Ventilation-Controlled Fire
Definition
A compartment fire in which the rate of energy release is limited by air inflow through ventilation openings. Fuel-rich conditions produce high CO and soot; the hottest burning zone is adjacent to air inlet openings.
- Limiting factor
- Air inflow through ventilation openings
- Byproducts
- High CO and heavy soot from fuel-rich combustion
- Hottest zone
- Adjacent to air inlet openings
- Contrast
- Fuel-controlled fire, limited by available fuel rather than air
Common questions
Why does a ventilation-controlled fire produce more soot and CO than a fuel-controlled one?+
With insufficient oxygen to complete combustion of all the fuel being pyrolysed, a larger fraction of the fuel converts to incomplete combustion products such as carbon monoxide and soot particles rather than fully burning to carbon dioxide and water, so smoke is denser and darker.
How does an investigator recognise a ventilation-controlled regime from fire scene damage patterns?+
Heavy soot deposition, low-burning patterns concentrated near door or window openings where fresh air entered, and evidence of pulsing or a potential backdraft event are indicators that the fire was starved for air rather than for fuel during part of its development.
Related terms
- Backdraft
- A deflagration event triggered when air is suddenly admitted to a compartment where a fire has been oxygen-depleted but has continued to...
- Deflagration
- A subsonic combustion front propagating through an explosive by thermal conduction. Characteristic of low explosives such as black powder and smokeless powder;...
- Equivalence Ratio (Phi)
- The ratio of actual fuel supply rate to the stoichiometric fuel supply rate for the available air. Values below 1 indicate fuel-controlled...
- Flashover
- The near-simultaneous ignition of all exposed combustible surfaces in a compartment, occurring when the upper gas layer reaches approximately 600°C and radiative...
- Fuel-Controlled Fire
- A compartment fire in which the rate of energy release is limited by the fuel supply (surface area, arrangement, reactivity) rather than...
- Hot Gas Layer
- The stratified layer of buoyant combustion gases that accumulates at ceiling level in a compartment fire. Its temperature rise drives flashover when...
- Low Burn Pattern (LBP)
- Fire damage at or near floor level in a compartment. Historically misattributed solely to poured accelerants; now recognised as producible by post-flashover...
- Neutral Plane
- The interface between the hot gas layer above and the cooler ambient air layer below in a compartment fire. Above the neutral...
- Ventilation Factor
- A parameter used in fully developed fire characterisation, calculated as Av × Hv^0.5, where Av is the area of ventilation openings (m²)...