Hay is flammable!

So… in the process of making Terry a flare video, I had to light up the truck using the new blowers. First time ever!

I learned several things last night, not all of them pleasant. I’m passing all this along for your benefit.

First off, I had a major air leak, from all the jockeying around I had pulled it loose. It was the joint coming into the base of the hay filter. Hard to see, since the rubber connector was still in place. I didn’t know this but I suspected. Because it was loose I had a devil of a time drawing any vacuum on the gasifier.

Finally once I had a bit of gas I touched it with a torch… BANG! Right back through the blowers, into the hay filter, and flames even shot out of the loose connection by my feet. Wow! "I guess that’s where the leak was… "

So I set to work repairing it, and at some point accidentally touched a hot part on the gasifier… only it was the plastic hay filter. Once I realized what this meant, I pulled the lid off, and was greeted by hay-smoulder-smoke, very different than woodgas and not pleasant… I managed to soak the filter with water and put out the fire. No damage done, far as I can tell.

After repairing the connection I tried again, and made this video of a decent flare. Flare from new blowers - YouTube Note when I stop the flow it creeps back in the pipe and stays lit for when I turn it back on. Indicating I still have leaks. I will be soap-bubble checking everything.

Later I tried starting the truck on woodgas, as per usual. At some point while cranking I got a backfire (timing was down) and I heard a sound like a gunshot, then something hit the ground. Turns out my hay filter lid is capable of being removed from the barrel, ring and all - given enough force. The bang blew it across the yard about 10 feet. No harm done, I reassembled and drove around on gas a bit. It runs and drives fine, even with all the leaks. Air valves closed though.

I rechecked the hay filter several times and didn’t see any signs of heat. But I will say to anyone who follows - these barrels can’t stand flames for very long, they’re plastic. If you suspect a flame front traveled through your hay, even wet hay may catch and smoulder. Touch all the walls you can reach to check for temperature. Pull the lid and check for smoke (not woodgas).

And in future I’ll be tying a string to my lid bolt, just in case. :slight_smile:


Oh, that made me cringe! Wow, glad there was no damage, and since there was no damage I can laugh a little too. Blowing the lid across the yard, :slight_smile:

Wow at least it didn’t melt your hay filter , that would have been sad to look back and see all your hard work melting away …

Chris…guys like us should get paid by our neighbors for the cheap entertainment we provide them. Glad everything is ok, like Carl I gotta laugh as I picture it all happening.

I’m still trying to get mine done and drive to Argo…we will see. Not really wanting it to be my maiden voyage but if I get done its going to be close to it.

Hope to see you guys there.


Wish you would of had that camera running, it just sounds so much like something that would happen to me…LOL


Hi Chris, That BANG meant good gas … I warned you about the flex of plastic … Add a simple wire cage to keep the lid from crossing the 4 lane … Been there done that. A week from Friday … I’m busy as heck right now. No energy left at the end of the day to play… I got nailed by 2 deer ticks yesterday. One spent the night on my jaw … Not good … Mike

Back in 2010 we were doing some testing and gas analyses at Auburn University. I drove the wood burner about 500 miles stopping often and pulling gas off the hay filter for testing . The average hydrogen content running with several fuels were around 20-24% .

On another experiment on a different day we had the analyzer pulling from the hay filter and let it set for a while with the gasifier and truck shut down.

The below pictures were taken over a 15 minute span. I don’t really know what was happening in the gasifier but I do know the hay filter had some powerful gas with near 40% hydrogen content.

Air , good gas and spark could have made a big bang.

Wayne: Would letting the woodgas seep into the rest of the system from an idle gasifier be similar effect to having a deeper char bed (much longer resident time in the hot char) and thus make richer gas?

Hello Brian ,

I have thought along the same lines . At shut down there still being a little pressure in the hopper causing a slow movement of gas through the still hot char migrating through the system and to the top of the hay filter and as you have stated a longer resident time.

Or maybe some gases may be lighter than others and stratify themselves with the gasifier shut down .?

I don’t think it has ever cause any problems but still interesting .

I would think that Hydrogen being the lightest element… it probably would stratify and go to the uppermost part of the gasifier… just my 2 cents… we don’t actually have cents anymore in canada though so they are getting rare…

Arvid: That makes a lot of sense. I think the top of the Hay Filter (where Auburn seemed to be measuring from) would be one of the highest points in the gas loop and thus where the light hydrogen would stratify to.

Arvid, it was the first I heard of a looney and twooney was in Canada.