HOTWC 2002

Aerosol Fire Suppression for High Rise Structural Applications

Aircraft Distribution using MetalStorm Technologies

John BrooksFirepak Oil and Gas Industries Ltd.

Dr. Julia BerezovskyPyrogen Australia Pty Ltd.

Mike O’ Dwyer Metal Storm Pty Ltd.

Copyright © 2001 J. Brooks, FO&GI

ABSTRACT

Aerosol Fire Extinguishment Agents havebeen under development for the last ten years.PyroGen aerosol is a widely accepted directreplacement for HALON 1301. In high risebuildings above the reach of ladder or aerialapparatus the fire departments are reduced torelying on stairwells to reach fires above thethirty ninth floor. Sprinklers have historicallyprovided suppression in these structures. IfPyroGen flooding systems are not installed inthese higher floors, Metal Storm technologymay provide a method to deliver enoughaerosol agent into burning buildings tosuppress the fire until fire fighters can gainaccess and extinguish the fire. Pyrogengrenades have proven to be effective instructural fires in rooms less than 20 cubicmeters. The agent is effective at suppressionand extinguishment, the problem has been theability to get enough aerosol formingcompound into the space to reachextinguishing concentrations. Metal Storm withits high fire rates and Pyrogen with itsexceptional suppression and distribution

are a solution to high rise building fires in thefuture.

PyroGen Generator and Metal Storm launchersmounted on a military or law enforcementhelicopter can provide advanced suppressionand buy time for the fire fighters to confront afire in upper floors preventing a reoccurrenceof the World Trade Center structural collapse.Prior to metal storm technology the ability toget enough Pyrogen into a structural fire limitedthe use of aerosols to total floodingapplications. Suppression or extinguishment oflarge structural fires was just too hard. MetalStorm now allows the ability to introduce up toone thousand kilos of aerosol formingcompound into a building floor in less than 10seconds from hovering aircraft.

INTRODUCTION

PyroGen Aerosol is a solid propellantextinguishment agent that is proven to be moreeffective for flooding than Halon 1031. Withestablished extinguishment concentrations at100 grams per Cubic Meter (100g/M3)Pyrogen is an effective and efficient chemical

agent. Metal Storm originally designed as aelectronic controlled gun system, has fire ratedin excess of one million rounds per minute(1,000,000 RPM). With no moving parts andelectronic control a Metal Storm 40MM-launchtube is perfect to deploy large amounts ofPyroGen Aerosol Agent. A 40MM PyroGenGenerator containing 250g of aerosol formingcompound (AFC) is fitted into the Metal StormLauncher Box. The 40MM Grenade is launchedinto the fire in large enough quantities toextinguish or suppress high rise structural fires.Large quantities of fire fighting agent can berapidly deployed up to rates of 20,000 perminute.

Fig 1. 40 MM PyroGen Generator

MAIN SECTION

Historically fixed sprinkler systems have beenused to suppress or control high rise structuralfires. Recent events have shown that underhigh fuel loads or when the sprinklers fail,structural failure can lead to building collapse.Structural failure has always been a mainconcern for fire fighters, especially in buildingswhere access is restricted or flame fronts aretoo high limiting hose team access.

PyroGen Aerosol

Pyrogen is a patented, US EPA SNAP listedchemical Aerosol Fire Fighting Agent. Startingin a solid pellet the aerosol forming compoundis thermally decomposed in a canister orgenerator. The Out gas components are mainlynitrogen N2, water vapor and a carbonpotassium compound the actual fire fighting.PyroGen is a chemical agent. Thiscarbon/potassium crystal prevents thecombination of free radicals of Oxygen O andHydrogen H in the flame reaction. PyrogenAerosol Forming Compound (PAFC) is aPolymer composition highly impregnated withendothermic ingredients into a solid pellet.

KNO3(s) + CnHmNpOq(s) + C(s)

The size and shape of this pellet determinesthe discharge time and internal pressure of the

aerosol generator. Out gas componentsconsist of solid potassium carbonates, carbondioxide gas, nitrogen gas and water vapor.

KHCO3(s) + K2CO3(s) + CO2(g) + N2(g) + H2O(g)

The out gases from the thermal decompositionprocess of the PAFC is passed through acooling medium of magnesium-oxide The AFCand coolant are enclosed in a metal cylinder,This assembly is referred to as an PyroGenAerosol Generator. The generators aremanufactured in various sizes from 20g to20Kg. For discussion this paper will focus on anewly designed 250g generator capable ofbeing launched from a 40mm Metal Stormfiring tube. This design has a discharge time of8-10 seconds creating a 2.5 cubic meteraerosol cloud at 100g/M3.

Fig 2. 250g Air Launch PyroGen Generator

The PyroGen generators produce an gas cloudof inert gases and chemical fire fighting agent.The chemical agent, a micron sized solid, actslike a gas and will follow the natural convectioncurrents created by the fire. As air is drawn intothe flame front, PyroGen aerosol is also drawnin also. Even at concentrations below 100g/M3it is effective at reducing flame intensity andabsorbing thermal energy.

