What are the typical characteristics of a "Flashover" during a fire?

Flashover is a critical phenomenon in fire dynamics characterized by a rapid spread of fire through an area as a result of the simultaneous ignition of combustible materials. During flashover, the temperature in the room increases dramatically, often exceeding 1,000°F (540°C), causing the surfaces of all combustible materials to reach their ignition temperatures almost simultaneously.

This event typically occurs when the thermal layers within a room become well established, allowing heat to build up. As combustible materials heat up and reach their auto-ignition temperature, they ignite quickly, resulting in a simultaneous ignition that can engulf the entire area. This swift transition from localized flames to widespread fire poses significant dangers for firefighters and occupants, as everything in the room can ignite almost instantaneously.

In contrast, gradual increases in temperature fail to capture the immediacy and intensity of flashover. Events that are limited to smoke without flames or those that start with minimal heat release do not reflect the overwhelming and sudden nature of a flashover scenario, where heat and flames proliferate rapidly. Understanding the characteristics of flashover is essential for effective fire attack strategies and ensuring firefighter safety.