Ribbon burner help

[Adriaan Gerber]

Not sure whether this is the right place to ask this, but here goes: I’m trying to build a ribbon burner tempering oven for swords and I’m having trouble lighting it. My guess is it needs to be blown air, not just Venturi. The pipe has 1/4” holes on both sides, 1” apart. I can’t get it to burn a bunch of little flames like a gas grill. Obviously I don’t know what I’m doing  Any suggestions, please?

[John Page]

I've made a ribbon burner but it's the only one I've used so take that for what it's worth. Never seen a high temp venturi ribbon burner before so the lack of blower is probably the right source of your issues. However you might also run into issues with even pressure distribution along the burner tube. I had to add a baffle inside my (cast, more traditional looking burner manifold) to get it to distribute even remotely evenly between all the holes. Also I found that the needed air pressure was more sensitive than I expected. The first few times I ran it I had to fiddle with the blower for a good while to get it to light and stay lit. Given mine was for use as a welding forge and thus significantly higher temps than you intend for heat treatment. For this application you will still need some way to regulate blower pressure to at minimum keep the burner from back burning into the tube and maximum no so powerful that it blows the flame out. I ended up adding a 3 way pool valve just below the blower so I could vent excess air before it gets to mixing with propane. A variable speed fan would also do the trick but I didn't have one on hand and the valve was a cheaper option that happened to fit the air pipe diameter. 

[Alan Longmire]

Those 1/4" holes are way too big for a venturi to handle.  Look at a gas grill burner, that's what you're after with a tempering oven.  Like 3/32" instead of 1/4".  Mine is problematic as well, with 1/16" holes 1" apart.  I really should bore them out to 3/32"...  If you rebuild it with smaller holes, be sure to light it from the end opposite the burner.  Took me a long time to figure out why when I lit mine from the burner end the far end holes wouldn't ever light.  They were starved for fuel!  And I'm leery enough of homemade gas appliances I was hesitant to wait until I had a water heater tank full of propane until I lit it.  New procedure is to turn on the gas, count to three, and hold a torch on the very last holes until the whole thing goes off with a big "SHWOOOMPH" noise.  And usually blows itself out, they have to run on really low pressure.

 

I'll fix it next time I'm in sword mode...

[Adriaan Gerber]

Thanks, guys, onwards and upwards :)