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I Forge Iron

Burner works but in forge


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The burner works as you can see. but when I set it up on the forge it pulsate and I have know idea what to do now. here are the #s. burner 2 1/2" at top. tube is 1'X14" I have used .045&.035 tips. the forge is 10 1/2X10 1/2X5 1/2"




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Just going from a quick glance it looks like your burner tube might be a bit on the long side?

Sometimes the burner will huff a bit, and then settle down once the forge is up to a good working temperature. A bit more gas pressure is often needed for a consistent burn.

You can check if your jet is aligned down the tube by running water through it at pressure! check that you havent got anything messing up your gas flow through the jet (ptfe tape, burrs etc).

The flame looks weak lit outside the forge, but it might just be the photos.

Im assuming your forge has got decent sized doors when your using it so there are no back pressure issues.

Im sure someone with a bit more know how will have some better ideas that the above! :)

for reference a picture of my venturi burner outside the forge, this is running on a fairly low gas pressure, I would regard this as a good burn / flame cone shape and it can be achieved by 'streamlining' all the components of the burner. I based this on the tube burners in Micheal Porters book, which is well worth reading!


Edited by John N
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have you got a pressure gauge on your fuel line? I was having problems with mine huffing like your saying and i found that at a higher pressure (i have a 0-30 psi pressure gauge) anything over 5 psi then they worked fine. hope this helps. Chad

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"huffing" is a result of poor air / fuel mixture. I assume your burner there is set up like any furnace inshot burner where a jet of fuel draws the primary air with it through the blast tube, into the fire box, or in this case, forge. The velocity of the fuel jet, acts on the air in the burner tube, causing it to move along with the fuel jet, which in turn creates a partial vacuum, sucking the air into the tube to replace the air moving toward the forge. once the gas burns you have a couple things going on. First the LP gas is converted into its various products of combustion--CO2, CO (incomplete combustion, itself flammable), water vapor, ect. Second, the primary air is heated, causing it to expand in volume--this back pressure, if not allowed to exit the forge volume, may try to force its way back into the blast tube, slowing the induced flow of primary air with the gas jet. A short chimney may be all you need to remedy this (or a bit higher one than what you may have allready).

I couldn't tell by the pictures, but I assume you have a regulator on your LP tank. If it can be adjusted, you may try that as well. A smaller flame may give you more heat if it is burning more efficiently, (and less CO) and this would also cause less combustion gasses that must leave the forge to allow a fresh mixture in. Watch your flame if you adjust the pressure. You don't want it to lift off the burner, nor do you want it to burn inside the tube either. LP gas will only burn in a small window of air / fuel mixture, about 5 to 10% ratio. Above or below that it won't burn.

Try adjusting your primary air too. It could be that outside the burner all that lovely O2 floating around it makes up for the air / fuel mixture

Edited by TimB
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It's not inducing combustion air well.

First, the tube should be between 8-9" for a 1" burner.

Secondly, If you're using a mig tip for the jet it's almost undoubtedly too deep in the throat. The tip of the jet should be at least 1/2-3/4" back from the throat. (narrowest part of the tube, or where the intake narrows into the tube.)

I think the biggest factor is the depth of the jet but shortening the tube will help as well. Judging by the shape of the flame's cone I'd say the alignment of the jet is good. The color of the flame however tells me it isn't getting enough air nor is it mixing. The color is pale blue with a clear center. You should be able to see the flame all the way through the cone. (kind of like looking at a milky liquid as opposed to looking at a clear liquid in a milky glass) In this instance the combustion is taking place on the outside of the cone meaning it's getting the bulk of it's combustion air after it leaves the burner tube.

The picture of John's burner shows the almost opaque nature of a flame with sufficient air and good mixing. When well mixed the bulk of combustion takes place in a short space making for the short tight combustion cone.



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What was happening to make it huff was it was intaking it's own exhaust. Each huff would blow the exhaust out a little faster and the burner would get a gulp of fresh air and then it'd huff again. This is one of the more common reasons for burners to flutter and huff but for some reason I don't think of it and I've been trouble shooting these things for a long time. Oh well.

About CO; words of wisdom are don't take any chances. Buy a CO detector! You can buy a good one for under $30 and that's less than they'll charge you for a couple aspirin for your headache in the hospital if you gas yourself. Providing you survive of course.


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