NIST Technical Note 1466 

FY2004 Annual Report

Next Generation Fire Suppression 

Technology Program (NGP) 

Richard G. Gann

NIST Technical Note 1466 

FY2004 Annual Report

Next Generation Fire Suppression 

Technology Program (NGP) 

Richard G. Gann 

Building and Fire Research Laboratory

January 2005 

U.S. Department of Commerce 

Donald L. Evans, Secretary 

Technology Administration 

Phillip J. Bond, Under Secretary for Technology

National Institute of Standards and Technology 

Hratch Semerjian, Acting Director
Certain commercial entities, equipment, or materials may be identified in this 

document in order to describe an experimental procedure or concept 

adequately. Such identification is not intended to imply recommendation or 

endorsement by the National Institute of Standards and Technology, nor is it 

intended to imply that the entities, materials, or equipment are necessarily the 

best available for the purpose. 

National Institute of Standards and Technology Technical Note 1466 

Natl. Inst. Stand. Technical Note 1466, 44 pages (January 2005) 

CODEN: NSPUE2

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FY2004 ANNUAL REPORT 

Next Generation Fire Suppression 

Technology Program (NGP) 

[PP-1059] 

January 2005

Richard G. Gann, Ph.D. 

Technical Program Manager 
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ABSTRACT 

The Department of Defense’s Next Generation Fire Suppression Technology Program (NGP) has 

completed its eighth year of research with a goal to develop and demonstrate 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. Research on new flame suppression chemistry and improved suppressant delivery has 

produced substantive results. The report includes a description of the research the NGP will 

perform en route to completing its work in FY2006. 

The NGP is supported by the DoD Strategic Environmental Research and Development Program 

(SERDP). 

Keywords: fire research, fire suppression, halon, aircraft 
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TABLE OF CONTENTS 

I. INTRODUCTION...................................................................................................... 1 

II. TECHNICAL PROGRESS ....................................................................................... 2 

A. Knowledge of the Flame Suppression Process .................................................... 2 

B. Minimum Release Temperature ........................................................................... 4 

C. CF3I Properties ..................................................................................................... 7 

D. New Candidate Suppressants .............................................................................. 8 

E. Limits to Effectiveness of Metal-containing Compounds .................................... 11 

F. Fire Suppressant Dynamics in Cluttered Engine Nacelles ................................. 13 

G. Verification of NGP-Developed Fire Suppression Principles .............................. 19 

H. Recent Publications............................................................................................ 20 

III. INDEPENDENT PROGRAM ASSESSMENT..................................................... 22 

IV. WHAT LIES AHEAD?......................................................................................... 23 

APPENDIX A. NGP PROJECTS.................................................................................. 25 

APPENDIX B. REPORT OF THE INDEPENDENT REVIEW PANEL .......................... 29 

APPENDIX C. TIME LINE FOR COMPLETION OF THE NGP.................................... 35 
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I. INTRODUCTION 

Initiated in 1997, the Department of Defense’s Next Generation Fire Suppression Technology 

Program (NGP) has completed its eighth year of research with considerable accomplishment. 

Supported by the DoD Strategic Environmental Research and Development Program (SERDP), 

the NGP goal is to “Develop and demonstrate 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.” 

Fires and explosions continue to be among the greatest threats to the safety of personnel and the 

survivability of military aircraft both in peacetime and during combat operations. Production of 

halon 1301 (CF3Br), long the fire suppressant of choice, ceased as of January 1, 1994 due to its 

high ozone depleting potential (ODP). By 1997 the DoD had identified the best available 

replacement for halon 1301 in aircraft, HFC-125 (C2H5F)1

, but it requires two to three times the 

mass and storage volume and contributes to global warming. The new Program was to identify 

fire suppression technologies with reduced compromises. 

While research to identify replacement suppressants for engine nacelle and dry bay fires has 

declined considerably over the past five years, the demand for new approaches is unabated. New 

aircraft are in various stages of design. No commercial or military aircraft have yet had their 

halon 1301 systems replaced, while new systems are being installed in the cargo bays of 

commercial jetliners. The international community is questioning the necessity of maintaining 

the large halon 1301 reserves and even considering the requirement of a total phaseout. 

The demands on the new technologies remain daunting. The requirements for environmental 

protection, fire suppression efficiency, materials compatibility, and personnel safety are severe 

constraints. 

The presentation of technical progress and new products and the genesis of ideas have been 

abetted by the Halon Options Technical Working Conferences, founded in 1991. In 2002, the 

NGP assumed responsibility for these workshops. The cumulative papers have been indexed and 

are available on CD and at www.bfrl.nist.gov/866/HOTWC. 

The systematic NGP search for new suppressant chemicals and technologies for assured, 

efficient delivery is continuing to produce new results. During the past year, an Independent 

Review Panel (IRP) was "Impressed by the thoughtful way its recommendations have been 

addressed and by the tightened focus of the program" and "confident that valuable design 

products will be delivered by this program." 

As the NGP approaches its conclusion, it is clear that the participants have generated 

unparalleled contributions to the published literature in the field, all of which can be obtained via 

the NGP web site: www.bfrl.nist.gov/866/NGP. The following pages highlight the new 

knowledge gained from the NGP research and the progress made towards the NGP Goal. Recent 

publications are listed at the end of the Technical Progress section. A concluding section 

summarizes the concluding steps for the Program. Three appendices list the NGP projects to 

date and present both the latest IRP report and the timetable for the Program completion. 

 

1 Technology Development Plan for Alternatives to Ozone-depleting Substances for Weapons Systems Use; Final 

Report (TDP), Office of the Deputy Undersecretary of Defense (Science and Technology)/Weapons Systems, 1998. 

1 
II. TECHNICAL PROGRESS 

A. Knowledge of the Flame Suppression Process 

The NGP search for alternative suppressant technologies has included those for both volatile 

fluids and compounds whose vapor pressures were sufficiently low that they had to be dispensed 

as powders or aerosols. Research on the latter category has been completed. New technology 

for the dispersion of such compounds in solid propellant fire extinguishers and powder panels 

has been passed to the testing and evaluation community. Their preliminary efforts have been 

encouraging.

Through this year, NGP research has evolved the following structure for describing the potential 

for an agent to emerge from its storage bottle, flow through distribution plumbing, be dispersed 

into the engine nacelle or dry bay, transport around obstructions to reach the site of the fire, and 

volatilize sufficiently to overwhelm the flames. More complete exposition of some of these 

components is the subject of remaining NGP research. 

• If the agent is above its freezing point and if the pressure in the storage bottle is 

maintained as the agent is ejected, then all (or nearly all) the mass of stored chemical will 

reach the distribution plumbing. 

• In different systems, the length of the distribution plumbing ranges from well under a 

meter to several meters. The flow through the piping depends on the temperature, the 

phase distribution of the fluid, the number and severity of bends, etc. The NGP has 

modeled (and validated) the transport of this transient two-phase flow in past years.2

• The dispersed agent is generally a combination of vapor and liquid. 

o If the boiling point of the fluid is at or below the gas temperature in the nacelle, 

the liquid blobs that emerge from the storage bottle will flash evaporate. The 

fraction converted to gas is estimated using the Jakob number, the ratio of the 

fluid's sensible heat to its heat of vaporization. This flashing is rapid relative to 

the transit time of the air flow through a nacelle and imparts substantial 

momentum to the gas and the smaller droplets that are formed. This favors rapid 

and efficient dispersion throughout the nacelle. 

o If the fluid's boiling point is above the nacelle air temperature and if the fluid is 

dispensed, rather than atomized, gravity will cause most of the fluid to drop to the 

bottom surface of the nacelle. At that point its entry into the air stream is by 

evaporation. Unless the evaporation rate is high, the storage of large amounts of 

suppressant is necessary to achieve the concentration needed to extinguish flames. 

o If there are nozzles at the end of the distribution plumbing, then some ensemble of 

 

2

 Tuzla, K., Palmer, T., Chen, J., Sundaram, R., Yeung, W., "Development Of Computer Program for Fire 

Suppressant Fluid Flow Final Technical Report Volume I -- Main Report," (6b1 Suppressant Flow Through Piping 

Final Report Vol. 1), September, 2000. 

