일부 부분적인 내용을 Monthly 업데이트 하고 있으며 최종 완료 되면 추가로 공지합니다.

Some partial contents are being updated monthly, and additional notices will be announced when finalized.

部分内容每月更新,最终确定后另行通知。

 

2024

NFPA 921

Guide for Fire and Explosion Investigations

화재 및 폭발 조사 지침

Chapter 3 — Definitions

3.1 General.

3.1.1 

The definitions contained in this chapter apply to the terms used in this guide.

이 장에 포함된 정의는 이 가이드에 사용된 용어에 적용됩니다.

3.1.2 

Where terms are not defined in this chapter or within another chapter, they should be defined using their ordinarily accepted meanings within the context in which they are used.

이 장이나 다른 장에서 용어가 정의되지 않은 경우에는 해당 용어가 사용되는 문맥 내에서 일반적으로 허용되는 의미를 사용하여 정의해야 합니다.

3.1.3 

Merriam-Webster’s Collegiate Dictionary, current edition, is the source for the ordinarily accepted meaning.

현재 판인 Merriam-Webster 대학 사전은 일반적으로 받아들여지는 의미의 출처입니다.


3.2 NFPA Official Definitions.

NFPA 공식 정의
3.2.1* Approved.

Acceptable to the authority having jurisdiction.

관할권을 가진 당국이 수락할 수 있습니다.
3.2.2* Code.

A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards.

광범위한 주제를 다루는 조항을 광범위하게 편집한 표준이거나 다른 규정 및 표준과 관계없이 법률로 채택하기에 적합한 표준입니다.
3.2.3* Guide.

A document that is advisory or informative in nature and that contains only nonmandatory provisions. A guide may contain mandatory statements such as when a guide can be used, but the document as a whole is not suitable for adoption into law.

본질적으로 권고적이거나 정보를 제공하는 문서이며 비필수 조항만 포함되어 있습니다. 지침에는 지침을 사용할 수 있는 경우와 같은 필수 진술이 포함될 수 있지만 문서 전체가 법률 채택에 적합하지 않습니다.
3.2.4* Recommended Practice.

A document that is similar in content and structure to a code or standard but that contains only nonmandatory provisions using the word “should” to indicate recommendations in the body of the text.

3.2.5* Standard.

An NFPA Standard, the main text of which contains only mandatory provisions using the word “shall” to indicate requirements and that is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Nonmandatory provisions are not to be considered a part of the requirements of a standard and shall be located in an appendix, annex, footnote, informational note, or other means as permitted in the NFPA Manual of Style. When used in a generic sense, such as in the phrase “standards development process” or “standards development activities,” the term “standards” includes all NFPA Standards, including Codes, Standards, Recommended Practices, and Guides.


3.3 General Definitions.

3.3.1* Absolute Temperature.

A temperature measured in Kelvins (K) or Rankines (R).

3.3.2 Accelerant.

A fuel or oxidizer, often an ignitible liquid, intentionally used to initiate a fire or increase the rate of growth or spread of fire.

3.3.3 Accident.

An unplanned event that interrupts an activity and sometimes causes injury or damage or a chance occurrence arising from unknown causes; an unexpected happening due to carelessness, ignorance, and the like.

3.3.4 Active Fire Protection System.

A system that uses moving mechanical or electrical parts to perform an action to achieve a fire protection goal, including fire detection, fire alarm, and fire suppression systems.

3.3.5 Ambient.

Someone’s or something’s surroundings, especially as they pertain to the local environment; for example, ambient air and ambient temperature.

3.3.6 Ampacity.

The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. [70, 2023]

3.3.7 Ampere.

The unit of electric current that is equivalent to a flow of one coulomb per second; one coulomb is defined as 6.24 × 1018 electrons.

3.3.8 Arc.

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

3.3.9 Arc Map.

The diagram created as a result of an arc survey used to document the locations of arc sites on an electrical system to aid in the determination of fire origin or spread.

3.3.10 Arc Melting.

Melting of conductors and conducting surfaces as a result of electrical arcing. The characteristics of arc melting are described in 6.6.6.3.

3.3.11 Arc Site.

The location on a conductor with localized damage that resulted from an electrical arc.

3.3.12 Arc Survey.

The examination of an electrical system for the presence of arc sites.

3.3.13 Arcing Through Char.

Arcing associated with a matrix of charred material (e.g., charred conductor insulation) that acts as a semiconductive medium.

