Fire Behaviour

Question 1

Name the 3 types of fire behaviour?

Answer 1

Backdraught, Flashover and Fire Gas ignition.

Question 2

What are the signs and symptoms of backdraught?

Answer 2

1. Limited or no ventilation
2. Hot doors and windows
3. Smoke pulsating through small gaps
4. Soot blackened windows
5. Smoke/Air being drawn back into small gaps could make whistling noises.
6. Ghosting tongues of flames
7. Lack of visible flames
8. Steady darkening of smoke colour

Question 3

What is flashover?

Answer 3

This is when there is total thermal radiation, hot gases and hot compartment boundaries cause all things to pyrolyse and ignite. This is the transition from a growing fire to the fully developed fire.

Question 4

Name the signs and symptoms of a flashover?

Answer 4

1. Well ventilated free burning fire
2. High heat conditions
3. Ghost flames overhead
4. Sudden lowering of smoke layer (neutral plane)
5. Rapidly rising temperatures causing windows to fail
6. Low level materials starting to pyrolise

Question 5

What is fire gas ignition?

Answer 5

Where the fire gases leak into another compartment where then something can cause this to ignite and cause an increase in pressure with or without an explosion

Question 6

What is backdraught?

Answer 6

Limited ventilation of a fire will lead to flammable fire gases being produced. If air is admitted through an opening in the compartment it can lead to a sudden deflagration, moving through the compartment and out of the opening.