Chapter 5: Fire Behavior Flashcards by Chris Me

In the British System (Which is what we use) distance is measured in?

Liquid volume is measured in?

Temperature is measured in?

Pressure is measured in?

Feet & Inches
Gallons
Degrees Fahrenheit
Pounds per square inch

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In the Metric System, distance is measured in?

Liquid is measured in?

Temperature is measured in?

Pressure is measured in?

Meters
Liters
Degrees Celsius
Pascals or Kilopascals

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Matter is made up of atoms and molecules. What are the three stages in which matter exist?

Solid: A material that has three dimensions and is firm in substance, such as wood.

Liquid: A fluid (such as water) that has no independent shape, but has a definite volume and does not expand indefinitely and that is only slightly compressible.

Gas: The physical state of a substance that has no shape or volume of its own and will expand to take the shape and volume of the container or enclosure it occupies (like propane).

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What is a Fuel?

Materials that store energy. Think of the vast amount of heat that is released during a fire. The energy released in the form of heat and light has been stored in the fuel before it is burned. The release of the energy in a gallon of gasoline, for example, can move a car many miles down the road. Many common household materials such as computers, TV’s, furniture and carpets, consist of fuels that will burn under the right conditions.

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There are five types of energies, what are they?

Chemical Energy
Mechanical Energy
Electrical Energy
Light Energy
Nuclear Energy

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What is a Chemical Energy?

Energy created by a chemical reaction. Some chemical reactions produce or give off heat (Exothermic) and others absorb heat (Endothermic). The combustion process (Fire) is an example of an exothermic reaction, because it releases heat energy. Ice cubes melting (absorbing heat) is an example of an endothermic reaction. Most chemical reactions occur because bonds are established between two substances or bonds are broken as two substances are chemically separated. Heat is produced whenever oxygen combines with a combustible material. If the reaction occurs slowly in a well ventilated area, the heat is released harmlessly into the air. If the reaction occurs rapidly or within an enclosed space, the mixture can be heated to its Ignition Temperature and can begin to burn.

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What is a Exothermic?

What is an Endothermic?

Chemical reactions that result in the release of energy in the form of heat. It gives off heat (Such a Fire).

Chemical reactions that absorbs heat or requires heat to be added (Such as Ice).

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What is a Ignition Temperature?

The minimal temperature at which a fuel, when heated, will ignite in the presence of air and continue to burn. Fire is an example of energy being released as a result of a chemical reaction. An example of this occurs when a bundle of rags soaked with linseed oil releases enough heat through oxidation causing the rags to ignite spontaneously.

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What is a Mechanical Energy?

Mechanical energy is converted to heat when two materials rub against each other and create friction. Heat is also produced when mechanical energy is used to compress air in a compressor.

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What is a Electrical Energy?

Heat that is produced by electricity. Electrical energy is converted to heat energy in several ways. For example, electricity produces heat when it flows through a wire or any other conductive material. The greater the flow of electricity and the greater the resistance of material, the greater the amount of heat produced. Examples of electrical energies that can produce enough heat to start a fire is electric heating elements, overloaded wires, batteries etc.

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What is a Light Energy?

Light energy is produced by electromagnetic waves packaged in discrete bundles called photons. This energy travels as thermal radiation, a form of heat. When the light energy is hot enough, it can sometimes be seen in the form of visible light. One example of light energy is the radiant energy we receive from the sun. We think of candles, fires, light bulbs and lasers as forms of light energy. Recognize that while these produce light, they also produce heat. They transfer most of their heat via convection or radiation. If they are touching something, they also transfer heat using conduction. If light energy is of a frequency that we cannot see, the energy may be felt as heat but not seen as visible light.

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What is a Nuclear Energy?