Metal Storm Launcher

The Metal Storm launching system is a multibarreled computer controlled system. ACaseless propellant is used to propel the andarm the PyroGen generator. Operating like anInk jet printer it can direct a firing voltage to anybarrel and can fire from one to ninety sixgenerators at a time. In addition to fire fightingaerosol generators, the same launcher can

also launch warning devices or alarm sirensThis can allow for evacuation of offices prior todischarging the aerosol generators. The lacksof moving components, propellant cases orshells make the deliverable agent to podweight ratio of the launchers one of the highestever designed.

The air launched system is designed to bemounted externally to any military or civil lawenforcement helicopter. The box launchercontains ninety-six (96) barrels each containing20 air launched PyroGen generators. Onethousand nine hundred twenty (1920)generators per launcher. Two box launchersare place on each side of the helicopter. Aquick attach system is used to allow for rapidloading and re-arming of the delivery aircraft.Launcher systems can be pre positioned atrefueling heliports or transported to landingsights for rapid employment of this novel firefighting system. A simple self-contained / selfpowered box launcher can quickly be added toany helicopter.

Fig.3 Skid Mounted Launcher

The Metal Storm Launcher is fitted to the skid /side door with an firing control imbecile cableprovided to the copilot or crewman. Dischargeand fire rates are computer controlled anddetermined by building / floor volumes and areindependently configurable based on theemergency. Copilot/observer can rely pre fireplans to predict the number of generators andthe delivery timing to produce the best results.The flexibility of the MetalStorm launchingsystem allows on scene adjustments ofdelivery rates and the amount of aerosolforming compound introduced into the fire. Thisallows for adjusting from a single office fire to afull conflagration like the World Trade Centerinferno. Weather conditions, winds and thermalconvection currents can be fed into thecomputer to insure the best aerosoldistribution.

Rapid Deployable, self contained system

Fig 4. Launch Tube Configuration

Metal Storm/PyroGen fire fighting methodcombines two new technologies providing anew and novel fire fighting system. A highlyefficient fire extinguishing agent with a rapidvariable delivery system, PyroGen, as aflooding agent is three times more efficientthan Halon 1301. Its ability to be used as astreaming agent is yet to be fully proven.

Fig 5 Airborne Launcher

The ability to achieve adequate agent levels asa streaming agent have never tried and havebeen limited by the ability to get the requiredamount aerosol forming compound into theflame front. This delivery problem has beenover come with the airborne launcher system.

A generator departure velocity of 35 meters persecond and convergence laser aiming systemmounted to each launcher allow for aiming anddelivery without a great deal of training. Thepilot simply flies the aircraft and points thelaser spots on the agent entry point. This isdone up wind allowing good visibility for thecrew and introduction of the fire fighting agentinto the fire the same way the oxygen is beingintroduced. When the laser spots from thelaunchers collate the observer or copilot firesthe system.

Pre loading the launcher firing rates in the podcomputer or controller can be done prior tolaunch or on scene depending on the systemdesign. This flexibility allows for an initial

knockdown and follow up depending on the onscene commanders requirements.

In the past if the PyroGen Aerosol System wasnot pre engineered and installed as asuppression system, it was not practical todeploy the system after the fire wasdiscovered. With the adaptation of theMetalStorm Technology now allows us to lookat the aerosol agents as a new method ofsuppression or extinguishment. When firedfrom a helicopter into a burning structure, thesuperior knockdown capabilities of PyroGencan be exploited. Metal storm launcher boxeshave the capability of introducing far in excessof the 100g/M3 extinguishing concentrationsrequired. Four launchers can carry over 1800Kg (4000 lbs.) of aerosol forming compound.Enough to flood over 1900 cubic meters (1900M3) or 31,000 cubic feet. Load factors forindividual helicopter airframes also dictate thenumber of pods and delivery rates. Distributiontimes can be varied based on the volume toprevent overpressure caused by the volume ofthe fire fighting agent. The out gas of the40mm air delivered generator is approximately3 liters of gas per gram of aerosol formingcompound. Delivery rates and entry points willneed to be determined on scene by thepilot/observer.

The launcher box is attached to the helicopterskid via a quick clamping system. Thecomplete fire fighting system is self-containedwith multi launch tubes containing the aerosolgenerators, laser aiming system and power.Total weight and carrying capacity of eachhelicopter will need to be reviewed and aUnited States Department of Transportation,Federal Aviation Administration, SupplementalType Certificate (STC) will need to beapproved by the administrator for each typeand model aircraft used to deploy the system.The same self-contained launcher can also beconfigured to fired from land vehicles in futureapplications.

Replacement or reloading of the helicopterlauncher can be done in the field, new freshlaunchers can be carried close to theemergency, and quickly replaced by groundcrew. The quick disconnect skid mountingattachment system is designed to be rapidly reloaded allowing re attack of the fire if required.Prepositioned systems can be located on rooftop helopads in large cities. The system isdesigned to fit on commercial or militaryhelicopter. Local News or traffic helicopters can

be used to ferry launchers into the scene of theemergency.

