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Fire Dynamics Flashcards

(80 cards)

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1
Q

To understand how to control or predict fire behavior, firefighters must gain understanding of:

A

combustion, fire, heat, temperature

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2
Q

Physical science

A

study of matter and energy

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3
Q

physical change occurs when:

A

a substance remains chemically the same but changes in size, shape, appearance

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4
Q

oxidation

A

chemical reaction involving an oxidizer and other materials

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5
Q

work

A

increasing a substances temperature

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6
Q

potential energy

A

amount of energy that an object can release at some point in the future

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7
Q

heat of combustion

A

total amount of thermal energy (heat) that could be generated by the combustion reaction if a fuel were completely burned

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8
Q

chemical and physical changes almost always :

A

involve an exchange of energy

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9
Q

exothermic reaction

A

emit energy as they occur / fire

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10
Q

endothermic reactions

A

absorb energy/ steam

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11
Q

fire triangle

A

how to extinguish fire

fuel, oxygen, heat

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12
Q

fire tetrahedron

A

chemical chain reaction to explain flaming gas - phase combustion

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13
Q

fuels must be in a gaseous state to burn solids

A
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14
Q

liquids must become gaseous for ignition

A
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15
Q

pyrolysis

A

solid fuel turns to gaseous fuel

couch catch on fire from christmas tree

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16
Q

vaporization

A

conversion of liquid to a vapor by heat energy of combustion

boiling water

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17
Q

piloted ignition

A

fuel and oxygen encounters and external heat source to start combustion

lighting match to paper

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18
Q

autoignition

A

no external flame needed to ignite fuel gases

oil rag heating up

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19
Q

autoignition temperature

A

minimum temp that fuel in air has to heat self sustained combustion

oil rag

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20
Q

fire tetrahedron illustrate :

A

flaming combustion

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21
Q

fire compared to a pump

A

fresh oxygen pumped in and mixes with fuel gases. it burns, the fire pumps out combustion products

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22
Q

opening burning

A

fire burning in the open with no restriction to its oxygen supply

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23
Q

entrained

A

drawn in .. (hydraulic ventaliation)

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24
Q

the fire triangle illustrates:

A

nonflaming combustion

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25
flaming combustion
gas phase known as fire with visible flame
26
nonflaming combustion
solid phase occurs more slowly and low temperature … smoldering
27
products of combustion
heat and smoke
28
incomplete combustion
smoke / ash
29
complete combustion of methane
heat, light, water vapor, carbon dioxide
30
structure fires involve two basic types of fuel:
natural- wood / cotton synthetic- polyurethane, polyester (hotter, faster.. modern furniture)
31
carbon monoxide
colorless, odorless, toxic gas cause of death in civilians chemical asphyxiant
32
hydrogen cyanide (HCN)
toxic and flammable substance produced in the combustion of material with nitrogen bedding, carpets, upholstered furniture
33
houseshold furnitures are made of :
polyurethane foam
34
HCN is 35 times more toxic than CO acts as a chemical asphyxiant
35
pressure
force per unit of area applied perpendicular to a surface differences in pressure can create movement .. gas always moves from higher pressure areas to lower
36
37
power
rate energy transfers (Watts)
38
Heat Release Rate
energy released per unit of time as a fuel burns more oxygen , HRR increases
39
Heat is the thermal kinetic energy needed to release potential chemical energy in a fuel
40
Heat flux
measures heat transfer how quickly materials heat up
41
self - heating
oxidation that increases temperature of a material without adding external heat
42
spontaneous ignition
ignition without external heat rag in oil
43
resistance heating
heat produced by electric current flowing through conductor house heater
44
overcurrent
current exceeds its design limit/ may over heat too many plugs
45
arcing
high temp electrical discharge across gap or frayed wires
46
sparking
glowing particles can form and splatter
47
friction and compression general mechanical energy
48
transfer of heat
from initial fuel package (burning object)) to other fuels beyond the area of fire origin
49
thermal conductivity
greater temperature differences between objects the greater transfer area you can feel the fire in PPE
50
conduction
material is heated by direct contact firefighter hand and door
51
convection
heat transfer through movement of hot smoke and fire gases
52
radiation
transmission of energy as electromagnetic waves
53
radiation is common cause of:
exposure fires
54
hydrocarbons
petroleum products higher combustion and HRR
55
56
vapor density
1< will sink 1> will rise
57
flash point
minimum temp liquid produces vapors to ignite
58
fire point
temp liquid produces vapors that ignite and start combustion
59
air consists of :
21% oxygen available for combustion
60
ambient temperatures :
68 degree F material can ignite and burn oxygen concentration as low as 15%
61
flammable range
upper flammable limit and lower flammable limit a substance can ignite
62
lower flammable limit (LFL)
lower limit a flammable gas will ignite and support combustion too lean to burn (too much oxygen, not enough gas)
63
Upper Flammable Limit (UFL)
upper limit a flammable gas will ignite gas too rich to burn (lacks oxygen)
64
free radicals
increases speed of oxidation reaction
65
chemical flame inhibition
substance interferes the sustaining a flame, stopping or slowing combustion without removing heat or fuel
66
compartment
enclosed room
67
fuel limited
sufficient oxygen is available for flaming combustion
68
ventilation limited
have all the fuel for combustion but the fire does not have enough oxygen to continue to burn covering a candle
69
incipient stage of fire development
starts with ignition with all 3 elements of fire triangle come together starting combustion
70
growth stage
more initial fuel package becomes involved and smoke and heat increases . fire continues to grow
71
fully developed stage
all combustible materials in compartment are burning at their peak HRR. Fire is consuming max oxygen
72
decay stage
as fire consumes all oxygen, HRR begins to decline. fuel limited fires may self extinguish/ smoldering ventilation limited fire may self extinguish but if oxygen becomes available it could enter growth stage
73
ceiling jet
hot gases rise until they encounter the ceiling and spread horizontally
74
thermal layering
tendency of gases to form into layers according to temperature , gas density, pressure
75
flow path
space between the air intake and exhaust outlet
76
neutral plane
split between hot gas layer and cooler layer of air smoke out top window, cooler air coming in at bottom
77
tenable
capability of sustaining life
78
backdraft
instant explosion or rapid burning due to oxygen introduced
79
flashover
rapid transition from growth stage to fully developed stage. combustible materials in compartment ignite simultaneously for full room fire involvement growth… decay … door opened… flashover
80

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