Chapter 5: Fire Behavior Flashcards Preview

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Flashcards in Chapter 5: Fire Behavior Deck (73)
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1

Ambient Conditions

Common, prevailing, and uncontrolled atmospheric weather conditions. The term may refer to the conditions inside or outside of the structure.

2

Autoignition

Initiation of combustion by heat but without a spark or flame. (NFPA 921)

3

Autoignition Temperature

The lowest temperature at which a combustible material ignites at which a combustible material ignites in air without a spark or flame. (NFPA 921)

4

Backdraft

The explosive burning of heated gases the occurs when O2 is introduced into a compartment that has a high concentration of flammable gases and a depleted supply of O2 due to an existing fire.

5

Buoyant

The tendency or capacity to remain afloat in a liquid or rise in air or gas.

6

Carbon Dioxide (CO2)

Colorless, odorless, heavier than air gas that neither supports combustion nor burns; used in portable fire extinguishers as an extinguishers as an extinguishing agent to extinguish Class B or C fires by smothering or displacing the oxygen.

7

Carbon Monoxide (CO)

Colorless, odorless, dangerous gas (both toxic and flammable) formed by the incomplete combustion of carbon. It combines with hemoglobin more than 200 times faster than oxygen does, thus decreases the blood’s ability to carry oxygen.

8

Ceiling Jet

A relatively thin layer of flowing hot gases that develops under a horizontal surface (ceiling) as a result of plume impingement and the flowing gas being forced to move horizontally (NFPA 921).

9

Chemical Flame Inhibition

Extinguishment of a fire by interruption of the chemical chain reaction.

10

Combustible Liquid

Liquid having a flash point at or above 100 degrees F and below 200 degrees F.

11

Combustion

A chemical process of oxidation that occurs at a rate fast enough to produce heat an usually light in the form of either a glow or flame. (Reproduced with permission from NFPA 921-2011, Guide for Fire and Explosion Investigations, Copyright 2011, NFPA).

12

Conduction

Transfer of heat through or between solids that are in direct contact.

13

Convection

Heat transfer by circulation within a medium such as a gas or a liquid. (NFPA 921)

14

Endothermic Reaction

Chemical reaction that absorbs thermal energy or heat.

15

Engergy

Capacity to perform work; occurs when a force is applied to an object over a distance, or when a chemical, biological, or physical transformation is made in substance.

16

Exothermic Reaction

Chemical reaction that releases thermal energy or heat.

17

Fire Point

Temperature at which a liquid fuel produces sufficient vapors to support combustion once the fuel is ignited. Fire point must exceed 5 seconds of burning duration during the test. The fire point is usually a few degrees above the flash point.

18

Fire

A rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities. (NFPA 921)

19

Fire Tetrahedron

Model of the four elements/conditions required to have a fire. The four sides of the tetrahedron represent fuel, heat, oxygen, and self-sustaining chemical chain reaction.

20

Fire Triangle

A model used to explain the elements/conditions necessary for combustion. The sides of the triangle represent heat, oxygen, and fuel.

21

Flame

Visible, luminous body of a burning gas emitting radiant energy including light of various colors given off by burning gases or vapors during the combustion process.

22

Flammable Liquid

Any liquid having a flash point below 100 degrees F (37.8 degrees C) and a vapor pressure not exceeding 40 psi absolute (276 kPa) {2.76 bar}.

23

Flammable (Explosive) Range

The range between the upper flammable limit and lower flammable limit in which a substance can be ignited.

24

Flashover

A rapid transition from the growth stage to the fully developed stage.

25

Flash Point

Minimum temperature at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquid’s surface.

26

Fire Point

Temperature at which a liquid fuel produces sufficient vapors to support combustion once the fuel is ignited. Fire point must exceed 5 seconds of burning duration during the test. The fire point is usually a few degrees above the flash point.

27

Flow Path

Composed of at least one inlet opening, one exhaust opening, and the connecting volume between the openings. The direction of the flow is determined by difference in pressure. Heat and smoke in a high pressure area will flow toward areas of lower pressure.

28

Free Radicals

Molecular fragments that are highly reactive.

29

Fuel

A material that will maintain combustion under specified environmental conditions. (NFPA 921)

30

Fuel-Controlled

A fire with adequate O2 in which the heat release rate and growth rate are determined by the characteristics of the fuel, such as quantity and geometry (NFPA 921).