Other aiming or control technologies may beadded in the future as they mature. Electro-optical and computer controlled systems in thefuture may assist in computing and determiningdelivery rates. Thermal Imaging, analyzingheat flux density or flame propagation / spreadin the structure can improve the effectivenessof the system. Location of the air entry pointfeeding the flame front through this mediumwould enhance the efficiencies of the aerosolfire fighting system. Introduction of thechemical aerosol agent with the natural thermalcirculation of the fire will enhance the gas likedistribution of the fire fighting agent.

Pyrogen Aerosol works in two ways toextinguish fire

Primary:Chemical - Removal of chain carriers

Secondary:Physical - Heat absorption

1. Chemical - removal of free radical chaincarriers OH, H and O in the flame chain

in gaseous phase:K + OH = KOHK + O = KOKOH + H = K + H2O

on particles surface:O + H = OHH + OH = H2O

2. Physical - heat absorption Lowering thefire temperature to a level below which thefire reaction cannot continue

KHCO3 = K2CO3 + CO2+ H2OK2CO3(s) = K2CO3(g)

Heat absorption via endothermic phasechanges

K2CO3(s) = K2CO3(l) = K2CO3(g)

Heat absorption via endothermicdecomposition changes

2KHCO3(s) = K2CO3(S) + CO2(G) + H2O(g)

These two properties combine to make thisone of the most efficient extinguishing agentsystems developed to date.

Metal Storm Technology

The metal storm launcher overcomes severalobstacles that have limited the delivery rates oflaunchers in the past. This innovative approachhas revolutionized the science of rapidcontrollable ballistic delivery systems. Priorsystems were limited by:

1. Cycle time of mechanical componentsused to expel empty propellant cases

2. Heating of launch tubes or barrels

3. Volume of magazines and ammunitionfeed systems

4. Weight of conventional launchers andthese mechanical systems

With no moving parts the cycle time of eachlaunch barrel is controlled only by the timedelay of the computer firing pulse. Storing theprojectile in the launch tube removes themagazines and feed system. The majority ofthe metal storm system weight is fire fightingaerosol generators. Components made fromadvanced composite materials also reduce thesystem weight. Electronic control allowsselection of individual rounds, from individualbarrels, one at a time. These can beprogrammed in cycles or volleys to maximizethe effectiveness of the fire fighting system.

Lifting or payload weight is critical for helicopteroperations. Weight and balance of externalloads have a severe impact on performanceand station keeping of rotary winged aircraft.Metal Storm through its unique computercontrolled delivery system can insure theaircraft remains inside its operation limitations.By selecting launch tubes automatically theside load and weight of each launched pod canbe monitored. Recoil thrust can becounteracted by small counter charges firedfrom the aft end of the launcher. This systemensured that in the heat of the battle apilot/observer do not get the helicopter out of itdesign limits.

Metal storm and PyroGen are a novel blend oftwo evolving technologies. With most majorcities of the world building larger and tallerbuildings innovative methods of firesuppression are required.

CONCLUSION

Incorporation of Pyrogen Aerosol Generatorswith Metal Storm Technology has created anew and novel method of fire fighting.Combating high fuel loading fires in high risebuildings will continue to create challenges tofire departments in the future. A rapiddeployable highly efficient fire fighting systemis needed. The three dimensional propertiesand efficiencies of aerosols agents are onemethod of combating this problem. in .

ACKNOWLEDGMENTS

Richard Healing, Staff Assistant Secretary ofthe Navy, Director Safety and Survivability,Washington, DC.

Joseph E. Wolfe NAVAIR NAWDLAKLakehurst, NJ

Julia Berezovsky PyroGen Australia.

Mike O’Dwyer MetalStorm Inc. Arlington Va.

CONTACT

John Brooks, President, Firepak Oil and GasIndustries 7171 Harwin Dr. Suite 306 HoustonTexas 77036 jbrooks@pyrogen.com

Julia Berezovsky, Ph.D. General ManagerPyrogen Pty Ltd. Australia,

Mike O’Dwyer, President, Metal Storm Pty.Ltd.

REFERENCES.

1. HOTWC Proceedings 1996. ToxicologicalEvaluation of exposure to two forms ofPyrotechnically-Generated Aerosol: rangeFindings and Multiple Dose.

2. NAWCADLKE-MISC-435100-0012 reporton Testing of PyroGen Fire SuppressionAerosol on Boeing 737 EE Bay JosephWolfe VAIRSYSCOM

3. HOTWC Proceedings 1999 PyrogenGrenades Julia Berezovsky, Ph.D. GeneralManager Pyrogen Pty Ltd. Australia

4. NAWCADLKE-MISC-435100 January 14,2002." Follow on testing

DEFINITIONS, ACRONYMS, ABBREVIATIONS

PAFC PyroGen Aerosol Forming Compound

ADFFP Air Delivery fire fighting Pod

NFPA National Fire Protection Association

FAA Federal Aviation Administration

AUVSI Association of Unmanned Vehicles andSystems International.

ALDS Air Launched Delivery System

MSLB Metal Storm Launch Box