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What's wrong with my burner


beardking

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I just finished building a Frosty Tee burner and I'm trying to get it tuned up. So far, I can't seem to keep it lit unless I have the pressure up around 25 or 30 psi. Even then, it sounds more like a pulse jet than a burner. I've trimmed the mig tip (.035) just a little, but I don't want to keep trimming if that's not the direction I need to go.

Here is a video of the forge "running." Thanks in advance. 

 

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Welcome aboard, glad to have you. Still pics please. It's burning WAY rich. How about a pic of the whole burner and one in the air intake so I can see where the jet is. 

Pictures of your pressure gauge are pretty meaningless, I recommend folk don't use them at all and tune by eye and ear. 

Frosty The Lucky. 

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Sorry for the delay, sleep was necessary. 

Here are a couple of pics of my burner setup. Looking at the one of the mig tip, I notice that I trimmed it back at a little bit of an angle and I'll need to fix that. 

gf-1.jpg

gf-2.jpg

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Your jet is WAY too deep in the burner. The departure point where I begin tuning is approx 1/2 way back across the intake ports as viewed straight through the T. Remember to debur the orifice GENTLY. Torch tip files are THE BEST tool to use. Lots of things might work in a pinch but commercial gas jets are always clean straight holes, ZERO chamfer. do not get carried away deburring the orifice, any change in the jet will degrade it's performance.

By too deep I mean the jet is too close to the mixing tube. When I say forward or back, it's in reference to the gas flow in the forge. 

Frosty The Lucky. 

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Ok, I shortened the mig tip. I may have gotten it a little too short, but I'm not sure. 

Here are a couple of pics of the trimmed jet and the resultant flame. I've also included a video to show how it looks and sounds once the forge has heated up. 

 

 

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Flame is moving off your burner end.  Start firing at lower gas pressure and keep there till forge heats further.  Did you use the exact reducing Tee from Frosty's design?  In picture the run dimension looks a little large.  You need forge doors.  Hard brick splits used for forge body? If so efficiency will suffer and you will have trouble getting to running temperature. 

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It is still running rich, trim it a LITTLE BIT more. 1/32", debur and try it again. Keep a notebook of what you did and what the effect was when you tested it. Do ONE THING AT A TIME or you'll never know what caused what to happen. 

Still pictures PLEASE. 

It might've had a bur Mike but it wouldn't matter that close to the mixing tube unless it was a really bad bur. It couldn't have run anything but rich unless he were running a way small jet. 0.035 has to come back, WAY back from the throat. 1/2 way across the air intake port is too far in but it's close enough to be a good place to begin tuning. 

Latticino: It looks like it's a larger run that 1" but that's okay. It's running too rich if a too large an air intake were a problem it'd be too lean to tune. 

Frosty The Lucky. 

 

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On 5/3/2020 at 10:55 AM, Latticino said:

Flame is moving off your burner end.  Start firing at lower gas pressure and keep there till forge heats further. 

When I light at a lower pressure the flame keeps trying to go out. I'll keep trying though. I'm not sure what you mean by "Hard brick splits used for forge body?" I used these bricks to build the forge. 

image.png

 

On 5/3/2020 at 2:22 PM, Frosty said:

It is still running rich, trim it a LITTLE BIT more. 

I'll trim up the mig tip some more tomorrow. I normally do try to limit any changes that I make to new things too one thing, because like you said, you'll never know which one did what if you change more than one.

Haven't had a chance to work on it more yet, been working on trying to figure out a new noise on my truck. 

I did include still pics (it, at least, a link to them) in my previous post. I included the link to the video because the still pics don't really convey the sound the flame is making as well as a video does. 

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Yes those are hard brick splits.  Fine for a forge lining (though the thermal mass might be too much for some folks), but they have minimal insulating value and so make a forge that is rather inefficient.

I'm confused, if you copied some You-tuber's version of the Frosty Tee burner, why not ask them how to correctly trim it?  When you say the flame keeps "trying to go out", does it exhibit the same characteristics as when it goes out on higher gas pressure (flame front moving off the front of the burner)? 

Are you sure you used a 1 x 1 x 3/4 reducing Tee?  Sure looks larger to me than 1" connection in the run dimension.  Might be misleading photo.  If it is larger you might have to block off some of the air inlet.  You can test it by covering that inlet with a  temporary shroud (slide a piece of material over it and see if the flame stability increases at lower gas pressures).  Ideally you should be able to run your burner anywhere between 5 PSI and 20 PSI.

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48 minutes ago, Latticino said:

I'm confused, if you copied some You-tuber's version of the Frosty Tee burner, why not ask them how to correctly trim it? 

I used that YouTuber's build to buy my supplies because A) he built closest to Frosty's instructions and B) he had links to each item so I could order them without having to visit my local HD and deal with the infected. I'm asking for help here because this is where Frosty posted his instructions and there seems to be a wealth of information and here, so I thought this would be the best place to ask about it. 

As for the tee, yes it is a 1x1x3/4, per the YouTuber's supplies list. 

About the flame going out, yes, the flame seems to either move away from the burner (into the forge) or back up the burner. I'd get a video of it, but I'm starting to get the impression that videos aren't really liked around here. 

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Yes, if anyone can get your Frosty T burner working well, it is the man himself.

It is all about relative speed of flame front (the actual burning which goes in direction from the inside of the forge towards the burner) and the gas/air mixture (which goes from the inside of the burner towards the forge).  If the former is too fast you get burn-back or preignition, which is bad because it heats up your mixing tube and can lead to mini explosions inside the tube (usually characterized by a popping sound).  The latter is bad because if the flame lifts too far away it can blow out so the room fills up with gas...

It gets a little trickier when you consider that the flame front burn speed changes as your forge heats up.  As you would expect, it burns faster the hotter the forge interior gets.

The corollary is that your burner stability (good flame burning at the very end of the mixing tube or flare outlet if you have one) varies depending on how hot your forge is.  That is why I earlier posted that you should start the forge burning at the point of low fire where the flame is stable and doesn't either lift off the end of the tube, or burn back into the mixing chamber.  As your forge heats up you can increase the gas pressure and therefore the firing rate.

One problem you have with your forge design is that  the bricks you are using for insulation don't really insulate very well at all, and you don't seem to have any forge doors.  That means the forge won't  heat up well at low fire, or it will take a really long time to do so.  Which means it will take longer to switch to high fire and thus the catch 22.  You can improve this by using any left over bricks you have to block off some of the door opening part way, but you really need to use an insulating material to help keep that expensive heat in your forge.  Glen sells some good stuff on this site here: https://www.iforgeiron.com/forum/254-gas-forge-refractories-and-supplies/, but you need to construct a shell to build into.  If you still insist on going with a "pile of bricks" forge you can get some Morgan K-26 insulating firebricks and build one as well.

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