RFT 001: Fire Science 1 Flashcards Preview

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Flashcards in RFT 001: Fire Science 1 Deck (26):
1

What is the definition of combustion?
Give an example

An irreversible chemical reaction producing heat and light
Burning wood will produce ash, but ash cannot be transformed back into original wood

2

What three components form the triangle of fire?

Heat
Oxygen
Fuel

3

What is the difference between vapour and permanent gas?

Vapour has the potential to change back to a liquid with a change of pressure

4

Heat is a form of what?

Energy

5

What is an ignition source?
Name some examples of an ignition source

The heat energy required for combustion to occur

Naked flames
Electrical arcs or sparks
Frictional heat or sparks
Chemical reactions
Pressurisation of gas
Spontaneous heating

6

Heat energy is measured in what?

Joules
Joules per kilogram

7

Temperature is measured in what?

Celcius

8

How much oxygen is in the air and how much is needed for combustion?

21% in the air
16% needed for combustion

9

What is an oxidizing agent?

A substance that releases oxygen when heated, that can lead to combustion

10

What are passive agents or passives?
Name some examples

Substances that take no part in the chemical reaction of combustion, but can have an effect on the fire's behaviour by absorbing heat

Non flammable gases
Spot
Weather, temperature and humidity
Nitrogen in the air
Walls and ceilings
Furniture

11

The amount of oxygen available for combustion will determine what three things?

How quickly and efficiently a substance will burn
The type of fire gases that are released
The amount of smoke produced

12

What is pyrolysis?
What is the process of pyrolysis

The self-sustaining decomposition of a substance by heat

Heat from the flame radiates onto the surface of the fuel, causing it to pyrolysis, producing flammable gases to feed the flame

13

What is the flash point?

The lowest temperature at which vapours are being produced for a momentary flash to occur when an ignition source is introduced

Does not continue to burn once the ignition source is removed

14

What is the fire point?

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

Temperatures are only very slightly above the flash point

15

What is the auto-ignition temperature (AIT)?

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

Often referred to as the spontaneous ignition temperature (SIT)

16

What is surface oxidisation?
Give an example

A reaction in which the substances making up the surface of the solid react with oxygen, generating sufficient heat to be a self-sustaining process

17

What are the three methods in which heat spreads, and what are they?

Convection - movement of warmer gases through cooler surroundings

Conduction - the passage of heat through a material

Radiation - the transfer of heat energy as electromagnetic waves

18

In order to extinguish a fire, it is necessary to break the triangle of fire by removing one or more of the components. What three methods achieve this?

Cooling - removing the heat
Starving - removing the fuel
Smothering - removing the oxygen

19

Name six examples of extinguishing media?

Water
Foam
Dry powder
Carbon dioxide
Sand
Fire blanket

20

What are the advantages of using water on a fire?
Five answers

The rapid expansion of steam dilutes flammable gases
Reduces further production of flammable gases by pyrolysis
Absorbs heat from the fire
Absorbs latent heat when turning to steam
Limits the amount of oxygen reaching the fire

21

What are the four classes of fire?

Class A - carbonaceous solids
Class B - liquids and liquifiable solids
Class C - gases and liquifiable gases
Class D - metals

22

What is the best extinguishing media for Class A fires?

Water

23

What is the best extinguishing media for Class B fires?
What other extinguishing media can be used?

Foam
Fire blanket
Dry powder
Carbon dioxide

Not water

24

What should be done when trying to extinguish Class C fires?

Try and isolate the gas supply

25

What is the best extinguishing media for Class D fires?

Sand
Specialist dry powder (TEC powder)

26

What is the best extinguishing media for electrical fires?
What shouldn't be used?

Carbon dioxide can be used
Water definitely shouldn't be used