3S Fire LLC. FIRE BEHAVIOR 1. 3S Fire LLC. 2 TACTICAL TRIANGLE 3 TACTICAL DECISION FIRE BEHAVIOR...
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Transcript of 3S Fire LLC. FIRE BEHAVIOR 1. 3S Fire LLC. 2 TACTICAL TRIANGLE 3 TACTICAL DECISION FIRE BEHAVIOR...
3S Fire LLC.
FIRE BEHAVIOR
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3S Fire LLC.
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3S Fire LLC.
TACTICAL TRIANGLE
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TACTICAL DECISIONFIR
E B
EH
AVIO
RBU
ILDIN
G
CO
NSTR
UC
TION
CAPABILITIES AND LIMITATIONS
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Science A branch of knowledge or study
dealing with a body of facts or truths systematically arranged and showing the operation of general laws.
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Fire Fighters that use scientific factsEarn CredibilityCan Defend their Actions LegallyTeach to Referenced/Documented
Standards and PracticesCan Protect Themselves Are Fire Fighter’s that Think for
Themselves
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Scientific Testing ProvidesCommon standards used by manufacturers
for designMeasurable limits and capabilitiesPoints of reference to base tactical and
strategic decisionsFire Fighting Facts that are referenced and
documentedFacts for lawyers
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Science = Life Measurable
Documented
Justifiable
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FIRE BEHAVIOR
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A FOUNDATION BUILT ON SCIENCE
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UNDERSTANDING OUR ENEMY
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GETS RID OF THE BOOGIE MAN
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A BASE LINE PERSPECTIVE11
GETS US ALL ON THE SAME PAGE
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FIRE BEHAVIOR SCIENTIFIC FACTSFire Triangle – Fuel, Air, HeatASTM E-119 TestStandard Time Temperature Curve (1916)Ordinary fuel load – Btu’s - configurationBtu’s in a cubic ft. of air – rate?Flame spreadSmoke expansion – Charles LawFlammable Range of smoke (CO)Temperature at the floorReading the heat in the smokeThermal BalanceRate of Change
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FIRE TRIANGLE/TETRAHEDRON
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Understanding the science within the fire triangle/tetrahedron builds your tactical & strategic
perspective on a scientific foundation, that verifies your experience and the experience of others.
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FUELThree States of
Matter:1. Solid2. Liquid3. Gas
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FUELTwo Categories:Hydrocarbon Based: Gasoline Diesel Fuel Oil Plastics, etc
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FUEL
Cellulose Based: Wood Paper Cotton Natural Fiber
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COMMON FUELSMost Common Fuels
Contain:1. Carbon2. Hydrogen3. Oxygen
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SOLID FUELSThe Initiation of Combustion Requires Phase
Conversion to a Gaseous State by HeatingFuel Gases are Evolved from Solid Fuels by
PyrolysisThe Speed of Pyrolysis is Affected by it’s
Arrangement and Surface Mass Ratio
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SOLID FUELS
Ignition Temp. 451 Deg. FOrdinary Combustibles- 8,000 btu’s per lb.Hydrocarbon (Plastics)- 16,000 btu’s per lb.
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Air - Ventilation
Fuel controlled fire, the growth is determined by the amount of available fuel with an abundant supply of air
When burning in the open or early stage of compartment fire, where there is excess air available
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Air - Ventilation
Ventilation controlled fire, the growth is determined by the amount of available air
A ventilation controlled fire occurs when there is not enough air to burn the materials being pyrolyzed
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Air – Ventilation - Profile
Based on ASTM- E119 testsRatio of ventilation opening to floor area
involvedOrdinary Development =10% to 15%
ventilation to floor area ratio Accelerated Development = More than 15%
ventilation to floor area ratioVentilation Controlled = Less than 10%
ventilation to floor area ratio
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THORTON’S RULEThe Heat of Combustion per kg of O2
Consumed is Nearly Constant for Most Organic Fuels, 13.1 kg per Gram of O2 Consumed
Most fires We Go to Are Ventilation ControlledThis Means that Hydrocarbon based Fuels
and Cellulose based Fuels have About the Same (hrr) Heat Release Rate
Once the Fire is No Longer Ventilation Controlled, the Hydrocarbon Based Fuels can Release Almost 3 Times the (hrr) Energy as Cellulose based
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THORTON’S RULE
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LIQUID FUELSFlammable Liquids Like Gasoline, Ignition
Temp. Under 100 Deg. FCombustible Liquids Like Diesel, Ignition
Temp. Above 100 Deg. F125,000 to 140,000 btu’s per GallonMost Flammable and Combustible Liquids
Will Float on Water as They Have a Lower Specific Gravity than Water
Polar Solvents and Alcohol Will Mix With Water
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GAS FUELSCompressed Gas Fuels like Propane and
Natural Gas, or Carbon Monoxide and Hydrogen
Propane -2,500 btu’s per cu/ftNatural Gas -1,100 btu’s per cu/ftCarbon Monoxide – 323 btu’s per cu/ftHydrogen – 325 btu’s per cu/ftRequires No Pre Heating to Ignite
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British Thermal UnitsBTU’s WE LOVE EM!
