Small Scale Fire Behavior Prop Demonstration

Summary

This video demonstrates small-scale fire behavior training using a specialized box prop. Led by Sean Gray and Deputy Chief PJ Norwood, the session covers how to set up, burn, and teach firefighters the fundamentals of fire behavior. The box simulates different fire scenarios, highlighting how ventilation, oxygen control, and modern vs. legacy fuels affect fire dynamics. The training emphasizes the importance of understanding smoke color, velocity, and neutral planes. Techniques such as ventilation-induced flashovers and bi-directional flow are showcased, teaching valuable lessons in fire tactics and firefighter safety.

Takeaways

• 🔥 The fire behavior training uses a box to simulate real fire scenarios, allowing firefighters to understand and control fire behavior.
• 🌾 Fuel is placed only in the lower left compartment, consisting of dry straw and pine strips, with no additional fuel in the other compartments.
• 💨 Observing smoke characteristics, such as color, velocity, and density, is crucial for understanding fire behavior.
• 🚪 Ventilation control is key in manipulating fire growth, by opening or closing compartments to increase or decrease oxygen flow.
• 🧪 Polystyrene materials (e.g., styrofoam cups) are added to simulate modern fuel, showing the difference in smoke density and color.
• 🌫️ The demonstration emphasizes the importance of bi-directional flow and neutral planes in fire behavior, especially in structural fires.
• 🔥 Ventilation can drastically change fire behavior, sometimes leading to flashover if not carefully managed with proper openings.
• 🪵 Controlling airflow can effectively choke out a fire, similar to shutting an oven door during a fire to smother it.
• 🏠 The training simulates various fire scenarios, including vertical ventilation and roof operations, to demonstrate the effects of adding or removing oxygen.
• 💡 The drill highlights that ventilation does not cool a fire, only water does, and ventilation must be coordinated with firefighting operations.

Q & A

What is the main focus of the training discussed in the script?

The main focus of the training is small-scale fire behavior and how to teach firefighters about it using a fire behavior training prop.

What materials are initially used to start the fire in the training box?

The materials used to start the fire are dry straw and pine strips, which are placed only in the lower left compartment of the training box.

Why is only the lower left compartment filled with fuel?

The fire behavior is intended to begin in the lower left compartment, and as the fire progresses, the box itself becomes the fuel, hence no additional fuel is needed in the other compartments.

How does controlling ventilation openings affect the fire behavior?

Controlling ventilation openings by opening and closing them can change the fire behavior by either decreasing or increasing the amount of oxygen into each compartment.

What is the purpose of adding polystyrene materials to the fire?

Polystyrene materials are added to demonstrate the difference in smoke characteristics, such as density and color, when modern fuel packages are involved.

What does the color and density of the smoke indicate during the training?

The color and density of the smoke indicate the type of fuel burning. Light-colored smoke signifies legacy fuels like hay or straw, while darker and denser smoke indicates the presence of modern fuels.

What is a neutral plane and how is it demonstrated in the training?

A neutral plane is the level where the smoke and hot gases separate from the cooler, fresh air. It is demonstrated when the smoke escapes out the top of the box and fresh air is drawn in from the lower part.

How does the fire behavior change when the lower right compartment's door is opened?

Opening the door between the lower left and lower right compartments changes the fire behavior by allowing the lower left to become an outlet, and the lower right to experience bi-directional flow with an exhaust and intake of fresh air.

What is the significance of the fire flashing when the lower left compartment is opened?

The fire flashing when the lower left compartment is opened signifies that the fire is rapidly transitioning to a more aggressive state due to the increased availability of oxygen.

How does roof ventilation affect the fire behavior as demonstrated in the training?

Roof ventilation, when properly coordinated with fire attack, can be positive by increasing the velocity and density of the smoke, but it requires breaking down the sheetrock to be effective, as demonstrated by opening the slide trays.

What is the key takeaway from the training regarding ventilation and fire behavior?

The key takeaway is that ventilation, whether through opening compartments or roof operations, significantly affects fire behavior by controlling the amount of air available to the fire, which in turn affects the heat and potential for flashover.

Outlines

00:00

🔥 Introduction to Fire Behavior Training

The video opens with Sean Gray and Deputy Chief PJ Norwood discussing small-scale fire behavior training. The setup involves a firebox used to demonstrate the basics of fire behavior and tactics. The fire is started in the bottom left compartment with dry straw and pine strips, progressing as the firebox itself becomes fuel. Observing smoke color, velocity, and density is emphasized to teach students about fire growth and ventilation effects.

