Fire science

Question 1

Fire science

What is the definition of combustion?

Answer 1

An irreversible chemical reaction producing heat and light

Question 2

Fire science

Name the things required to make up the ‘triangle of fire’?

Answer 2

• fuel
• heat
• oxygen

Question 3

Fire science

Name the three states in which matter can exists?

Answer 3

• solid
• liquid
• gas

Question 4

Fire science

Name the SI unit that measures heat energy?

Answer 4

joules (J)

Question 5

Fire science

Heat is spread in three ways, what are they?

Answer 5

• convection
• conduction
• radiation.

Question 6

Fire science

What is the term used to descried a substance that contain oxygen “Lock-up” within its structure which is then released to allow combustion?.

Answer 6

Oxidising agent

Question 7

Fire science

To extinguish a fire it is necessary to break one of the legs on the triangle of fire how can this be achieved?

Answer 7

• cooling
• starving
• smothering.

Question 8

Fire science

What is a Flash Point?

Answer 8

The lowest temperature at which sufficient vapours are produced for a momentary flash to occur when an ignition source is introduced. But there are insufficient vapours for it to continue burning once the ignition source is removed

Question 9

Fire science

What is Fire Point?

Answer 9

The lowest temperature at which sufficient vapours are produced for the fuel to ignite and continue to burn once an ignition source is introduced.

Question 10

Fire science

What is meant by the term Auto-ignition temperature?

Answer 10

The lowest temperature at which a fuel will ignite and continue to burn without the need for an ignition source

Question 11

Fire science

What do the initials LEL stand for and explain there meaning?

Answer 11

lower explosive limit.

Below a fuels LEL it will be too lean to burn

Question 12

Fire science

What do the initials UEL stand for and explain there meaning?

Answer 12

Upper Explosive Limit.

Above this the mixture will be too fuel rich to burn

Question 13

Fire science

Describe what the ‘flammable range’ of a fuel is?

Answer 13

The ‘flammable’ range is between the LEL and the UEL and it is the percentage mixtures of fuel and air that are capable of being ignited

Question 14

Fire science

Describe the 4 classes of fire, class A,B,C and D ?.

Answer 14

• Class A - Carbonaceous
• Class B - Liquids and Liquefiable Solids
• Class C - Gases and Liquefied Gases
• Class D - Metals

Question 15

Fire science

What colour is a “diffused” flame?

Answer 15

red & yellow

Question 16

Fire science

What is meant by the term ‘pyrolisis’?

Answer 16

Pyrolisis is the decomposition of a substance by heat which can produce flammable gases

Question 17

Fire science

Define a flashover?

Answer 17

A sudden and sustained transition of a growing fire into a fully developed fire

Question 18

Fire Science

What are the signs of a flashover?

Answer 18

• Intense heat forces crews low
• Flames in gas layer
• Lowering of neutral plan
• All exposed surfaces pyrolising

Question 19

Fire Science

What actions should you take when dealing with a flashover?

Answer 19

• Pulse spray into ceiling , cool gases
• Stay low
• Consider withdrawing and fire fight from out side
• Consider ventilation

Question 20

Fire science

What are the signs of a flashover?

Answer 20

• intense heat forces crews low
• flames in gas layer
• lowering of neutral plan
• all exposed surfaces pyrolising

Question 21

Fire science

What actions should you take when dealing with a flashover?

Answer 21

• pulse spray into ceiling , cool gases
• stay low
• consider withdrawing and fire fight from out side
• consider ventilation

Question 22

Fire Science

What are the external signs of back draught ?

Answer 22

• Fire burning for some time
• Fire gases being pushed out under pressure from gaps
• Windows blackened with no visble sign of flame
• Fire gases (smoke) pulsing out from gaps

Question 23

Fire Science

What are the internal signs of backdraught ?

Answer 23

• Low neutral plane
• Darkening of fire gases
• Inrush of air & fire gases being forced out through openings
• Pulsation of fire gases through openings
• Deflagration through the opening

Question 24

Fire science

Define the term “Backdraught”?

