Day 5 Flashcards
Fire behaviour
What are the signs and symptoms of backdraught?
Fire with limited/no ventilation Hot doors and windows Smoke pulsating through small gaps in openings Soot blackened windows Smoke/air being drawn back into openings Ghosting tongues of flame Lack of visible flame Change in fire conditions - fast moving smoke and steady darkening
What is flashover?
The stage where the total thermal radiation from the fire plume, hot gases and hot compartment boundaries cause all exposed combustible surfaces to pyrolyse and ignite when there is adequate ventilation
What are the signs and symptoms of a flashover?
Well ventilated free burning fire High heat conditions Flaming combustion/ghost flames overhead Sudden lowering of smoke layer Rapidly rising temperatures Lower level materials pyrolising Change in fire conditions - fast moving smoke and change in smoke colour
Explain fire gas ignition
Gases from a compartment fire have leaked into an adjacent compartment - mixing with the air within this additional area.
This mixture may fall within the limits of flammability and if ignited will increase in pressure with or without an explosive force.
Define backdraught
The sudden deflagration of a compartment that deflagrated due to the admission of air into a compartment full fires gases due to limited ventilation
Why are backdraughts dangerous
Threat to life
Significant damage to building structure
