After flashover, fire burning transitions from which condition to another?

After flashover, the fire transitions from a fuel-controlled condition to a vent-controlled condition.

In a fuel-controlled fire, the availability of fuel limits the rate of combustion; the fire is primarily dependent on the amount of fuel present in the environment. However, once flashover occurs, the fire rapidly consumes all available fuel and begins to generate a significant amount of heat and smoke. This leads to a condition where heat and smoke are released through vents such as windows or doors, allowing more oxygen into the environment.

In this vent-controlled phase, the fire’s intensity is largely determined by the amount of oxygen entering the compartment. The fire can spread more rapidly because it can take advantage of the increased oxygen supply, leading to an overall more hazardous situation. This transition is crucial for fire investigators to understand because it significantly impacts fire behavior, spreads, and the effectiveness of firefighting strategies.