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 flame.
Combustion
A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities.
Fire
A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.
Heat
Measure of a material's ability to transfer heat energy to other objects; the greater the energy, the higher the temperature. Measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated o
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; a common example is the formation of 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 motion.
Kinetic energy
Chemical reaction that releases thermal energy or heat.
Exothermic reaction
Chemical reaction that absorbs thermal energy or heat.
Endothermic reaction
The chemical decomposition of a solid material by heating, often precedes combustion.
Pyrolysis
Physical process that changes a liquid into a gaseous state.
Vaporization
The process of initiating self-sustained combustion.
Ignition
Moment when a mixture of fuel and oxygen encounters an external heat (ignition) source with sufficient heat or thermal energy to start the combustion reaction.
Piloted ignition
Initiation of combustion by heat but without a 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 the combustion process.
Flame
A model used to explain the elements/conditions necessary for combustion. The sides of the triangle represent heat, oxygen, and fuel.
Fire Triangle
Model of the four elements/conditions required to have a fire. The four sides of the tetrahedron represent fuel, heat, oxygen, and self-sustaining chemical chain reaction.
Fire Tetrahedron
Materials that absorb heat but do not participate actively in the combustion process.
Passive agent
What product of combustion is an aerosol comprised of gasses, vapor, and solid particulates?
Smoke
______ combustion is commonly referred to as fire because it produces a visible flame above the material's surface.
Flaming
Materials produced and released during burning.
Products of Combustion
Colorless, odorless, dangerous gas (both toxic and flammable) formed by the incomplete combustion of carbon.
Carbon Monoxide (CO)
Colorless, toxic, and flammable liquid until it reaches 79F (26C). Above that temperature, it becomes a gas with a faint odor similar to bitter almonds; produced by the combustion of nitrogen- bearing substances.
Hydrogen Cyanide (HCN)
Colorless, odorless, heavier than air gas that neither supports combustion nor burns; used in portable fire extinguishers as an extinguishing agent to extinguish Class B or C fires by smothering or displacing the oxygen.
Carbon Dioxide (CO2)
The kinetic energy associated with the random motions of the molecules of a material or object.
Thermal energy
A form of oxidation, is a chemical reaction that increases the temperature of a material without the addition of external heat.
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
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
An ______ is a high-temperature luminous electric discharge across a gap or through a medium such as charred insulation.
Arc
When an electric arc occurs, luminous (glowing) particles can be formed and spatter away from the point of arcing.
Sparking
Transfer of heat through or between solids that are in direct contact.
Conduction
Heat transfer by circulation within a medium such as a gas or a liquid.
Convection
Heat transfer by way of electromagnetic energy.
Radiation
Heat transfer due to conduction is dependent upon three factors:
1. Area being heated.
2. Temperature difference between the heat source and the material being heated.
3. Thermal conductivity of the heated material.
The tendency or capacity to remain afloat in a liquid or rise in air or gas.
Buoyant
Buoyant layer of hot gases and smoke produced by a fire in a compartment.
Upper layer
The fuel that is being oxidized or burned during combustion.
Reducing agent
Total amount of heat released per unit time.
Heat Release Rate (HRR)
A unit of measure of power or rate of work equal to one joule per second.
Watt
Describes the density of gases in relation to air.
Vapor density
The ratio of the mass of a given volume of a liquid com- pared with the mass of an equal volume of water at the same temperature.
Specific gravity
______ pressure indicates how easily a substance will evaporate or go into air.
Vapor
The minimum temperature at which a liquid gives off sufficient va- pors to ignite, but not sustain combustion.
Flash point
The temperature at which sufficient vapors are being generated to sustain the combustion reaction
Fire point