r/Firefighting • u/wonderful_exile238 • May 08 '23

Videos WATCH: Firefighters full PPE saves them during flash reignition. The article I saw this video in says ALL VEHICLE FIRES ARE CLASS B. What are your thoughts?

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u/FF2001Vapor Idaho Volunteer Firefighter May 08 '23

Someone is bound to correct me on this, as it's probably not actual offgassing, but from what I understood from my FF1 course, it's when a solid material (Could be natural like wood or cotton, or something made with chemicals) gets hot enough to release chemicals/particulates into the surrounding environment without actually catching in fire. This is what actually catches a room on fire during a flashover event.

Again, this is what I've been taught to understand with my courses, so if anyone has a more precise answer or if I'm just straight up wrong please lemme know!

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u/FF2001Vapor Idaho Volunteer Firefighter May 08 '23

After double checking, I could be thinking of sublimation, where something goes from a solid to a gas, so now I'm gonna have to go double check when I get home from work!

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u/Odd-Audience2138 May 08 '23

Pyrolysis - solid starts giving off vapors- vapors are what actually burn. Sublimation is solid to gas also- dry ice as an example. But usually in firefighting pyrolysis is used. Flash over is a when all the vapors in the room reach a temperature in which they all ignite at once.

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u/FF2001Vapor Idaho Volunteer Firefighter May 08 '23

This^ Thank you. My training chief would be disappointed in me for forgetting pyrolysis!