Tuzla, K., Palmer, T., Chen, J., Sundaram, R., Yeung, W., "Development Of Computer Program for Fire 

Suppressant Fluid Flow Final Technical Report Volume II -- Input Manual for the Program Experimental Data 

Assessment of the Program," (6b1 Suppressant Flow Through Piping Final Report Vol. 2), September, 2000.

2 
droplet sizes is generated. 

o If the pressurizing gas is highly soluble in the liquid suppressant, flashing can 

occur at temperatures somewhat below the boiling point. 

• The gaseous agent and the finer droplets are transported downstream within the nacelle. 

The larger droplets will generally fail to follow the main flow streamlines around any 

clutter and will impact the surfaces, forming pools from which evaporation is needed to 

resume transport downstream. 

• Upon reaching the site of the flames, the agent available for suppression is the sum of the 

gaseous component plus that fraction of the droplets that can evaporate while in the high 

temperature environment of the flame. Smaller diameter droplets evaporate more 

efficiently than larger ones. However, the nozzles that can generate such fine sprays 

generally have low throughput. 

• The sustaining of a sufficient concentration of agent bathing the flame zone leads to 

flame extinction. 

The NGP has also developed a new understanding of how efficient volatile chemicals interact 

with flames and eventually suppress them. This is summarized as follows: 

Flame propagation results from the fast reactions of key species (H and O atoms, OH 

radicals) with vaporized fuel molecules. These species exist at concentrations far above 

those expected from thermal equilibrium at flame temperatures. Chemically active agents 

catalytically reduce the radical concentrations toward equilibrium levels. While this process 

slows the flame, it does not necessarily extinguish it. The suppressant also increases the heat 

capacity of the fuel/air mixture, reducing the flame temperature and thus the flame reaction 

rates below the level needed to sustain combustion. These two effects are synergistic. The 

contribution of both effects suggests that the lower limit for a suppression concentration may 

be at about 1 % by volume. 

With this knowledge the NGP had developed a list of criteria to guide the search for candidate 

suppressant fluids: 

1. Fire suppression efficiency at least comparable to halon 1301 (volume fraction about 

0.03) and certainly higher than the hydrofluorocarbons (HFCs). Based on prior 

experience, this focuses the search on compounds that contain at least one bromine, 

iodine or phosphorus atom, although other possible functionalities can arise. (See 

Section II.D.) 

2. Short atmospheric lifetime (current preference of the order of a month), to keep ozone 

depletion potential (ODP), global warming potential (GWP) and any future unidentified 

environmental contamination issues to a minimum. 

3. Boiling point sufficiently low that for gaseous agents, an extinguishing concentration can 

be achieved within a specified time following discharge. An approximate theoretical 

upper limit is near 30 °C if the minimum temperature in flight is -40 °C. New knowledge 

of this process is described in Section II.B. 

4. Low toxicity relative to the concentration needed for suppression. 

3 
B. Minimum Release Temperature 

There are few viable chemicals with boiling points, Tb, below the specified minimum operating 

temperature of -40 oC (-40 oF). Prior NGP experiments with CF3I (Tb = -22 oC) have shown that 

it does not flash at this minimum temperature. All new chemicals currently under consideration 

have boiling points higher than this and their dispersion is thus characterized by the ability to 

evaporate rapidly. 

The potential for a fire suppressant fluid to attain a sufficient vapor pressure to quench flames is 

strongly dependent on the difference between the fluid's boiling point and the operating 

temperature. Incorporating the chemical features that effect low atmospheric lifetime (criterion 

2) generally results in molecules that are larger than halon 1301 and thus tends toward higher 

boiling points. Any increase in the specification for minimum operating temperature would 

allow consideration of molecules with higher Tb values. As Tb rises, there are more compounds 

per, e.g., 10 °C band, so the domain of eligible chemicals increases significantly. 

 

In September 2004, following a year-long examination of mishaps, the DoD reaffirmed that 

safety should be designed into weapons systems, not added afterwards, and that systems safety 

risk management should be integrated into overall safety engineering.3 In anticipation of this, 

the NGP revisited the basis for the operating temperature requirement for halon (replacement) 

fire suppression systems. 

Aviation fire incident data for the years 1980 through 2002 were obtained from the U.S. Army, 

Navy and Air Force Safety Centers. Each Safety Center also provided information on the 

altitude, outside air temperature (OAT), and location associated with many of the incidents. 

Table 1 summarizes the number of incidents provided by the Safety Centers. 

Table 1. Numbers of Military Aviation Fire Incidents 1980 to 2002 

Aircraft Type Army Navy Air Force Total 

Fixed Wing 92 1,212 3,932 5236 

Rotary 503 834 98 1435 

Each fire incident was reviewed to determine whether agent release had occurred. Only agent 

releases associated with discharge of systems protecting the following were considered: engine 

nacelle, auxiliary power unit (APU), auxiliary power plant (APP), and gas turbine compressor 

(GTC) compartment. For those incident reports in which the OAT was not included, it was 

estimated using the reported altitude and standard altitude-temperature curves. [The pertinence 

of these curves was verified using the incidents for which complete data were reported.] For 

incidents in which neither altitude nor temperature information were recorded, a methodology 

for assuming flight altitude based on aircraft flight phase4 was applied, as shown in Table 2. The 

resulting distributions of discharges are shown in Figures 1 and 2 for fixed-wing and rotary wing 

aircraft, respectively. 

 

3

 Memorandum on Defense Acquisition System Safety from M.W. Wynne, USD(AT&L) of 23 September 2004. 4

 Kolleck, M. L. and Jeffery, K., Halon Discharges at Altitude, Booz-Allen, Dayton, OH, June 1994.

4 
Table 2. Altitude Assumptions from Previous Halon Discharge Analysis4

Phase 

Altitude Range 

(km) 

Assumed Altitude 

(km) 

Assumed Altitude 

(ft) 

Low below 1.5 1.00 3280 

Range work below 1.5 1.00 3280 

Bomb run below 1.5 1.00 3280 

After takeoff below 1.5 1.00 3280 

Cruise-fighter 6.06 to 7.58 6.82 22375 

Cruise-cargo 9.14 to 10.67 9.90 32480 

Refueling 8.79 8.79 28838 

6%

3%

1%

13%

2%

75%

< -40

-34 to -40

-32 to -34

-29 to -32

-25 to -29

> -25

Figure 1. Ambient Temperature (oC) at Halon 1301 Discharge for Fixed-wing 

Aircraft

5 
3% 4% 6%

87%

< -21

-21 to -12

-12 to -7

> -7

Figure 2. Ambient Temperature (oC) at Halon 1301 Discharge for Rotary Wing 

Aircraft

The evaporation rate of a fire suppressant is also affected by the air temperature within the 

engine nacelle. Accordingly, an in-flight nacelle air temperature model was constructed to 

estimate nacelle air temperature during flight conditions. The model treats the nacelle as an air 

heat exchanger and computes the terminal temperature difference based on average, bulk values. 

The inlet conditions at the ram scoop are computed to be the stagnation properties for the given 

flight conditions, and these are taken to be the same as those inside the nacelle, close to the inlet. 

The effects of conduction and radiation heat transfer are assumed negligible; i.e., heat losses 

from air through the nacelle wall to the ambient outside by convection and conduction. The 

inputs to the model include the average nacelle clearance, diameter, ventilation air velocity and 

length; the aircraft altitude; the engine surface temperature, and the airspeed. The model was run 

for about 1000 cases, covering 8 altitudes between ground level and 9 km (30,000 ft), and for 

two airspeeds: 26 m/s and 206 m/s (50 knots and 400 knots, respectively). 

