In which stage of the burning process does flameover occur?

Flameover, also known as backdraft, occurs during the explosive growth stage of a fire. In this stage, the materials in the fire have reached a critical temperature and are igniting rapidly. This stage is characterized by a sudden and intense increase in flames and heat.

As the fire consumes available oxygen, gases and heat accumulate within the space. When additional oxygen is introduced, either through ventilation or openings, the superheated gases ignite, causing a violent burst of flames. This can happen when doors or windows are opened, allowing fresh air to enter. The explosive growth stage is particularly dangerous, as it can lead to flashover, posing significant hazards to firefighters and occupants.

In contrast, the ignition stage involves the initial kindling of materials, while the initial growth stage sees the fire beginning to spread but not yet reaching its most dangerous point. The ventilation-limited stage refers to a point where the fire is being starved of oxygen, rather than experiencing explosive growth. Understanding the characteristics of each stage assists firefighters in making informed decisions for safety and effective firefighting strategies.