Answer 24

The explosive or rapid burning of heated gases that occurs when oxygen is introduced into a building or compartment that has not been properly ventilated and has a depleted supply of oxygen due to fire

Question 25

# Fire Science What are the common internal signs of a possible backdraught?

Answer 25

Low neutral plane No visible flame

Question 26

# Fire Science What actions should be taken when dealing with a backdraught?

Answer 26

* Stay low Cover door with charged hose * Spray gases exiting openings * Only open doors when crews insitu * Pulse spray * Consider high level opening with covering jet

Question 27

# Fire Science What conditions are needed for a back draught to occur?

Answer 27

A compartment that has sufficient heat & fuel but is poorly ventilated

Question 28

# Fire science What conditions are needed for a back draught to occur?

Answer 28

A compartment that has sufficient heat & fuel but is poorly ventilated

Question 29

# Fire science What are the signs of back draught ?

Answer 29

* fire with limited or no ventilation. * thick black, yellow or cold smoke. * small blue flames around doors and windows. * hot doors and windows. * soot blackened windows. * lack of visible flame within the compartment. * air drawn in (whistling noise). * smoke pulsating through small gaps in openings

Question 30

# Fire science What are the internal signs of backdraught ?

Answer 30

* low neutral plane * darkening of fire gases * inrush of air & fire gases being forced out through openings * pulsation of fire gases through openings * deflagration through the opening

Question 31

# Fire Science What are passive agents?

Answer 31

``` Passive agents (passives) exist alongside the triangle of combustion in the combustion process. They are present in any combustion process and take no part in the chemical reaction. But they do affect a fire’s behaviour by absorbing or stealing some of the heat that makes up part of the triangle ```

Question 32

# Fire Science What are the LEL & UEL for Acetylene gas?

Answer 32

Between 2.5% & 100%

Question 33

# Fire Science What are they LEL & UEL for Propane gas?

Answer 33

2.1% & 9.5%

Question 34

# Fire Science Give some examples of passive agents?

Answer 34

* Non-flammable gases: carbon dioxide, water vapour. * Soot: carbon particles * Weather: temperature and humidity * Nitrogen: a constituent of air that remains inert throughout combustion * Compartment boundaries: walls and ceilings.

Question 35

# Fire science What are the common internal signs of a possible backdraught?

Answer 35

low neutral plane no visible flame

Question 36

# Fire science What is the expansion Ratio When water turns to steam ?

Answer 36

The ratio is1700:1 @100^oC, although this ratio increases signifcantly as the temperature increases

Question 37

# Fire Science Define the term 'Fire Gas Explosion'?

Answer 37

Ignition of fire gases that have accumulated outside the original fire compartment

Question 38

# Fire Science What effect does cooling fire gases have on compartment involved fires?

Answer 38

* Creates a safer approach for Ff's * Helps prevent Flashovers * Helps prevent Backdraughts

Question 39

# Fire science Define the term 'Fire Gas Explosion'?

Answer 39

Ignition of fire gases that have accumulated outside the original fire compartment

Question 40

# Fire Science What would a yellow flame indicate ?

Answer 40

That a flame is fuel rich

Question 41

# Fire Science What are the three main headings when describing methods of extinguishing fires?

Answer 41

* Direct * Indirect * Gas cooling

Question 42

# Fire science What effect does cooling fire gases have on compartment involved fires?

Answer 42

* creates a safer approach for firefighters * helps prevent flashovers * helps prevent backdraughts

Question 43

# Fire science What are the three main headings when describing methods of extinguishing fires?

Answer 43

* direct * indirect * gas cooling

Question 44

# Fire science What would a yellow flame indicate ?

Answer 44

That a flame is fuel rich

Question 45

# Fire science What are passive agents?

Answer 45

``` Passive agents (passives) exist alongside the triangle of combustion in the combustion process. They are present in any combustion process and take no part in the chemical reaction. But they do affect a fire’s behaviour by absorbing or stealing some of the heat that makes up part of the triangle ```

Question 46

# Fire science What are the LEL & UEL for acetylene gas?

Answer 46

between 2.5% & 81%

Question 47

# Fire science What are they LEL & UEL for propane gas?

Answer 47

2.1% & 11.1%

Question 48

# Fire science Give some examples of passive agents?

Answer 48

* non-flammable gases: carbon dioxide, water vapour. * soot: carbon particles * weather: temperature and humidity * nitrogen: a constituent of air that remains inert throughout combustion * compartment boundaries: walls and ceilings.