Fire Behavior Understanding the Basics Pat Hultman FF/MICT/LEO-AAS Training Officer

Learning Outcomes List different types of Extreme Fire Behavior Differentiate between Fuel and Air controlled fires Understand the importance of reading smoke and fire Appreciate the dangers assosciated in regards to extreme fire behavior

Why this matters In 2007, 20 LODD due to Extreme Fire Behavior. Plus numerous close calls. Video 4.5 min. !!!1:41!!!

Fire Tetrahedron Fire Triangle H2O?? Combustion C 6 H 12 O 6 +6 O 2 =6 CO 2 +6 H 2 O

Flame Types

Fuel State What Burns? So how does a solid burn? –Pyrolisis

Fire Gases and Pyrolisis Common Fire Gases –CO –HCN –Hydro Carbons Methane Propane Pyrolisis –Decomposition by heat –↑ build up of combustible gases –Where does the heat come from?

Heat Transfer Conduction –Direct transfer through contact Convection –Transfer through a medium such as air, H2O, etc Radiation –Transfer in the form of light energy

Understanding Radiant Heat Is radiant heat visible? At 900° F visible Heat Release Rate –Cigarette 5w –Wastebasket KW –Pool of Gasoline (2 QTS) 1MW –Sofa 1-3 MW Direct Summer Sun –1kw/m² 100° F Surface No Pain Near Proximity to Fireplace –10kw/m² ° F Surface 2° Burns ≤ 10Sec Scorching of and Melting of Adjacent to flames –50 kw/m² 800° F Surface –Autoignition of nearly all materials in ≤ 5 sec The avg residential fire will double in size every secs

Limits of Flamability LFL/UFL What are some materials you can think of? Propane % Ideal 4% Gasoline 1-6% Acetylene % CO % What is this in PPM (move decimal right add 3 zeros) Think about the CGI –We know we are immersed in flammable gases when going into a fire

Smoke is Fuel Smoke Video

Smoke is Fuel

The Neutral Plane Two Separate Layers –Hot Buoyant Combustible gas Major source of radiant heat –Cooler, cleaner Commonly discussed as thermal layering (Discussed More Later)

Fire Progression Stages of Fire –Phase 1 Incipient and Growth Stage –What is happening? –What is the next phase? –Phase 2 Flashover What happened? Auto-ignition temp –What is the significance? »Transition From Room and Contents –Phase 3 Fully Developed –Phase 4 Decay Stage What is a significant threat at this stage?

Extreme Fire Behavior Smoke Explosion Flame Over Flash Fire Fire Gas Ignitions Flashover Back Draft The Firefighter must remain ever vigilant of the conditions around them These are not some strange uncontrolled phenomenen. There are key things to watch for both inside on the knob and outside as IC.

Flashover Sudden and Sustained transition from a developing fire to a fully developed fire. 2/3rds of the heat is radiated down from the neutral plane Video 1:01

Signs and Symptoms of Flashover Ventilated Fire Painful Radiant Heat (forces you down) Hot Surfaces (Conduction) Lowering Neutral Plane –Fingers of flame – Dancing angels Increased Pyrolisis Increased turbulence of smoke and flame

Back Draft The spontaneous ignition of combustible fire gases. What are some cause? Why? –Gases at auto ignition temperature –Lack of Oxygen  Pyrolisis will continue to occur until sufficient cooling Video 0:44

Signs and Symptoms of Back Draft No or limited ventilation Lack of visible or blue flame Thick rolling black, yellow, or white smoke Smoke Pulsating/Whistling

Point of No return 5 feet (Chief Dunn) Burns 118° F 131° F 152° F –Heat Output »Trash Can Fire

Methods of Extinguishment Direct vs. Indirect –Smooth Bore vs. Fog Gas Cooling –Can disrupt neutral plane –Use small fine droplets in short bursts to minimize –How much water in GPM for a 19x16 MBR »300 ft² approx »Round Up to 375 ft² or 3000 ft³ for chart »NFA- 125 GPM »Iowa – 30 GPM »3D- 75 GPM

Case Study April Y/O Kyle Robert Wilson 2 yrs exp AM Weather- 25 MPH sustained