88 % of the cases indicated nacelle air temperatures greater than -18 °C (0 oF). Nearly all the 

other cases were for altitudes of 6 km (20,000 ft) or greater and airspeeds of 26 m/s (50 knots). 

These cases are artifacts because (a) military rotorcraft typically have operational ceilings less 

than 6 km and (b) 50 knots is below the stall speed for military fixed-wing aircraft that have 

nacelle fire suppression capability. The remaining 1.5 % of the cases were for input conditions 

at 9 km (30,000 feet) and 206 m/s and indicated nacelle air temperatures ranging between -23 °C 

(-10°F) and -24°C (-12°F). 

The accuracy of the model was checked using data from recent in-flight temperature 

measurements in rotary aircraft. The model tended to predict temperatures lower than those 

measured and is thus conservative. 

6 
Since some halon 1301 discharges occurred shortly after take-off, consideration was given to the 

possibility that the system was "cold soaked," i.e., the temperatures had equilibrated with very 

cold ambient conditions. The data indicate that only about 1 % of the incidents (ground or inflight) occurred in cold or severe cold climates 

Thus, the principal findings of this analysis are: 

• Nearly all releases of halon 1301 in military aircraft have been at temperatures higher 

than the design temperature of -40 °C. For fixed-wing aircraft, 75 % of the releases were 

at OATs above -25 oC (-13 oF); for rotary aircraft, 97 % were above -21°C (-6 oF). 

• The gas temperature in the engine nacelle has almost always been above -18 °C (0 oF). 

This does not, of course, represent relief from the current specification; that is a DoD policy 

matter. Moreover, even if the specification were raised to -25 oC (-13 oF), this would not 

increase the list of otherwise acceptable chemicals that could flash. It would, however, increase 

the evaporation rate of those chemicals with moderately higher boiling points. 

As a result, the NGP will flag for possible further consideration any compounds that have 

desirable values of the other pertinent properties, but marginally high boiling points. The DoD 

can then perform risk analyses that would assist in the consideration of an alternate suppressant 

for a particular aircraft or the entire fleet. 

C. CF3I Properties 

This chemical has flame suppression capability similar to halon 1301, but a higher boiling point 

and toxic potency. To date, it has been rejected for use within the U.S., but is being considered 

for application in other countries. The NGP has been conducting two small efforts on this 

chemical. 

A fire extinguishing agent must be able to be stored for long periods of time at high pressure in 

metal containers without degrading and losing its effectiveness. CF3I (and a variety of other 

candidate suppressants) had been placed in individual PTFE-lined steel stainless cylinders that 

also contained coupons of various metals from which agent storage bottles might be fabricated. 

These cylinders were stored at temperatures ranging from 22 °C to 150 °C for three years. At 

that time, samples were extracted and analyzed using Fourier transform infrared (FTIR) 

spectroscopy. Most of the samples showed no degradation. However, the combination of 

elevated temperature and copper-containing metals had caused serious degradation of the CF3I in 

some of the vessels. The samples were then stored at about 22 °C for another five years. The 

subsequent FTIR analyses indicated no new spectral peaks, little change in any fluoroalkene 

peaks, and general stability of the CF3I peak within the experimental uncertainty of 1.2 %. 

Were CF3I to be substituted for halon 1301, it would likely be released to the environment in a 

similar manner and frequency. The NGP was created because of the effect of halon 1301 

releases on stratospheric ozone. CF3I is readily degraded at altitudes below the stratosphere, and 

has a very short atmospheric lifetime compared to halon 1301. Thus, it might well have a far 

smaller deleterious environmental effect, depending on the altitude of its release. A prior 

analysis of such a substitution for fuel tank inerting in the F-16 showed that the substitution 

7 
might not have a significant benefit for that application. 

The historic profile and magnitude of halon 1301 releases for engine nacelle fire suppression are 

different from that for fuel tank inerting. As recommended by the Independent Review Panel 

(see the 2003 NGP Annual Report), the NGP commissioned a calculation to estimate the effect 

of the substitution for the nacelle application. The data for the altitude release profile came from 

the compilation discussed in the prior section of this Report. A report on the atmospheric 

computation results is expected early in calendar 2005. 

D. New Candidate Suppressants 

Last year, the NGP had identified nine chemical families whose consideration would complete 

the screening for new alternatives to halon 1301. Based on commercial availability and a 

scouring of the community for sources to synthesize these compounds, combined with the above 

findings regarding volatility, the list has been refined, as described in Table 3. 

8 
Table 3. Representative Compounds for Screening 

Chemical Family Initial Compound(s) Notes 

bromofluoroalkenes 

CHF2CBr=CF2 A sample of this compound was acquired. Tb was es

30 °C. The cup burner extinguishment volume fract0.033, as expected for a bromine-containing compouhydrogen atom. 

Prior work indicated that lower atmospheric lifetimepoints than the trifluoro counterparts were likely and 

would likely be of low toxicity. 

Other compounds will be acquired only if they have 

CBrHFOCF3CBrF2OCHF2

Two prior compounds had high boiling points of 39 

good cup burner values of 0.032 and 0.036. 

The values of Tb for these compounds were expected 

However, attempts at synthesizing them failed. Othe

bromofluoroalkylethers being considered. 

CF2HCFBrOCF3CFBrHCFHOCF3

These compounds have been ordered. Tb values hav

about 42 °C and 37 °C, respectively, but these and thwill be checked 

Other compounds will be acquired only if they have 

bromofluorovinylethers 

CF2BrCF2OCF=CF2 A small sample of this compound has been acquired

to be about 55 °C, and the cup burner value was 0.04Other compounds will be acquired only if they have 

Changes in the bromination site might help. 

fluoronitriles CF3CN This commercially available compound has a very lo

However, the cup burner value was determined to be no chemical activity from the CN group. 

The compound is no better than HFC-125, and no fufrom this group being acquired. 

9 
Chemical Family Initial Compound(s) Notes 

bromofluoronitriles 

CF2BrCN A small sample of this compound was acquired. Tb i

burner value is less than 0.04. This compound should have a short atmospheric lifereactivity and is now a candidate for tropodegradabilare also considering an acute toxicity screen test and evaporation rate measurement. Recently, there has been a report of unpublished data compound is highly toxic. An attempt is underway tthe source of the finding. Additional compounds to be considered only if they 

likely occurrence. 

bromofluoropropeneoxides 

CF3CBr(O)CF2 A sample of this compound was acquired, with Tb es

The measured cup burner value was a marginal 0.04A low atmospheric lifetime was expected. However, additional compounds to be considered onTb, not a likely occurrence. 

N-bromofluoroalkylamines (CF3)2NBr Published syntheses of this compound appear favora

compound has been ordered. The published Tb is ab

Additional compounds will be considered only if the

bromofluoroalkylamines No sources of any compounds in this family have be

worldwide search. 

N-bromofluoroimines CF2=NBr There is a reported synthesis for this compound, with 

weight percent of bromine is higher than that of halopotential for high flame suppression efficiency. The ordered. Additional low boiling analogs may be worfirst suppression result is favorable. 

10 
E. Limits to Effectiveness of Metal-containing Compounds 

There has been extensive research on the extraordinary flame inhibition effectiveness of ironcontaining compounds. In these laboratory tests, small amounts of the compounds fractionally 

reduced the flame burning velocity far more efficiently than did halon 1301. However, in no 

cases were the flames extinguished. NGP research has developed an explanation for this binary 

behavior. The addition of small amounts of the compound catalytically recombines hydrogen 

atoms, reducing the concentration of the prime attacker of fuel molecules. As more of the 

compound is added, the higher concentration favors condensation to inert iron oxide particles. 

Thus there is never enough of the flame retarding species to drive the flame all the way to 

extinction. 

Compounds of other metals, if they were effective flame suppressants, would likely be either 

solids or viscous liquids, not suitable for use as suppressant fluids. They could, however, be 

incorporated into solid propellant fire extinguishers (SPFE). [In fact, it was NGP SPFE 

experiments with ferrocene that demonstrated the inability of an iron-containing compound to 

quench larger flames.] It was thus important to know whether any other metal-containing 

compounds might have potential for this use. 

