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Accelerant: A fuel or oxidizer, often an ignitable liquid, used to initiate a fire or increase the rate of growth or spread of fire. (NFPA 921 3.3.2)
Amorphous : Non-crystalline and without long-range order.
Ampere: The unit of electric current that is equivalent to a flow of one coulomb per second; one coulomb is defined as 6.24x10 18 electrons. (NFPA 921 3.3.6)
Arc: A high temperature luminous electric discharge across a gap or through a medium such as charred insulation. (NFPA 921 3.3.7) (Note: this definition is not universally accepted; in this program we use spark and arc interchangeably)
Arcing Through Char: Arcing associated with a matrix of charred material (e.g., charred conductor insulation) that acts as a semi conductive medium. (NFPA 921 3.3.8)
Area of Origin: The room or area where a fire began. (See also Point of Origin) (NFPA 921 3.3.9)
Arson: The crime of maliciously and intentionally, or recklessly, staring a fire or causing an explosion. (NFPA 921 3.3.11)
Autoignition: Initiation of combustion by heat but without spark or flame. (NFPA 921 3.3.12)
Autoignition Temperature: The lowest temperature at which combustion material ignites in air without a spark of flame. (NFPA 921 3.3.13) The autoignition temperature, a material property, varies substantially with conditions; the term is sometimes presumed to refer to the temperature measured for a given material using an ASTM specified procedure. In this program we use it the term to refer to the temperature of combustion without spark or flame in the conditions appropriate to the discussion at hand.
Backdraft : A deflagration resulting from the sudden introduction of air into a confined space containing oxygen deficient products of incomplete combustion. (NFPA 921 3.3.14)
Bead : A rounded globule of re-solidified metal at the end of the remains of an electrical conductor that was caused by arcing and is characterized by a sharp line of demarcation between the melted and unmelted conductor surfaces. (NFPA 921 3.3.15)
Bi-fuel vehicle : Vehicles with two separate fuel systems (storage tanks) with the capability of drawing from one or the other.
Cause : The circumstances, conditions, or agencies that brought about or resulted in the fire or explosion incident, damage to property resulting from the fire or explosion incident or bodily injury or loss of life resulting from the fire or explosion incident. (NFPA 921 3.3.22)
Ceiling Jet : A relatively thin layer of flowing hot gases that develops under a horizontal surface (e.g., ceiling) as a result of plume impingement and the flowing gas being forced to move horizontally. (NFPA 921 3.3.23)
Ceiling Layer : A buoyant layer of hot gases and smoke produced by a fire in a compartment. (NFPA 921 3.3.24)
Char : Carbonaceous material that has been burned and has a blackened appearance. (NFPA 921 3.3.25)
Combustible : Capable of burning, generally in air under normal conditions of ambient temperature and pressure, unless otherwise specific; combustion can occur in cases where an oxidizer other than oxygen in air is present (e.g., chlorine, fluorine, or chemicals containing oxygen in their structure). (NFPA 921 3.3.28)
Combustible Liquid : A liquid having a flash point at or above 37.8 degrees C (100 degrees F). (See also Flammable Liquid.) (NFPA 921 3.3.30)
Combustion Products : Heat, gases, or solid particulates, and liquid aerosols produced by burning. (NFPA 921 3.3.31)
Compressed natural gas (CNG): Natural gas is a mixture of hydrocarbons, mainly methane. The natural gas used in vehicles is either compressed natural gas (CNG) or liquefied natural gas (LNG). CNG is compressed to 2,400-3,600 pounds per square inch and stored on-board a vehicle in specially designed and constructed cylinders. (US Department of Energy, Vehicle Buyer’s Guide for Consumers, 2006.)
Conduction : Heat transfer to another body or within a body by direct contact. (NFPA 921 3.3.32)
Convection : Heat transfer by circulation within a medium such as a gas or liquid. (NFPA 921 3.3.33)
Cool-Flame Ignition: A relatively slow, self-sustaining, barely luminous gas-phase reaction of the sample or its decomposition products with an oxidant. Cool flames are visible only in a darkened area. (NFPA 325, 1994) See Hot-Flame Ignition.
Cool-Flame Ignition Threshold (CFT): The lowest temperature at which cool-flame ignitions are observed for a particular system.