3.3.14 Area of Origin.

A structure, part of a structure, or general geographic location within a fire scene, in which the point of origin of a fire or explosion is reasonably believed to be located. (See also 3.3.153, Point of Origin.)

3.3.15 Arrow Pattern.

A fire pattern displayed on the cross-section of a burned wooden structural member.

3.3.16 Arson.

The definition of the crime of arson varies by jurisdiction; however, it is generally defined as the crime of maliciously and intentionally, or recklessly, starting a fire or causing an explosion. (See 12.5.6.1.)

3.3.17 Autoignition.

Initiation of combustion by heat but without a spark or flame.

3.3.18 Autoignition Temperature.

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

3.3.19 Backdraft.

A deflagration resulting from the sudden introduction of air into a confined space containing oxygen-deficient products of incomplete combustion.

3.3.20 Bead.

A rounded mass of resolidified metal on the remains of an electrical conductor or conductors that was caused by arcing and is characterized by a sharp line of demarcation between the melted and unmelted conductor surfaces.

3.3.21 Blast Pressure Front.

The expanding leading edge of an explosion reaction that separates a major difference in pressure between normal ambient pressure ahead of the front and potentially damaging high pressure at and behind the front.

3.3.22 BLEVE.

An acronym for boiling liquid expanding vapor explosion.

3.3.23 Bonding.

The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.

3.3.24 British Thermal Unit (Btu).

The quantity of heat required to raise the temperature of one pound of water 1°F at the pressure of 1 atmosphere and temperature of 60°F; a British thermal unit is equal to 1055 joules, 1.055 kilojoules, and 252.15 calories.

3.3.25 Burning Rate.

See 3.3.113, Heat Release Rate (HRR).

3.3.26* Calcination of Gypsum.

A fire effect realized in gypsum products, including gypsum board, as a result of exposure to heat that drives off free and chemically bound water.

3.3.27 Calorie.

The amount of heat necessary to raise 1 gram of water 1°C at the pressure of 1 atmosphere and temperature of 15°C; a calorie is 4.184 joules, and there are 252.15 calories in a British thermal unit (Btu).

3.3.28 Cause.

The circumstances, conditions, or agencies that brought about or resulted in the fire or explosion incident, damage to property, bodily injury, or loss of life.

3.3.29 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.

3.3.30 Char.

Carbonaceous material that has been burned or pyrolyzed and has a blackened appearance.

3.3.31 Char Blisters.

Convex segments of carbonized material separated by cracks or crevasses that form on the surface of char, forming on materials such as wood as the result of pyrolysis or burning.

3.3.32 Circuit Protection Device.

An electrical system component that protects against faults, such as circuit breakers, fuses, arc fault circuit interrupting (AFCI) devices, and ground fault circuit interrupting (GFCI) devices.

3.3.33 Clean Burn.

A distinct and visible fire effect generally apparent on noncombustible surfaces after combustible layer(s) (such as soot, paint, and paper) have been burned away.

3.3.34* Combustible.

Capable of undergoing combustion.

3.3.35* Combustible Gas Indicator.

An instrument that samples air and indicates whether there are ignitible vapors or gases present.

3.3.36 Combustible Liquid.

Any liquid that has a closed-cup flash point at or above 37.8°C (100°F). (See also 3.3.92, Flammable Liquid.)

3.3.37 Combustion.

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.

3.3.38 Combustion Products.

The heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion.

3.3.39 Competent Ignition Source.

An ignition source that has sufficient energy and is capable of transferring that energy to the fuel long enough to raise the fuel to its ignition temperature. (See 19.4.2.)

3.3.40 Conduction.

Heat transfer to another body or within a body by direct contact.

3.3.41 Convection.

Heat transfer by circulation within a medium such as a gas or a liquid.

3.3.42 Creep.

The tendency of a material to move or deform permanently to relieve stresses.

3.3.43 Current.

A flow of electric charge.

3.3.44 Data Analysis.

The process of systematically utilizing logical techniques to dissect, reorder, evaluate, and interpret data.

3.3.45 Deductive Reasoning.

The process by which conclusions are drawn by logical inference from given premises.

3.3.46 Deflagration.

Propagation of a combustion zone at a velocity that is less than the speed of sound in the unreacted medium. [68, 2023]

3.3.47 Density.

The mass of a substance per unit volume, usually specified at standard temperature and pressure. The density of water is approximately one gram per cubic centimeter. The density of air is approximately 1.275 grams per cubic meter.