The NGP thus undertook a review and analysis of the literature to understand metal chemistry in 

flames. This included a detailed examination of the mechanism of inhibition of iron and the 

reasons for its loss of effectiveness. This was followed by summarizing the demonstrated flame 

inhibiting properties of other metals and composing a description of the potential loss of 

effectiveness for them. The literature analyzed included that on engine knock, premixed and 

diffusion flames, flame retardancy, ignition, rocket nozzles, and NO formation. The metals 

covered were chromium, lead, manganese, tungsten, molybdenum, tin, cobalt copper, and 

antimony. This work has uncovered that tungsten, molybdenum and cobalt are likely to be 

effective inhibitors at low concentrations, results that have not been suggested in previous 

reviews of flame inhibition by metal-containing compounds. 

There exist several screens for estimating whether other metallics will have a loss of 

effectiveness similar to that of iron, including: 

• Experimental data for flame systems in which the loss of effectiveness is evident. This 

requires that the inhibitor be added at volume fractions high enough to observe the loss of 

effectiveness. 

• Reported presence of particles in some flame system. Although the presence of particles 

will depend upon the temperature of the flame, the concentration at which the metallic 

compound is added, and the residence time for particle formation, the observed presence 

of particles in one flame system is an indication that it may be important in other flame 

systems as well. 

• Consideration of saturation (volume fraction as compared to local vapor pressure) in the 

flame of the local metal species. A limitation of this method is that it relies upon 

knowledge of the metal species present in a flame system, the mechanism of inhibition, 

as well as the vapor pressure (or gas-phase and condensed-phase thermodynamic data). 

Often, this information is incomplete. Further, the kinetic rates of the formation of more 

11 
stable oxides of the metal must be known to assess the contribution of those compounds 

to condensed-phase particles. 

Table 4 summarizes the results of this screening analysis for whatever compounds of these 

metals have been examined. The metals are listed in roughly decreasing order of inhibition 

effectiveness, based on the literature review. A prospective SPFE additive should have a mark in 

the first column and no marks in the three right-hand columns. The absence of a mark indicates 

that there are no reported studies or that the results are inconclusive. 

Table 4. Evidence Regarding Potential for High Flame Suppression Efficiency of 

Metal-containing Compounds

Metal 

High Inhibition 

Efficiency 

Loss of 

Effectiveness 

Presence of 

Particles 

Evidence of 

Saturation 

Cr Y Y Y Y 

Pb Y Y Y Y 

Mn Y Y Y Y 

W 

Mo 

Sn Y Y Y Y 

Co Y 

Cu 

Sb Y Y Y Y 

For W, Mo, Co, and Cu, there is no direct evidence of the potential for loss of effectiveness, and 

the vapor pressures of the suggested flame-quenching species (for which data are available) are 

reasonably high. For Co, the monoxide CoO is likely to be an important intermediate in the 

inhibition cycle. Its low vapor pressure can be taken as evidence for the potential for 

condensation. Nonetheless, the potential for condensation of metal species really depends upon 

the local super-saturation ratio in the inhibited flame. Calculation of the super-saturation ratio 

depends upon knowing both the detailed kinetic mechanism of inhibition as well as the vapor 

pressure of all of the intermediate species. Further, the kinetics of the condensation (and 

potential re-evaporation of particles) will be highly dependent on the flow-field of the particular 

flame system to be extinguished. Prediction of the potential loss of effectiveness due to 

condensation is beyond the current state-of-the-art. 

Prior NGP experiments with K2CO3 added to an SPFE have shown a significant increase in 

flame extinguishment efficiency relative to the same formulation without the potassium salt. 

These results were verified in real-scale engine nacelle fire tests. Thus, the current results 

provide backup only in case potassium salts manifest some other undesirable behavior. 

12 
Should more definitive information on compounds containing these metals be desired, two 

possible screening experiments are suggested: 

• Cup burner tests would determine the amount of a diluent (e.g., CO2, or N2) added to the 

air stream necessary to cause blow-off of the cup-burner flame, both with and without the 

metal agent added at increasing concentration in the oxidizer stream. Since, to some 

extent, the flames resemble the low-strain conditions of fires, there is expected to be a 

reasonable correlation between the behavior in this system and in actual suppressed fires. 

By adding the metal compounds in the form of organometallic agents (rather than metal 

salts), the complicating effects of particle evaporation and decomposition can be avoided. 

• Addition of metal-containing compounds to an SPFE. There is inert gas in the effluent, 

as well as fragmented metal-containing species, so that by proper application to an 

appropriate fire, the utility of the metal additive could be assessed at larger scale. The 

challenge would be to find a configuration that has the proper sensitivity to the inert gas 

flow so that the effects of the additive could be quantified. 

F. Fire Suppressant Dynamics in Cluttered Engine Nacelles 

The objective in this portion of the NGP is to provide the basis for optimizing the distribution of 

suppressants, thereby improving the suppression efficiency of gases and aerosols that are less 

effective than halon 1301. The tool by which this guidance is to be delivered is a validated 

computational fluid dynamic (CFD) model of suppressant flow, a fire, and fire extinguishment in 

cluttered environments. Earlier components of this effort had been: 

• Laboratory experiments to develop understanding of suppressant droplet dynamics 

around obstacles and upon impact on cold and heated surfaces. 

• Extension of this knowledge to spray-clutter interactions in a wind tunnel. 

• Adaptation of the Vulcan CFD model for simulating these suppressant-laden flows. 

• Examination of the effect on agent distribution of varying the number of agent injection 

nozzles. 

This year, a first series of fire suppression tests were conducted in the NAVAIR F-18 E/F 

Ground Engine Nacelle Simulator and the results compared with simulations previously made 

using the CFD computer code. The 25 experiments were designed to explore the envelope of 

test conditions under which flame extinguishment did and did not occur. 

Figure 3 is a photograph of the test fixture. The nacelle is ca. 3.18 m (125 in.) in length. The 

height and width vary along the length, but they are contained within a region 1.45 m high and 

1.15 m wide. The engine surface, a hollow cylinder, has a diameter of 0.77 m in the front (the 

left in the Figure), narrowing to 0.62 m at the rear. Air and agent are introduced into the nacelle 

through the diagonal pipe at the lower left of the photograph. The intake air flow is turbulent 

even without the clutter-induced mixing. 

13 
Figure 3. Photograph of the NAVAIR F-18 E/F Ground Engine Nacelle Simulator 

Clutter objects are located along its length. There are ribs and longerons, along with other 

clutter, along the length of the nacelle (Figure 4a) and a gearbox assembly located 0.1 m to 0.75 

m from the forward end and mostly below the engine (Figure 4b). 

4a 4b 

Figure 4. Photographs of Ribs/Longerons and Gear Box Assembly 

14 
Before conducting fire suppression tests, determinations were made of the accuracy with which 

the model simulated the distribution of fire suppressant in the fixture. Measurements of HFC125 (C2HF5) were made at 12 locations using a Halonyzer II. Figure 5 compares the predicted 

concentration of HFC-125 at two of those locations with the predicted concentrations for two 

different injection durations. The actual agent release duration was 2.7 s. As the agent 

concentration rises, the simulation with a 3 s injection period replicates both sets of test data 

well. The model reasonably replicates the flushing of the agent from the nacelle at location 3. 

For location 1, the model flushes the agent too quickly. The discrepancy is likely due to two 

idealizations in the model. First, the agent dispensing is simulated as a square wave, while in the 

test there is a "tail" to the ejection as the pressure in the storage bottle decreases. Second, the 

model assumes that the agent flashes completely upon injection, while in the tests there was 

some downstream evaporation of liquid. The discrepancies on the "down" side of the curves are 

relatively unimportant since the fires will typically be quenched before the peak concentration of 

agent is reached. 

