficiency on flame temperature, and changes in flame structure are significantly different for CF,Br than 

for other catalytic substances including iron and alkali metals. For this reason, the use of CF,Br as an archetype for 

catalytic suppressants must be qualified to account for these differences. 

INTRODUCTION 

The SERPD Next-Generation Fire Suppression Technology Program Element 2A, “Mechanisms of UltraHigh Efficiency Chemical Suppressants” seeks to understand how key chemical reactions or processes of 

combustion are affected by “superagent” suppressants and how these effects differ from those of Halon 

1301 (CF,Br). In this context, a “superagent” is defined as a substance whose fire suppression effectiveness is equal to or greater than CF,Br. 

CF,Br is often used as a benchmark for alternative fire suppressants, based on two primary motivations: 

(1) since much of the research and development in this area is focused on finding environmentally 

acceptable alternatives to Halon 1301 to provide equivalent protection against a specified fire threat, the 

effectiveness ofthe substitute agent relative to 1301 is an important parameter for system engineering; 

(2) inhibition properties and chemical kinetics of CF,Br relevant to fire suppression have been extensively studied for many years. The number of experimental and computational studies conducted on CF,Br 

has greatly increased since its manufacture was prohibited in developed countries at the end of 1993. 

These considerations raise the question of how applicable the knowledge gained in recent years on CF,Br 

will be in identi6ing alternative suppressants. The questions raised include the following: Is CF,Br 

‘‘typical” of efficient fire suppressants in general? In other words, will all promising replacements for 

CF,Br have properties that are “similar” in some respect? To what extent is commonality of properties 

with CF,Br a useful guide in the search for alternatives? To this end, we have performed modeling 

studies of premixed flames containing substances representative of different classes of inhibitors, including inert gases, fluorocarbons, and catalytic scavengers of flame radicals. We find that the behavior of 

CF,Br differs in several significant respects from that of other catalytic agents. 

TYPES OF SLJPPRESSANTS 

Suppressants may be grouped into various categories, based on the means by which they suppress combustion. Physical suppressants (such as nitrogen, argon, CF,, and water) do not participate in flame 

chemistry to a significant extent, and they inhibit combustion by adding heat capacity and diluting the 

reactants. Chemical suppressants also participate in the flame chemistry and may be subdivided into two 

groups: catalytic suppressants (including bromine, iodine, and various metallic elements) reduce concentrations of flame radicals through a regenerative cycle in which one molecule of suppressant recombines 

several radicals. Noncatalytic chemical suppressants (e.g., fluorocarbons) reduce the concentrations of 

flame radicals by scavenging, but do not have a catalytic cycle and are generally less effective. CF,Br is 

primarily a catalytic suppressant [I], due to an H + H recombination cycle involving the bromine atom, 

although the fluorine atoms add some noncatalytic suppression as well. 

144 Halon Options Technical Working Conference 24-26 April 2001 
Water mist having a drop size of less than 50 pm is comparable to or more effective than CF,Br on a 

mass basis at both reducing burning velocity of premixed flames and extinction strain rates of nonpremixed flames. This is a consequence ofthe high heat capacity and enthalpy of vaporization per unit mass 

of water. With this one exception, all other superagents identified are believed to be catalytic scavengers. 

Thus, the combustion chemistry of superagents is essentially that of catalytic scavenging cycles. 

The effectiveness of an inhibitor at reducing burning velocity in a fiiel/oxidizer mixture may be placed on 

a quantitative basis in terms of an “inhibition parameter” @ first proposed by Rosser et al. [2] and modified by Noto et al. [3]: 

Q, = MUdW (X02N) (1) 

where U, and U, are the burning velocities of the uninhibited and inhibited flames, respectively, and X,, 

and X, are the reactant mole fractions of oxygen and inhibitor. In Noto et al. [3], the burning velocity of a 

given fuel/air mixture was shown to exhibit an exponential dependence on the inhibitor concentration. 

This exponential dependence, by which the inhibition parameter was defined, was shown to hold for the 

inert agents N, and CF,, several hydrofluorocarbons, and CF,Br. 

Catalytic scavengers necessarily manifest saturation effects, because concentrations of flame radicals, 

which typically exist in superequilibrium, cannot be reduced below the thermal equilibrium values at the 

local flame temperature. The existence of a similarity relationship describing inhibition by CF,Br as well 

as noncatalytic agents is thus somewhat unexpected. Saso et ai. [4] modeled the combined effect of mixtures of CF,Br and inert inhibitors and found synergism, meaning that the two agents in combination had 

a greater inhibiting effect than the additive effect of the agents in isolation. The synergism was attributed 

to a temperature effect on the inhibition effectiveness of CF,Br, rather than a saturation phenomenon. 

