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99 Cards in this Set

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A chemical process of oxidation that occurs fast enough to produce heat and usually light in the form of glow or flame

Combustion

A rapid self-sustaining oxidation process accompanied with the evolution of heat and light in varying intesities

Fire

A form of energy characterized by vibration of molecules and capable of initiating and sustaining chemical changes and changes of state

Heat

Measure of a materials ability to transfer heat energy to other objects. Measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of degrees

Temperature

A material that will maintain combustion under specified environmental conditions

Fuel

Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials.

Oxidizer

Anything that occupies space and has mass

Matter

Capacity to perform work; occurs when a force is applied to an object over a distance, or when a chemical, biological, or physical transformation is made in a substance

Energy

Chemical process that occurs when a substance combines with an oxidizer such as oxygen in the air


E.G., rust on metal

Oxidation

Stored energy possessed by an object that can be released in the future to perform work once released

Potential Energy

The energy possessed by a body because of its own motion

Kinetic Energy

The measure for energy

Joules (J)

The amount of energy required to change the temperature of one gram of water 1 degree Celsius

4.2J

Chemical reaction that releases thermal heat or energy

Exothermic Reaction

Chemical reaction that absorbs thermal heat or energy

Endothermic Reaction

The chemical decomposition of a solid material by heating


Often produces combustion


Offgassing

Pyrolysis

Physical process that changes a liquid into a gaseous state. The rate of which depends on the substance involved, heat, pressure, and exposed surface area

Vaporization

The process of initiating self-sustained combustion

Ignition

Moment when a mixture of fuel and oxygen encounters an external heat source with sufficient heat or thermal energy to start the combustion reaction

Piloted Ignition

Initiation of combustion by heat but without spark or flame

Autoignition

The lowest temperature at which a combustible material ignites in air without a spark or flame

Autoignition Temperature

Visible, luminous body of a burning gas emitting radiant energy including light of various colors given off by burning gases or vapors during combustion

Flame

Model used to explain the elements required for combustion. Heat, Oxygen, and Fuel; removal of any one of these elements results in extinguishment

Fire Triangle

Model of the four elements required for combustion. Heat, Oxygen, Fuel, and a Self-Sustaining Chemical Reaction; removal of any one of these elements results in extinguishment

Fire Tetrahedron

Materials that absorb heat but do not actively participate in the combustion process

Passive Agent

Materials produced and released during burning

Products of Combustion

Colorless, odorless, dangerous gas formed by incomplete combustion of carbon. Chemical asphyxiant that binds with hemoglobin preventing those cells from distributing oxygen to the body

Carbon Monoxide (CO)

Colorless, faint odor similar to bitter almonds, produced in the combustion of materials containing nitrogen. Chemical asphyxiant preventing the body from using oxygen at the cellular level

Hydrogen Cyanide (HCN)

Product of complete combustion of organic materials. Colorless, odorless, and neither supports combustion or burns. Simple asphyxiant displacing oxygen from the air

Carbon Dioxide (CO2)

The kinetic energy associated with the random motions of the molecules of a material object; often used interchangeably with the terms heat and heat energy.


Measured in Joules or Btu

Thermal Energy

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

Self-Heating

Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material

Spontaneous Ignition

-The insulation properties of the material immediately surrounding the fuel must be such that the heat cannot dissipate as fast as it is being generated


-The rate of heat production must be great enough to raise the temperature of the material to its autoignition temperature


-The available air supply in and around the material being heated must be adequate to support combustion

Factors required for spontaneous iginition

Chemical, mechanical, electrical, light, nuclear, and sound energy are all sources of what

Sources of Thermal Energy

-Resistance heating


-Overcurrent or overload


-Arcing


-Sparking

Types of Electrical Heating

When electric current flows through a conductor, heat is produced

Resistance Heating

When the current flowing through a conductor exceeds its design limits, it may overheat and present an ignition hazard


Unintended resistance heating

Overcurrent or Overload



In general a high-temperature luminous electric discharge across a gap or through a medium such as charred insulation.


The luminous discharge

Arching

When an electric arc occurs, luminous particles can be formed and spatter away from the point of arcing


The spatter

Sparking

Energy generated by friction or compression

Mechanical Energy

Transfer of thermal energy over time per unit of surface area


Measured in killowatts per meter squared

Heat Flux

Conduction


Convection


Radiation

The ways heat can be transferred from one body to another

Transfer of heat through or between solids that are in direct contact

Conduction

The transfer of heat within a medium such as a gas or liquid

Convection

The transfer of heat by way of electromagnetic energy

Radiation

The tendency or capacity to remain afloat in a liquid or rise in air or gas



Buoyant

Composed of at least one inlet opening, one exhaust opening, and the connecting volume between the openings


The direction of the flow is determined by difference in pressure


Heat and smoke will flow toward areas of lower pressure

Flow Path

Effects of radiant heat decrease as

Distance increases



Dark materials emit and absorb heat more effectively than lighter color materials; smooth or highly-polished surfaces reflect more radiant heat than rough surfaces

Factor that the nature of exposed surfaces influences radiant heat transfer

Buoyant layer of hot gases and smoke produced by a fire in a compartment

Upper Layer

Temperature difference has a major effect on heat transfer through radiation. As the temperature of the heat source increases, the radiant energy increases by a factor to the fourth power.