Figure 5. Comparison of Measured and Simulated Concentration Throughout a 

Discharge Test 

For the fire suppression tests, pools of JP-8, each 0.09 m2

 in area, were situated at three locations 

(all downstream of ribs) on the nacelle floor below the engine. Variables in the tests included 

mass of suppressant in the storage bottle, discharge rate of the agent, air flow, and one-at-a-time 

capping of three of the four agent injection nozzles. Within the apparatus geometric limits and 

the physical properties of the suppressant, it was not possible to replicate exactly the Vulcan 

simulations in all cases. However, the test matrix did preserve the trends of configuration and 

flows from the simulations. 

15 
Two parameters determined the average overall suppressant mass fraction in the test fixture: 

1. The ratio of "suppressant" mass inflow to "suppressant plus air" mass flow determined 

the maximum value attainable for long times, referred to as the inflow ratio. 

2. The "suppressant plus air" flow determined the time to reach these maximum values. 

This time was generally much less than the injection duration, indicating that the 

maximum values were closely approached.

It was a very successful series of tests. In all but two cases, the model and the test agreed as to 

whether the fire was extinguished or not. Figure 6 shows the inflow ratio in the tests for which 

Vulcan simulation had been performed. For each test, the top three bars are the estimated inflow 

ratio based on the measured pressure drop at the storage bottle over 1 s, 2 s, and 3, s. The 

"target" bar represents the theoretical fraction, as employed in the Vulcan simulations. 

Figure 6. Agent Injection Ratios

When the agent inflow ratio, based on the bottle discharge was below about 0.43 (mole fraction 

about 0.15), the fires were not extinguished. This inflow ratio corresponds to an average mole 

fraction of 0.15, almost twice the cup burner suppression value. This indicates the significance 

of inhomogeneities within the nacelle, i.e., some regions have a much lower mole fraction than 

the average. 

Figures 7 and 8 are plots of the midsection of the nacelle from a simulation of a successful flame 

suppression. The air flow is from the left, and the blue cylinder indicates the location of the 

engine. The dimensions along the y-axis are measured from the nose of the airplane; all 

16 
dimensions are in meters. The three pool fires are located along the x = 0.5 line centered at 

about y = 15.5 m, y = 16.0 m, and y = 16.6 m. Two agent introduction ports are located just to 

the starboard of the middle pool fire, with one directed upward and the other directed 

horizontally toward the center of the nacelle. A third injector is located above the third pool fire 

and is directed upward at a roughly 45 ° angle. The fourth port is downstream of the third pool 

fire, high in the nacelle and pointing downward. 

In Figure 7, the heating of the lower level gas flow by the pre-burning pool fires just prior to 

discharge is evident. Figure 8 shows the agent distribution (mass fraction) 1 s after the start of 

the discharge. The black surfaces indicate the expanse of the heat from the fires. Prior to 

discharge, only the air inlet is cool, while 1 s after the start of injection, the pool fires are already 

nearly fully suppressed and the nacelle has cooled substantially. 

Figure 7. Contour Plot of Simulated Temperatures Just Before Agent Injection

17 
Figure 8. Contour Plot of Simulated Agent Distribution 1 s After Initiation of 

Discharge 

Additional tests were also conducted where individual nozzles were removed to increase the 

degree of inhomogeneity of agent distribution. The results indicate that Vulcan predicts 

somewhat greater sensitivity to removing nozzles than is observed in the tests. Analysis of all 

the data from the experiments and simulations is underway. 

18 
G. Verification of NGP-Developed Fire Suppression Principles 

Planning is underway for a series of about 1000 real-scale engine nacelle fire suppression tests. 

These are scheduled for summer 2005. Their purposes will be (a) to verify the fire suppression 

principles developed in the NGP by comparing the outcome of the tests with predictions based 

on NGP-developed technology and (b) to identify any as-yet unexplained suppression 

phenomena. Candidates for test variables include: 

 Nacelle temperature 

o Low in-flight value 

o Moderate in-flight value 

o Value related to the minimum volatility of a fluid suppressant 

 Agent storage temperature 

o Same as nacelle temperature 

o Below nacelle temperature (simulating cold soak) 

 Length and nature of distribution plumbing 

o Short, straight run 

o Longer, bent run 

 Number, nature and location of injection ports (based on outcome of modeling and 

experiments in Project 6A/1) 

o Two to three different numbers of ports 

o Two nozzle designs, possibly tuned to the suppressant properties 

o Two location sets 

 Agent injection momentum 

o High value, indicative of rapid release 

o Low value, to provide most effective flooding of the nacelle volume 

 Agent chemistry and thermophysical properties. Some agents likely would be introduced 

as compressed fluids, others from solid propellant fire extinguishers. 

o Three fluids, one non-catalytic, two catalytic (probably bromine-containing) with 

different boiling points relative to the nacelle temperatures 

o Two SPFEs, one with an additive to the propellant, one an HFE 

 Fire 

o One exposed location, one occluded location 

o Spray, pool 

 Agent mass 

o To generate concentration predicted for direct flame extinguishment 

o To generate concentration estimated (from prior experiments) to quench relight 

o An intermediate concentration (if relight is quenched) or a larger concentration (if 

relight is not quenched) 

Each test sequence involves tests at several agent concentrations (to determine the mass needed 

for flame extinguishment) and replicate tests (to mitigate the occurrence of single anomalous 

results). A factorial experimental design will be used to extract the maximum amount of 

information from the modest number of tests. 

19 
H. Recent Publications 

 (* indicates archival publications) 

Bein, D., "In-Flight Suppressant Deployment Temperatures," in Gann, R.G., Burgess, S.R., 

Whisner, K.C., and Reneke, P.A., eds., Papers from 1991-2004 Halon Options Technical 

Working Conferences (HOTWC), CD-ROM, NIST SP 984-2, National Institute of Standards and 

Technology, Gaithersburg, MD, (2004). 

Mather, J.D., and Tapscott, R.E., "Environmentally Acceptable Flame Extinguishants," in Gann, 

R.G., Burgess, S.R., Whisner, K.C., and Reneke, P.A., eds., Papers from 1991-2004 Halon 

Options Technical Working Conferences (HOTWC), CD-ROM, NIST SP 984-2, National 

Institute of Standards and Technology, Gaithersburg, MD, (2004). 

Mather, J.D., and Tapscott, R.E., "Tropodegradable Bromocarbon Extinguishants II," Final 

Report to SERDP, 2004. 

Linteris, G.T., "Limits to the Effectiveness of Metal-containing Fire Suppressants," Final Report 

to SERDP, December 2004; and NISTIR 7177, National Institute of Standards and Technology, 

Gaithersburg, MD, 2004. 

*Linteris, G.T., Katta, V.R., and Takahashi, F., "Experimental and Numerical Evaluation of 

Metallic Compounds for Suppressing Cup-burner Flames, Combustion and Flame 138, 78-96 

(2004). 

Donnelly, M.K., Harris, R.H., and Yang, J.C., "CF3I Stability Under Storage," NIST Technical 

Note 15452, National institute of Standards and Technology, Gaithersburg, MD, 2004. 

Fleming, J.W., and Yang, J.C., Modeling Study of the Behavior of Liquid Fire Suppressant 

Agents in a Simulated Engine Nacelle," in Gann, R.G., Burgess, S.R., Whisner, K.C., and 

Reneke, P.A., eds., Papers from 1991-2004 Halon Options Technical Working Conferences 

(HOTWC), CD-ROM, NIST SP 984-2, National Institute of Standards and Technology, 

Gaithersburg, MD, (2004). 

*Disimile, P.J., Tucker, .R., Croswell, B., and Davis, “The Transport of Water Sprays Past 

Generic Clutter Elements Found Within Engine Nacelles,” Fire Safety Journal 40, 65-78, 2005. 