Current : A flow of electrical charge. (NFPA 921 3.3.34)
Deductive Reasoning : The process by which conclusions are drawn by logical inference from given premises. (NFPA 921 3.3.35)
Deflagration : Propagation of a combustion zone at a velocity that is less than the speed of sound in the un-reacted medium. (NFPA 921 3.3.36)
Detection : 1) Sensing the existence of a fire, especially by a detector from one or more products of fie, such as smoke, heat, ionized particles, infrared radiation, and the like. 2) The act or process of discovering or locating a fire. (NFPA 921 3.3.37)
Detonation : Propagation of a combustion zone at a velocity that is greater than the speed of sound in the un-reacted medium. (NFPA 921 3.3.38)
Diffusion Flame : A flame in which fuel and air mix or diffuse together at the region of combustion. (NFPA 921 3.3.39)
Drop Down : The spread of fire by the dropping or falling of burning materials. Synonymous with “fall down.” (NFPA 921 3.3.40)
Electric spark : A small incandescent particle created by some arcs. (NFPA 921 3.3.42) (Note: this definition is not universally accepted; in this program we use spark and arc interchangeably)
Electric vehicle (EV): A vehicle driven by an electric motor with power supplied by on-board batteries.
Fire : A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities. (NFPA 921 3.3.53)
Fire Cause : The circumstances, conditions, or agencies that bring together a fuel, ignition source, and oxidizer (such as air or oxygen) resulting in a fire or a combustion explosion. (NFPA 921 3.3.55)
Fire Patterns : The visible or measurable physical effects that remain after a fire. (NFPA 921 3.3.58)
Fire Propagation : The movement of fire from one place to another.
Flame : A body or stream of gaseous material involved in the combustion process and emitting radiant energy…In most cases some portion of the emitted radiant energy is visible to the human eye. (NFPA 921 3.3.63)
Flameover : The condition where unburned fuel (pyrolysate) from the originating fire has accumulated in the ceiling layer to a sufficient concentration (i.e., at or above lower flammable limit) that it ignites and burns; can occur without ignition and prior to the ignition of other fuels separate from the origin. (NFPA 921 3.3.65)
Flammable : Capable of burning with a flame. (NFPA 921 3.3.66)
Flammable Limit : The upper and lower concentration limit at a specified temperature and pressure of a flammable gas or vapor of an ignitable liquid and air, expressed as a percentage of fuel by volume that can be ignited. (NFPA 921 3.3.67)
Flammable Liquid : A liquid that has a closed-cup flash point that is below 37.8 degrees C (100 degrees F) and a maximum vapor pressure of 2068 mm Hg (40 psia) at 37.8 degrees C. (NFPA 921 3.3.68)
Flammable Range : The range of concentrations between the lower and upper flammable limits. (NFPA 921 3.3.69)
Flash Fire : A fire that spread rapidly through a diffuse fuel, such as dust, gas or the vapors of an ignitable liquid, without the production of damaging pressure. (NFPA 921 3.3.70)
Flash Point of a Liquid : The lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapor at a sufficient rate to support a momentary flame across its surface. (NFPA 921 3.3.71) Like autoignition, there is a specific ASTM test procedure for repeatably measuring flashpoint; the value of which will vary considerably with conditions.
Flashover : A transition phase in the development of a compartment fire in which surfaces exposed to thermal radiation reach ignition temperature more or less simultaneously and fire spreads rapidly throughout the space, resulting in full room involvement or total involvement of the compartment or enclosed space. (NFPA 921 3.3.72)
Flex-fuel vehicles (FFV) : Vehicles constructed with a single drive system and single fuel tank, but the engine may operate on different fuels. FFVs provide options for operation with a choice of fuels, depending on what is available at any given time.