3.3.48 Detection.

(1) Sensing the existence of a fire, especially by a detector from one or more products of the fire, such as smoke, heat, infrared radiation, and the like. (2) The act or process of discovering and locating a fire.

3.3.49 Detonation.

Propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium. [68, 2023]

3.3.50 Diffuse Fuel.

A gas, vapor, dust, particulate, aerosol, mist, fog, or hybrid mixture of these, suspended in the atmosphere, which is capable of being ignited and propagating a flame front.

3.3.51 Diffusion Flame.

A flame in which fuel and air mix or diffuse together at the region of combustion.

3.3.52 Drop Down.

The spread of fire by the dropping or falling of burning materials. Synonymous with “fall down.”

3.3.53 Effective Fire Temperatures.

Temperatures reached in fires that produce physical effects that can be related to specific temperature ranges.

3.3.54 Electric Spark.

A small, incandescent particle created by some arcs.

3.3.55 Electronically Stored Information (ESI).

A broad concept that includes public or private information stored in an electronic or digital medium, such as data available from computers (including email), CD-ROM discs, DVDs, Internet, cloud storage, personal digital assistants (PDAs), smart phones, tablets, GPS systems, satellites, and drones. ESI includes writings, drawings, graphs, charts, photographs, sound recordings, images, video recordings, data compilations, computer-aided design files such as blueprints or maps, metadata, equipment/process control and data logging system files, and any other data that is stored electronically.

3.3.56* Empirical Data.

Factual data based on actual measurement, observation, or direct sensory experience rather than on theory and capable of being verified or known to be true.

3.3.57 Energy.

The ability to perform work(See 5.1.2.)

3.3.58 Entrainment.

The process of air or gases being drawn into a fire, plume, or jet.

3.3.59 Explosible.

A material with a pressure ratio (maximum pressure/pressure at ignition, in absolute units) equal to or greater than 2.0 in any test when tested using the explosibility or Go/No-Go screening test described in Section 13 of ASTM E1226, Standard Test Method for Explosibility of Dust Clouds. [68, 2023]

3.3.60 Explosion.

The sudden conversion of potential energy (chemical or mechanical) into kinetic energy with the production and release of gases under pressure, or the release of gas under pressure. These high-pressure gases then do mechanical work such as moving, changing, or shattering nearby materials.

3.3.61 Explosion Dynamics.

Study of how chemistry, physics, fire science, engineering disciplines of fluid and solid mechanics, and heat transfer interact to influence explosion behavior.

3.3.62 Explosive.

Any chemical compound, mixture, or device that functions by explosion.

3.3.63 Explosive Material.

Any material that can act as fuel for an explosion.

3.3.64 Exposed Surface.

The side of a structural assembly or object that is directly exposed to the fire.

3.3.65 Extinguish.

To cause to cease burning.

3.3.66 Failure.

Distortion, breakage, deterioration, or other fault in an item, component, system, assembly, or structure that results in unsatisfactory performance of the function for which it was designed.

3.3.67 Failure Analysis.

A logical, systematic examination of an item, component, assembly, or structure and its place and function within a system, conducted in order to identify and analyze the probability, causes, and consequences of potential and real failures.

3.3.68 Fall Down.

See 3.3.52, Drop Down.

3.3.69* Fault Current.

The current delivered at a point on the system during a short-circuit condition. [70, 2023]

3.3.70 Finish Rating.

The time in minutes, determined under specific laboratory conditions, at which the stud or joist in contact with the exposed protective membrane in a protected combustible assembly reaches an average temperature rise of 121°C (250°F) or an individual temperature rise of 163°C (325°F) as measured behind the protective membrane nearest the fire on the plane of the wood.

3.3.71 Fire.

A rapid oxidation process, which is an exothermic chemical reaction, resulting in the evolution of light and heat in varying intensities.

3.3.72 Fire Analysis.

The process of determining the origin, cause, development, responsibility, and, when required, a failure analysis of a fire or explosion.

3.3.73 Fire Area.

The boundary of fire effects within a scene in which the area of origin will be located. The fire area is characterized by identifying the border between damaged and undamaged areas, which are distinguishable by fire effects and patterns created by flame, heat, and smoke.

3.3.74 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.

