Flashcards in Chapter # 5 Fire Behavior Deck (144):
Physical science is the study of ...... and ...... and includes chemistry and physics.
matter and energy
Anything that occupies space and has mass.
What type of change occurs when a substance changes in size, shape or appearance, but the chemically stays the same?
Physical Change Ex: Water freezing, Water boiling
What type of change occurs when a substance changes from one type of matter to another?
When two or more substances combine they form a?
A chemical reaction involving the combination of a oxidizer, with another material.
The capacity to perform work.
Stored energy possessed by an object that can be released in the future to to perform work once released.
The energy possessed by a body because of its motion.
List seven types of energy.
chemical, thermal, electrical, mechanical, light, nuclear, sound
Can all energy change from one type to another?
In terms of a fire, the potential chemical energy of a fuel is converted to thermal energy and released as?
Name the measure of energy in the International System of Units (SI) and also for the customary system.
SI = Joules (J) Customary = Btu
How many joules does it take to change the temperature of one gram of water by one degree Celsius?
The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
How many joules = 1 Btu?
Reactions that emit energy are called?
Exothermic ex: fire
Reactions that absorb energy are called?
Endothermic ex: converting water to steam.
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or a flame?
A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities?
A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and change of state.
Measure of a materials ability to transfer heat energy to other objects.
A material that will maintain combustion under specific environmental conditions.
Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials.
Name two forms of ignition.
Piloted and auto (nonpiloted)
The most common type of ignition. Occurs when a mixture of fuel and oxygen encounter an external heat source with sufficient heat or thermal energy to start the combustion process.
Occurs with out any external flame or spark to ignite the fuel gases and vapors.
The auto ignition temperature of a substance is always higher then its ............
Piloted ignition temperature
The chemical decomposition of a solid material by heating. Often precedes combustion.
Physical process that changes a liquid into a gaseous state; the rate depends on the substance involved, heat, pressure, and exposed surface area.
The process of initiating self sustained combustion.
Pyrolysis occurs in what type of fuel
Vaporization occurs in what type of fuel?
The lowest temperature at which a combustible material ignites in air without a spark or a flame.
Autoignition Temprature (AIT)
True or False Combustion is a chemical reaction while fire is possible result of combustion.
Name two modes of combustion.
Flaming and nonflaming
Occurs slowly, lower temps, produces a smoldering glow.
Produces a visible flame above the materials surface.
Name the two models that are used to describe the element of fire and how to extinguish it.
Fire Triangle, Fire Tetrahedron
Materials that absorb heat but do not participate actively in the combustion process. Given a example.
Passive Agents. ex: Gypsum/Humidity
Smoke is a product of incomplete combustion. It is a aerosol comprised of what?
gases, vapor, and solid particulates
Materials produced and released during burning.
Products of combustion.
A toxic and flammable product of incomplete combustion of organic materials. The most common product of combustion encountered in structure fires. Chemical asphyxiant that binds with hemoglobin preventing O2 from binding with it.
Carbon Monoxide (CO)
Toxic, flammable, produced in the combustion of materials containing nitrogen. Chemical asphyxiant that prevents the body from using O2 at the cellular level.
Hydrogen Cyanide (HCN)
Product of complete combustion of organic material, acts as a simple asphyxiant by displacing O2, also stimulates respiratory system causing increase in resp rate,
Carbon Dioxide (CO2)
Substances that cause breathing discomfort. Inflammation of the eyes, resp tract, and skin.
How many irritants have test shown are in smoke? Give three examples.
20. hydrogen chloride, formaldehyde, acrolein
True or False. Flame is also considered to be a product of combustion?
The kinetic energy associated with the random motions of the molecules of a material or object.
Thermal Energy. aka: heat and heat energy
the measurement of heat.
Equation. Celsius to Fahrenheit
F = (C x 1.8) + 32
Equation: Fahrenheit to Celsius
C = (F -32) / 1.8
Name six sources of thermal energy.
Chemical, Mechanical, Electrical, Light, Nuclear, Sound
The most common source of heat energy in combustion.