05:02

🚪 Ventilation and Fire Behavior

This section delves into the role of ventilation in fire behavior, as firefighters control air flow by opening and closing compartments. By adjusting the air supply, the fire's intensity changes. The video demonstrates how the compartment fire can be extinguished by limiting oxygen, similar to closing an oven door during a fire. The importance of controlling air sources and its effects on fire is highlighted.

10:02

🏠 Fire Movement and Compartmentalization

In this part, the video focuses on fire movement through compartments. Opening up compartments allows fire and smoke to migrate, illustrating how fire seeks oxygen. As openings are manipulated, changes in fire behavior are observed, with increased turbulence and smoke density. The explanation ties into real-world scenarios, showing how controlling openings in a building can either snuff or spread a fire.

15:03

🏗️ Understanding Fire in Multi-Story Structures

The video explores how fire behavior differs in multi-story buildings, with smoke and heat spreading across various levels. As compartments are opened, more oxygen feeds the fire, increasing heat and the chance of flashover. Ventilation strategies are examined, demonstrating that more air leads to more intense fires, reinforcing that ventilation alone doesn’t cool a fire—water is necessary to manage the heat.

Keywords

💡Fire behavior

Fire behavior refers to the way fire reacts, grows, and spreads under different conditions. In the video, the presenters demonstrate how different materials, ventilation, and fuel sources influence the fire's intensity, heat, and smoke. By observing the fire in different compartments of the training box, firefighters can learn how fire behaves in real-life situations.

💡Ventilation

Ventilation is the process of controlling the airflow in and out of a fire-affected area. In the video, ventilation is demonstrated by opening and closing compartments in the box, which alters the fire’s behavior by either providing or restricting oxygen. The video stresses that ventilation can either help control or intensify a fire, depending on how it’s managed.

💡Polystyrene materials

Polystyrene materials, such as styrofoam, are used in the video to show the difference in smoke production when burning modern synthetic materials. When these materials are added to the fire, the smoke becomes denser, darker, and more dangerous. This is contrasted with legacy fuels like straw, demonstrating how modern home fires often burn differently due to synthetic materials.

💡Bi-directional flow

Bi-directional flow occurs when heated gases escape through the top of an opening, while fresh air is drawn in through the bottom. In the video, this phenomenon is observed in the box as fire spreads, helping firefighters understand how air movement affects the growth and spread of the fire. It’s a key concept in understanding fire ventilation.

💡Neutral plane

The neutral plane is the boundary where hot gases and smoke exit through the upper part of an opening, and cooler air enters from the lower part. The video demonstrates this during the fire in the compartments, showing how it becomes more visible as the fire progresses. Recognizing the neutral plane helps firefighters gauge the fire’s intensity and the effectiveness of ventilation.

💡Legacy fuels

Legacy fuels refer to traditional materials like wood, hay, and straw that were common in older homes. In the video, these materials are burned first to demonstrate their slower fire growth and lighter smoke. This contrasts with modern synthetic materials, highlighting how fires in older buildings behave differently from those in newer, synthetic-furnished homes.

💡OSB (Oriented Strand Board)

Oriented Strand Board (OSB) is a type of engineered wood made from layers of wood strands. In the video, OSB is used in the training box, and once it heats up and starts off-gassing, the fire rapidly intensifies. The inclusion of OSB in the burn shows how common building materials can become significant fuel sources in a fire.

💡Flashover

Flashover is the near-simultaneous ignition of all combustible materials in a space due to intense heat. In the video, a ventilation-induced flashover is demonstrated when the fire intensifies rapidly after an air source is provided. Understanding flashover is critical for firefighter safety, as it marks a dangerous escalation in fire conditions.

💡Backdraft

Backdraft is an explosive event caused by the sudden introduction of oxygen to a fire that is oxygen-starved but still producing combustible gases. In the video, the instructors explain the difference between flashover and backdraft, emphasizing the importance of controlling ventilation to prevent such dangerous occurrences.

💡Compartmentalization

Compartmentalization in the video refers to dividing the fire training box into different sections, each with its own air and fuel supply. By opening and closing these compartments, the trainers simulate different fire scenarios and demonstrate how controlling airflow can either limit or accelerate fire spread. This concept is applicable to real-world firefighting tactics in buildings.

Highlights

Introduction of the fire behavior training using a small-scale fire behavior prop to simulate various fire dynamics.

