IFSTA(5th)-Chapter 3 Flashcards
0
Q
physical change
A
substance changes size, shape, or state
1
Q
Matter
A
anything that occupies space and has mass
2
Q
chemical change
A
substance changes from one type of matter to another
3
Q
Exothermic
A
heat is produced
4
Q
Endothermic
A
heat is absorbed
5
Q
Combustion
A
rapid, self-sustaining chemical reaction that produces heat and light
6
Q
fire
A
form of combustion. can be smoldering or flaming
7
Q
Fire triangle
A
fuel, oxygen, heat
best describes smoldering combustion
8
Q
Fire tetrahedron
A
Fuel, oxygen, heat, self-sustaining chemical chain reaction. best describes flaming combustion
9
Q
Heat
A
kinetic energy associated with the movement of the atoms and molecules in matter. measured in Joules (Newtons/meters)
10
Q
Temperature
A
measurement of KE due to heat
11
Q
KE
A
kinetic energy
energy of a moving object
12
Q
PE
A
potential energy
energy within an object at rest that can be released in the future
13
Q
Heat movement
A
from hot objects to cold ones conduction radiation convection flame impingement
14
Q
Energy
A
capacity to perform work
15
Q
Work
A
force applied over distance
(mass x acceleration)/distance
16
Q
force
A
mass x acceleration
Kg)(meters/s squared
17
Q
BTU
A
British thermal unit
amount of heat required to raise Temp of 1# of water 1 degree F.
18
Q
Fahrenheit
A
F=(C x 1.8) + 32
19
Q
Celsius
A
C = (F-32)/1.8
20
Q
auto ignition temp.(AIT)
A
point at which a material ignites without an external ignition source
21
Q
Pyrolysis
A
chemical decomposition of a substance due to heat
22
Q
piloted ignition
A
ignition due to external source
23
Q
6 energy forms that can create heat
A
chemical electrical light mechanical nuclear sound
24
oxidation
occurs when a combustible comes into contact with oxygen. when an oxygen electron is added to something. almost always produces heat.
25
Increase in 10 degrees C
results in most chemical reaction rates doubling
26
electrical heating occurs 4 ways
resistance heating
overload/overcurrent
arcing
sparking
27
Resistance heating
electric current flowing through a conductor
28
overload/overcurrent
when electric current exceeds conductor capacity
29
Arcing
high temp. luminous electric discharge across a gap or through a medium. e.g., when a conductor is separated, lightning, static electricity, or due to excessive voltage
30
Sparking
the glowing particles that spatter away from the point of arcing
31
Mechanical heat energy
due to friction or compression
32
Rate of heat transfer
is greater between 2 objects with a greater Temp. difference.
heat transfer/time.
33
Conduction
transfer of heat from one solid object to another solid object by direct contact.
34
Thermal conductivity
measure of an object's capacity to transfer heat via conduction. the greater the conductivity, the faster the heat transfer!
35
insulating materials
slow conduction.
made of fine particles or fibers with lots of air filled voids.
because molecules are far apart in gases, air doesn't conduct heat very well.
36
Convection
transfer of heat from a liquid or a gas to a solid
37
Radiation
transmission of heat energy as an electromagnetic wave through space.
examples: infrared, radio, x-rays
360 degree spread at the speed of light
38
As Temp. increases the radiant energy...
increases by a factor to the 4th power. for example: if T is doubled, then 2 to the 4th is 16. so T is doubled and the radiant energy is 16x greater
39
Passive agents
substance such as water that is inside a substance or within a gas and absorbs heat but does not participate actively in combustion. relative humidity and fuel moisture are examples.
40
Reducing agent
the fuel that is being oxidized. it is being reduced 2 ways: reduction of fuel and the addition of electrons(negative charge)
41
organic
contains carbon
42
2 types of organic fuels
hydrocarbons
| cellulose-based materials
43
flaming combustion only occurs in which state?
gaseous
44
Vapor density
if > 1 the gas will sink
| if < 1 the gas will rise
45
methane VD
0.55, rises
46
Propane VD
1.52, sinks
47
LPG
liquid petroleum gas
| also known as propane
48
CO VD
carbon monoxide
| VD=0.96, rises
49
Specific Gravity
if SG < 1, floats on water
| if SG > 1, sinks in water
50
Vaporization
transformation of a liquid to a gas
51
Rate of Vaporization depends on...
vapor pressure of substance
| amount of heat energy applied
52
Flash Point
Minimum Temp. when a liquid gives off enough vapors to form an ignitable mixture with air.
53
Fire Point
Temp. at which a liquid fuel produces enough vapors to support combustion once the fuel is ignited. normally a few degrees higher than the flash point.