Created by splitting the nucleus of an atom into two smaller nuclei (nuclear fission) or by combining two small nuclei into one large nucleus (fission). Nuclear reactions release large amounts of energy in the form of heat. These reactions can be controlled as in a nuclear power plant or controlled as in an atomic bomb explosion. Nuclear energy is stored in radioactive materials and converted to electricity by nuclear power generating stations.

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What does the law of conservation of energy states?

States that energy cannot be created or destroyed by ordinary means. Energy can however, be converted from one form to another. Think of an automobile, chemical energy in the gasoline is converted to mechanical energy when the car moved down the road. When you press the breaks, the mechanical energy is converted into heat energy by the friction between the wheel rotators and break pads.

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What is the difference between Oxidation, combustion and pyrolysis?

Oxidation: The process in which oxygen combined chemically with another substance to create a new compound. For example, steel that is exposed to oxygen results in rust. The process of oxidation can be very slow. It can take years for oxidation to become evident. Slow oxidation does not produce easily measurable heat.

Combustion: By contrast, combustion is a rapid chemical process in which the combination of a substance with oxygen produces heat and light. For FF, combustion and fire can be used interchangeably.

Pyrolysis: The process that liberates gaseous fuel vapors, due to the heating of a solid fuel. Pyrolysis is evident when wood is heated sufficiently and breaks down into vapors and char (Fig 5.5).

The difference between Combustion and Pyrolysis’s is that combustion is done under the presence of oxygen, where as pyrolysis is done under the absence (or near absence) of oxygen.

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What is a Thermal Column (Heat Stratification)

Heat layers that occur in a room as a result of a fire.

The phenomenon of gases forming into layers according to temperature.

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What is a Neutral Plane

The common boundary or interface between the hot gases and cooler gases.

It is the volume of space in a compartment opening at which the pressure of hot gases and smoke leaving the compartment and the pressure of the cooler air entering the compartment are equal.

In order for a neutral plane to exist, there must be a flow of cooler air entering the compartment and a flow of hot gases exiting the compartment.

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What is a Ventilation Limited Fire

A fire in which the heat release rate and fire growth are regulated by the available oxygen within the space.

A ventilation-limited fire is restricted because there is not enough oxygen available for the fire to burn as rapidly as it would with an unlimited supply of oxygen.

What is a Rollover?

Also, what other name is it known as?

Is the spontaneous ignition of hot gases in the upper levels of a room or compartment. This is a sign that the temperature is rising and if it gets hotter the room and the contents will spontaneously and rapidly ignite.

Also known as a Flameover.

What is a Flashover

Not a specific moment, but rather a transition from a fire that is growing by igniting one type of fuel to another, to a fire where all of the exposed surfaces have ignited. It is a rapid change or transition from the growth stage to the fully developed stage.

According to FF Skills there are four stages of fire. What are they?

According to Norman, what are the three stages of fire?

FF SKILLS
1. Incipient Stage
2. Growth Stage
3. Fully Developed Stage
4. Decay Stage

NORMANS
1. Incipient Stage

Free Burning Stage
Smoldering Stage

DEFINITIONS
1. Incipient Stage; Beginning Stage

Growth Stage: This stage the fire produced more interaction and is more dependent on the environment in the compartment around it.
Fully Developed Stage: This stage the fire is consuming the maximum amount of of fuel possible. The fire is either ventilation limited (No oxygen) or Fuel Limited (A lot of oxygen).
Decay Stage: Can occur due to a decreasing fuel supply or because of a limited oxygen supply.

What is a Backdraft

What are the eight signs of a backdraft?

Caused by the introduction of oxygen, a change of the ventilation profile, into an enclosure with the superheated gases and contents are already hot enough for ignition, but do not have sufficient oxygen to combust.

Any confined fire with a large heat build up.
Little or no visible flame from the exterior of the building.
A living fire, where the building appears to be breathing, due to smoke puffing out of and then being sucked back into the building.
Smoke that seems to be pressurized.
Smoke-stained windows (An indication of a significant fire).
No smoke showing.
Turbulent Smoke.
Thick yellowish smoke, containing sulfur compounds).