Explanation of how the box simulates different compartments where fire can behave in unique ways based on fuel placement and ventilation.

Importance of observing smoke color, density, and velocity to understand the type of fuel burning and the fire’s behavior.

Comparison of legacy fuels like straw and pine with modern fuels like polystyrene, showing how they produce different smoke characteristics.

Demonstration of how ventilation control impacts fire behavior by opening and closing compartments to either fuel or starve the fire.

Illustration of the neutral plane and bi-directional flow in the box, where hot gases escape and fresh air is pulled in to sustain combustion.

Discussion of how controlling airflow can snuff out fires, similar to closing an oven door in a household fire scenario.

Incorporation of flashover concepts, where increasing air can rapidly heat up the box and cause a ventilation-induced flashover.

Explanation of how unburned combustion products, like smoke, can ignite when heated to sufficient temperatures, showcasing the danger of incomplete combustion.

Observation of how smoke and heat can migrate through the compartments of the box, simulating fire spread in a two-story wood frame house.

Emphasis on the importance of coordinated fire ground operations, showing how ventilation without water application can actually increase fire growth.

Demonstration of roof ventilation and the importance of breaking down sheetrock after cutting a hole to effectively release smoke and heat.

Highlight of the effects of multiple ventilation points, where more air increases fire intensity and growth, eventually compromising the structural integrity of the box.

Reinforcement of the principle that ventilation alone does not cool fires—water application is essential to control and extinguish a fire.

Conclusion with a summary of how the training covers fire behavior, fire attack, search and rescue, and ventilation techniques.

Transcripts

[Music]