The result of exothermic reactions, occurring spontaneously in some materials under certain conditions, whereby heat is generated at a rate sufficient to raise the temperature of the material.
Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.
Name three things that must happen for spontaneous ignition to take place.
heat can not dissipate faster then it is produced, materials temp must reach its auto ignition temp, available air must be able to support combustion.
Name four ways that electrical heating can occur.
Resistance, Overcurrent / overload, Arcing, Sparking
Type of energy generated by friction or compression.
True or false. Some appliance are designed to make use of resistance heating?
What is unintended resistance heating?
Overload or Overcurrent
What is a high temp luminous discharge across a gap or through a medium?
What is the spatter that make be produced from a arc?
True or false? Heat is transferred from warmer to cooler objects. Materials at the same temp can not transfer heat?
The measure of the rate of heat transfer to a surface, expressed as kilowatts per meter squared (KW/m2)
Name three ways heat con be transferred.
Conduction, Convection, Radiation.
Transfer of heat through or between solids that are in direct contact.
Heat transfer by circulation within a medium such as gas or liquid.
Heat transfer by way of electromagnetic energy.
What is believed to be the weakest part of a PPE ensemble.
Name three factors that effect radiant heat transfer.
Nature of the exposed surface, Distance, Temp difference between the source and the exposed surface.
As the temperature of the heat source increases, the radiant energy increases by a factor of?
Can hot smoke in the upper layers radiate heat?
The fuel that is being oxidized or burned during combustion.
Total amount of thermal energy that could be generated by the combustion reaction if a fuel were completely burned.
Heat of combustion
Total amount of heat released per unit of time.
Heat release rate
The rate at which energy is being transferred over time.
A unit of measure of power or rate of work equal to one joule per second.
Heat release rate is dependent on what three things?
type, quantity, and orientation of the fuel.
T or F? Gaseous fuels are already in their physical state required for ignition?
Weight of a given volume of pure vapor or gas compared to the weight of an equal volume of dry air at the same temp and pressure. Less then 1 = rise. Greater then 1 = sink.
Mass of a substance compared to the mass of an equal volume of water at a given temp. Less then 1 = float Greater then 1 = sink.
What is the vapor pressure of air at sea level?
Measure of the tendency of a substance to evaporate.
Vapor Pressure. Liquids with a higher tendency to evaporate will have a higher vapor pressure.
Any liquid having a flash point below 100 F and a vapor pressure not above 40 psi absolute.
The ease with which a liquid gives off vapor.
The minimum temperature at which a liquid gives off sufficient vapor to ignite, but not sustain combustion.
The temperature at which sufficient vapors are being generated to sustain combustion.
Fire point. Must exceed 5 seconds of burning duration.
A increase in surface area decreases the extent at which a liquid will give off vapor. T or F?
The degree to which a solid, liquid, or gas will mix / dissolve with water.
Materials that will mix with water in any proportion
A liquid with a attraction to water.
Liquid having a flash point at or above 100 f and below 200 f.
Chemical decomposition of a material through the action of heat.
Matter with a definite shape and size?
Surface to mass ratio. As the ratio increases the fuel particles become smaller. T or F?
Proximity and orientation of a solid fuel affect the way it burns. T or F?
Oxidizers are not combustible but will support and enhance combustion. T or F?
At normal ambient temps (68F) materials can ignite and burn at O2 levels as low as?
Percentage of O2 that equals a deficient atmosphere and the percent that equals a enriched atmosphere.
Can variations in temp and pressure cause the flammable range of a gas or vapor to be vary?
The range between the LFL and UFL in which a substance can ignite.
Flammable (Explosive) range
Upper limit at which a gas or vapor will ignite. Above the limit the vapor is to rich to burn.
Upper Flammable Limit (UFL)
Lower limit at which a gas or vapor will ignite and support combustion. Below the limit the fuel is said to be to lean to burn.
Lower Flammable Limit (LFL)
Molecular fragments that are highly reactive.
Because of the release of free radicals during the combustion of methane, the production of CO and formaldehyde could be formed. T or F?