What is a Smoke Explosion?

What three conditions is needed to produce a smoke explosion?

Occurs when a mixture of flammable gases and oxygen is present, usually in a void or other area separate from the fire compartment. Smoke may travel some distance from the fire. When it come in contact with a source of ignition, the flammable mixture ignites in a violent manner.

The presence of a void space.
Combustible building materials.
Ventilation-limited fire that produces unburned fuel.

Wind Effect greatly influences fire behavior. For example, when the wind is still, the best approach to a fire is through the A side of a building. Conversely, if the wind is blowing at 20 to 25 miles per hour from the C side, entering the A side may be a deadly miscalculation. Fig 5-25

CHARACTERISTICS OF LIQUID-FUEL FIRES:

Liquids (just like solids) must be converted into a vapor before they can burn.
What are the three conditions that must be present for a vapor and air mixture to ignite?

The fuel and air must be present at a concentration within a flammable range.
There must be an ignition source with enough energy to start ignition.
The ignition source in the fuel mixture must make contact for long enough to transfer the energy to the air – fuel mixture.

What is a Boiling Point What is the boiling point of water?

The temperature at which a liquid will continually give off vapors in sustained amounts and, held at the temperature long enough, will turn completely into a gas. 212 degrees Fahrenheit. As the boiling point is reached, the amount of flammable vapor generated increases significantly (Fig 5-26)

What is Volatility

The ability of a substance to produce combustible vapors. The amount of liquid that vaporizes is related to the volatility of the liquid.

What is a Flash point: What is a Fire point (Aka Flame Point):

The lowest temperature at which a liquid or solid produces a flammable vapor. The lowest temperature at which a liquid produces enough vapor to sustain a continuous fire. For most materials, the fire point is only slightly higher than the flash point.

CHARACTERISTICS OF GAS-FUEL FIRES: What are the two terms used to describe the characteristics of flammable vapors? Explain both:

1. Vapor Density: Refers to the weight of a gas fuel and measures the weight of the gas compared to air (Table5-3) 2. Flammable Range (Explosive Limit): The range in concentration between the lower and upper flammable limits.

Lower Explosive Limit (LEL) Aka Lower Flammable Limit: Upper Explosive Limit (UEL) Aka Upper Flammable Limit:

The minimum amount of gaseous fuel that must be present in a gas-air mixture to be flammable. The maximum amount of gaseous fuel that must be present in a gas-air mixture to be flammable.

BLEVE

Boiling Liquid/Expanding Vapor Explosion: Occurs when a liquid fuel is stored in a vessel under pressure. The key to preventing a BLEVE is to cool the top of the tank, which contains the vapor, which prevents the fuel from building up enough pressure to cause a catastrophic rupture of the container.

SMOKE READING: Being able to read smoke enables you to learn three things. What are they? At a fire most untrained people look at flames. What does flames indicate? The ability to read smoke Gives firefighters information that they need to mount or more effective attack on a fire, and this may help to save either their lives or the lives of the buildings occupants.

1. Where the fire is. 2. How big it is. 3. Where it is moving. • Flames indicate where the fire is now.

It is helpful to think of smoke as being fuel. Fuel behaves in a predictable way when they are combined with the right mixture of oxygen and heat. Both flashes vets and backdrafts are fed by superheated fuel, in the form of smoke. Smoke is composed of three components. What are they? Where is the best place to observe patterns of smoke?

1. Particles (Solids) 2. Vapors (Finely suspended liquids or aerosols). 3. Gases. • From the outside of the fire building.

What is the first four steps in reading smoke? What are the four key attributes of smoke?