Quantifies heat release rate for building construction strength.
Quantifies heat release rate for fire development
Quantifies water1 BTU is the amount of heat required to raise a pound of water 1 degree fahrenheit from 60 degrees fahrenheit.
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ASTM E-119
POINT “A”A Place to START!
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ASTM - E119Methods of Fire Tests of Building Construction and MaterialsHelps to build a SCIENTIFIC perspective for
fuel loading and configuration Still used today -Standard Time Temperature
Test (since 1918)Helps to build a SCIENTIFIC perspective for
HEAT IN YOUR WORK PLACE!Our battlefield the fire structure is built on
this testing
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Ordinary fuel load is 8,000 btu’s per pound,10 pounds per square foot. 80,000 btu’s per square foot
1 Hour FireWood, paper, textiles
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Minimum size for test specimensFloors and Roofs 160 squ. Ft.Partition and Walls are 380 squ. Ft.
Length x Width x Height = Cubic Feet
8 x 10 x 8 = 640 cu. ft.
The Box
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Furnace test replicates the wood crib test fuel load’s heat release rate of 8,000 btu’s per pound at 10 pounds per square foot. 80,000 btu’s per square foot for a 1 Hour Fire.
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STANDARD TIME TEMPERATURE CURVE (1917-1918)
Temperatures at Ceiling5 minutes 1000 deg. F. TP - ignition source10 minutes 1300 deg. F. 15 minutes 1400 deg. F. 20 minutes 1460 deg. F. 25 minutes 1510 deg. F. 30 minutes 1550 deg. F.45 minutes 1638 deg. F.TP- wired glass60 minutes 1700 deg. F.
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1 hour 1700 deg. F. 80,000 btu’s/square foot2 hour 1850 deg. F3 hour 1920 deg. F. 4 hour 2000 deg. F. 8 hour 2300 deg. F.
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ASTM E-119Pass/fail criteria are based upon the peak
temperature attained at the back of the test article and/or whether or not the test article collapses or distorts in a fashion that allows hot gases to escape (and in the case of E119, whether the wall can withstand the pressure of a hose stream).Wall & Floor Assemblies: 325 deg. F. at any one point or 250 deg. F. overall•FF Practical Tactical – non burning side touch.Structural Elements Supporting the Load: 1200 deg. F. at any one point and 1000 deg. F. overall•FF Practical Tactical – water sheen.
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NFPA Surveyed Fuel LoadsType of Room Contents
lbs. per square footBtu’s
per square foot
Bedroom 4.3 34,400
Living Room 3.9 31,200
Dining room 3.6 28,800
Kitchen 3.2 25,600
Family room 2.7 21,600
Nursing home Pt. room 2.6 20,800
Hospital Pt. room 1.2 9,600
ASTM-TEST (STTC) 10 80,000
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Peak Development for Ordinary Fire is 4,8oo (Vito)
BD
FO
Fully Developed4,800 - 5,000 btu’s /squ.
ft./min.129 – 135 cfm
DecayGrowth
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ASTM E-119 Test load vs. N.F.P.A. surveyed load
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Real World Half the Load!
5 lbs/sq.ft.
10 lbs/sq.ft.
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What about plastics? 16,000 btu’s per pound!
Remember half the load compared to the test loadLess Mass: plastic is stronger per pound than
woodVentilation effect in structures
Incomplete combustionWhat is the air flow rate?
How much water do you really need?
How much air does the fire need?
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Factors that affect Fire Development
Surface to Mass Ratio Location of the fuel (center , wall, corner) Size, number, and arrangement of the vent
openingsVolume of the boxCeiling Height of the box 8’Target Fuels
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Surface to Mass RatioThe more air that reaches the surface of the
fuel the higher the HRR. The lighter the fuel the faster the HRR.
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Location of the Fire in the BoxFires in the middle of the room entrains air
and are cooler.Fire against the wall is 50% higher HRRFire in the corner is 70% higher HRRThe walls reflect heat back to the fire
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You & Your EnvironmentVolume of the box 8’x20’x8’=1,280 cu’In a room of a 160 square feet (8x20, 16x10) a
fuel load of 16 square feet (4x4)at 10 lbs per square foot (2) upholstered chairs, That would fill the box with incomplete combustion.Limited space for heat & conversion space
The same fire in Costco would be complete combustion and you would be able to walk right up to the fire.Plenty of room for conversion and convected heat
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Ceiling Height8’ ceilings - Residential StructuresAllow for horizontal spread of 40% of the heat of
the fire by convection. (touch)Heat is radiated to the other target fuels and the
floor from the convected heat layer trapped below the ceiling
When convected gas ignites and can add an additional 40% of the fires heat by radiation (light)
In general, during a growth stage fire, when 500 degrees F. is reached at mid wall, zero visibility opposite wall from fire, and off gassing at the floor, flashover is possible.
