Torchwood, WTH?

[spot]

O.K. here's the scenario: Your fire is burning nicely, you hear the 'fluff' of the flames, the 'crackle' of the wood ... and then you hear a 'whoosh' noise and see a jet of flame coming out the side or end of a log.
All other flames are dancing normally, but this rebel shoots out at an angle and blasts the side of the firebox.
This lasts only a few seconds - then the little blowtorch burns itself out.

What causes this? Is it the same thing that causes some wood to 'pop'?

There never seems to be any harm done, it's just weird.

 

[Roospike]

Its your pilot light. :cheese:

 

[Hogwildz]

I am guessing its gases ecaping out the side of the split and burning off.

 

[begreen]

what kind of wood was it? seen that with fir.

 

[spot]

Some oak and ash.

 

[stoveguy2esw]

ive seen some "sappy" woods do that , the sap pocket is cracked open under pressure from the sap expanding during the char phase, if the wood cracks open to it the jet of gassified sap shoots out and ignites forming the "jet" of flame you describe, its actually cool to watch , when we do test burns in the lab douglas fir is used dried to a consistant moisture content, weighted at 15 lbs (this is the test charge used for all woodstove certifications) the fir has little pockets of sap in it that do exactly what you describe.

 

[restorer]

Mike:
I agree 100%. Sap pockets get super heated and rapidly expand, vaporize and burn like a ram jet. Most frequently seen in softwoods, pine, and fir. Can also occur with all trees that have been subjected to extreme weather and wind. A condition called, Shake, actually tears the fibers away from neighbors. If it happens at or near the cambrian layer, the living/growing wood, the tree will try and repair itself by filling in with sap. In cherry and maple it will harden, but many other woods it becomes the consistency of pine pitch. I think the popping is similar, but can also be caused by air pockets rapdily expanding.

ive seen some "sappy" woods do that , the sap pocket is cracked open under pressure from the sap expanding during the char phase, if the wood cracks open to it the jet of gassified sap shoots out and ignites forming the "jet" of flame you describe, its actually cool to watch , when we do test burns in the lab douglas fir is used dried to a consistant moisture content, weighted at 15 lbs (this is the test charge used for all woodstove certifications) the fir has little pockets of sap in it that do exactly what you describe.