Over a range of adiabatic flame temperatures, Saso et al. found CF,Br to have virtually identical inhibition parameters at concentrations of 0.5% and 1% in methandoxygenhert mixtures, indicating the absence of significant saturation effects. 

MODELING RESULTS: BURNING VELOCITIES AND SPECIES PROFILES IN 

INHIBITED PREMIXED FLAMES 

In the calculations described below, the PREMIX code [5] was used to compute burning velocities and 

flame structures of atmospheric pressure flames. An 85 cm domain was used in the calculations. Comparison with thermal equilibrium calculations showed that at the final grid point, temperatures were generally within 5K and radical concentrations within a few percent of their equilibrium values. Flames were 

stoichiometric, atmospheric pressure methane/oxygen, with various inhibitors added as indicated below. 

For the hydrocarbon chemistry, GRIMech 2.1 1 was used as the kinetic mechanism. Fluorocarbon chemistry was based on mechanism refinement previously performed in our laboratory [6,7]. Bromine chemistry used for CF,Br was that developed by Noto et al. [3]. The kinetic mechanism for sodium was based 

on that of Zamansky et al. [SI, while that for Fe(CO), was described by Rumminger and Linteris [9]. 

Changes in burning velocity, adiabatic flame temperature, radical superequilibrium, as well as the inhibition parameter @ as defined by Noto et al., are plotted as a function of (NaOH), concentration (Figure 1) 

and CF,Br concentration (Figure 2). A constant value of Q, indicates that the exponential dependence of 

burning velocity on inhibitor concentration is well observed. Since sodium is known to be a catalytic 

agent with suppression efficiency some 10 times that of bromine [IO], a comparison of changes in flame 

structure between the two agents tests which effects of CF,Br are generic to catalytic inhibitors in general. 

Halon Options ‘Technical Working Conference 24-26 April 2001 145 
~"""""""'""""'" ,, 2250 

B + OH 

-0 

4 

5' 

e 

E 

2100 w 

E 

m 

U 

2050 3 

c 

LL 

v 2200 g! 

3 

c 

2150 

? 

- 

._ 

2000 

0.0 0.1 0.2 0.3 0.4 0.5 

(NaOH), Concentration (Mole %) 

Figure 1. Flame speed, final flame temperature, inhibition parameter (defined in Noto et a1.[3]), 

and superequilibrium concentrations of flame radicals computed for atmospheric pressure 

stoichiometric methane/air mixtures inhibited by sodium hydroxide. To simulate the evaporation process, NaOH was added to the reactants as a dimer and required to undergo an 

endothermic decomposition process before inhibition chemistry could occur. 

146 Halon Options Technical Working Conference 24-26 April 2001 
45 I 

2250 Q 1- F 

CZ 

l5 iZi50 

e 2o i 

01 ' 1 

CF,Br % Mole Fraction 

0.0 0.2 0.4 0.6 0.8 1.0 

Figure 2. Flame speed, final flame temperature, inhibition parameter (defined in Noto et ai. [3]), 

and superequilibrium concentrations of flame radicals computed for atmospheric 

pressure stoichiometric methane/air mixtures inhibited by CF,Br. 

Halon Options Technical Working Conference 24-26 April 2001 147 
In the flame inhibited by NaOH, the radical superequilibrium is drastically reduced as the inhibitor is 

added, eventually reaching unity for all primary flame radicals for a sufficiently large inhibitor concentration (meaning that the radical concentrations never overshoot their equilibrium values). For inert 

agents, by contrast, the radical superequilibrium is increased as the flame is inhibited, even though the 

absolute concentrations decrease, because the predominant effect is the lowering of the final flame temperature. Notably, the inhibition parameter is not constant as a function of inhibitor concentration, but 

varies by more than a factor of three over the range of sodium concentrations considered here. The 

similarity relationship identified by Noto et al. [3] does not hold for sodium. 

