Matter
Anything that occupies space and has mass.
Exothermic Heat Reaction
Chemical reaction between two or more materials that changes the materials and produces heat, flames, and toxic smoke.
Endothermic Heat Reaction
Chemical reaction in which a substance absorbs heat energy.
Combustion
An exothermic chemical reaction that is a self-sustaining process of rapid oxidation of a fuel, that produces heat and light.
Physical Change
A change that occurs when a substance remains chemically the same but changes in size, shape or appearance. Example: Water freezing or boiling.
Chemical Change
A reaction that occurs when a substance changes from one type of matter to another.
Fire Triangle
Oxygen, Fuel, Heat. Old system of thought.
Fire Tetrahedron
Oxygen, heat, fuel, a self sustained chemical chain reaction. Each element must be in place for flaming combustion to occur.
Heat
Kinetic energy associated with the moving atoms and molecules within atom and is the actual energy component of the Fire Tetrahedron
Temperature
Measurement of Kinetic energy, or energy being released.
Energy
is the capacity to perform work.
Joule
is equal to 1 newton over a distance of 1 meter.
British thermal unit (BTU)
is the amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Potential Energy
Stored energy possessed by an object that can be released in the future to perform work.
Kinetic Energy
The energy possessed by a moving object.
Pyrolysis
Chemical decomposition of a substance through the application of heat in solid fuels.
Vaporization
Release of ignitable vapors through the application of heat in liquid fuels.
Piloted Ignition
occurs when a mixture of fuel and oxygen encounter an external heat source with sufficient heat energy to start combustion reaction.
Autoignition
Occurs without any external flame or spark to ignite the fuel gases or vapors.
Autoignition Temperature (AIT)
Is the temperature to which the surface of a substance must be heated for ignition and self-sustained combustion to occur spontaneously. This temperature is always higher than the Piloted Ignition Temperature.
6 sources of Heat
Chemical, Electrical, Mechanical, Light, Nuclear, Sound
Chemical Heat Energy
Most common source of heat energy in combustion reactions. Caused by combination of Oxygen and combustible materials causing Oxidation.
Self Heating or Spontaneous Heating
Oxidation releases heat energy, usually dissipates to the environment faster than it is released. If it is accelerated by sunshine or an insulator the fuel can reach auto ignition temperatures.
Electrical Heat Energy
Resistance Heating, Over-current/overload , Arcing, Sparking
Resistance Heating
Electric current flows through a conductor, heat is produced. Oven's, lamps, Ranges, portable heaters. "Intended
Over-Current Heating, Overload Heating
Current flowing through a conductor exceeds its design limitations, causing it to overheat and possibly ignite. Unintended resistance heating.
Arcing
High temperature luminous electric discharge across a gap or through a medium such as charred insulation.
Sparking
Electric arc occurs, luminous particles can be formed and spatter away from the point of arcing.
Mechanical Heat Energy
Heat development caused by 2 surfaces moving against one another. Friction heat or Compression Heat.
Conduction
Transfer of heat within a body to another body by direct contact. Heat flow between solids.
Convection
Transfer of heat from a fluid or gaseous substance to a solid.
Radiation
Transmission of energy as an electromagnetic wave with out an intervening medium. Light, X-ray, Infrared Thermal Waves
Passive agent
Materials that absorb heat but do not actively participate in the combustion process.
Fuel
The substance being oxidized or burned in the combustion process. Also known as the reducing agent.
Characteristics of Gaseous Fuels
Vapor density: Describes the gases behavior with air. Heavier than air, gas sinks. Lighter than air: Gas will rise. Diffusion: A gas will fill the container it is released into evenly. Ignition: Fuel is already in its most ignitable state.
Characteristics of Liquid Fuels
Affected by gravity, will spread out over a surface or flow downhill. Density: compared to water, will either float on the surface of water or sink below water. Fuel must be vaporized prior to ignition
Vaporization
Ability for a liquid fuel to be converted to a gaseous fuel. Must overcome ambient atmospheric pressure.
Flash Point
Temperature at which a liquid gives off sufficient vapors to ignite, but NOT sustain, combustion. Liquid vapor is ready to burn but requires piloted ignition continuously to remain burning.
Fire Point
Temperature at which sufficient vapors are being generated to sustain the combustion process.
Solubility
Describes the extent to which a substance will mix with water.
Characteristics of Solid Fuels
Have a definite shape and size. Solids can change when exposed to heating, (Vaporizing, Melting). Pyrolysis: Heat causes decomposition and release of combustible gases from the solid.
Surface to mass ratio
Where flammability is concerned, surface area can dramatically influence ignitability. Compare a burning log to burning wood chips or shavings.
Oxidizing agents (Oxidizers)
Materials that react with fuels to support the combustion reaction. Non-Combustible.
Nomex*
Will not burn in low or normal oxygen environments. However when exposed to high concentrations of oxygen, this will burn vigorously
Lower explosive limit (LEL)
Lowest concentration of oxygen and fuel vapors required to cause risk of ignition and explosion.
Upper explosive limit (UEL)
Up most concentration of oxygen and fuel vapors required to cause risk of ignition and explosion.
