| Term | Definition |
|---|
| matter | anything that occupies space and has mass |
| oxidation | a chemical reaction involving the combination of oxygen with other materials |
| 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 | a rapid and self-sustaining chemical process that yields heat and usually light |
| fire tetrahedron | explains flaming combustion and is composed of oxygen, fuel, heat, and a self-sustained chemical reaction |
| 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 |
| energy | the capacity to perform work |
| joule | measure of heat energy in the metric system |
| British thermal unit | measure of heat energy; amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit |
| pyrolysis | thermal or chemical decomposition of fuel (matter) because of heat that generally results in the lowered ignition temperature of the material |
| piloted ignition | when a mixture of fuel and oxygen encounter an external heat with sufficient heat to start combustion |
| autoignition | when no external flame or spark is used to ignite fuel gases or vapors |
| autoignition temperature | same temperature as ignition temperature except that no external ignition is required for ignition |
| chemical heat energy | heat produced from a chemical reaction including combustion, spontaneous heating, heat of decomposition, and heat of solution; most common source of heat in combustion |
| self-heating | form of chemical energy that occurs when a material increases temperature without the addition of external heat |
| electrical heat energy | heat energy that is electrical in origin including resistance heating, dielectric heating, heating from arcing, and heat from static electricity |
| resistance heating | when electric current flows through a conductor, heat is produced |
| overcurrent | when a current flowing through a conductor exceeds its design limits |
| arcing | a high-temperature luminous electric discharge across a gap or through a medium |
| sparking | spatter of luminous (glowing) particles from an electric arc |
| mechanical heat energy | is generated by friction or compression |
| heat of compression | generated when a gas is compressed |
| conduction | transfer of heat within a body or to another body by direct contact (flow of heat between solids) |
| convection | the transfer of heat energy from a fluid (liquid or gas) to a solid surface |
| radiation | the transmission or transfer of heat energy from one body to another body at a lower temperature through intervening space by electromagnetic waves |
| passive agents | materials that absorb heat but do not participate actively in the combustion reaction |
| reducing agent | the fuel that is being oxidized or burned during combustion |
| vapor density | describes the density of gases in relation to air |
| specific gravity | the ratio of the mass of a given volume of a liquid compared with the mass (weight) of an equal volume of water at the same temperature |
| vaporization | the transformation of a liquid to vapor or gaseous state |
| flash point | minimum temperature at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquid's surface |
| fire point | temperature at which a liquid fuel produces sufficient vapors to support combustion once the fuel is ignited |
| polar solvents | liquids such as alcohols (i.e. methane and ethanol) that will mix readily with water |
| solubility | degree to which a solid, liquid, or gas dissolves in a solvent (usually water) |
| miscible | materials that are capable of being mixed (in water) |
| surface-to-mass ratio | surface area of the fuel in proportion to the mass |
| heat of combustion | total amount of energy released when a specific amount of that fuel is oxidized (burned) |
| heat release rate | energy released per unit of time as a given fuel burns |
| flammable range | the range between the upper flammable limit and lower flammable limit in which a substance can be ignited |
| chemical flame inhibition | when a Halon-replacement extinguishing agent interferes with a chemical reaction, forms a stable product, and terminates the combustion reaction |
| carbon monoxide | colorless, odorless, dangerous gas formed by the incomplete combustion of carbon |
| carbon dioxide | colorless, odorless, heavier than air gas that neither supports combustion nor burns |
| hydrogen cyanide | produced in the combustion of materials containing nitrogen |
| Class A fire | involves ordinary combustible materials such as wood, cloth, paper, rubber, grass, and many plastics |
| Class B fire | involves flammable and combustinble liquids and gases such as gasoline, oil, lacquer, paint, mineral spirits, and alcohol |
| Class C fire | involves energized electical equipment like household appliances |
| Cass D fire | involves combustible materials such as aluminum, magnesium, potassium, sodium, titanium, and zirconium |
| Class K fire | involves oils and greases normally found in commercial kitchens |
| fuel controlled | when sufficient oxygen is available and fire development is controlled by the characteristics and configuration of the fuel |
| ventilation controlled | when fire development is limited by the air supply |
| incipient | first stage of fire development in a compartment in which the substance being oxidized is producing some heat, but it has not spread |
| plume | what is created when hot gases and flame rise from the fire and mixes with the cooler air in the room |
| mushrooming | when a plume spreads horizontally across a ceiling (ceiling jet) |
| growth stage | the early stage of a fire during which fuel and oxygen are virtually unlimited |
| thermal layering | 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 |
| neutral plane | the interface of the hot and cooler gas layers in a compartment fire |
| ghosting | when flames move through hot gases above the neutral plane during the growth phase of a compartment fire (fire gas ignition) |
| rollover | the condition in which the unburned combustible gases released in a confined space ignite and flames propagate through the hot gas layer or across the ceiling |
| flashover | stage of a fire at which all surfaces and objects within a space have been treated to their ignition temperature and flame breaks out almost at once over the surface of all objects in the space |
| fully developed stage | stage of burning process where energy release is at maximum rate and is limited only by availability of fuel and oxygen |
| decay stage | stage of fire development when fuel is consumed and energy release diminishes, and temperatures decrease. |
| backdraft | instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space |
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