'Motorboating' with new burner...

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Chet
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Location: Avon Lake, OH
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'Motorboating' with new burner...

Post by Chet » Wed Mar 31, 2010 12:30 pm

Just finished a modified Oliver burner.
I'd heard that the Oliver is sometimes plagued with air starvation, so instead of 3 holes, I milled a 3/8 slot from first hole to third on each side.
The other modification was simply feeding the burner from the end, rather than perpendicular to to burner tube.
Testing with a front end choke gave good results, with a good solid roar with only 7 1/2 pounds propane pressure.
However, when I placed the burner in my new foundry (fed from side for circular rotation of gas) I keep getting a motorboating sound.
Increasing gas pressure beyond 7 1/2 pounds doesn't appear to help.
Yes, I have a crucible in the furnace.
Thoughts?

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steamin10
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Post by steamin10 » Wed Mar 31, 2010 7:12 pm

Ya, most likely too lean in my experience, it is popping off, and relighting giving a buzz sound, sometimes like a buzz bomb over England. It is tuning the nozzle to the space it feeds, and is hard to explain, because the Crucible may make it stop, or blow out altogether. I dunno. I had a small nozzle that did this, and would go out at odd times. I started over, and got a BIG tube. It runs with a whisper or a roarfrom under 5 lbs to over 20 on a 100lb cylinder.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
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Chet
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Re: 'Motorboating' with new burner...

Post by Chet » Fri Apr 16, 2010 8:31 am

I thought I'd bring everybody up to speed on the solution to my problem.
I'd suspected it was the burner, so I went ahead and made a Reil burner with a #57 drilled orifice hole.
The Reil burned beautifully outside the foundry (with a tapered nozzle), but I ran into the same problem when it was placed in the furnace.
I eliminated the airgap between my 3/4 burner and my 1-1/4 inlet tube by added a 1" sleeve.
But it was a suggestion by Rupert Wenig that finally solved it: Pull the burner half-way out.
Now I get a nice smooth roar from roughly 1 to 10 lbs psi.
I also have to make a new lid with a 3" opening...
I'd hoped to use the lid from my electric foundry, but it's exhaust hole was only 1-1/2 inches...
Progress one small step at a time...

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