For inhibition by CF,Br, the degree of radical superequilibrium is reduced with increasing agent concentration, though not as dramatically as for sodium. By this measure, CF,Br shows behavior typical of catalytic agents. The inhibition parameter, unlike for sodium, is nearly constant as a function of inhibitor 

concentration (except for the initial data point at an inhibitor concentration of 0.1%, which has a high 

uncertainty due to the small differences in flame speeds). This nearly constant inhibition parameter was 

found by Noto et al., although the modifications to the fluorocarbon kinetics yield somewhat higher 

inhibition parameters, which is in excellent agreement with the experimental value of 14.0 [3]. 

This raises the question of why the exponential relationship between burning velocity and inhibitor concentration is observed for CF,Br but not for other chemical inhibitors. The present results support the 

conclusion of Saso et al. [4] that saturation is a minor effect in the suppression effectiveness of CF,Br/ 

inert mixtures. One point is that for inhibition by CF,Br, the H atom superequilibrium is only reduced by 

some 30% for a 50% reduction in flame speed, whereas for NaOH the H atom superequilibrium is reduced by nearly 80% for the same reduction in flame speed. Thus saturation is not as pronounced for CF,Br 

in part because the peak radical concentrations are still far out of equilibrium even when the burning 

velocity has been substantially reduced. 

The other important point for CF,Br is that the bromine catalytic cycle involves the sequence of reactions 

[I 11 

Bp + Bp+ M => Bp2 + M 

H + Bp2 => HBp + Bp (W 

as an important pathway in regeneration of HBr, since the direct reaction 

H + Br + M => HBr+ M (W 

has rather slow kinetics. This has two consequences: the increasing importance of Reaction (R1) (since 

it has a second-order dependence on the inhibitor concentration) compensates for the saturation effect as 

the inhibitor concentration is increased. Also, a much higher concentration of bromine is required for this 

reaction to be significant. Compared to sodium and iron, whose suppression kinetics are not thought to 

depend significantly on any second-order pathways, bromine is a relatively inefficient scavenger. 

COMBINED EFFECTS OF MIXTURES OF AGENTS 

Since various studies have described the synergism of combinations of CF,Br and inert agents, it is worth 

exploring the extent to which the observations carry over to other combinations of agents. Furthermore, 

is there any advantage to combining different chemical scavengers that act independently (Le., recombine 

different flame radicals)? 

To this end, inhibition by iron was modeled in combination with both nitrogen and sodium. For this 

modeling, iron was considered to participate in a three-step mechanism involving only an 0 + 0 recombination. This pathway was identified by Rumminger and Linteris [9]; however, it is usually secondary 

in importance to an H + H recombination pathway. Using this simplified model, sodium and iron do not 

148 Halon Options Technical Working Conference 24-26 April 2001 
tion cycle. This model is not intended as an accurate description of iron’s combustion chemistry but to 

investigate the combined effect of scavengers that operate through different pathways. 

In Table 1, the effects of iron and sodium both separately and in combination, are given. The effectiveness of the inhibitors when combined is described by their “differential inhibition parameters.” The differential inhibition parameter of substance A is determined by comparing the burning velocity of a mixture inhibited by A and B in combination to that of the mixture inhibited by B alone. As seen in Table 1, 

the differential inhibition parameters of iron and sodium in combination are much less than those of the 

two dements taken separately. Even though the two elements do not directly compete for the same flame 

radicals, the rapid exchange between H, 0, and OH means that the two suppressants reduce each other’s 

effectiveness. Furthermore, comparison between different scavenging cycles (for instance, the 0 + 0 

scavenging cycle of iron and the H + OH scavenging cycle of sodium [Table 21) shows that, for a coinparable reduction in flame speed, the peak H atom and 0 atom concentrations are esscntially independent 

of which scavenging cycle is occurring. 

TABLE 1. INHIBITION BY TWO CATALYTIC CHEMICAL AGENTS IN COMBINATION. 

Flame: Stoichiometric methaneiair, atmospheric pressure I E 

Agent Flame Specd (cds) Inhibition Parameter Q IEq. (I)] 

None 39.6 .... 