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Target FuelsThe fire spreads to other target fuel in the
box hot to cold40% radiation
Light source40% convection
Suspended gas heat20% conduction
Through a solid hot to cold
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Ventilation Profile for Ordinary DevelopmentBased on ASTM - E119 testsRatio of ventilation opening to floor area
involvedOrdinary Development =10% to 15%
ventilation to floor area ratio Accelerated Development = More than 15%
to floor area ratioVentilation Controlled = Less than 10%
ventilation to floor area ratio
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Air - VentilationOrdinary fire development needs a
minimum of 10 -15% of the floor area in ventilation openings not to exceed 25-30% related to the exposed fuel surface area.
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Ignition Temperature of 4510 F
Ordinary fire development needs a minimum of 10 -15% of the floor area in ventilation openings (square foot of fire)
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640 cubic feet of air = 23,680 BTU’s available
(for this moment in time)
23,680 BTU’s / 9,330 BTU’s = 2.53gallons
536 btu’s in a cubic ft of pure oxygen
21% Oxygen in Air with 7% of the 21% available for combustion
536 btu’s times 7% = 37 btu’s per cubic foot of air
How many btu’s per cubic foot of air?
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Every increase of 459O F, Gas Volume Doubles
Charles’s Law – Volume of a given mass of gas is directly proportional to absolute temperature if pressure is kept constant. Every increase of 459 deg. F., Gas Volume Doubles
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910O F Gas Volume Doubled
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1000O F at 5 minutes STT
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6 to 12” per second – Flame spread
Jet Flame vs. CO burning
1000O F at 5 minutes STT
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1000O at 5 minutes
6” to 12” per second – Flame spread
Ref: NFPA 19th ed. Vol.1 chp.2 pg.106
CO Ignition Temp: 1128 deg. F.
Flammable Range: 12.5 – 74%
Btu’s per cubic foot: 323 btu’s
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Flammable Range of Carbon Monoxide
Carbon Monoxide12.5% to 74%Ignition Temperature
1128 deg. F.
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1000O at 5 minutes
6” to 12” per second – Flame spread
13.2 btu’s / sq. ft.
CO Ignition Temp 1128 deg. F.
Flam. Range 12.5 – 74%
30 ft./second
Flashover progressing in less than ONE minute
1.8 btu’s per sq. ft./ sec. Off gassing off the Floor
1.8 btu’s per sq. ft./sec. Radiating to the Floor
Opposite wall from fire - zero visibility - 500 deg. F. at mid wall
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“ HOSTILE FIRE”Flashover
Backdraft
The box can only absorb a limited amount of heat.
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Flashover - Science8 foot ceiling Zero Visibility Opposite Wall of the Fire500 deg. F. mid wall and Fire on the
Ceiling1.8 btu’s / second / sq. ft. of energy off the
ceiling radiating to the floor, bringing common combustibles to their ignition
temperatureThe structure is unable to absorb heat8 – 15 minutes to FLASHOVER
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FLASHOVERWARNING SIGNS:Growth Stage FireExtreme Heat -1128 F.
at ceiling or 500 F. mid wall
Heat Stained Cracked Windows – 600 F.
Box can’t Absorb HeatHigh Velocity SmokeTurbulent Dense Smoke Inadequate VentilationVent Point Ignition
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Life of the WindowClear WindowLight smoke, non – obscureMedium smoke, obscure, life concerns (12,500ppm
or 1.28% of CO)Medium smoke, obscure, condensation, room below
212 deg. F. life, (150 deg. F. not likely to exit into).Heavy smoke, obscure, heat stained without
moisture, room above 212 deg. F. life, (300 deg. F. can be lethal).
Heavy smoke, obscure, cracked, life?, (600 deg. F. single pane window failure) fire on ceiling
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Life of The Window3 mm single pain float glass cracks at about
600 deg. F.4-6 mm single pain float glass cracks at about
800 deg. F.6 mm double glazed about 1100 F.Vinyl Frame Window failure 8-16 kw m2, the
window glass drops from frame
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Life of The WindowTempered Plate Glass fails after flashover
about 1200 F., generally it will just shatterFire Resistive Glass failure 26 kw m2Wired Glass will generally fail and fall from
frame about 1638 deg. F.Correlate cracked or failed windows to fire
behavior, what’s going on in the box
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N.F.P.A. Prediction of Flashover Method
Qfo=610(HkAsAv h2)1/2
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BACKDRAFTBackdraft is triggered by O2 being
introduced to a pressurized “box” Yellowish-grey smoke Whistling Heat Stained Windows with Extreme
Heat “Sealed” containers Hot and Quiet
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Door ProceduresCheck Fire FlowAssess Door as
Shield/ControlCheck for HEATCheck for PressureOpen door for VentilationFeel for HEAT LiftRead the Smoke directionLook & listen for life & fireAssess the “Rate of Change”
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Rate of Change
Are conditions getting better, staying the same, or getting worse?
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Thermal Balance
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MAINTAIN THERMAL BALANCE
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BETTER TO BE LUCKEY, OR GOOD?
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