Found out creosote can actually explode, not just catch fire

Been sweeping chimneys for 11 years now. Last Tuesday I was reading through an old NFPA 211 handbook that a retired sweep left at the shop years ago, and there's a section about creosote flash point and explosive ignition. I always knew creosote was flammable, but I never realized that under the right conditions, a hot ember can ignite creosote vapor so fast it vents out the top like a cannon. There was a documented case in the book from a house in Ohio in the 80s where the chimney pipe actually blew apart. My apprentice was standing right there when I read it out loud and we both just looked at each other. We've been doing this for years, and neither of us ever got a specific number on how hot it needs to get, I think it was around 240 degrees for the vapor to ignite if it's concentrated enough. Has anyone else run into this on a job, or had a near miss with a chimney that was caked up worse than the homeowner thought?

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sagecooper27d ago

Creosote vapor can actually ignite at a lower temp than that depending on how dry and flaky it is, closer to 200 degrees in some cases I've read about. The real kicker is when it's glazed and hard, that stuff can trap heat and flash way hotter than folks expect.

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