3.3.75* Fire Chemistry.

The study of chemical processes that occur in fires including changes of state, decomposition, and combustion.

3.3.76* Fire Dynamics.

The detailed study of how chemistry, fire science, and the engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior.

3.3.77 Fire Effects.

The observable or measurable changes in or on a material as a result of a fire.

3.3.78 Fire Hazard.

Any situation, process, material, or condition that can cause a fire or explosion or that can provide a ready fuel supply to augment the spread or intensity of a fire or explosion, all of which pose a threat to life or property.

3.3.79 Fire Investigation.

The process of determining the origin, cause, and development of a fire or explosion.

3.3.80* Fire Investigator.

An individual who has demonstrated the skills and knowledge necessary to conduct, coordinate, and complete a fire investigation. [1033, 2022]

3.3.81 Fire Patterns.

The physical changes, or identifiable shapes, formed by a fire effect or group of fire effects.

3.3.82 Fire Propagation.

See 3.3.85, Fire Spread.

3.3.83 Fire Scene Reconstruction.

The process of recreating the physical scene during fire scene analysis investigation or through the removal of debris and the placement of contents or structural elements in their prefire positions.

3.3.84* Fire Science.

The body of knowledge concerning the study of fire and related subjects (such as combustion, flame, products of combustion, heat release, heat transfer, fire and explosion chemistry, fire and explosion dynamics, thermodynamics, kinetics, fluid mechanics, fire safety) and their interaction with people, structures, and the environment.

3.3.85 Fire Spread.

The movement of fire from one place to another.

3.3.86 First Fuel Ignited.

The first fuel ignited is that which first sustains combustion beyond the ignition source.

3.3.87 Flame.

A body or stream of gaseous material involved in the combustion process and emitting radiant energy at specific wavelength bands determined by the combustion chemistry of the fuel. In most cases, some portion of the emitted radiant energy is visible to the human eye. [72, 2022]

3.3.88 Flame Front.

The flaming leading edge of a propagating combustion reaction zone.

3.3.89 Flameover.

The condition where unburned fuel (pyrolysate) from the originating fire has accumulated in the upper layer to a sufficient concentration (i.e., at or above the lower flammable limit) that it ignites and burns. This can occur without ignition of, or prior to the ignition of, other fuels separate from the origin.

3.3.90 Flammable.

Capable of burning with a flame.

3.3.91 Flammable Limit.

The upper or lower concentration limit at a specified temperature and pressure of a flammable gas or a vapor of an ignitible liquid and air, expressed as a percentage of fuel by volume that can be ignited.

3.3.92 Flammable Liquid.

A liquid that has a closed-cup flash point that is below 37.8°C (100°F) and a maximum vapor pressure of 2068 mm Hg (40 psia) at 37.8°C (100°F). (See also 3.3.36, Combustible Liquid.)

3.3.93 Flammable Range.

The range of concentrations between the lower and upper flammable limits. [68, 2023]

3.3.94 Flash Fire.

A fire that spreads by means of a flame front rapidly through a diffuse fuel, such as dust, gas, or the vapors of an ignitible liquid, without the production of damaging pressure.

3.3.95 Flash Point of a Liquid.

The lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapors at a sufficient rate to support a momentary flame across its surface.

3.3.96 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, given sufficient availability of oxygen, fire spreads rapidly throughout the space, resulting in full room involvement or total involvement of the compartment or enclosed space.

3.3.97 Forensic (Forensic Science).

The application of science to answer questions of interest to the legal system.

3.3.98 Fuel.

A material that will maintain combustion under specified environmental conditions. [53, 2021]

3.3.99 Fuel Gas.

Natural gas, manufactured gas, LP-Gas, and similar gases commonly used for commercial or residential purposes such as heating, cooling, or cooking.

3.3.100 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.

3.3.101 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.

3.3.102* Full Room Involvement.

Condition in a compartment fire in which the entire volume is involved in combustion of varying intensities.

3.3.103 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.

3.3.104 Glowing Combustion.

Luminous burning of solid material without a visible flame.

3.3.105 Ground.

A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and earth or to some conducting body that serves in place of the earth.

3.3.106 Ground Fault.

A current that flows outside the normal circuit path, such as (1) through the equipment grounding conductor; (2) through conductive material in contact with lower potential (such as earth), other than the electrical system ground (metal water or plumbing pipes, etc.); or (3) through a combination of these ground return paths.