Extinguishment of a fire by interruption of the chemical chain reaction
Chemical chain Inhibition.
List the four stages of fire development.
Incipient, Growth, Fully Developed, Decay
List seven things that influence fire development within a compartment.
Fuel Type, Availably and location of additional fuels, Compartment volume and ceiling height, Ventilation, Thermal properties of the compartment, Ambient Conditions, Fuel Load.
List four factors that influence the availability and location of additional fuels.
Building Configuration, Construction Materials, Contents, Proximity of the initial fire to expose fuel sources.
A fire in a larger compartment will develop more slowly then one in a small compartment. T or F? Why?
True. Radiant heat has to travel farther to heat a larger area. Will maintain longer due to increased air source.
Name the two forms that room or compartment fires take.
Fuel or Ventilation controlled.
A fire with adequate oxygen in which the heat release rate and growth rate are determined by the characteristics of the fuel, such as quantity and geometry.
A fire with limited ventilation in which the heat release rate or growth is limited by the amount of oxygen available to the fire.
The total quantity of combustible contents of a building, space, or fire area, including interior finishes and trim, expressed in heat units of the equivalent weight of wood.
Stage of fire that starts with the ignition of a fuel. Typically a fuel controlled fire. Radiant heat begins to warm additional fuels. Hot gas begins to mix with cooler air in the room. Temps in the room are not much above ambient temps.
Stage of fire where the location of the fire in the room effects the amount of air entrained and thus the amount of cooling that is taking place. A higher plume is more rapidly increasing the temps at the upper level of the room. Heat is radiated back to the fire by surfaces in the room.
Tendency of gases to form into layers according to temp.
Thermal Layering. aka: heat stratification, thermal balance.
The area where the pressure of hot gas exiting a room and cooler gas exiting a room are equal.
Rapid transition from growth to fully developed?
Typically flash over occurs in what stage of fire?
Growth. May occur in the fully developed stage.
Most fires that grow beyond the incipient stage will become ventilation or fuel controlled?
Stage of fire where all combustible materials in a compartment are burning, burning fuels are releasing the max amount of heat possible, large volumes of fire gas, ventilation controlled, fire may extent to other compartments.
Fully Developed Stage
Stage of fire where all fuel is consumed or where o2 levels are to low to sustain combustion.
In a limited ventilation decay fire the temp may decrease but what is still taking place?
Name three types of rapid fire development.
Flashover, Backdraft, Smoke Explosion
Flash over occurs when the environment changes from two layers to one untenable layer. T or F?
List four common elements of flashover.
Transition in fire development, Rapidity, Compartment, Ignition of all exposed surfaces.
Flashover typically occurs at what temp?
List smoke indicators of flashover.
rapidly increasing volume, turbulence, darkening color, optical density, lowering of the hot gad layer.
List a heat indicator of flash over.
List a flame indicator of flashover.
Isolated flames in the hot gas layer or at the ceiling.
A increase in low level ventilation before upper level ventilation can result in what?
List smoke indicators of potential back draft.
Optically dense smoke, light colored or black becoming dense gray-yellow. neutral plane rising and lowering (breathing movement).
List heat indicators of potential back draft.
high heat, smoke stained windows.
List a flame indicator of potential back draft.
little or no visible flame.
Will a back draft always occur after a opening has been made into the compartment?
No, it may take some time for the proper air to fuel mixture to occur.
This may occur before or after the decay stage. If smoke that is within its flammable range finds a ignition source this may happen.
List five ways that firefighters influence fire behavior.
Temp reduction, Fuel removal, O2 exclusion, Chemical Flame inhibition, Ventilation and fire behavior.
Cooling with water cannot sufficiently reduce vapor production to extinguish fires involving low flash point flammable liquids and gases. T or F?
When water is converted to steam at 212 F it expands by how many times?
Chemical flame inhibition is effective on gas and liquid fuels because they must flame to burn. T or F?
True. They are ineffective to non flaming fires.
The planned, systematic, and coordinated introduction of air and removal of hot gases and smoke from a building.