In a fire context, what does "rollover" refer to?

In a fire context, "rollover" specifically refers to the ignition of fuel vapors in superheated gases. This phenomenon occurs when the gases produced by burning materials reach a temperature that ignites the unburned fuel vapors present in those hot gases, often resulting in a sudden burst of flames moving across the ceiling area. This is a critical stage in fire progression since it indicates the potential for rapid fire spread and increased intensity, which can signal an imminent flashover.

Understanding rollover is essential for firefighters and emergency responders, as recognizing the signs of this event can help in assessing the fire's behavior and determining the necessary tactical approaches to combat it safely.