3.3.107 Hazard.

A condition that presents the potential for harm or damage to people, property, or the environment.

3.3.108 Hazardous Material.

A substance (solid, liquid, or gas) that when released is capable of creating harm to people, the environment, and property.

3.3.109* Heat.

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

3.3.110 Heat and Flame Vector.

An arrow used in a fire scene drawing to show the direction of heat, smoke, or flame flow.

3.3.111 Heat Flux.

The measure of the rate of heat transfer to a surface or an area, typically expressed in kW/m2, or W/cm2.

3.3.112* Heat of Ignition.

The heat energy that brings about ignition.

3.3.113* Heat Release Rate (HRR).

The rate at which heat energy is generated by burning.

3.3.114 Heat Transfer.

The exchange of thermal energy between materials through conduction, convection, and/or radiation.

3.3.115 High Explosive.

A material that is capable of sustaining a reaction front that moves through the unreacted material at a speed equal to or greater than that of sound in that medium [typically 1000 m/sec (3000 ft/sec)]; a material capable of sustaining a detonation. (See also 3.3.49, Detonation.)

3.3.116 High-Order Damage.

A rapid pressure rise or high-force explosion characterized by a shattering effect on the confining structure or container and long missile distances.

3.3.117* Hybrid Mixture.

An explosible heterogeneous mixture, comprising gas with suspended solid or liquid particulates, in which the total flammable gas concentration is ≥10 percent of the lower flammable limit (LFL) and the total suspended particulate concentration is ≥10 percent of the minimum explosible concentration (MEC). [68, 2023]

3.3.118 Hypergolic Material.

Any substance that will spontaneously ignite or explode upon exposure to an oxidizer.

3.3.119* Ignitible Liquid.

Any combustible or flammable liquid.

3.3.120 Ignition.

The process of initiating self-sustained combustion.

3.3.121 Ignition Energy.

The quantity of heat energy that should be absorbed by a substance to ignite and burn.

3.3.122* Ignition Temperature.

Minimum temperature a substance should attain in order to ignite under specific test conditions.

3.3.123 Ignition Time.

The time between the application of an ignition source to a material and the onset of self-sustained combustion.

3.3.124 Incendiary Fire.

A fire that is intentionally ignited in an area or under circumstances where and when there should not be a fire.

3.3.125 Inductive Reasoning.

The process by which a person starts from a particular experience and proceeds to generalizations. The process by which hypotheses are developed based upon observable or known facts and the training, experience, knowledge, and expertise of the observer.

3.3.126 Interested Party.

Any person, entity, or organization, including their representatives, with statutory obligations or whose legal rights or interests may be affected by the investigation of a specific incident.

3.3.127 Investigative Team.

A group of individuals working on behalf of an interested party to conduct an investigation into the incident.

3.3.128 Isochar.

A line on a diagram connecting points of equal char depth.

3.3.129 Joule.

The preferred SI unit of heat, energy, or work. A joule is the heat produced when one ampere is passed through a resistance of one ohm for one second, or it is the work required to move a distance of one meter against a force of one newton. 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 3.3.24, British Thermal Unit (Btu), and 3.3.27, Calorie.]

3.3.130 Kilowatt.

A measurement of energy release rate.

3.3.131 Kindling Temperature.

See 3.3.122, Ignition Temperature.

3.3.132 Layering.

The systematic process of removing debris from the top down and observing the relative location of artifacts at the fire scene.

3.3.133 Lines of Demarcation.

The borders defining the differences in fire effects on materials between the affected area and adjacent, less-affected areas.

3.3.134 Low Explosive.

An explosive that has a reaction velocity of less than 1000 m/sec (3000 ft/sec).

3.3.135 Low-Order Damage.

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.

3.3.136 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.

3.3.137 Minimum Explosible Concentration (MEC).

The minimum concentration of a combustible dust cloud that is capable of propagating a deflagration through a uniform mixture of the dust and air under the specified conditions of test. [68, 2023]

3.3.138 Minimum Ignition Energy (MIE).

The lowest capacitive spark energy capable of igniting the most ignition-sensitive concentration of a flammable vapor-air mixture or a combustible dust-air mixture as determined by a standard test procedure. [652, 2019]

3.3.139 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.

3.3.140 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.

3.3.141 Non-Scene Data.

Data from sources other than those collected from the scene of a fire or explosion incident.

