Structural

Question 1

4 stages of combustion

Answer 1

1. Incipient Stage: Invisible products of combustion given off. No visible smoke, flame or appreciable heat is present yet.
2. Smouldering Stage: Combustion products now visible as smoke. Flame or appreciable heat is still not present.
3. Flame Stage: Actual fire now exists. Appreciable heat is still not present but follows almost instantaneously.
4. Heat Stage: Uncontrolled heat and rapidly expanding air now complete the dangerous combination.

Question 1

4 Stages of a compartment fire

Answer 1

Developing, Flashover, Fully developed, Decay

Question 2

Expansion ratios of water to steam

Answer 2

1700:1 at 100degrees
3500:1 at 450 degrees

Question 3

Define flashover

Answer 3

Flashover is accepted as the sudden and sustained transition from the developing stage to the fully developed stage of a fire, within an enclosure.

Question 4

Define Backdraught

Answer 4

It is the sudden introduction of oxygen in a burning room full of unignited super-heated gas, which has been starved of oxygen (below 15%). The oxygen combines with the superheated gases, creating an explosion of fire

Question 5

Define Fire gas ignition

Answer 5

The formation of variable-sized flammable fire gases The addition of air is not a requirement for ignition of these gases, which have already formed into an ideal premixed state, simply awaiting an ignition source or to reach auto ignition temperatures