Fuel : A material that will maintain combustion under specified environmental conditions. (NFPA 921 3.3.74)
Fuel Gas : Natural gas, manufactured gas, LP-Gas, and similar gases commonly used for commercial or residential purposes such as heating, cooling, or cooking. (NFPA 921 3.3.75)
Fuel Load : The total quantity of combustible contents of a building, space, or fire area, including interior finish and trim, expressed in heat units or the equivalent weight in wood. (NFPA 921 3.3.76)
Fuel-Controlled Fire : A fire in which the heat release rate and growth rate are controlled by the characteristics of the fuel, such as quantity and geometry, and in which adequate air for combustion is available. (NFPA 921 3.3.77)
Fuel-Controlled Fire : A fire in which the heat release rate and growth rate are controlled by the characteristics of the fuel, such as quantity and geometry, and in which adequate air for combustion is available. (NFPA 3.3.77)
Full Room Involvement : Condition in a compartment fire in which the entire volume is involved in fire. (NFPA 3.3.78)
Gas : The physical state of a substance that has no shape or volume of its own and will expand to take the shape and volume of the container or enclosure it occupies. (NFPA 3.3.79)
Glowing Combustion : Luminous burning of solid material without a visible flame. (NFPA 3.3.80)
Ground Fault : An unintended current that flows outside the normal circuit path, such as (a) through the equipment grounding conductor, (b) through conductive material in contact with lower potential (such as earth), other than the electrical system ground (metal water or plumbing pipes, etc.), (c) through a combination of these ground return paths. (NFPA 3.3.81)
Hazard: Any arrangement of materials and heat sources that presents the potential for harm, such as personal injury or ignition of combustibles. (NFPA 3.3.82)
Heat : A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state. (NFPA 3.3.83)
Heat and Flame Vector : An arrow used in a fire scene drawing to show the direction of heat, smoke, or flame flow. (NFPA 3.3.84)
Heat Flux : The measure of the rate of heat transfer to a surface, expressed in kilowatts/m2, kilojoules/m2*s, or Btu/ft*s. (NFPA 3.3.85)
Heat of Combustion: The heat liberated when a fuel (usually a hydrocarbon) reacts with oxygen to yield water and carbon dioxide. [1] The value is reported as a unit of energy per unit of mass or volume.
Heat of Ignition : The heat energy that brings about ignition. (NFPA 3.3.86)
Heat Release Rate (HRR): The rate at which heat energy is generated by burning. (NFPA 3.3.87) Heat release rate is used as an objective means of comparing burn rate of a fuel or groups of fuels. The measured HRR of a motor vehicle fire will vary with the ignition source used, placement of the ignition source, and other conditions.
High Explosive: A material that is capable of sustaining a reaction front that mves through the unreacted material at a speed equal to or greater than that of sound in that medium [Typically 1000 m/s (3000 ft/sec)]; a material capable of sustaining a detonation (See also detonation) (NFPA 3.3.88)
High-Order Explosion : A rapid pressure rise or high-force explosion characterized by a shattering effect on the confining structure or container and long missile distances. (NFPA 3.3.89)
Hot Flame Ignition: A rapid, self sustaining, sometimes audible gas-phase reaction of the sample, or its decomposition products with an oxidant. A readily visible yellow or blue flame usually accompanies the reaction. (NFPA 325, 1994) This visible means of identifying ignition was previously relied upon in test measurements of ignition temperature. Recent test procedures use other means of flame detection. See Cool-Flame Ignition.
Hybrid vehicles : Characterized by having more than one drive system. Typically, gasoline engines and electric motors are employed to use the most effective operation of each.
Hypergolic Material : Any substance that will spontaneously ignite or explode upon exposure to an oxidizer. (NFPA 3.3.90)
Ignitable Liquid : Any liquid or the liquid phase of any material that is capable of fueling a fire, including a flammable liquid, combustible liquid, or any other material that can be liquefied and burned. (NFPA 3.3.91)
Ignition : The process of initiating self-sustained combustion. (NFPA 3.3.92)
Ignition Energy : The quantity of heat energy that should be absorbed by a substance to ignite and burn. (NFPA 3.3.93)
Ignition Temperature : Minimum temperature a substance should attain in order to ignite under specific test conditions. (NFPA 3.3.94)
Inductive Reasoning : The process by which a person starts from a particular experience and proceeds to generalizations. (NFPA 3.3.96)
Isochar : A line on a diagram connecting points of equal char depth. (NFPA 3.3.97)
Joule : The preferred SI unit of heat, energy or work; there are 4.184 joules in a calorie, and 1055 joules in a British Thermal Unit (Btu). A watt is a Joule/second. (See also British Thermal Unit and Calorie). (NFPA 3.3.98)
Kilowatt : A measurement of energy release rate. (NFPA 3.3.99)
Kindling Temperature : See Ignition Temperature. (NFPA 3.3.100)
Layering : The systematic process of removing debris from the top down and observing the relative location of artifacts at the fire scene. (NFPA 3.3.101)
Liquid petroleum gas (LPG) : LPG is 90% propane, with the balance made up of butane, propylene and other gases.
Low Explosive : An explosive that has a reaction velocity of less than 1000 m/s (3000 ft/sec). (NFPA 3.3.102)
Low-Order Explosion : A slow rate of pressure rise or low-force explosion characterized by a pushing or dislodging effect on the confining structure or container and by short missile distances. (NFPA 3.3.103)
Material First Ignited : The fuel that is first set on fire by the heat of ignition; to be meaningful, both a type of material and a form of material should be identified. (NFPA 3.3.104)
Minimum Ignition Energy The lowest possible energy that will result in the ignition of a flammable mixture by an electrical discharge. The minimum ignition energy depends on the composition of the mixture and other conditions.