3.3.142 Ohm.

The SI unit of electrical impedance or, in the direct current case, electrical resistance.

3.3.143* Open Flame.

Any device that emits a flame that is exposed to outside elements.

3.3.144 Origin.

The general location where a fire or explosion began. (See 3.3.153, Point of Origin, or 3.3.14, Area of Origin.)

3.3.145 Overcurrent.

Any current in excess of the rated current of equipment or the ampacity of a conductor; it may result from an overload (see 3.3.147), short circuit (3.3.179), or ground fault (3.3.106).

3.3.146 Overhaul.

firefighting term involving the process of final extinguishment after the main body of the fire has been knocked down. All traces of fire must be extinguished at this time.

3.3.147* Overload.

Operation of equipment in excess of normal, full-load rating or of a conductor in excess of rated ampacity that, where it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.

3.3.148 Oxygen Deficiency.

Insufficiency of oxygen to support combustion. (See also 3.3.211, Ventilation-Controlled Fire.)

3.3.149 Passive Fire Protection System.

Any component of a building or structure that provides protection from fire or smoke without any type of system activation or movement. [3, 2024]

3.3.150 Piloted Ignition Temperature.

See 3.3.122, Ignition Temperature.

3.3.151* 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.

3.3.152 Plume.

The column of hot gases, flames, and smoke rising above a fire; also called convection columnthermal updraft, or thermal column.

3.3.153 Point of Origin.

The physical location within the area of origin where a heat source, a fuel, and an oxidizing agent first interact, resulting in a fire or explosion.

3.3.154 Power.

A property of a process, such as fire, which describes the amount of energy that is emitted, transferred, or received per unit time and is measured in joules per second (J/s) or watts (W).

3.3.155 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.

3.3.156 Preservation.

Application or use of measures to prevent damage, change or alteration, or deterioration.

3.3.157 Print Data.

Print data includes writings, drawings, graphs, charts, photographs, images, and other material in paper or print form, including ESI that has been reproduced on paper or print media.

3.3.158 Products of Combustion.

See 3.3.38, Combustion Products.

3.3.159 Protocol.

A description of the specific procedures and methodologies by which a task or tasks are to be accomplished.

3.3.160 Proximate Cause.

The cause that directly produces the effect without the intervention of any other cause.

3.3.161 Pyrolysate.

Product of decomposition through heat; a product of a chemical change caused by heating.

3.3.162 Pyrolysis.

A process in which material is decomposed, or broken down, into simpler molecular compounds by the effects of heat alone; pyrolysis often precedes combustion.

3.3.163 Pyrophoric Material.

Any substance that spontaneously ignites upon exposure to atmospheric oxygen.

3.3.164 Radiant Heat.

Electromagnetic transmission of heat energy; increases the sensible temperature of any substance capable of absorbing the radiation, especially solid and opaque objects.

3.3.165 Radiation.

Heat transfer by way of electromagnetic waves that are longer than visible light waves and shorter than radio waves.

3.3.166 Rekindle.

A return to flaming combustion after apparent but incomplete extinguishment.

3.3.167 Responsibility.

The accountability of a person or other entity for the event or sequence of events that caused the fire or explosion, spread of the fire, bodily injuries, loss of life, or property damage.

3.3.168 Risk.

The degree of peril; the possible harm that might occur that is represented by the statistical probability or quantitative estimate of the frequency or severity of injury or loss.

3.3.169 Rollover.

See 3.3.89, Flameover.

3.3.170 Scene.

The general physical location of a fire or explosion incident (geographic area, structure or portion of a structure, vehicle, vessel, piece of equipment, etc.) designated as important to the investigation because it may contain physical damage or debris, evidence, victims, or incident-related hazards.

3.3.171 Scientific Method.

The systematic pursuit of knowledge involving the recognition and definition of a problem; the collection of data through observation and experimentation; analysis of the data; the formulation, evaluation and testing of hypotheses; and, where possible, the selection of a final hypothesis.

3.3.172 Seat of Explosion.

A craterlike indentation created at the point of origin of some explosions.

3.3.173 Seated Explosion.

An explosion with a highly localized point of origin, such as a crater.

3.3.174 Secondary Explosion.

Any subsequent explosion resulting from an initial explosion.

3.3.175 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.

3.3.176 Self-Ignition.

Ignition resulting from self-heating, synonymous with spontaneous ignition.