Keyser, D.R., and Hewson, J.C., "Fire Suppressant Distribution in an F-18 E/F Nacelle," in 

Gann, R.G., Burgess, S.R., Whisner, K.C., and Reneke, P.A., eds., Papers from 1991-2004 Halon 

Options Technical Working Conferences (HOTWC), CD-ROM, NIST SP 984-2, National 

Institute of Standards and Technology, Gaithersburg, MD, (2004). 

Hewson, J.C., and Keyser, D.R., "Predicting Fire Suppression in an F-18 E/F Engine Nacelle," in 

Gann, R.G., Burgess, S.R., Whisner, K.C., and Reneke, P.A., eds., Papers from 1991-2004 Halon 

Options Technical Working Conferences (HOTWC), CD-ROM, NIST SP 984-2, National 

Institute of Standards and Technology, Gaithersburg, MD, (2004). 

Disimile, P.J., and Davis, J.M., "The Effect of Optical Configuration Selection on Phase Doppler 

Anemometer Fire Suppressant Nozzle Characterizations," in Gann, R.G., Burgess, S.R., 

20 
Whisner, K.C., and Reneke, P.A., eds., Papers from 1991-2004 Halon Options Technical 

Working Conferences (HOTWC), CD-ROM, NIST SP 984-2, National Institute of Standards and 

Technology, Gaithersburg, MD, (2004). 

Disimile, P.J., Tucker, J.R., Stern, J., Mehl, L., and Croswell, B., “Velocity and Drop 

Distributions Downstream Generic Clutter Elements Found Within Engine Nacelles,” in Gann, 

R.G., Burgess, S.R., Whisner, K.C., and Reneke, P.A., eds., Papers from 1991-2004 Halon 

Options Technical Working Conferences (HOTWC), CD-ROM, NIST SP 984-2, National 

Institute of Standards and Technology, Gaithersburg, MD, (2004). 

*S. S. Yoon, P. E. DesJardin, J. C. Hewson, C. Presser, C. T. Avedisian, “Numerical Modeling 

and Experimental Measurements of Water Spray Impact and Transport over a Cylinder,” 

International Journal of Multiphase Flow, submitted for publication, 2004. 

Davis, J., and Disimile, P.J., “The Effect of Lens/Aperture Selection on Phase Doppler 

Anemometer Measurements,” AIAA 42th Aerospace Sciences Meeting and Exhibit, January 14-

17th 2004, Reno, Nevada. 

*Ghee, T.A., and Keyser, D.R., "Aerodynamics of Circular Cylinder Shapes in Low-Speed, 

Highly Turbulent Flow," AIAA Journal of Aerodynamics, submitted for publication, 2004. 

Presser, C., Avedisian, C.T., and Johnson, B.S., "Phase Doppler Measurements of Liquid Fire 

Suppressants over a Heated Cylinder," AIAA 2004-0479, American Institute for Aeronautics and 

Astronautics, Washington, DC, 2004. 

Cyphers, D.C., "Enhanced Powder Panels," Final Report to SERDP, Skyward, Inc., 2004. 

Cyphers, D.C., “Enhanced Powder Panels - Applying New Ideas to an Old Fire Extinguishing 

Method,” Military Fire Protection Systems Edition, FS-World.com Magazine, 2004 

Johnsson, E.L., Mulholland, G.W., Fraser, G.T., Leonov, I.I., and Golubiatnikov, G.Y., 

"Description and Usage of a Fast-response Fire Suppressant Concentration Meter," NIST 

Technical Note 1463, National Institute of Standards and Technology, Gaithersburg, MD, 

(2004). 

Johnsson, E.L., Mulholland, G.W., Fraser, G.T., Leonov, I.I., and Golubiatnikov, G.Y., 

"Development of a Fast-response Fire Suppressant Concentration Meter," NIST Technical Note 

1464, National Institute of Standards and Technology, Gaithersburg, MD, (2004). 

21 
III. INDEPENDENT PROGRAM ASSESSMENT 

For a third year, the NGP Independent Review Panel (IRP) was asked to assess progress to date 

and to recommend actions that could enhance the prospects for NGP research to result in viable 

and practical alternative fire suppression technologies with NGP resources remaining at or near 

currently projected levels. 

The IRP was impressed by the thoughtful way their prior recommendations have been addressed 

and by the tightened focus of the program. They made no additional recommendations that 

entailed either course changes or significant project modification. Rather, their report comprises 

a series of observations on the content and output of the individual projects. These are contained 

in the draft report (Appendix B). 

This will be the last report from the Panel. One of the members has retired and another is 

deceased. Since the sitting Panel had commented on all current and planned NGP projects, the 

decision was taken not to re-constitute the IRP for the last year of NGP research. 

22 
IV. WHAT LIES AHEAD? 

The Next Generation Fire Suppression Technology Program will reach completion in FY2006. 

At that time, the NGP will have met its goal to develop and demonstrate 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 completion of the NGP will mark the end of DDR&E's program in fire suppression 

and will provide a sound technical basis for future fire suppression systems and research efforts. 

There are a small number of key technical tasks, mostly underway but yet to be completed, 

needed in order to deliver the intended products: 

• A well documented and archived science base for fire suppression research; 

• Identification of the best chemicals to consider as alternatives to halon 1301 for 

extinguishing in-flight fires in aircraft engine nacelles and dry bays; 

• Guidance for engineering the fire suppression system to obtain the most efficient use of 

the suppressant chemicals; 

• Development of practicable non-fluid-based suppression technologies (completed); and 

• Creation of means for deciding among candidate solutions for a given application 

(completed). 

The remaining tasks are: 

• Completion of assessment of the nine chemical families listed in Table 3. 

• Completion of guidance for efficient agent delivery, as described in Section 3.F. 

• Verification of the effectiveness of the new distribution principles and the relative 

performance of chemicals, as described in Section III.G. 

• Preparation of the NGP final report. Due to the quantity of the material and the 

interactive nature of the NGP projects, this extensive undertaking will be in book form. 

The NGP has re-established the disciplinary science of fire suppression, creating a viable 

foundation and framework for future R&D in fire suppression, particularly for weapon 

systems and even for needs in outer space. This book will pull together the new 

knowledge into a unified package. 

In addition to these, the NGP expects to continue sponsorship of the Halon Options Technical 

Working Conferences through FY2006. This focused meeting is a prime venue for ensuring that 

the latest developments are incorporated in NGP results and for efficient transfer of the NGP 

results to a wide national and international user community. 

The estimated timeline for completion of the NGP is shown in Appendix C. 

The prognosis for successfully meeting the NGP goal is excellent, given the technical 

infrastructure and cadre of experts advanced by the NGP. The Department of Defense has 

already made use of NGP technology in testing, selecting, and designing suppression 

technologies for some Military Service aircraft. More such test series are being planned and 

presumably will become the norm for the remaining platforms. 

23 
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24 
APPENDIX A. NGP PROJECTS 

The system for the identifier codes for the projects was developed at the beginning of the NGP 

and follows the now outdated program structure in the original NGP Strategy Document, which 

is available at the NGP web site. For current use, the important information is located following 

the second slash (e.g., 3A/1/789). In this example, the project was funded in fiscal years 1997, 

1998, and 1999. 

