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TFD > Fire Behaviors > Flashcards

Fire Behaviors Flashcards

1
Q

Define Fire

A

Fire is the term used to describe the rapid oxidation of combustible materials accompanied by a release of energy in the form of heat and light.

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2
Q

Define Combustion

A

Combustion is the self-sustaining process of rapid oxidation of a fuel, being reduced by an oxidizing agent along with the evolution of heat, gases, vapors soot and light

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3
Q

Components of fire tetrahedron

A

Oxygen
Fuel
Heat
Chemical Chain reaction

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4
Q

Oxygen facts

A

i. 21% in air
1. Oxygen enriched is 23.5%
2. Oxygen deficient is 19.5%
3. If oxygen deficient, then SCBA
ii. Approximately 16% required for free burning and visible flame
iii. +/- 8% before combustion stops
Does not burn, but rather facilitates combustion

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5
Q

How much oxygen is in each stage of the fire?

A
  1. 16-19% is incipient free burning
  2. 12-15% is smoldering, dying out
  3. 8% is dead
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6
Q

What forms does fuel come in?

A

Liquid
Gas
Solid

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7
Q

_____ and ____ of fuel particles will influence the ease of ignition and rate of burning

A

Size

shape

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8
Q

Physical properties and characteristics of fuel

A 
Flash point
Fire point
Ignition Tempurature
Flammable limits/range
Boiling point
Specific gravity
Vapor Density
Solubility
British Thermal Units
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9
Q

Define flash point

A

the temperature at which a liquid will give off sufficient vapor to flash (but not continue to burn) with an ignition source

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10
Q

Define fire point

A

the temperature at which a liquid gives off sufficient vapor to flash and to continue to sustain combustion with an ignition source present. Normally a couple of degrees higher than flash point

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11
Q

Define ignition tempurature

A

(Also known as auto-ignition temperature) The temperature at which a material will self-ignite without and ignition source

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12
Q

Define flammable limits/range

A

maximum and minimum concentrations of a gas in air which will ignite.

a. UEL – upper explosive limit
b. LEL – lower explosive limit

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13
Q

Define boiling point

A

the temperature at which the pressure at the surface of the liquid becomes greater than the atmospheric pressure

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14
Q

Define specific gravity

A

molecular weight of a liquid compared to the molecular weight of water (>1 sinks/

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15
Q

Define vapor density

A

molecular weight of a vapor compared to the weight of air (>1 sinks/

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16
Q

Define solubility

A

the ability to mix with water or another liquid

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17
Q

Define British Thermal Units

A

the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit

18
Q

Define heat

A

the form of energy that raises tempurature

19
Q

Define tempurature

A

the measurement of heat intensity

20
Q

How to find Fahrenheit when given Celcius

A

F=C*1.8+32

21
Q

How to find Celsius when given Fahrenheit

A

C=(F-32)/1.8

22
Q

How to find Kelvins when given Celsius

Not in PP

A

K=C+273

23
Q

How to Find Kelvins when given Fahrenheit

Not in PP

A

K=(F-32)/1.8+273

24
Q

What is a BTU?

A

the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.

  1. Grill = 30,000 BTU
  2. Dragon = 5,000,000 BTU
25
Q

Sources of heat energy are….

A
  1. Mechanical – friction, compression, percussion
  2. Electrical – arching, sparking, overload, resistance
  3. Chemical
  4. Nuclear – Fission and Fusion
26
Q

Methods of heat transfer

A

Conduction
Convection
Radiation
Direct contact

27
Q

Products of combustion are….

A

Flame
Heat
Smoke
Fire gases

28
Q

Fire gases (according to fire behavior class) are

A

i. Hydrogen Cyanide
ii. Carbon monoxide
iii. Carbon Dioxide
iv. Hydrogen Chloride
v. Phosgene
vi. Nitrous Oxides
vii. Sulfur Dioxides
viii. Formaldehydes

29
Q

The stages of a fire are…

A

incipient
free burning
smoldering phase

30
Q

Incipient stage of the fire

A
  1. Oxygen 20-21%
  2. Celling temperature ~100F
  3. Fire gases include water, carbon dioxide, carbon monoxide, sulfur dioxide
  4. Possibility of rollover
31
Q

Free Burning stage of fire

A
  1. Oxygen 16-19%
  2. Ceiling temperature ~1300-1800F
  3. Rapid flame spread
  4. Probability of flashover
    Thermal balance established
32
Q

Smoldering phase

A
  1. Oxygen less than 15%, flame may stop
  2. Temperature throughout the room approximately 1000deg
  3. Room filled with dense smoke and gases
  4. Possibility of backdraft, signs include:
    i. Smoke under pressure
    ii. black smoke becoming yellow-gray (the less O2 content, the darker the smoke)
33
Q

Warning signs of backdraft

A

a. Smoke under pressure!
b. Black smoke becoming yellow gray (less oxygen content= darker smoke)
c. Confinement and excessive heat
d. Little or no visible flames
e. Smoke leaving room in puffs
f. Smoke stained glass
g. Muffled sounds
h. Sudden inrush of air when opening is made

34
Q

Rollover:

A

A hazard that takes place during the incipient stage. Gases hot enough to ignite at the ceiling that travels. May ignite behind you and cut off egress. Precedes flashover.
(Might not be totally accurate. Open to suggestions)

35
Q

Flashover:

A

During the free burning stage, all the fuels in the room ignite simultaneously due to high temperatures. Not survivable (for most people!)

36
Q

Backdraft:

A

During the smoldering stage, a sudden introduction of air into an enclosed area that will cause an explosive reaction

37
Q

Classes of fires

A

a. Class A: ordinary solid combustibles
b. Class B: flammable liquids, gases, and semisolids
c. Class C: energized electrical equipment
d. Class D: combustible metals

38
Q

Principles of fire control

A

a. Heat control or cooling
b. Oxygen dilution or exclusion
c. Fuel removal or consumption
d. Chemical chain inhibition

39
Q

Extiguishing agents

A

a. Carbon Dioxide extinguishes fires by displacing oxygen
b. Dry Chemicals inhibits chain reactions in Class B and C fires and smothers Class A
c. Halon agents disrupt chemical chain reactions.
d. Foams separate fuel and inhibit chemical chain reactions
e. Dry powders are used for Class D fires
f. Water

40
Q

Physics of water

A

a. Law of specific heat: 212-water temp = BTU
b. Latent heat of vaporization: the amount of heat required to turn a liquid into a gas. 970*lbs. of water= energy absorbed
c. Water expands 1700 times

41
Q

Fire attack

A

a. Fog streams for efficient vaporization
b. Straight streams for penetration
c. Direct attack:
Used on fires in the incipient stage. A close fog pattern (30 or less) is applied directly to the seat of the fire in short bursts until the fire darkens down. Should not be applied for a long time or the thermal balance will be upset. This can harm firefighters or drive smoke to the floor
d. Indirect:
use of latent heat of vaporization. Nozzle pattern is set anywhere 30-60 degrees and directed into the upper atmosphere. This attack is not desirable when victims may still be present. Does not work without super high temperatures and confined areas.
e. Combination
T, S, or O pattern.

TFD (39 decks)

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