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Devil Forge burners not burning properly


jt0119

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Hi guys,

I've been trying to figure this out for just over a month at this point to absolutely no avail. I recently built a new forge after I decided relining my Devil Forge wasn't going to work, and reused the Venturi burners from that. When I removed the burners, I noticed the flare on the burner I used most was crumbling and blown out, so I initially tried to remake my own based off the ones they had on there. When I installed them into the new forge, they ran perfectly for the first 10-15 minutes until it got up to heat, then started fluttering. The flame was still going, but it was burning way less efficiently than I was used to in the Devil Forge. It would jump back and forth between a nice roaring blue cone and a much quieter teal flame. After ruling out a failing regulator, debris in the hose/connections, airflow issues, and basically anything else I could think of, I swapped the homemade flares for some of the ones Larry Zoeller makes, and now I'm not even getting the blue cone. I'm at my absolute wit's (and wallet's) end with this. I didn't think to get better pictures of the current setup, but I got a video of what was going on before swapping over to some properly made flares. What's happening now is similar to what you see in 90% of the video, minus the fluttering sound. Any help at this point will be greatly appreciated.

 

This video can not be accessed without permission.

https://tinyurl.com/y8u7pedf

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Gas flames don't need to be running lean (oxidizing), to wear away the end of a burner by oxidation. Combustion is a high energy chemical process. Even a reducing flame is super-heating oxygen molecules right in the same area as it is super-heating the burner nozzle; this will gradually where away the nozzle wall. The hotter the flame the faster it happens.

Also, #304 stainless parts are bright and shiny. Bright and shiny sells equipment. ##16 stainless parts have 2% molybdenum, which resists high heat oxidation, but makes the parts dull; bad for sales you know :rolleyes:

You is a victim of merchandising :o

So, post photos and we'll see if there is a cheap solution:)

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I'm not worried about the nozzles corroding. I know they're a consumable to some extent. My issue is the flame that's produced. Before I replaced the flares, I was getting a much better flame that I can't seem to get now. I'm headed over to my shop to get some more pictures and should have those for you soon, though. 

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The "fluttering" when the nozzles heat up is pre-ignition IN the nozzle which causes explosive back pressure and disrupts the fuel air flow. The "explosions" are tiny little pops you can't really hear over the sound of the burner but can be recognized once you know what to listen for.

Try making the same nozzles with less flare. Make one and test it, if that isn't right it'll save you from making two that don't work. 

What it's made of isn't a real factor in how it works so once you get one right is a good time to think about making ones that will last.

Frosty The Lucky.

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Alright, got some pictures for you guys. The first two are the flame I'm getting with the flares I purchased, the second two are using my homemade flares, which are 316 stainless.

And yes, I know the top of my forge lining needs to be replaced :D

IMG_20200714_130029.jpg

IMG_20200714_132230.jpg

IMG_20200714_133109.jpg

IMG_20200714_132144.jpg

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I don't see any "flare" in your flame retention nozzles. Am I not seeing them well enough, or are they just simple tubing? Are they stepped flares? Do they have spacer rings. What is the amount of Increased diameter between the outside the the burner's mixing tubes, and the inside diameter of the flame retention nozzles?

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The purchased ones have a very slight flare to them, just under 1/4" wider than the OD of the burner tubes at the end. The homemade ones do not, and are as close as I could get to exact replicas of the factory nozzles. They're very slightly larger than the burner tubes, but it's almost negligible. A few thou at most. 

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I don't know what to suggest other than maybe tweak the ratio of the flares a little at a time.

A mixing tube that long must be using a pretty small jet diameter or friction would be a real problem but if they work they work. When they were new that is.

I'm sorry, I don't know if I can be much help. Unless you want to make your own. That I'm pretty good at.

Frosty The Lucky.

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I'm not gonna lie, if I've stumped you, I feel a lot better about being unable to figure it out :lol:

At this point, a new burner was my only option left. I was looking at just buying a Z burner, but I'll take a look at your plans first. 

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Okay, I couldn't stand it and reread much of the thread and watched the video that SAYS you have to have permission to see. It played okay.

What I see going on looks like the burners are taking in some exhaust gasses instead of just clean air. Every once in a while the volume goes up, the flame becomes longer and more opaque then goes back to more transparent and sputtery. My bet is at lower output the exhaust isn't so great and the burners clear the worst and start working and produce more exhaust which swirls up into the burner's air. 

The fast check would to to turn your burner on it's side and fire it up.  If the flame's louder, longer and more opaque then it's breathing exhaust. I have to use a sheet of steel over the openings on my shop forge to deflect exhaust away from the burner intakes. Mine are vertical on top of the forge as well. 

If you still have one good flare or enough remains, make a pattern and copy them. Maybe think of a brow or bill out over the openings to deflect the exhaust farther out. 

Frosty The Lucky.

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Yeah, when I initially posted it I forgot to give that file open permission to be shared, hence the warning. Both the flares that work better are installed, so I'll see what I can cobble together for a hood. I'll report back once I have some kind of result. 

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Well, we have a result: no difference. It did initially seem to take longer at first, but after modifying the hood slightly and letting the forge cool, it took about 5 minutes to go back to that teal flame. The fluttering is maybe slightly less aggressive, but it's minimal at best. The only other thing I can do is fill the receivers with kaowool to keep any exhaust from escaping there, but I don't know if enough is escaping there to really be of note. 

IMG_20200715_165259.jpg

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Nah, I had just shut it down for the day and buttoned everything up to prevent making things even worse for myself lol. The picture was more to make sure my hood was enough to make any difference or if I need to go back to the drawing board. 

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Try rotating the hood 90* so it's wider than long. The brow I use on mine is maybe 6" out but a good 24 wide. The lid on my too large shop forge is 18" square and it needs to get the exhaust away from the burners. I believe the wide flat lid tends to draw exhaust in towards the center by it's shape which may not apply to yours.

I'm running (Please try to contain your shock) T burners and they suffer from lack of clean air just like any NA burner so making T burners, fancy or not isn't likely to cure the problem in itself.

However I'd sure like to see FANCY T burners that actually work. We've all seen some WT:wacko:  mods to T and other burners that . . . :rolleyes:

Frosty The Lucky.

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I'd lay it flat so it doesn't form a chimney up and over the deflector. Mine just lays flat on the forge lid. Maybe my forge is high enough it doesn't effect my vision much. If a breeze is blowing crosswise it doesn't need the deflector.

I had a sheet steel corner thing that sat on top of the forge and made a big difference but it looked really hokey and was really in the way.

Frosty The Lucky.

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