0.2% (NaOH)> 17.0 40.18 

0.1 % Fe 0, + 0.2%(NaOH), 14.9 24.9(Fe), 32.4(Na)h 

0.1 % Fe0, 29.5 56.1 

a per sodium alom 

differential effect of specified inhibitor relative to other inhibitor alone 

TABLE 2. COMPARISON OF RADICAL CONCENTRATIONS FOR FLAMES INHIBITED 

BY DIFFERENT SCAVENGNG CYCLES. ~ 

Superequilibrium Factors 

Inhibitor Major Scavenging Cycle Burning Velocity H 0 OH 

500 ppm Fe02 0+0 33.3 cds 13.1 9.6 2.2 

200 ppm (NaOH)2 1% + OH 33.0 cids 12.6 9.8 2.2 

Iron, in combination with nitrogen, does exhibit synergy. Figure 3 shows the burning velocity, flame 

temperature, and differential inhibition parameter of iron (using the 0 + 0 recombination mechanism) as 

a function of nitrogen addition to a methaneiair mixture. The differential inhibition parameter of 

500 ppm FeO, increases by some 23% as the flame temperature is lowered by nitrogen addition from 

2230 K to 2010 K. These results may be compared to those of Saso et al. [4], who found that the inhibition parameter of CF,Br increased by some 45% (at both 0.5% and I .O% mole fractions of agent) over 

the same range of final flaine temperatures. 

Of the three reactions making up the 0 + 0 catalytic cycle of iron: 

QE+ O7 + M =>QE 0, + M 

oE02+0=>~&O+ o2 

FeO+O => Fe + O2 

Halon Options Technical Working Conference 24-26 Aprll 2001 149 
....o... N, + 500 ppm FeO, 

0 2 4 6 8 10 12 14 16 

% N, added to Air 

Figure 3. Flame speed, differential inhibition parameter (see text), and superequilibrium concentrations 

of atomic hydrogen computed for atmospheric pressure stoichiometric methane/air mixtures 

inhibited by nitrogen and FeO, in combination. 

150 Halon Options Technlcal Working Conference 24-26 April 2001 
(RS) and (R6) are assumed to have rate coefficients independent of temperature. (R4) has a slight 

increase in rate with increasing temperature, but the product of the rate coefficient and the number density of third body colliders varies by less than 10% over the temperature range from 1400 K and 2500 K. 

Thus the kinetics of this scavenging cycle have no explicit dependence on temperature and changes in 

efficiency are due to variations in the radical pool with the addition of the inert agent. While the findings 

of synergism agree qualitatively between CF,Br/inert and Felinert mixtures, the final flame temperature 

influences the inhibition parameter of CF,Br twice as much as that of the 0 + 0 recombination cycle of 

iron. Therefore while synergism in catalyticlinert mixtures may be a general characteristic, its magnitude 

can vary considerably depending on the kinetics of the catalytic component. 

CORRELATION OF BURNING VELOCITIES, FINAL FLAME TEMPERATURE, AND 

RADICAL CONCENTRATIONS 

According to laminar flame theory, the burning velocity of a premixed flame is proportional to the square 

root of the overall reaction rate. In modeling the burning velocity of a large number of inhibited flames, 

the burning velocity correlates in almost all cases with the product of the peak H atom mole fraction and 

global activation energy: 

S,' = AX,exp(-EJkT,). (2) 

where S, is the laminar burning velocity, X, the peak mole fraction of atomic hydrogen, and T, the final 

flame temperature. The fitted parameters A and E,, obtained by considering the flame inhibited by nitrogen, are A=7940 cmls, E,=24.7 kcallmol. The same empirical correlation holds for inhibition by other 

inert gases, by iron and sodium, by nitrogen and iron in combination (Figure 3). and by artificially 

increasing the H + OH recombination rate. For the catalytic agents, which do not cause appreciable 

changes in the final flame temperature, the flame speed correlates with the peak mole fraction of atomic 

hydrogen, but not with that of atomic oxygen or OH radicals. 

The observation that atomic hydrogen controls the burning velocity is not unexpected, due to the high 

diffusivity and reactivity of this species. Nevertheless, some noteworthy conclusions can be made: 

(I) this correlation can quantitatively describe the effect of a wide variety of inhibitors, both individually 

and in combination; and (2) catalytic agents reduce the flame speed by reducing the atomic hydrogen 

concentration, whether or not the scavenging cycle directly involves H atom recombination. The partial 

equilibrium between H, 0, and OH is not disrupted in most inhibited flames. 

Table 3 compares the burning velocities estimated using Eq. (2) to the calculated values for a variety of 

flame inhibitors. In almost all cases, the reduction in burning velocity relative to the uninhibited flame, 

predicted by Eq. (2) is within 10% ofthe actual value using the full kinetics. This relationship between 

burning velocity, final flame temperature, and peak H atom mole fraction holds for many agents (catalytic 

and inert). At the same time, there are a few notable exceptions: the fluorocarbons CHF, and C,HF, are 

much better inhibitors (by nearly a factor oftwo) than Eq. (2) would predict, and so are CF,Br and HBr. 

