NFPA 921

 

Hansard Investigations follow the 7 steps of the NFPA 921 scientific method:

1. Recognising the need,

2. Defining the problem, 

3. Collecting data, 

4. Analysing data, 

5. Developing a hypothesis, 

6. Testing the hypothesis, and 

7. Selecting a final hypothesis. 

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NFPA OFFICIAL DEFINITIONS (Commonly found in our reports) 

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3.3.2 Accelerant. A Fuel or oxidizer, often an ignitable liquid, intentionally used to initiate a fire or increase the rate of growth or spread of fire.

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

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

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

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

3.3.19 Bead. A rounded mass of resolidified metal on the end of 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 un-melted conductor surfaces.

3.3.21 BLEVE. Boiling liquid expanding vapor explosion.

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

3.3.28 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.

3.3.31 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.

3.3.35 Combustion. A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light the form of either a glow or flame.

3.3.37 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)

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

3.3.78 Fire Patterns. The visible or measurable physical changes, or identifiable shapes, formed by a fire effect or group of fire effects.

3.3.83 First Fuel Ignited. The first fuel ignited is that which first sustains combustion beyond the ignition source.

3.3.84 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.

3.3.85 Flame Front. The flaming leading edge of a propagating combustion reaction zone.

3.3.87 Flammable. Capable of burning without a flame (NFPA 921).

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

3.3.90 Flammable Range. The range of concentrations between the lower and upper flammable limits.

3.3.93 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.

3.3.95 Fuel. A material that will maintain combustion under specific environmental conditions.

3.3.97 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.

3.3.98 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 adequate air for combustion is available.

3.3.99 Full Room Involvement. Condition in compartment fire in which the entire volume is involved in combustion of varying intensities.

3.3.101 Glowing Combustion. Luminous burning of solid material without a visible flame.

3.3.117 Ignition. The process of initiating self-sustaining combustion.

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

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

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

3.3.130 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 Minimum Explosible Concentration (MEC). The minimum concentration of combustible dust cloud that is capable of propagating a deflagration through uniform mixture of dust and air under the specified conditions test.

3.3.158 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.

3.3.167 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.

3.3.171 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.

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

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

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

3.3.182 Spalling. Chipping or pitting of concrete or masonry surfaces.

3.3.186 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.

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

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

3.3.198 Thermal Runaway. The uncontrollable self-heating of a battery cell, beginning when the heat generated within the battery exceeds the amount of heat that can be dissipated to its surrounds.

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

3.3.207 Ventilation-Controlled Fire. A fire in which the heat release rate or growth is controlled by the amount of air available to the fire.