3.3.177 Self-Ignition Temperature.

The minimum temperature at which the self-heating properties of a material lead to ignition.

3.3.178 Sever Arc.

An arc site where one or more of the circuit conductors were physically severed by the arcing event at that location.

3.3.179 Short Circuit.

An abnormal connection (including an arc) of relatively low impedance, whether made accidentally or intentionally, between two or more points of different potential. [70, 2023]

3.3.180 Site.

The general physical location of the incident, including the scene and the surrounding area deemed significant to the process of the investigation and support areas.

3.3.181 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. [3182022]

3.3.182 Smoke Condensate.

The condensed residue of suspended vapors and liquid products of incomplete combustion.

3.3.183 Smoke Explosion.

See 3.3.19, Backdraft.

3.3.184 Smoldering.

Self-sustained glowing combustion without flame, usually with incandescence and smoke.

3.3.185 Soot.

Black particles of carbon produced in a flame.

3.3.186 Spalling.

Chipping or pitting of concrete or masonry surfaces.

3.3.187 Spark.

A moving particle of solid material that emits radiant energy due either to its temperature or the process of combustion on its surface. [654, 2020]

3.3.188 Specific Gravity (of a gas or vapor).

The ratio of the average molecular weight of a gas or vapor to the average molecular weight of air, or the ratio of the density of a gas to the density of dry air at standard temperature and pressure.

3.3.189 Specific Gravity (of a liquid or solid).

The ratio of the mass of a given volume of a substance to the mass of an equal volume of water at a temperature of 4°C.

3.3.190 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.

3.3.191* Spontaneous Heating.

Process whereby a material increases in temperature without drawing heat from its surroundings.

3.3.192 Spontaneous Ignition.

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

3.3.193 Suppression.

The sum of all the work done to extinguish a fire, beginning at the time of its discovery.

3.3.194 Target Fuel.

A fuel that is subject to ignition by thermal radiation such as from a flame or a hot gas layer.

3.3.195* Temperature.

The degree of sensible heat of a body as measured by a thermometer or similar instrument.

3.3.196 Thermal Column.

See 3.3.152, Plume.

3.3.197* Thermal Expansion.

The increase in length, volume, or surface area of a body with rise in temperature.

3.3.198 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 (ρ), and its heat capacity (c).

3.3.199 Thermodynamics.

The branch of physics that deals with the relationship between heat and other forms of energy.

3.3.200 Thermometry.

The study of the science, methodology, and practice of temperature measurement.

3.3.201 Thermoplastic.

Plastic materials that soften and melt under exposure to heat and can reach a flowable state.

3.3.202 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.

3.3.203 Time Line.

Graphic representation of the events in a fire incident displayed in chronological order.

3.3.204 Total Burn.

A fire scene where a fire continued to burn until most combustibles were consumed and the fire self-extinguished due to a lack of fuel or was extinguished when the fuel load was reduced by burning and there was sufficient suppression agent application to extinguish the fire.

3.3.205 Trailer.

Solid or liquid fuel used to intentionally spread or accelerate the spread of a fire from one area to another.

3.3.206 Understanding or Agreement.

A written or oral consensus between the interested parties concerning the management of the investigations.

3.3.207 Upper Layer.

A buoyant layer of hot gases and smoke produced by a fire in a compartment.

3.3.208 Vapor.

The gas phase of a substance, particularly of those that are normally liquids or solids at ordinary temperatures. (See also 3.3.103, Gas.)

3.3.209 Vent.

An opening for the passage of, or dissipation of, fluids, such as gases, fumes, smoke, and the like.

3.3.210 Ventilation.

The movement of gases within, into, or from any compartment or space or the firefighting operation of removing smoke and heat from the structure by opening windows and doors or making holes in the roof.

3.3.211 Ventilation-Controlled Fire.

A fire in which the heat release rate or growth is controlled by the amount of air available to the fire.

3.3.212 Venting.

The escape of smoke and heat through openings in a building.

3.3.213 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.

3.3.214 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.

3.3.215 Work Plans.

An outline of the tasks to be completed as part of the investigation including the order or time line for completion. See Chapter 15, Planning the Investigation.


3.4* Canine Definitions.

Deploying canine-handler teams in fire investigations requires the investigator to understand certain concepts that are described by specialized terminology. This section provides definitions of terms used in relation to the canine section (see Section 17.7).

