Which temperature range is widely accepted as flashover conditions?

• A. 900-1200 degrees
• B. 600-900 degrees
• C. 1200-1500 degrees
• D. 300-600 degrees

Answer: (A)

Flashover is the rapid transition where a room becomes fully involved in flame, with contents igniting almost simultaneously due to intense heat. The temperature at which this dramatic change commonly occurs is about nine hundred to twelve hundred degrees Fahrenheit (roughly 480 to 650 degrees Celsius). At these temperatures, radiant heat and accumulated fuel gases push materials to their ignition points, causing a sudden, dangerous spread of fire. That’s why the range of 900–1200 degrees Fahrenheit is widely accepted as flashover conditions.

Temperatures lower than this range are still in the growth stage and haven’t reached the point where everything in the room ignites at once, while temperatures higher than this range indicate heat levels that are more extreme than typical flashover and may reflect a continuing, post-flashover scenario. The 300–600 and 600–900 ranges fall short of triggering full involvement, which is why they aren’t the standard flashover range.