A. SUPPRESSANT SCREENING TESTS 

3A/1/789. DISPERSED LIQUID AGENT FIRE SUPPRESSION SCREEN; Principal 

Investigator: Jiann C. Yang, NIST 

3A/2/890. TRANSIENT-APPLICATION-RECIRCULATING-POOL-FIRE AGENT 

EFFECTIVENESS SCREEN; Principal Investigator: William Grosshandler, 

NIST 

3B/1/89. TOXICOLOGICAL ASSESSMENT OF HUMAN HEALTH CONSEQUENCES 

ASSOCIATED WITH INHALATION OF HALON REPLACEMENT 

CHEMICALS; Principal Investigator: Darol Dodd, AFRL 

3B/2/8. AGENT COMPATIBILITY WITH PEOPLE, MATERIALS AND THE 

ENVIRONMENT; Principal Investigators: Marc Nyden, NIST, and Stephanie 

Skaggs, Universal Technical Services 

B. NEW FLAME SUPPRESSION CHEMISTRY

2A/1/7890, /2/890. MECHANISMS OF ULTRA-HIGH EFFICIENCY CHEMICAL 

SUPPRESSANTS; Principal Investigators: James Fleming, NRL, and Kevin 

McNesby, ARL 

4D/2/7. IDENTIFICATION AND PROOF TESTING OF NEW TOTAL FLOODING 

AGENTS; Principal Investigator: Robert E. Tapscott, NMERI; COR: Andrzej 

Miziolek, ARL 

4D/5/8. MAIN GROUP COMPOUNDS AS EXTINGUISHANTS; Principal Investigator: 

J. Douglas Mather, NMERI; COR: Ronald Sheinson, NRL. 

4B/1/8,4D/15/01. TROPODEGRADABLE BROMOCARBON EXTINGUISHANTS; 

Principal Investigator: J. Douglas Mather, NMERI; COR: Ronald Sheinson, NRL 

4B/2/8,4D/3/7. FLAME INHIBITION BY PHOSPHORUS-CONTAINING COMPOUNDS; 

Principal Investigator: Elizabeth M. Fisher, Cornell University; COR: Andrzej 

Miziolek, ARL 

4D/14/1. FLUOROALKYL PHOSPHOROUS COMPOUNDS; Principal Investigator: 

Douglas Mather, NMERI 

4C/1/890. SUPER-EFFECTIVE THERMAL SUPPRESSANTS; Principal Investigator: 

William Pitts, NIST 

25 
4D/13/1. EFFECTIVE, NON-TOXIC METALLIC FIRE SUPPRESSANTS; Principal 

Investigator: Gregory Linteris, NIST 

4B/3/8901. ENVIRONMENTAL IMPACT OF NEW CHEMICAL AGENTS FOR FIRE 

SUPPRESSION; Principal Investigators: Robert Huie and Marc Nyden, NIST; 

Andrzej Miziolek, ARL 

4B/4/01234. LOW TEMPERATURE PERFORMANCE OF HIGH BOILING POINT 

SUPPRESSANTS; Principal Investigator: Jiann Yang, NIST 

4B/5/01234. ALTERNATIVE SUPPRESSANT CHEMICALS; Principal Investigator: Richard 

Gann, NIST 

4B/6/234. ENVIRONMENTALLY ACCEPTABLE SUPPRESSANTS; Principal 

Investigator: Douglas Mather, Chemical Development Systems; Scientific 

Officer: Richard Gann, NIST 

C. NEW AND IMPROVED AEROSOL SUPPRESSANTS 

2B/1/78901. SUPPRESSION EFFECTIVENESS OF AEROSOLS AND PARTICLES; 

Principal Investigator: Ronald Sheinson, NRL 

2B/2/89. DROPLET INTERACTIONS WITH HOT SURFACES; Principal Investigator: 

Yudaya Sivathanu, En’Urga, Inc.; COR: William Grosshandler, NIST 

2B/3/89. TECHNICAL SUPPORT FOR THE STUDY OF DROPLET INTERACTIONS 

WITH HOT SURFACES; Principal Investigator: Jiann Yang, NIST 

4A/1/890. POWDER-MATRIX SYSTEMS; Principal Investigator: Gregory Linteris, NIST 

4D/1/7. ELECTRICALLY CHARGED WATER MISTS FOR EXTINGUISHING 

FIRES; Principal Investigator: Charles H. Berman, Titan Corp.; COR: Ronald 

Sheinson, NRL 

4D/4/7. DEVELOPMENT OF A SELF ATOMIZING FORM OF WATER; Principal 

Investigator: Richard K. Lyon, EER, Inc.; COR: William Grosshandler, NIST 

4D/7/8. DENDRITIC POLYMERS AS FIRE SUPPRESSANTS; Principal Investigator: 

Nora Beck Tan, ARL 

D. IMPROVED SUPPRESSANT DELIVERY 

2C/1/789. STABILIZATION OF FLAMES; Principal Investigator: Vincent Belovich, 

AFRL 

4D/6/8. DUAL AGENT APPROACH TO CREW COMPARTMENT EXPLOSION 

SUPPRESSION; Principal Investigator: Douglas Dierdorf, ARA Corp.; COR: 

Andrzej Miziolek, ARL 

4D/17/0. A METHOD FOR EXTINGUISHING ENGINE NACELLE FIRES BY USE OF 

INTUMESCENT COATINGS; Principal Investigator: Leonard Truett, Eglin AFB 

5A/1/012. PARAMETRIC INVESTIGATION OF DROPLET ATOMIZATION AND 

26 
DISPERSION OF LIQUID FIRE SUPPRESSANTS; Principal Investigator: Cary 

Presser, NIST 

5D/1/9013. ADVANCED PROPELLANT/ADDITIVE DEVELOPMENT FOR GAS 

GENERATORS; Principal Investigators: Gary Holland, Aerojet, and Russell 

Reed, NAWC-WPNS; COR: Richard Gann, NIST 

5E/1/12. ENHANCED POWDER PANELS; Principal Investigator: Dan Cyphers, 

Skyward, Ltd.; COR: Martin Lentz, Eglin AFB 

6A/1/01234. FIRE SUPPRESSANT DYNAMICS IN CLUTTERED WEAPONS SYSTEM 

COMPARTMENTS; Principal Investigator: David Keyser, INS, Inc. 

6A/2/3. GUIDANCE FOR RE-IGNITION SUPPRESSION; Principal Investigator: 

 Anthony Hamins, NIST 

6B/1/89. SUPPRESSANT FLOW THROUGH PIPING; Principal Investigator: John Chen, 

Lehigh University; COR: William Grosshandler, NIST 

6C/1/1. MECHANISM OF UNWANTED ACCELERATED BURNING; Principal 

Investigator: Anthony Hamins, NIST 

E. VIABILITY OF NEW SUPPRESSANT TECHNOLOGIES 

1A/1/78. DEVELOPMENT OF MODEL FIRES FOR FIRE SUPPRESSION RESEARCH; 

Principal Investigator: Anthony Finnerty, ARL; Associate Investigators: James 

Tucker, AFRL and Juan Vitali, ARA; Ronald Sheinson, NRL 

1C/1/8901. RELATIVE BENEFIT ASSESSMENT OF FIRE PROTECTION SYSTEM 

CHANGES; Principal Investigator: Michael Bennett, Eglin AFB 

3C/1/789. LASER-BASED INSTRUMENTATION FOR REAL-TIME, IN-SITU 

MEASUREMENTS OF COMBUSTIBLE GASES, COMBUSTION BYPRODUCTS, AND SUPPRESSANT CONCENTRATIONS; Principal 

Investigator: Kevin McNesby, ARL 

3C/2/890. FAST RESPONSE SPECIES CHARACTERIZATION DURING FLAME 

SUPPRESSION; Principal Investigator: George Mulholland, NIST 

6E/1/34. VERIFICATION OF SUPPRESSION PRINCIPLES; Principal Investigator: 

Michael Bennett, Bennettech; COR: Martin Lentz, Eglin AFB 

F. FUEL TANK INERTION 

5C/1/9. ACTIVE SUPPRESSION FOR FUEL TANK EXPLOSIONS; Principal 

Investigator: Leonard Truett, Eglin AFB 

 

27 
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28 
APPENDIX B. REPORT OF THE INDEPENDENT REVIEW PANEL 

February 20 Draft 

REPORT OF THE INDEPENDENT REVIEW PANEL 

ON THE 

NEXT GENERATION FIRE SUPPRESSION TECHNOLOGY 

PROGRAM (NGP)

 

February 20, 2004 

Documenting the November 2003 Review 

_________________________ 

Thor I. Eklund, Ph.D. 

