Combustion

Question 1

What is the fire tetrahedron?

Answer 1

The fire tetrahedron is made up of
Heat
Oxygen
Fuel
Chain reaction
All of these are required for a fire to exist, if any of the elements are removed the fire will be extinguished

Question 2

What is an exothermic reaction?

Answer 2

A reaction that releases heat into its surrounding
(Think of your ex, you wanted to get rid of them, like an EXothermic reaction gets rid of heat)

Question 3

What are the two types of flame?

Answer 3

Premixed
Diffusion

Question 4

What is a premixed flame?

Answer 4

Occur when fuel is well mixed with an oxidant. Energy must be supplied to the system for ignition to occur. A self-sustaining flame will then be established around the ignition source and propagate outwards in all directions

Question 5

What is a diffusion flame?
Give an example

Answer 5

Occur at the interface where fuel vapour and air meet. Fuel vapour and oxygen mix with each other by molecular diffusion.
An example of this is a candle flame/bunsen burner when air inlet is closes

Question 6

What is a chain carrier?
And how do they effect fire development?

Answer 6

Chain carriers are atoms or fragments of molecules known as free radicals that are extremely reactive.

Chain carriers move into the next layer of gas above a flame starting oxidation and heat releasee processes there.

Question 7

Define spontaneous ignition temperature

Answer 7

The lowest temperature at which the substance will ignore spontaneously.

Ie the substance will burn without the application of a flame or other ignition source

Question 8

What is smouldering?

Answer 8

Combustion of a solid in an oxidizing gas such as air, without the appearance of a flame.

Question 9

What is meant by flammability limits?

Answer 9

A flammable gas will only burn in air if it’s composition lies between certain limits.
If the mixture is too lean or too rich burning will not take place