NFPA 921 Definitions || with 100% Errorless Answers.
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Course
NFPA 921
Institution
NFPA 921
Absolute Temperature. correct answers A temperature measured in Kelvins (K) or Rankines (R).
Accelerant. correct answers A fuel or oxidizer, often an ignitible liquid, intentionally used to initiate a fire or increase the rate of growth or spread of fire.
Accident. correct answers An unplanne...
NFPA 921 Definitions || with 100% Errorless Answers.
Absolute Temperature. correct answers A temperature measured in Kelvins (K) or Rankines (R).
Accelerant. correct answers A fuel or oxidizer, often an ignitible liquid, intentionally used to
initiate a fire or increase the rate of growth or spread of fire.
Accident. correct answers 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.
Ambient. correct answers Someone's or something's surroundings, especially as they pertain to
the local environment; for example, ambient air and ambient temperature.
Ampacity. correct answers The maximum current, in amperes, that a conductor can carry
continuously under the conditions of use without exceeding its temperature rating. [70, Article
100]
Ampere. correct answers 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.
Arc. correct answers A high-temperature luminous electric discharge across a gap or through a
medium such as charred insulation.
Arc Mapping. correct answers The systematic evaluation of the electrical circuit configuration,
spatial relationship of the circuit components, and identification of electrical arc sites to assist in
the identification of the area of origin and analysis of the fire's spread.
Arc Site. correct answers The location on a conductor with localized damage that resulted from
an electrical arc.
Arcing Through Char. correct answers Arcing associated with a matrix of charred material (e.g.,
charred conductor insulation) that acts as a semiconductive medium.
Area of Origin. correct answers 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 3.3.132, Point of Origin.)
Arrow Pattern. correct answers A fire pattern displayed on the cross-section of a burned wooden
structural member.
Arson. correct answers The crime of maliciously and intentionally, or recklessly, starting a fire
or causing an explosion.
Autoignition. correct answers Initiation of combustion by heat but without a spark or flame.
, Autoignition Temperature. correct answers The lowest temperature at which a combustible
material ignites in air without a spark or flame.
Backdraft. correct answers A deflagration resulting from the sudden introduction of air into a
confined space containing oxygen-deficient products of incomplete combustion.
Bead. correct answers 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.
Blast Pressure Front. correct answers 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.
Bonding. correct answers 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.
British Thermal Unit (Btu). correct answers 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.
Burning Rate. correct answers See 3.3.99, Heat Release Rate (HRR).
Calcination of Gypsum. correct answers A fire effect realized in gypsum products, including
wallboard, as a result of exposure to heat that drives off free and chemically bound water.
Calorie. correct answers 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).
Cause. correct answers 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.
Ceiling Jet. correct answers 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.
Ceiling Layer. correct answers A buoyant layer of hot gases and smoke produced by a fire in a
compartment.
Char. correct answers Carbonaceous material that has been burned or pyrolyzed and has a
blackened appearance.
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