What term describes the spontaneous ignition of hot gases at the upper level of a room?

What term describes the spontaneous ignition of hot gases at the upper level of a room?

• A. Flashover
• B. Ignition
• C. Rollover
• D. Backdraft

Answer: (C)

Rollover is the moment when the hot, flammable gases that have built up under the ceiling ignite and flames begin to roll across the upper part of the room. In a compartment fire, heat drives the smoke and gases to the ceiling, and if the gas-air mix there reaches ignition temperature, the layer catches fire and flames spread horizontally along the ceiling. This is different from a backdraft, which involves a sudden ignition when fresh air rushes into a confined space with a smoldering fire, and from flashover, which is when the entire room’s contents ignite and the fire becomes fully involved. Observing flames moving along the ceiling is a classic sign of rollover, indicating dangerous heat and gas conditions that can advance to flashover if conditions worsen.