Temperature Difference between the Heat and Exposed Surfaces

The fuel that is being oxidized or burned during combustion

Reducing Agent

Total amount of thermal energy that could be generated by the combustion reaction if a fuel were completely burned. The heat of combustion is measured in Btu per pound or Megajoules per kilogram

Heat of Combustion

Total amount of heat released per unit time. Measured in kilowatts and megawatts of output

Heat Release Rate (HRR)

The rate at which energy is being transferred over time

Power

A unit of measure of power or rate of work equal to one joule per second

Watt

Weight of a given volume of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure. Less than 1 is lighter than air


More than 1 is heavier than air

Vapor Density

Weight of a substance compared to the weight of an equal volume of water at a given temperature


Less than 1 floats on water


More than 1 sinks in water

Specific Gravity

Any liquid having a flash point below one hundred degrees and a vapor pressure not exceeding forty psi absolute

Flammable Liquid

Measure of the tendency of a substance to evaporate


The pressure at which a vapor is in equilibrium with its liquid phase for a given temperature; liquids that have a greater tendency to evaporate have higher vapor pressures for a given temperature

Vapor Pressure

Minimum temperature at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquid's surface, but not sustain combustion

Flash Point

Temperature at which a liquid fuel produces sufficient vapors to support combustion once the fuel is ignited. Must exceed 5 seconds of burning duration during the test.

Fire Point

Degree to which a solid, liquid, or gas dissolves in a solvent (usually water).

Solubility

Materials that are capable of being mixed in all proportions

Miscible

Petroleum based organic compound that contains only hydrogen and carbon

Hydrocarbon Fuel

Flammable liquids that have an attraction for water. Mix readily with water.

Polar Solvents

Liquid having a flash point at or above one hundred degrees and below two hundred degrees

Combustible Liquid

Normal Oxygen Level in the Air

21% oxygen in the air

Oxygen Deficient Environment

Less than 19.5% oxygen in the air

Oxygen Enriched Environment

More than 23.5% oxygen in the air

The range between the upper flammable limit and lower flammable limit in which a substance can be ignited

Flammable (Explosive) Range

Upper limit at which a flammable gas or vapor will ignite; above this limit the gas or vapor is too rich to burn

Upper Flammable Limit (UFL)

Lower limit at which a flammable gas or vapor will ignite and support combustion; below this limit the gas or vapor is too lean

Lower Flammable Limit (LFL)

Molecular fragments that are highly reactive

Free Radicals

Extinguishment of a fire by interruption of the chemical chain reaction

Chemical Flame Inhibition

Incipient, Growth, Fully Developed, and Decay

Stages of Fire Development

-Fuel Type


-Availability and location of additional fuels


-Compartment volume and ceiling height


-Ventilation


-Thermal properties of the compartment


-Ambient conditions


-Fuel Load

Factors that Affect Fire Development

A fire with adequate oxygen in which the HRR and growth rate are determined by the characteristics of the fuel

Fuel-Controlled

A fire with limited ventilation in which the HRR or growth is limited by the amount of oxygen available to the fire

Ventilation-Controlled

Common, prevailing, and uncontrolled atmospheric weather conditions.

Ambient Conditions

The total quantity of combustible contents of a building, space, or fire area, including interior finish and trim, expressed in heat units of the equivalent weight in wood.

Fuel Load

First stage of the burning process in a compartment in which the substance being oxidized is producing some heat, but the heat has not spread to other substances nearby. During this phase, the oxygen content of the air has not been significantly reduced and the temperature within the compartment is not significantly higher than the ambient temperature.

Incipient Stage

The column of hot gases, flames, and smoke rising above a fire.


AKA: convection column, thermal updraft, or thermal column

Plume

A relatively thin layer of flowing hot gases that develops under a horizontal surface as a result of plume impingement and the flowing gas being forced to move horizontally.


Mushrooming

Ceiling Jet

During this stage of fire, oxygen and fuel are plentiful

Incipient

During this stage of fire, the fire influences the environment and begins to be influenced by the ventilation conditions of the compartment.

Growth

Outcome of combustion in a confined space in which gases tend to form into layers, according to temperature, with the hottest gases found at the ceiling and the coolest gases at floor level


AKA: heat stratification, thermal balance

Thermal Layering

The level at a compartment opening where the difference in pressure exerted by expansion and buoyancy of hot smoke flowing out of the opening and the inward pressure of cooler, ambient temperature air flowing in through the opening is equal.

Neutral Plane

A rapid transition from growth to fully developed

Flashover

All combustible materials actively burn during this stage

Fully Developed

The fire begins to cool and die as fuel and/or ventilation run out of supply during this stage

Decay

A condition where the unburned fire gases that have accumulated at the top of a compartment ignite and flames propagate through the hot-gas layer or across the ceiling

Rollover

The explosive burning of heated gases that occurs when oxygen is introduced into a compartment that has a high concentration of flammable gases and a depleted supply of oxygen due to an existing fire

Backdraft

Transition in fire development- Flashover represents a transition from the growth stage to the fully developed stage


Rapidity- Although not instantaneous, flashover happens rapidly


Compartment- There must be an enclosed space such as a single room or enclosure


Ignition of all exposed surfaces- Virtually all combustible surfaces in the enclosed space become ignited

The Four Common Elements of Flashover

Flashover


Backdraft


Smoke Explosion

Three Types of Rapid Fire Development

Form of fire gas ignition; the ignition of accumulated flammable products of combustion and air that are within their flammable range.



Smoke Explosion

Temperature reduction


Fuel removal


Oxygen exclusion


Chemical flame inhibition


Ventilation and fire behavior

Ways Firefighters Influence Fire Behavior

Planned, systematic, and coordinated removal of heated air, smoke, gases or other airborne contaminants from a structure, replacing them with cooler and/or fresher air to meet the incident priorities of life safety, incident stabilization, and property conservation.

Tactical Ventilation

The most commonly found oxidizer

Oxygen in the air