Editing Flashover (section)

{{Short description|Rapid ignition of combustible material in an enclosed area}}
{{other uses|Flashover (disambiguation)|Electric arc}}

A '''flashover''' is the near-simultaneous ignition of most of the directly exposed [[combustible]] material in an enclosed area. When certain [[organic materials]] are heated, they undergo [[thermal decomposition]] and release flammable [[gases]]. Flashover occurs when the majority of the exposed surfaces in a space are heated to their [[autoignition temperature]] and emit flammable gases (see also [[flash point]]). Flashover normally occurs at {{convert|500|C}} or {{convert|1100|F|C|order=flip|sigfig=2}} for ordinary combustibles and an incident [[heat flux]] at floor level of {{convert|20|kW/m2}}.{{Technical statement|date=April 2024}}

An example of flashover is the ignition of a piece of [[furniture]] in a domestic room. The fire involving the initial piece of furniture can produce a layer of hot [[smoke]], which spreads across the ceiling in the room. The hot buoyant smoke layer grows in depth, as it is bounded by the walls of the room. The [[thermal radiation|radiated heat]] from this layer heats the surfaces of the directly exposed combustible materials in the room, causing them to give off flammable gases, via [[pyrolysis]]. When the temperatures of the evolved gases become high enough, these gases will ignite throughout their extent.<ref>{{cite web | url=https://www.fireengineering.com/fire-prevention-protection/kiurski-flashover/ | title=Understanding Flashover | work=Fire Engineering | date=June 22, 2010 | access-date=August 21, 2023 }}</ref>