Flame structure modeling indicates that the breakdown of this relationship involving the peak H atom 

concentration is a consequence of these agents reducing the H atom concentration mostly in the early part 

ofthe flame, as demonstrated below. 

CHANGES IN FLAME STRUCTURE DUE TO DIFFERENT AGENTS 

The explanation for why the correlation between flame speed, H atom concentration, and temperature 

does not hold for either fluorocarbons or bromine containing compounds can be gained from examination 

of the effects of these compounds on flame structure. In Figure 4 the mole fraction of atomic hydrogen is 

plotted against the local temperature for flames inhibited by the inert agent N,, the catalytic agent 

Fe(CO),, the noncatalytic fluorocarbon CF,CHFCF,, and CF,Br. All the inhibited flames have burning 

Halon Options Tcchnical Working Conference 24-26 April 2001 15 1 
TABLE 3. COMPARISON OF CALCULATED FLAME SPEEDS TO VALUES FROM EQ. (2) 

S,. = A(X,,,,*exp(-EJkTad))'" A=7940 cm/s E,=24.7 kcal/mol 

Flame Condition Tadmbet#c X,max spremix seqn ASpm,JAScv' 

CH,/air (uninhibited) 2234 6.64e-3 39.8 39.8 _____ +3.85%N2 2187 5.96e-3 35.5 35.6 1.01 

+9.09%N2 2121 5.12e-3 30.2 30.2 1 .oo 

+16.67%N2 2015 3.94e-3 22.6 22.7 1.01 

+I 3 .04%N2 2065 4.45e-3 26.1 26.0 0.99 

+8.26%CF4 (inert) 1968 3.50e-3 18.4 19.9 1.07 

+500ppmFe02 (O+O cycle) 2220 2.52e-3 33.3 32.7 0.92 

+I.O%CF,Br 2203 3.42e-3 18.9 27.6 1.71 

+O.S%HBr (H+H cycle) 222 1 5.36e-3 30.3 35.2 2.08 

+0.5%HBr (H+OH cycle) 2220 5.47e-3 33.3 35.5 1.52 

+5.2%CHF, (phi=l.l) 2036 4.04e-3 16.3 23.7 1.46 

+0.05% (NaOH), 2219 2.97e-3 28.0 26.2 0.87 

+0.40%(NaOH), 2177 3.31e-4 9.4 8.3 0.97 

Increase H + OH + M Rate: 

+3%C,HF, (phi=O.9) 2161 3.86e-3 17.8 27.7 1.81 

XI0 2234 4.04e-3 32.0 31.1 0.90 

XI00 2234 1.35e-3 19.8 18.0 0.92 

XlOOO 2234 3.64e-4 11.2 9.3 0.94 

a (39.8-S,,.i,)/(39.8-S.,) 

velocities approximately 50% ofthat of the uninhibited flame, whose structure is also plotted for comparison. For all the flames considered here, temperature overshoot does not occur; the temperature monotonically increases with position passing from reactants to products. 

The way in which the relationship between H atom mole fraction and local temperature is altered is characteristic of each type of agent. Other agents modeled (not shown on the plot for clarity) produce H atom 

profiles that closely resemble each other within the same class: CF, and N,, NaOH and Fe(CO),, and 

CH,FCF, and CF,CHFCF,. The physical agents reduce the final flame temperature, but the H atom mole 

fraction at a given isotherm (above approximately 1300K) is changed very little from its value in the 

uninhibited flame. Both iron and sodium reduce the H atom mole fraction by a relatively constant factor 

throughout the reaction zone, in other words the inhibition occurs throughout the flame. The fluorocarbons, on the other hand, reduce the H atom mole fraction early in the flame (in the region below about 

1200 K) but have relatively little impact on the peak concentration. The same situation occurs for CF,Br; 

in this respect CF,Br bears more resemblance to nonbrominated fluorocarbons than it does to other catalytic agents such as iron and sodium. It is noteworthy that all the flames inhibited by chemically active 

suppressants show nearly identical H atom concentrations at 1700 K. 