Flammable Range
Range between the UEL and LEL in which a substance can be ignited.
Carbon Monoxide (CO)
Colorless, Odorless, Dangerous gas being both toxic and flammable. Formed by incomplete combustion of carbon. Combines 200 times more quickly with hemoglobin as oxygen thus decreasing the blood's ability to carry oxygen.
Carbon Dioxide CO2
Colorless, Odorless, heavier than air gas that neither supports combustion or burns. Used in extinguishers to smother a fire by displacing available oxygen.
Hydrogen Cyanide (HCN)
Producted in the combustion of materials containing nitrogen. Acts as a chemical asphyxiant by preventing the body from using oxygen at a cellular level.
Class A Fire
Ordinary combustible materials, such as wood, cloth, paper, rubber, grass, plastics. Primary method of extinguishment is cooling the fuel to slow or stop the release of pyrolysis products.
Class B Fire
Involves flammable and combustible liquids and gasses such as gasoline, oil, paint, alcohol. Fires involving burning gasses, are most easily extinguished by shutting off the source. Burning liquid fuels are extinguished by a proper application of foam or
Class C Fire
Involve energized electrical equipment. Computers, Appliances, Transformers, electric motors. Usually, the burning materials in the fire are class A products. Extinguishment should NOT include any conductive agent such as water until it has been de-energi
Class D Fire
Involved combustible metals, such as aluminum, Magnesium, potassium, sodium, titanium, zirconium. Note that air born metal dusts can cause violent explosions. Extinguishment requires separation, isolation, and individual treatment of specific substance ac
Class K Fire
Involves burning oils and greases normally found in commercial kitchens and food preparation facilities using deep fryers. Require specifically formulated agent for extinguishment.
Saponification
Process of turning fats and oils into a soapy foam that extinguishes the fire.
Compartment Fire
Fire that occurs within an enclosed space where heat and energy are trapped and are not being lost to the ambient atmosphere.
Fuel Controlled Fire Development
Sufficient oxygen is available, fire development is regulated and controlled by the characteristics and configuration of the fuels.
Ventilation Controlled Fire Development
Fire grows in size to where the amount of oxygen available to support further fire development is depleted.
Incipient Stage
Fire stage of the burning process in a confined space in which the substance being oxidized is producing some heat, but the heat has not spread to the other substances nearby. During this phase, oxygen content of the air has not been significantly reduced
Growth Stage
The early stage of a fire during which fuel and oxygen are virtually unlimited. This phase is characterized by a rapidly increasing release of heat.
Thermal Layering or Thermal Balance or Heat Stratification
Gasses form into layers, according to temperature, with the hottest gasses found at the ceiling and the coolest gases at the floor.
Isolated Flames or Ghosting
Pockets of flames observed moving through the hot gas layers above the neutral plane. Indication that gasses are within their flammable range and that there is significant temperature to support ignition. Indicator of developing flash over conditions!!!!
Rollover or Flameover
Unburned gases collect at the ceiling in the thermal layer. The layer is oxygen deprived, but materials are within their flammable range. As pressure increases, it pushes gasses to unaffected areas, where they mix with oxygen. This will cause flames to ro
Flashover
Stage of a fire at which all surfaces and objects within a space have been heated to their ignition temperature and flame breaks out almost at once over the surface of all objects in the space.
"When Temperature in room results in the simultaneous ignitio
Situational Awareness
Look: Visible indicators, unusual fire behavior. Smoke density color and movement.
Listen: audible clues to what is happening in the immediate area, Pass devices, calls for help, Escaping gases, Crackling of Fire.
Feel: Vibrations in structure, changes in
Full Developed stage
Stage of burning process where energy release is at maximum rate and is limited onl by availability of fuel and oxygen
Decay Stage or Hot-Smoldering Phase
Stage of fire development when fuel is consumed and energy release diminishes while temperatures decreases. During this stage, fire goes from ventilation controlled to fuel controlled.
Backdraft
Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space. The stalled combustion resumes with explosive force. It may occur because of inadequate or improper ventilation pro
6 factors that affect fire development
1.) Fuel Type 2.) Availability and location of additional fuel in relation to fire location 3.) Compartment Geometry 4.) Ventilation and Changes in Ventilation 5.) Thermal Properties 6.) Ambient Conditions (Wind, Temperature, Humidity)
Fire Control: Temperature Reduction
Most common methods of fire control and extinguishment. Depends on reducing the temperature of a fuel to a point where it does not produce sufficient vapor to burn. Also used to reduce temperature of ambient unburned gasses, to reduce likelihood of flasho
Fire Control: Fuel Removal
Effectively extinguishes any fire. Also is key in defensive fire fighting tactics. Allowing fire to continue until all fuel is burned out.
Fire Control: Oxygen exclusion
Removal of oxidizer, allowing for combustion reactions to continue. Effective on small area, or isolated fire incidents. not practical in structural firefighting.
Chemical Flame Inhibition
Extinguishing agents such as Dry-Chemical, Halogenated Agents, Halon-Replacement Agents, interrupt the combustion reaction and stop flame production. Effective on gas and liquid fuels because they must flame to burn.