Noncombustible Material : A material that, in the form in which it is used and under the condition anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat. Also called incombustible material (not preferred). (NFPA 3.3.105)
Nonflammable : (1) Not readily capable of burning with a flame. (2) Not liable to ignite and burn when exposed to flame. Its antonym is flammable. (NFPA 3.3.105)
Ohm : The unit of electrical resistance (R) that measures the resistance between two points of a conductor when a constant difference of potential of one volt between these two points produces in this conductor a current of one ampere. (NFPA 3.3.107)
Origin : See Point of Origin, or Area of Origin. (NFPA 3.3.108)
Overcurrent : Any current in excess of the rated current of equipment or the ampacity of a conductor; it may result from an overload, short circuit, or ground fault. (NFPA 3.3.109)
Overload : Operation of equipment in excess of normal, full-load rating or of a conductor in excess of rated ampacity, which, when it persists for a sufficient length of time, would cause damage or dangerous overheating. (NFPA 3.3.110)
Oxygen Deficiency : Insufficiency of oxygen to support combustion. (See also Ventilation-Controlled Fire.) (NFPA 3.3.111)
Parting Arc : A brief electrical discharge that can occur when the current in an energized circuit is interrupted by the separation of conductors.
Piloted Ignition Temperature : See 3.3.94, Ignition Temperature. (NFPA 3.3.112
Plastic : Any of a wide range of natural or synthetic organic materials of high molecular weight that can be formed by pressure, heat, extrusion, and other methods into desired shapes. (NFPA 3.3.113) (See polymers)
Plume : The column of hot gases, flames, and smoke rising above a fire; also called convection column, thermal up draft, or thermal column. (NFPA 3.3.114)
Point of Origin : The exact physical location where a heat source and a fuel come in contact with each other and a fire begins. (NFPA 3.3.115)
Polymers : Large molecules of nonmetallic elements composed of many repetitive units (mers). Commonly called plastics. (See plastic)
Pool Fire : A pool fire is a fire burning above a horizontal pool of vaporizing hydrocarbon fuel where the fuel has zero or low initial momentum. Pool fires may be static (e.g. where the pool is contained) or 'running' fires.
Pre-Flame Reaction: A slow, non-luminous gas-phase reaction of the sample or its decomposition products with an oxidant. (NFPA 325, 1994) Recent ignition temperature test procedures use non-visual means of flame detection to identify temperatures of ignition that cause pre-flame reactions
Pre-Flame Reaction Threshold (RTT): The lowest temperature at which exothermic gas-phase reactions are observed for a particular system. (NFPA 325, 1994)
Premixed Flame : A flame for which the fuel and oxidizer are mixed prior to combustion, as in a laboratory Bunsen burner or a gas cooking range; propagation of the flame is governed by the interaction between flow rate, transport processes, and chemical reaction. (NFPA 3.3.116)
Preservation : Application or use of measures to prevent damage, change or alteration, or deterioration. (NFPA 3.3.117)
Products of Combustion : See Combustion Products. (NFPA 3.3.118)
Propagation time: Time required for fire to spread from one point of the vehicle to another, often used with respect to the time for fire spread from some point on the vehicle to the passenger compartment.
Proximate Cause : The cause that directly produces the effect without the intervention of any other cause. (NFPA 3.3.119)
Pyrolysis : The chemical decomposition of a compound into one or more other substances by heat alone; pyrolysis often precedes combustion. (NFPA 3.3.120)
Pyrophoric Material : Any substance that spontaneously ignites upon exposure to atmospheric oxygen. (NFPA 3.3.121)
Quenching : The cessation of combustion due to either heat transfer and mass transfer to the surface or aerodynamics effects like strain fields and rapid mixing.
Quenching Distance : A characteristic length scale associated with laminar flame quenching during propagation in a narrow channel or tube.
Radiant Heat : Heat energy carried by electromagnetic waves that are longer than light waves and shorter than radio waves; radiant heat (electromagnetic radiation) increases the sensible temperature of any substance capable of absorbing the radiation, especially solid and opaque objects. (NFPA 3.3.122)
Radiation : Heat transfer by way of electromagnetic energy. (NFPA 3.3.123)
Rate of Heat Release . See Heat Release Rate. (NFPA 3.3.124)
Rekindle : A return to flaming combustion after apparent but incomplete extinguishment. (NFPA 3.3.125)
Rollover : See 3.3.65, Flameover.
