Certified Fire Investigator Practice Exam

How does the size (geometry) of a compartment influence flashover?

1. Smaller compartments are safer

2. Bigger compartments can delay or prevent flashover conditions

3. Size does not affect flashover

4. Smaller compartments burn faster

The correct answer is: Bigger compartments can delay or prevent flashover conditions

The size and geometry of a compartment play a significant role in the occurrence and timing of flashover. In larger compartments, there tends to be more space for smoke and gases to disperse, which can lead to a more gradual increase in temperature. This dispersal allows for better ventilation and can help to reduce the buildup of flammable gases that might otherwise ignite rapidly. In contrast, when combustion occurs in a smaller compartment, the heat and smoke can quickly concentrate, raising the temperature more rapidly. This situation can lead to an earlier onset of flashover, as the conditions for it—high temperature and sufficient fuel—are achieved more quickly in tighter spaces. Larger spaces may also allow for alternative pathways for smoke and heat to escape, potentially leading to cooling and a delayed flashover. Therefore, the geometry of the compartment greatly influences the dynamics of fire behavior, allowing larger spaces more time to manage and suppress dangerous flashover conditions.