What happens to flames during the free burning stage of a fire?

During the free burning stage of a fire, the combustion process is generally characterized by an adequate supply of oxygen and the free movement of heat and smoke. Flames are actively consuming the available fuel, and the temperature rises considerably. As the fire continues to burn and consumes available oxygen, the oxygen content in the environment decreases.

This decrease in oxygen can lead to conditions where flashover is likely to occur. Flashover is a rapid spread of fire that happens when the temperature reaches a critical point, causing all combustible materials in the vicinity to ignite almost simultaneously. This transition marks a significant change in the behavior of the fire, transforming it from a free-burning stage into a more destructive phase with an intense, widespread fire.

In contrast, the other options do not accurately describe this stage. Flames being extinguished would imply a lack of combustion, which is not characteristic of the free burning stage. Spread of flames downward does not typically occur as a primary behavior during this stage; instead, flames often spread horizontally and upward. Likewise, the idea of temperature stabilizing does not align with the dynamics of a free-burning fire, which tends to escalate in temperature due to the continuous input of heat and combustion activity. Thus, the conditions present during the free burning stage are a vital