3.4.1 Canine-Handler Team.

A canine-handler team is a human and working dog who train and work together as an operational unit. [SC1, 2011]

3.4.2* Certification.

Certification is the recognition that a canine-handler team has acquired and demonstrated specialized knowledge, skills, and abilities in the standard practices necessary to execute the duties of a canine team. Certification also provides the fire investigator a means of identifying those canine-handler teams that have successfully demonstrated compliance with established requirements. In addition, certification establishes that a canine-handler team achieves and maintains proficiency.

3.4.3 Handler.

The handler is a person who has successfully completed a documented training and certification process in canine handling in the specific discipline of ignitible liquid canine detection and maintains those abilities through field application, maintenance training, scheduled recertification, and continuing education. (See 3.4.2, Certification.) [SC1, 2011]

3.4.4* Ignitible Liquid Detection Canines (IGL Canines).

Ignitible liquid detection canines (IGL canines) are dogs specifically trained to locate and respond to the presence of certain classes of ignitible liquids by associated odor.

3.4.5* Scent Discrimination.

Operational usage: A dog’s olfactory ability to distinguish between various odors.


3.5 Terminology Specific to Wildfire Investigations.

The community of wildfire investigators has developed discipline-specific terminology to address detailed aspects of fires occurring in the wildland environment and processes. This includes terms such as general origin areaspecific origin area, and ignition area, which have been established to address important areas of the wildland fire investigation process. These terms, and other wildfire investigation-specific terms, can be found in the National Wildfire Coordinating Group’s (NWCG) Guide to Wildland Fire Origin and Cause Determination, and Glossary of Wildland Fire Terminology.

3.5.1 Advancing Fire.

Fire characterized by rapid fire spread with higher intensity, normally burning with the wind or up slope—also known as a forward fire or a run.

3.5.2 Aerial Fuels.

Those flammable materials located from approximately 2 m (6 ft) above the surface to the crowns of the canopy, and which can include tree branches, leaves, needles, snags, moss, and tall brush.

3.5.3 Backing Fire.

A fire spreading against the wind or downslope.

3.5.4 Crown Fire.

A fire that advances from top to top of trees or shrubs more or less independent of a surface fire—also classed as passive, active, or independent to distinguish the degree of independence from a surface fire.

3.5.5 Duff.

The layer of decomposing organic materials lying below the litter layer of freshly fallen twigs, needles, and leaves and immediately above the mineral soil.

3.5.6 Ember.

See 3.5.7, Firebrand.

3.5.7 Firebrand.

Flaming or glowing fuel particles that can be carried naturally by wind, convection currents, or by gravity into unburned fuels.

3.5.8 Fire Head.

The portion of a fire moving most rapidly.

3.5.9 General Origin Area.

The larger area where the fire first established itself and is identified by an analysis of the fire behavior context, macroscale fire pattern indicators, and witness statements.

3.5.10 Ground Fuels.

All flammable materials located between the mineral soil layer and the ground surface, which typically include twig, leaf, and needle litter and decomposing vegetation such as duff, peat moss, buried limbs, and roots.

3.5.11 Heel.

The opposite end of the fire from the head.

3.5.12 Ignition Area.

The smallest area that a wildfire investigator can define based on the physical evidence of the fire pattern indicators, within the specific origin area, in which a competent ignition source came into contact with the first fuel ignited.

3.5.13 Lateral Fire.

Rate or spread and intensity of a fire usually falling somewhere in between advancing and backing with spread lateral to the main direction of fire travel—also known as a flanking fire.

3.5.14 Specific Origin Area.

The smaller area within the general origin area where the fire’s direction of spread was first influenced by fuel, weather, or topography.

3.5.15 Surface Fuels.

Ignitable materials located from the surface of the ground to approximately 2 m (6 ft) above the surface, which includes grasses, leaves, twigs, needles, field crops, slash, and downed limbs.

3.5.16 Transition Zone.

Where random or erratic fire travel transitions to fire effects causing patterns to indicate a directional spread of fire, which may be lateral, advancing, or backing.

3.5.17 Wildfire.

An event dealing with a fire in the wildland; originating from an unplanned ignition, such as lightning, volcanos, unauthorized and accidental human-caused fires, and prescribed fires that are declared wildfires.

3.5.18 Wildland.

An area in which development is essentially nonexistent, except for roads, railroads, powerlines, and similar transportation facilities and where structures, if any, are widely scattered.