Creosote pyrolysis?

[Ctwoodtick]

i understand the concept of pyrolysis and its role in lowering the temperature that wood can self ignite. Was wondering if creosote also is subject to pyrolysis, where the temperature required for it to spontaneously combust becomes lower if it is subjected to heat over time.

 

[bholler]

i understand the concept of pyrolysis and its role in lowering the temperature that wood can self ignite. Was wondering if creosote also is subject to pyrolysis, where the temperature required for it to spontaneously combust becomes lower if it is subjected to heat over time.

I don't think so but I really don't know

 

[jetsam]

Run a brush through there and it won't matter!

 

[Doc C]

That’s my new word for today. Pyrolysis...i like it!

 

[jetsam]

That’s my new word for today. Pyrolysis...i like it!

You need to know that word if you heat with wood.

It is why 150° steam pipes used to be a common cause of house fires.
http:// https://www.doctorfire.com/low_temp_wood1.pdf
(broken link removed to https://www.doctorfire.com/low_temp_wood1.pdf)

 

[begreen]

You need to know that word if you heat with wood.

It is why 150° steam pipes used to be a common cause of house fires.
(broken link removed to https://www.doctorfire.com/low_temp_wood1.pdf)

Maybe a bit warmer than that. Steam pipes are at 100ºC or 212ºF typically. The example listed shows a fire that started from hot water pipes going thru a floor. The boiler was heating the water to 88-9ºC or 190-200ºF. They do state in the article that cases of pyrolysis as low as 170ºF have been noted.

"For wood building members exposed to such long-term heating conditions, case incidents indicate that ignition is possible at a hot-object temperature as low as 77ºC (170ºF). It must be emphasized that the hot-object 6 temperature is the starting-point temperature of the self-heating process and that the self-heating process progressively raises the temperature of the wood member, so that when it actually ignites it will be at a temperature that is much higher than the starting-point temperature."

 

[WoodyIsGoody]

i understand the concept of pyrolysis and its role in lowering the temperature that wood can self ignite. Was wondering if creosote also is subject to pyrolysis, where the temperature required for it to spontaneously combust becomes lower if it is subjected to heat over time.

Creosote is a general term and forms in different compositions. All of which are called "creosote". In this sense, I presume that pyrolysis could turn a less "pure" creosote with a higher ignition temperature into a more "pure" form of creosote with a lower ignition temperature over time.

So, yes. But it would likely take higher minimum temperatures for this to occur than the 170 degrees that can effect wood pyrolysis. Because creosote was formed at temperatures higher than that to begin with.

 

[yooper08]

Yes, it can go through pyrolysis. Now, whether it lowers it's autoignition temperature and/or can occur under normal conditions in a chimney, that I'm not sure of.