Eklund Consulting Services 

_________________________ 

Phillip R. Westmoreland 

Professor and Head, Department of Chemical Engineering 

University of Massachusetts Amherst 

_________________________ 

Glenn Harper – Chair 

Technical Fellow 

Boeing - Phantom Works 

29 
The 2003 Independent Review Panel Report 

on the 

Next Generation Fire Suppression Technology Program (NGP)

Summary:

The 2003 Independent Review Panel (IRP) met December 4-5, 2003, coincident with the 2003 

Annual Research Meeting (ARM) of NGP at NIST in Gaithersburg MD. 

The IRP is impressed by the thoughtful way the 2001 and 2002 recommendations have been 

addressed and by the tightened focus of the program. The following general observations are 

presented: 

General Comments:

a. The 6E/1/3 Project (Bennett) is the real key to transition the long-term value of 

the NGP to future aviation programs and fire protection engineers. We 

recommend that the program management insures that all PIs for each NGP 

element be actively involved in generating the lessons learned to insure that no 

important positive or negative results are lost, and that everyone concentrate on 

the needs of the end user, whether he or she be some future fire protection 

engineer or R&D scientist. 

b. The relight work reported in 2002 (6C/1/1) was promising with reasonable focus 

on the end user. The continuation of the 2003 work, as presented to the IRP, 

suggests the possibility of less focus on the end user. Should that be true, an 

increased emphasis on how the end user might use the results of this work would 

be valuable. 

c. Progress on some of the elements is not as rapid as some might like but is as 

much or more than would be expected with the limited budget allotted. 

d. The droplet work by Presser (5A/1/012) and the gas generator work by Holland 

(5D/1/9013) are particularly impressive. 

Specific on Specific Programs:

 1) 5E/1/12 Enhanced Powder Panels 

a. The program is ending and the IRP sees no reason to extend it. 

b. The traditional aircraft environment “Shake and Bake” testing (vibration, shock, 

thermal cycling, humidity, etc.) will need to be performed before the concept can 

be fully accepted. The design changes that give this concept the improved 

performance may degrade performance in these environmental tests. 

30 
2) 5D/1/9013 Advanced Propellant / Additive Development for Gas Generators 

a. The progress of this element is one of the high points of the 2003 review. 

b. The improved performance resulting from the presence of active species can 

significantly reduce installation penalties however, the following issues need to be 

considered: 

i. Residual powders may cause clean-up problem 

ii. Residual powders may not follow the gas flow path. There needs to be a 

test to determine how well it follows the gas streamlines through complex 

paths if we intend to certify aircraft with this technology by only 

measuring gas species. 

c. The reduced performance variation with temperature of the new design can be a 

significant benefit in new applications. 

d. The reduced exhaust gas temperature of the new design can also be a significant 

benefit in new applications. 

3) 4B/4/013 Low Temp Performance of High Boiling Point Suppressants 

a. Vapor loading is an important part of this effort. 

b. This analysis is appropriate for the experimental simulation device. 

c. Not enough data was presented to evaluate the end product fully at this time 

4) 6A/2/3 Guidance for Re-ignition Suppression 

a. Responds to earlier recommendation (2001 and reaffirmed in 2002) 

b. Addresses a fundamental and important consideration in real life applications. 

The IRP has some concern that the present approach may not lead to realistic 

guidance to the design community. The fire protection engineer really needs 

guidance on how to address ventilation rate, air temperature, surface temperature, 

fuel volatility, etc. to establish re- ignition limits. 

c. The PI should insure that the pre-1990 work (Clodfelter, Goodal and Ingle, 

Mullin, etc.) has been properly considered. 

d. The resources needed to fully address this issue may be beyond the limits of the 

funds available. Maybe this needs to become a guideline document for 

addressing certification issues with re-ignition issues in mind. 

e. A study of the “eddying” in the chamber may explain some of the apparent 

inconsistencies in earlier data. 

31 
5) 6A/1/0123 Fire Suppression Dynamics in Fire Compartments 

a. The data and automation presented appear to show progress and seem to be 

developing insight into agent dispersion. 

b. There is the suggestion that this may eventually be adapted into a design tool. If 

this is one of the goals, management must insure that it does not become much too 

complicated or labor hour intensive for that purpose. 

c. The IRP would like to see more prominent expression of the fire suppression 

mechanism and models used in this effort to improve understanding (species 

concentration, strain rate, fuel volatility, etc.). 

d. It was not clear how the concentration threshold was being set or what its validity 

is. 

6) 5A/1/012 Parametric Investigation of Droplet Atomization and Dispersion of Liquid 

Fire Suppressants 

a. This work seems technically sound and several elements will be useful 

(vaporization, impingement, etc.). 

b. We are comfortable with the progress, and we are pleased to see work with 

additional High Boiling Point (HBP) fluids and the results formed related to 

vaporization and rebounding. 

c. The physics illuminated have strong relevance to practical applications. 

d. This element is also relevant for test methods (difference between water and 

chemical agents.) 

e. This element also has possible use of HBP agents in mist form, screening of HBP 

agents, etc. 

7) 6E/1/3 Verification of Suppression Principles 

a. This program is likely to be the primary method of transitioning many of the more 

valuable results of this program to fire protection engineers and future 

researchers. 

b. The “lessons-learned” portion of this program will be valuable and will respond to 

the previous recommendations of the IRP. 

c. Management must insure that the original PIs for each of the elements of the NGP 

participate fully in contributing to the database. 

d. The lessons learned should include both positive and negative results and be 

focused on both future researchers (Science, R&D Process, etc.) and fire 

protection engineers (Condensed engineering guidelines and data). 

e. The test portion of this program is important but may exceed the resources 

available. 

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8) 4B/5/0123 Assessment of the Search for Alternate Chemicals 

a. Coming to closure on some of the chemical families is important and needs to 

continue. 

b. Establishing rational and realistic low-temperature performance limits is 

particularly satisfying. These limits can easily eliminate promising chemicals if 

the limits are too tight or casually established. This work needs to continue. 

c. The “In Place” IR based detection system reports now planned needs to continue, 

but should concentrate on the methodology, architecture and fundamental 

principals involved because of the advances in technology which are likely to 

occur by the time the concept is likely to be deployed. 

9) 4B/6/23 Environmental Acceptable Suppressants 

a. There is a need for this type of program, especially for the early screening tools. 

b. This program now shows progress on an expanded list of candidate chemicals and 

more information on some chemicals, which may hold promise. The 2004 work 

is expected to provide an expanded set of test data. 

c. The more detailed plan on a cardiac sensitivity-screening tool is particularly 

satisfying. 

d. The 2004 work is expected to provide an expanded set of test data, which may 

offer new opportunities. 

e. This element is maturing fairly late in the program. Anything that can expedite 

this work is encouraged. 

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34 
APPENDIX C. TIME LINE FOR COMPLETION OF THE NGP 

 FY 04 FY05 FY06 

⎪⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎪⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎪⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

 10/1/03 10/1/04 10/1/05 

 HOTWC 2005 (5/05) →⏐ HOTWC 2006 (5/06) →⏐

Project 4B/6 ⏐ -------------------------------⏐ Procure and test set 1 agents (2/04-12/04) 

→ ⏐ Complete final set of agents (6/05) 

→⏐ Final project report (9/05)

Project 6A/1 ⏐-------------------------⏐ Conduct cold flow nacelle tests (3/04-10/04) 

→ ⏐ Complete agent transport/extinguishment mod

→ ⏐ Final report on model (6/05) 

⏐----------------------------⏐Conduct fire extinguishment tests; compa

→⏐Final project report (9/05)

Project 6E/1 →⏐Complete analysis of lessons learned (1/05) 

→⏐ Complete test plan (4/05) 

⏐------------------⏐ Conduct verification tests (6

→⏐Final project report (12/

 Index and archive NGP publications (3/06-6/06) ⏐------------

Final Report Annotated outline (1/05) ⏐---⏐

 Review Draft (2/05-11/05) ⏐--------------------------------⏐

 Review and Completion (12/05-3/06)⏐------------⏐

 Publication (6/06) →

 Complete PP-1059 (≈7/06) 

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