The depletion of radical species early in the flame has a marked influence on the flame speed. It is for 

this reason that fluorocarbons and bromine compounds are better inhibitors than the changes in temperature and peak H atom concentrations would predict. This observation implies that agents that deplete 

radicals in high temperature regions but not early in the flame are likely to be less effective inhibitors 

152 Halon Options Technical Working Conference 24-26 April 2001 
1 e-2 

1 e-3 

r= 

._ 

0 

c 

le-4 

I; 

a, 

0 

- 

le-5 

E 

2 t uninhibited (39.4 cmls) 

I le-6 - 1% CF3Br (18 9 cmls) 

2.9% CF3CHFCF3 (16 3 cmls) 

+ 200 ppm Fe(CO), (18.4 cmls) 

22.7% N, (18.3 cm/s) 

0 

1 e-? 

500 1000 1500 2000 

Temperature (K) 

Figure 4. Mole fraction of atomic hydrogen as a function of local flame temperature for an uninhibited 

atmospheric pressure methane/air flame, and the same flame inhibited by various classes of 

suppression agents. 

than would otherwise be expected. This may be the case, for instance, for condensed-phase agents which 

must undergo a vaporization process before inhibition chemistry can begin. 

CONCLUSIONS 

In several respects, CF,Br is not representative of catalytic fire suppressants io general. Several features 

of its kinetics, including the strong temperature dependence of the catalytic suppression cycle, the apparent absence of significant saturation effects for a burning velocity reduction of more than 50%, and the 

preferential reduction of atomic hydrogen concentrations in low temperature regions of the flame, are not 

shared by other catalytic suppressants. At the same time, catalytic suppressants all appear to reduce buming velocity by reducing concentrations of atomic hydrogen, either directly or indirectly. 

ACKNOWLEDGMENTS 

We thank V. Babushok and G. Linteris for helpfid discussions and for providing kinetic mechanisms used 

here. This work is part of the Department of Defense Next-Generation Fire Suppressant Technology 

Program, funded by the DoD Strategic Environmental Research and Development Program. 

REFERENCES 

1. Sheinson, R.S., Penner-Hahn, J.E., and Indritz, D., “The Physical and Chemical Action of Fire 

Suppressants,” Fire Safely J. 15:437-450, 1989. 

2. Rosser, W.A., Wise, H., and Miller, J., “Mechanism of Combustion Inhibition by Compounds 

Containing Halogen,” Proc. Combust. Inst. 7: 175-1 82, 1958. 

Halon Options Technical Working Conference 24-26 April 2001 I53 
3. Noto, T., Babushok, V., Hamins, A., and Tsang, W., “Inhibition Effectiveness of Halogenated Compounds,” Combusfion andFlame 112:147-160, 1998. 

4. Saso, Y., Ogawa, Y., Saito, N., and Wang, H., “Binary CF,Br- and CHF,-Inert Flame Suppressants: 

Effect of Temperature on the Flame Inhibition Effectiveness of CF,Br and CHF,,” Combust. Flame 

11 8:489-499, 1999. 

5. Kee, R.J., Grcar, J.F., Smooke, M.D., and Miller, J.A., PREMIX A Forfran Program for Modeling 

Laminar One-Dimensional Premixed Flames, Sandia Report SAND85-8240, Sandia National Laboratories, 1985. 

6. L‘EspCrance, D., Williams, B.A., and Fleming, J.W., “Intermediate Species Profiles in Low Pressure 

Premixed Flames Inhibited by Fluoromethanes,” Combustion and F/ame 117:709-73 1, 1999. 

7. Williams, B.A., L’EspCrance, D.M., and Fleming, J.W., “Intermediate Species Profiles in Low 

Pressure Methane/Oxygen Flames Inhibited by 2-H Heptafluoropropane: Comparison of Experimental Data with Kinetic Modeling,” Combustion and Flame 120:160-172, 2000. 

8. Zamansky, V.M., Lissianski, V.V., Maly, P.M., Ho, L., Rusli, D., and Gardiner, Jr., W.C., “Reactions 

of Sodium Species in the Promoted SNCR Process,” Combustion and Flame 117:821-831, 1999. 

9. Rumminger, M.D., and Linteris, G.T., “Inhibition of Premixed Carbon Monoxide-Hydrogen-OxygenNitrogen Flames by Iron Pentacarbonyl,” Combustion andFlame 120:45 1-464,2000. 

10. Babushok, V., and Tsang, W., “Inhibitor Rankings for Alkane Combustion,” Combustion and FIame 

123: 488-506,2000. 

1 1. Westbrook, C.K., “Inhibition of Laminar Methane-Air and Methanol-Air Flames by Hydrogen 

Bromide,” Combust. Sci. Technol. 23:191-202, 1980. 

154 Halon Options Technical Working Conference 24-26 April 2001