Scientific Method : The systematic pursuit of knowledge involving the recognition and formulation of a problem, the collection of data through observation and experiment, and the formulation and testing of a hypothesis. (NFPA 3.3.129)
Seat of Explosion : A crater-like indentation created at the point of origin of an explosion. (NFPA 3.3.130)
Secondary Explosion : Any subsequent explosion resulting from an initial explosion. (NFPA 3.3.132)
Self-Heating : 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. (NFPA 3.3.133)
Self-Ignition : Ignition resulting from self-heating. Synonymous with spontaneous ignition. (NFPA 3.3.134)
Self-Ignition Temperature : The minimum temperature at which the self-heating properties of a material lead to ignition. (NFPA 3.3.135)
Short Circuit : An abnormal connection of low resistance between normal circuit conductors where the resistance is normally much greater; this is an overcurrent situation but it is not an overload. (NFPA 3.3.136)
Smoke : The airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combustion, together with the quantity of air that is entrained or otherwise mixed into the mass. (NFPA 3.3.137)
Smoke Condensate : The condensed residue of suspended vapors and liquid products of incomplete combustion. (NFPA 3.3.138)
Smoke Explosion : See 3.3.14, Backdraft. (NFPA 3.3.139)
Smoldering : Combustion without flame, usually with incandescence and smoke. (NFPA 3.3.140)
Soot : Black particles of carbon produced in a flame. (NFPA 3.3.141)
Spalling : Chipping or pitting of concrete or masonry surfaces. (NFPA 3.3.142)
Spark : A moving particle of solid material that emits radiant energy due either to its temperature or the process of combustion on its surface. (NFPA 3.3.143)
Spoliation : Loss, destruction, or material alteration of an object or document that is evidence or potential evidence in a legal proceeding by one who has the responsibility for its preservation. (NFPA 3.3.144)
Spontaneous Heating : Process whereby a material increases in temperature without drawing heat from its surroundings. (NFPA 3.3.145)
Spontaneous Ignition : Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material. (NFPA 3.3.146)
Suppression : The sum of all the work done to extinguish a fire, beginning at the time of its discovery. (NFPA 3.3.147)
Target Fuel : A fuel that is subject to ignition by thermal radiation such as from a flame or a hot gas layer. (NFPA 3.3.148)
Temperature : The degree of sensible heat of a body as measured by a thermometer or similar instrument. (NFPA 3.3.149)
Thermal Column : See 3.3.114, Plume. (NFPA 3.3.150)
Thermal Expansion : The proportional increase in length, volume, or superficial area of a body with rise in temperature. (NFPA 3.3.151)
Thermal Inertia : The properties of a material that characterize its rate of surface temperature rise when exposed to heat; related to the product of the material's thermal conductivity (k), its density (?), and its heat capacity (c). (NFPA 3.3.152)
Thermoplastic : Plastic materials that soften and melt under exposure to heat and can reach a flowable state. (NFPA 3.3.153)
Thermoset Plastics : Plastic materials that are hardened into a permanent shape in the manufacturing process and are not commonly subject to softening when heated; typically form char in a fire. (NFPA 3.3.154)
Upper Layer : See Ceiling Layer. (NFPA 3.3.156)
Vapor : The gas phase of a substance, particularly of those that are normally liquids or solids at ordinary temperatures. (See also Gas.) (NFPA 3.3.157)
Vapor Density : The ratio of the average molecular weight of a given volume of gas or vapor to the average molecular weight of an equal volume of air at the same temperature and pressure. (NFPA 3.3.158)
Vent : An opening for the passage of, or dissipation of, fluids, such as gases, fumes, smoke, and the like. (NFPA 3.3.159)
Ventilation : Circulation of air in any space by natural wind or convection or by fans blowing air into or exhausting air out of a building; a fire-fighting operation of removing smoke and heat from the structure by opening windows and doors or making holes in the roof. (NFPA 3.3.160)
Ventilation-Controlled Fire : A fire in which the heat release rate or growth is controlled by the amount of air available to the fire. (NFPA 3.3.161)
Venting : The escape of smoke and heat through openings in a building. (NFPA 3.3.162)
Volt (V) : The unit of electrical pressure (electromotive force) represented by the symbol "E"; the difference in potential required to make a current of one ampere flow through a resistance of one ohm. (NFPA 3.3.163)
Watt (W) : Unit of power, or rate of work, equal to one joule per second, or the rate of work represented by a current of one ampere under the potential of one volt. (NFPA 3.3.164)
References
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