54
As surface area of a liquid increases, vapor production...
increases
55
solubility
degree of a substance to dissolve in a solvent (usually water)
56
Polar sovents ____ with water
mix
57
Hydrocarbons_____with water
do not mix
58
SG gasoline
0.72, floats on water
59
Miscible
material that can mix with water in any proportion
60
SG diesel
is > 1, sinks
61
SG ethanol
= 0.78, floats
62
SG methanol
= 0.79, floats
63
for solids, as surface-to-mass ratios increase, ignitability...
increases
64
4 stages(Temp. Ranges) of Pyrolysis
< 392 degrees F, moisture is being releases
392 - 536 degrees F, charring begins
536 - 932 degrees F, rapid pyrolysis occurs, charcoal is produced, ignition can occur
> 932 degrees F, free burning as wood is converted to flammable gases
65
Do solids burn more rapidly due to position?
yes, due to convection solids that are vertical burn more rapidly
66
Heat of Combustion
total amount of energy released when a fuel is burned(oxidized).
kiloJ/gram
67
HRR
heat release rate
| energy released over time for a given fuel
68
"Oxygen deficient"
atmosphere with less than 19.5% oxygen
69
"oxygen enriched"
atmosphere with > 23.5% O2
70
Common Oxidizers(other than O2)
calcium hypochlorite-chlorination of water in pools
chlorine gas-water purification
ammonium nitrate-fertilizer
hydrogen peroxide-antiseptic, industrial bleaching
methyl ethyl ketone peroxide-plastics
71
31% O2
O2 concentration that Nomex ignites and readily burns
72
Flammable(explosive) Range
range of concentrations of fuel vapor and air that allow for combustion. LFL-UFL lower flammable limit to the upper flammable limit
73
"Lean"
fuel vapor concentration in air is < LFL
74
"rich"
fuel vapor concentration in air is > UFL
75
Common Flammable Ranges
methane: 5-15%
propane: 2.1-9.5%
CO: 12-75%
gasoline: 1.4-7.4%
diesel: 1.3-6%
ethanol: 3.3-19%
methanol: 6-35.5%
76
Methane is also known as _____
natural gas
77
free radicals
electrically charged, highly reactive parts of molecules that combine with other components of a fuel to create new substances
78
Chemical flame inhibition
extinguishing agent interrupts the self-sustaining chemical reaction and terminates combustion. halon is an example...or a halon replacement. this cannot be done on smoldering combustion
79
Smoke
mixture of gases, vapor, and solid particulates
80
CO
carbon monoxide
asphyxiant
formed by the incomplete combustion of carbon
combines to hemoglobin 200x quicker than O2
81
CO2
carbon dioxide
colorless, odorless, heavier than air.
neither burns or supports combustion.
used as an extinguishing agent by displacing O2 or smothering fires
82
HCN
hydrogen cyanide
produced in the combustion of materials containing nitrogen. produced when polyurethane foams burn (furniture/bedding)
prevents the body from using O2 at the cellular level.
83
flame
visible, luminous body of a burning gas
84
Class A Fire
ordinary combustibles
wood, cloth, paper, plastics, rubber, grass, etc.
primary extinguishment via cooling with water
85
Class B Fires
flammable liquids and gases
remove supply
use class B foams to blanket or dry chemicals.
86
Class C Fires
energized electrical fire
| de-energize before extinguishment.
87
Class D Fire
```
combustible metals
aluminum
magnesium
potassium
zirconium
titanium
sodium
```
88
Class K Fire
cooking fuels
89
Saponification
when extinguishing agents turn fats and oils into a soapy foam that extinguish the fire
90
fuel controlled fire
when O2 is sufficiently available
91
Ventilation controlled fire
when fire is limited by air supply
92
4 stages of fire
incipient
growth
fully developed
decay
93
Incipient stage
ignition occurs
fuel controlled
mostly confined to the material burning
94
Growth Stage
2-in/2-out is now required
rapidly increasing heat
other materials are now burning
95
Thermal layering
gases form into layers according to temperature. hottest are at the ceiling and coolest are at the floor.
also known as stratification and thermal balance.
96
Neutral plane
where high pressure gases level off thru an opening with inward moving cooler air.
97
Rollover
when fire gases ignite at the ceiling level and flames propagate through the hot gas layer across the ceiling
98
Flashover
rapid transition from growth to fully developed fire stage that is when all contents within a structure reach their ignition Temp. and flames erupt all at once.
99
Flashover Indicators
```
lower hot gas layers
strong bidirectional air/smoke movement
rapid increase in heat
isolated flames in a hot gas layer
rollover
```
100
flashover Temp. Range
900-1200 degrees F
| btw, CO auto ignites at 1128 F
101
Fully Developed Fire
when all combustible materials in a compartment are burning
102
Decay
when most fuel has been consumed or the O2 has diminished enough where flaming combustion is no longer supported
103
Is decay fuel or ventilation controlled?
fuel
104
Fully developed fire is _____ controlled
ventilation
105
Backdraft
instantaneous explosion or rapid burning of superheated gases that occurs when O2 is introduced into a confined space
106
Deflagration
explosively rapid combustion
107
T or F. the more confined the deflagration, the more violent it will be.
true
108
Backdraft Indicators
```
little or no visible flame
inward sucking smoke
pressurized smoke exiting small openings
smoke puffing
dense gray/yellow smoke
smoke stained/cracked windows
confined excessive heat
```
109
6 factors that affect fire development
```
fuel type
location/availability of another fuel
compartment shape
ventilation
thermal properties of structure
ambient conditions(wind/temp/humidity/etc)
```
110
HVAC
heating ventilation and AC
111
4 thermal properties that affect fire
insulation
conductivity
retention
reflection
112
4 ways to control fire
temp. reduction
O2 exclusion
fuel removal
inhibit chemical reaction