welcome to fire engineering training

minutes I'm Sean gray out here with

deputy chief PJ Norwood and today we're

going to be talking about small scale

fire behavior training here behind us we

have the box that we have all the plans

and building plans that you'll be able

to get and PJ is going to walk you

through the whole entire process of

setup how to burn the box and how to

teach your firefighters fire behavior so

welcome so this is an excellent fire

behavior training prop that can be used

to show the basics of fire behavior but

you can also incorporate your tactics

into today we're going to show you the

basics of fire behavior and how we burn

this box and move the fire through this

box that we demonstrate multiple facets

of fire behavior might help us hear from

Cobb County Georgia they're going to

come in they're going to light the fire

in this box and while they do that I'm

going to show you what we're using for

materials so we're starting off with

some dry straw and some pine strips this

dry straw pine strips is located only in

the lower left compartment of this box

that's the only compartment that we're

putting fuel into because that's where

the fire behavior is going to begin as

this fire progresses and burns the box

itself becomes the fuel that's why there

is no additional fuel needed in

compartment 3 or compartment 2 which is

the bottom right and the top right

compartment so again the only

compartments that fuel is going into is

the bottom left what we want to explain

to our students as this fire is lit and

begins to grow you start looking at the

smoke start looking at the color of the

smoke start looking at the velocity and

the density of the smoke and you'll see

the color of the smoke here is light in

color almost a white or a gray you want

to explain to your students that this is

more of a legacy fuel it's your hay your

straw your pine once this compartment

gets going we're going to change that

fire behavior and change how the fire

reacts by controlling the ventilation

openings by opening and closing those

ports to decrease the amount of oxygen

or increase the amount of oxygen into

each compartment

we're also going to add some polystyrene

materials to show the difference in the

smoke so now we can then look at modern

fuel package that we're actually seeing

in today's homes the beginning part of

this drill it will at times seem like it

takes a long time for the box to get

going but once the box heats up the OS

and B starts burning and starts off

gassing will rapidly transition to it to

an excellent fire behavior drill so my

two partners here from Cobb County at

this point they're watching the fire

behavior they're taking a look at how

the fire progresses and we're giving it

plenty of air we're allowing the

materials the legacy materials that are

in there to get going to start burning

and start preheating that compartment so

we can get the OS and B burning and off

gassing so now that we have that

compartment going a little bit we're

going to go ahead and introduce some

polystyrene materials so we can see the

difference in the smoke so we're going

to go throw these styrofoam cups into

that compartment and we'll start seeing

a change of the smoke the smoke will

start getting a little denser and a

little darker and you'll start seeing a

little bit more volume they'll also

begin to shut down that compartment and

decrease the amount of air the decrease

the amount of available air in that

compartment to burn as they do that

there's some things you should start to

look for you can see a change in the

color of smoke you can see the neutral

plane you can explain to them the

difference between the new what the

neutral plane actually is in

bi-directional flow so that the smoke

the heating gases are escaping out the

top of the box and the fresh air is

coming in the lower part of the box you

can begin discussing conduction

convection and radiation how your year

actually works when you're in these

environments when you're fighting

structural fires you see my partners at

this point they're just opening and

closing that open they're controlling

the openings just to progress the fire a

little bit more and by adding more air

it's going to increase the speed of that

fire and how that fire will will develop

you'd see now they provided a lot of air

we started seeing that fire come out of

that compartment as he shut that down

you can clearly see a neutral plane you

can

the bi-directional flow and you'll begin

to start seeing that smoke almost puff

and get turbulent as it comes out of

that compartment because that fire

that's burning is just looking for more

air it's looking for air so it's trying

to pull all the available air into that

compartment this is the same as we have

in our house fires now you can see the

smoke is a little bit darker and denser

you can clearly see a neutral plane and

some bi-directional flow and we started

to have a little bit of fire coming out

of that compartment now as he opens up

that compartment just a crack at this

point you'll see that smoke start to

push and you'll see the bi-directional

flow in that air being drawn into that

compartment as he opens up that

compartment more we're providing more

air so we're going to have a greater

fire we have to remember is in our fire

tact tactics whatever we doing on the

building is creating a hole which is

ventilation whether we're fire tack

we're forcing entry were search or

whether a door fails or a window fails

that's providing ventilation in the past

our ventilation was that we thought of

just breaking a window or just cutting a

hole in the roof and what happened here

is he closed down that compartment he

limited the oxygen into that compartment

and actually snuffed the fire out so

same thing we like to talk about during

our fire prevention and education is

when there's an oven fire they just we

tell our occupant to us shut the oven

door and the fire would go out we just

did the same thing here in a wood

structure we just controlled the amount

of air and we actually choked that fire

out

so just by controlling the openings

affects the fire behavior so at this

point in the drill you want to let this

compartment get going again you want to

really start heating that OS and be up

and shortly we're going to open up

compartment three and we're going to

remove the door that goes from four

which is lower right to three to the

lower right so you see we opened up

three but we don't have a lot of smoke

pushing out of there but now as he takes

opens up the door between the lower

right and lower left you're going to see

a change in the fire behavior you're

going to see this lower left become an

outlet only when we stay outlet that's

just where the fire is exhausting out of

that compartment

you don't see a lot of air you don't see

a lot of bi-directional

slow or neutral plane if you take a look

at compartment 3 that compartment is the

SM bi-directional flow you have an

exhaust port but also in the lower part

of that compartment you see the intake

or the inlet of the fresh air that's

traveling across to the lower left

compartment to feed that fire if we were

to shutdown compartment three completely

and lower left we could again choke this

fire out just by limiting the amount of

air as he closes this compartment and we

shut down lower left and you opens that

up just a little bit you're going to

start seeing that smoke puff and you see

it really starving and looking for that

air source so we open up lower left a

little bit more give it the air that it

needs as you can see very little air

allowed that compartment to almost flash

all over like a ventilation induced

