Editing Flashover (section)

==Types==
* A ''lean flashover'' (sometimes called ''[[rollover (fire)|rollover]]'') is the ignition of the gas layer under the ceiling, leading to total involvement of the compartment. The [[air–fuel ratio]] is at the bottom region of the flammability range (i.e. lean).
* A ''rich flashover'' occurs when the flammable gases are ignited while at the upper region of the flammability range (i.e. rich). This can happen in rooms where the fire subsided because of lack of oxygen. The ignition source can be a [[smouldering]] object, or the stirring up of embers by the air track. Such an event is known as ''[[backdraft]]''.
* A ''delayed flashover'' occurs when the colder gray smoke cloud ignites after congregating outside of its room of origin. This results in a volatile situation, and if the ignition occurs at the ideal mixture, the result can be a violent ''smoke gas explosion''. This is referred to as ''smoke explosion'' or ''fire gas ignition'' depending on the severity of the combustion process.
* A ''hot rich flashover'' occurs when the hot smoke with flammable gas ratio above the upper limit of flammability range and temperature higher than the ignition temperature leaves the compartment. Upon dilution with air it can spontaneously ignite, and the resultant flame can propagate back into the compartment, resulting in an event similar to a rich flashover. The common definition of this process is known as ''auto-ignition'', which is another form of fire gas ignition.