1. Determine The Key Attributes Of Smoke. 2. Determine what is influencing the key attributes. 3. Determine the Rate of Change. 4. Predict the event. 1. Smoke Color: The attribute of smoke that reflects the stage of burning of a fire and the materials that is burning in the fire. Solid materials like wood will emit white-colored smoke when they are first heated. The white color is primarily a result of moisture being released from the material. The same effect happens when applying water to fire, the smoke goes from black to white. As the materials dry out, the color changes. Smoke from wood for example, turns to tan or brown. Plastics and painted or stained surfaces emit to gray smoke, which is a combination of black from the hydrocarbons and white from the escaping moisture. The color can also help FF determine its location of the fire. As smoke travels, its heat evaporates moisture from some of the materials it passes through. This added moisture tends to change black smoke to lighter smoke the farther it travels from the fire. Carbon rich black smoke often becomes lighter in color as it travels farther from the initial fire site, because of the loss of carbon from the smoke. 2. Smoke Density: The thickness of smoke. Because it has a high mass per unit volume, smoke is difficult to see through. The denser the smoke, the more fuel it contains. 3. Smoke Volume: Quantity of Smoke, which indicates how much fuel is being heated. 4. Smoke Velocity: The speed of smoke leaving a burning building, which suggest how much pressure is accumulating inside the building. Smoke is pushed by both HEAT and VOLUME. When smoke is pushed by heat, it will rise and then slow down gradually. When smoke is pushed by volume, it will slow down immediately. Determine whether it is being pushed by heat or volume.

There are two type of flow that smoke can have. What are they and its definition?

Laminar Smoke Flow: A smooth or streamlined flow, which indicates that the box and its contents are absorbing heat and the pressure in the box is not too high (Fig. 5-29). Turbulent Smoke Flow: Is agitated, boiling, or angry. This expansion occurs when the box (building) cannot absorb any more heat. When you see turbulent smoke, be aware that flashover is likely to occur soon.

How do you differentiate between white smoke caused by early heating and white smoke from a hot fire that has traveled a distance?

White smoke that is lazy or slow indicates early heating. White smoke that has its own pressure indicates smoke from a hot fire that has traveled for some distance.

What is Black Fire?

A high-volume, high-velocity, turbulent, ultra-dense, black smoke. Temperatures up to 1000 degrees. Its presence indicates impending auto ignition and flashover. When black fire occurs, there is usually no lives to be saved in that location. FF with full PPE are effected.

Step 2: Determine what is Influencing the Key Attributes What 4 things could influence the key attributes?

1. Wind: Changes the direction in which smoke travels. 2. Thermal Balance: The normal thermal balance in a room or building can be affected by the heating and air conditioning. Especially in HighRise buildings. 3. Ventilation Openings: 4. Sprinkler Systems: Causes smoke to be cooled; which will hang close to the bottom of the room, making it difficult to see.

Step 3: Determine the Rate of Change Flames indicate what is happening now. Smoke gives a more complete picture of the characteristics of the fire and where it’s going. The questions you should ask: (Is it getting better or worst) Is the Volume of smoke, the velocity of smoke, density of smoke, and color of smoke changing? How are they changing? How rapidly are the changes occurring? What do these changes suggest about the progression and f the fire?

Step 4: Predict the Event: You must learn how to read through the smoke.

Smoke Reading through a door: When you see indications of a hot fire, such as darkened windows, but little visible smoke is coming from around closed doors and from around windows, what stage the fire may be in? Which means the fire is? When you open a door, watch what the smoke does, and identify the neutral plane. If smoke exits through the top half of the door and clean air enters through the bottom half of the opening, then the fire is probably where? When you open a door, if smoke rises and the opening clears out, fresh air is being pulled into the building. Which indicates the fire is where? If smoke thing when the door is opened, but smoke still fills the door, the fire may be where?

• Decay Stage/ Ventilation Limited • On the same level • Above the level of the opening. • Below the level of the opening.

Fuel Limited Fire

A fire in which the heat release rate and fire growth are controlled by the characteristics of the fuel, because there is adequate oxygen available for combustion.