flashover so we're going to open up the

lower left and get that compartment

going again and we can open up three

that close down lower left strictly by

controlling where the fire is getting

its air source from we can control where

the fire goes to so we can control our

buildings by playing with the openings

you see over here on the lower left you

just open and closing that compartment

and we're clearly showing you a neutral

plane there some bi-directional flow and

you're going to see that as gases or the

smoke the unburned products of

combustion that fuel start lighting off

remember there's no fuel lower right

that is strictly the smoke that's the

gases that's beginning to flame over and

it's night in the lower right hand

compartment you'd see lower left is

still burning we have plenty of plenty

of heat in that compartment and now over

to the right we're getting the heat the

fuel and the oxygen that we need to have

ignition

you'll also notice if you look up

towards the top or the ridgeline of this

house you start having increased smoke

production at multiple levels or

multiple floors to this house the same

way you would with the standard

two-story wood wood frame private

dwelling you're going to start having

smoke migrate to the entire house

along with the heat and decreasing the

amount of oxygen on all levels of the

house when you do this drill it's always

good to have a water sprayer from a

garden hose or two and a half can

pressurized water extinguisher available

because you want this drill to go on as

long as you can so if you keep wetting

the exterior of the box you can keep

that compartment and that box intact as

much as you can what do you see now the

partners they're just controlling the

openings allowing air in or allowing air

out we saw a little ventilation induced

flash over there see compartment three

we have the smoke is a lot darker it's a

lot denser so we're creating a lot more

heat within this box now he's going to

close up three and we're going to start

moving up to the second floor and we're

going to open up number two I see as we

add the opens that we don't we have some

decent smoke and we have that

bi-directional flow and you can see the

building's start really pushing and

pulling and really looking for more

oxygen

he's going to reach in and he's going to

remove the hole in the floor that

simulating a door and you're going to

see things change a little bit what

we're going to do is we're going to

actually draw the fire up into that

compartment because what's the fire

always going to do it's going to travel

to the source of oxygen and you just

clearly saw that we just had a add a

little phenomena there where it grabbed

the oxygen and it flashed a little bit

and standing here you can actually

almost feel a little pressure wave so we

can start showing the differences are

talking differences between flashover

and backtrack as we close the lower left

lower left compartment we'll start

seeing that we have fire that has moved

all the way up into the top right here's

your water sprayer if you want it for

that outside of that farm if necessary

now we have good fire going in the

entire bottom left compartment that's

migrated to the bottom right and now

you're starting to see an increase of

heat you're starting to see that smoke

become a little bit more turbulent a

little bit darker we still can clearly

see a neutral plane there we have that

bi-directional flow if he opens up

number two just a crack at this point

which is the bottom left we're going to

open up bottom left you're going to see

a change in that opening you see the bus

the smokes increase of speed so now

watch as he closes the lower left will

see the smoke it's still present but the

smoke slows because it doesn't have his

have a an oxygen source below that level

as he opens up no bottom left you see

that smoke increase in pressure increase

in velocity and it's also increasing in

heat so that would be similar to a

two-story house at the window let's go

or you perform horizontal ventilation on

the floor above the fire as we keep

playing with these openings those gases

will excite the more air the hotter the

fire gets for a long time we were always

taught that ventilation equals cooling

ventilation doesn't equal cooling water

equals cooling so ventilation will

increase your heat release rates and

will increase your opportunity or

chances of flashover or backups without

water application

you see the more air or less air that

they provide to this box really changes

the fire behavior so as you see as we

plot we supply more air into into this

environment the fire that we are

increasing the temperatures we're

increasing the products of um convert

unburned combustion which is more fuel

and the fire is lighting off in the

smoke as you'll see as he opens up

bottom left again we're going to see

this smoke in the top right begin to

light off and that's just because we're

increasing the heat even though we're

ventilating we're increasing the heat

and that smoke will begin lighting off

they say we've provided a lot of air

below the fire and also above the fire

so it's getting really turbulent it's

getting very dense and you can see that

upper right doesn't have a neutral plane

that's strictly an outlet your new your

Inlet is your bottom left you can see

the smoke and the heat getting drawn

right in there now we can shut those

down we can cool the outside of the box

with the water what I want to do is we

want to simulate roof operations so when

the small-scale fire behavior prop we

also want to show that the the positive

and negative effects of roof ventilation

we have to slide trays or to slide

trades built into this prop we have one

at the roof or at the peak so that we

can open that up and it shows what

performing roof ventilation or cutting

the hole the roof actually does but the

important note to our students is that

just cutting the hole in the roof is

enough we always need to push down and

break down the sheetrock so we have

another slide tray that we're going to

open now to simulate break and open the

sheetrock and as we do that you can see

the velocity and density of the smoke

increase and without water application

we will have far that comes out of this

roof we have to this is important point

to show to our students that vertical

ventilation is positive but it's only

positive when we have a coordinated fire

ground and we utilize that with fire

attack at the same time the speed of

this drill depends on the speed of

materials and how quickly the box burns

we're just going to open up a couple

more compart

to show you we've lost the integrity of

the box we have a hole in the back of

the box we may not be to show you too

much more fire behavior because we're

just adding too much here but we're

going to go ahead and open up a couple

compartments and you guys can get and

play with those openings see if we can

get some flash overs to occur all right

close them all up what I want you to do

is open up all four at the same time so

as you can see it at this point we've

lost the integrity of the box we have

some collapse of the second floor floor

and you can see the more holes that we

put in the building the more air that we

supply the bigger the fire grows the

increase of the heat so again this drill

or this training could be utilized to

show fire behavior you can talk about

fire attack you could talk about search

and rescue you talk about vent and to

isolate search as well as horizontal and

vertical ventilation alright so we just

had a good demonstration of fire

behavior and want to thank you guys for

showing up today

PJ Norwood Sean Gray fire engine in

training minutes

you

you

[Music]