IFSTA(5th)-Chapter 3 Flashcards Preview

Keith's Cards > IFSTA(5th)-Chapter 3 > Flashcards

Flashcards in IFSTA(5th)-Chapter 3 Deck (113):
0

Matter

anything that occupies space and has mass

1

physical change

substance changes size, shape, or state

2

chemical change

substance changes from one type of matter to another

3

Exothermic

heat is produced

4

Endothermic

heat is absorbed

5

Combustion

rapid, self-sustaining chemical reaction that produces heat and light

6

fire

form of combustion. can be smoldering or flaming

7

Fire triangle

fuel, oxygen, heat
best describes smoldering combustion

8

Fire tetrahedron

Fuel, oxygen, heat, self-sustaining chemical chain reaction. best describes flaming combustion

9

Heat

kinetic energy associated with the movement of the atoms and molecules in matter. measured in Joules (Newtons/meters)

10

Temperature

measurement of KE due to heat

11

KE

kinetic energy
energy of a moving object

12

PE

potential energy
energy within an object at rest that can be released in the future

13

Heat movement

from hot objects to cold ones
conduction
radiation
convection
flame impingement

14

Energy

capacity to perform work

15

Work

force applied over distance
(mass x acceleration)/distance

16

force

mass x acceleration
(Kg)(meters/s squared)

17

BTU

British thermal unit
amount of heat required to raise Temp of 1# of water 1 degree F.

18

Fahrenheit

F=(C x 1.8) + 32

19

Celsius

C = (F-32)/1.8

20

auto ignition temp.(AIT)

point at which a material ignites without an external ignition source

21

Pyrolysis

chemical decomposition of a substance due to heat

22

piloted ignition

ignition due to external source

23

6 energy forms that can create heat

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