New burner design - prototype testers wanted

This is my opinion mind you so take it with a grain of salt. That burner is WAY to far in the forge. It should be be exposed to the inside even a little bit. I smooth the opening in the wool with refractory to create a smooth transition. Then I pull the burner back at least 1" from the edge of the forge lining. And like I said if the opening around the burner tube is larger then the burner you will draw extra air in which helps burn the extra gas.
 
JTknives said:
This is my opinion mind you so take it with a grain of salt. That burner is WAY to far in the forge. It should be be exposed to the inside even a little bit. I smooth the opening in the wool with refractory to create a smooth transition. Then I pull the burner back at least 1" from the edge of the forge lining. And like I said if the opening around the burner tube is larger then the burner you will draw extra air in which helps burn the extra gas.
Click to expand...

Thanks JT, pulled the burner out almost all of the way, fiddled with it a little, and Viola!
 
Seams to be working much better. Still a good amount of dragons breath but at least your getting the forge up to temp. I would wager a bet that if you took a 1/2” drill bit and drilled 4 holes around the burner tube about an 1-2” down from the end where the gas is injected you would get a better burn. The problem I think your seeing is that those burners use gas velocity to suck air in using a ventury action and as you turn the psi down your gas velocity is dropping which is drawing less air.
 
I would not add holes to Charles burners. However, the position of things is important.

First, lets talk about the burner mount:
The burner port tube is the pipe sticking out the forge to mount the burner. It should be about 3" long. Too short or too long may affect the burner operation, especially on smaller venturi burners. The tube ID should be about 150% the size of the burner OD. This space allows additional air to be drawn by the flame as it enters the chamber, as well as allows some cooling space around the burner. In a 2BF, the opening needs the same extra space. Never make the burner port a snug fit to the burner.
I recommend two sets of retainer bolts instead of one set ( the three bolts at 120° spacing that hold the burner in place). This assures the burner is straight down the port tube and has an even space around it to draw extra air ( and stay cooler).

Lets talk venturi:
The gas ejects from the orifice at a high speed. This pulls air molecules along with it by creating low pressure around the jet. This is the "draw" of the burner. The position of the jet, and the amount of space around it are important to get the right draw. Charles had been working on a sliding choke to move up and down the burner tube to adjust the draw. That is how you tune a venturi burner. Charles has worked out the orifice size and position of the jet pretty well, but a sliding choke may help a lot. You can make one from a piece of thin sheet metal. It doesn't need to move much to change the burn.

Now, the flame entry point:
Next, the flame needs the right path to enter the chamber without creating turbulence. Besides the right size port tube, the size and shape of the entry port matters. Normally, the end of the burner tube is about 1/2" to 1" back from the chamber wall. Additionally, the shape of the entrance hole changes things. A straight hole through the refractory (or just the burner sitting flush) will cause turbulence. Bits of loose refractory wool, and jagged refractory will make it worse. A smooth bell shaped entry ( called a flare) is better. I shape the hole in the wool to flare out and use satanite to make it smooth and have a nice bell shape. Some folks make a wooden or wax bell shape and use it as a forming mandrel as the refractory dries. Some folks put a slight flare on the end of the burner tube, which can help, too. You can either forge in the flare on a tapered mandrel, or use a slip-on flare. HTT&R sells these flares.

By moving the burner in and out in the burner port tube ... and keeping it centered ... you get the best position for smooth running. Adjusting the choke (if you have one) can tune the flame for a neutral atmosphere. It take some trial and error, and you have to go back and forth between the things that change the flame to get the perfect balance. Now, on word of caution - do all adjustments on a fully heated forge. Let it run 5-15 minutes before you make any fine adjustments. If you do it cold, you can pretty much guarantee that it will burn different when the chamber is heat soaked.
 
Stacy E. Apelt - Bladesmith said:
I would not add holes to Charles burners. However, the position of things is important.

First, lets talk about the burner mount:
The burner port tube is the pipe sticking out the forge to mount the burner. It should be about 3" long. Too short or too long may affect the burner operation, especially on smaller venturi burners. The tube ID should be about 150% the size of the burner OD. This space allows additional air to be drawn by the flame as it enters the chamber, as well as allows some cooling space around the burner. In a 2BF, the opening needs the same extra space. Never make the burner port a snug fit to the burner.
I recommend two sets of retainer bolts instead of one set ( the three bolts at 120° spacing that hold the burner in place). This assures the burner is straight down the port tube and has an even space around it to draw extra air ( and stay cooler).

Lets talk venturi:
The gas ejects from the orifice at a high speed. This pulls air molecules along with it by creating low pressure around the jet. This is the "draw" of the burner. The position of the jet, and the amount of space around it are important to get the right draw. Charles had been working on a sliding choke to move up and down the burner tube to adjust the draw. That is how you tune a venturi burner. Charles has worked out the orifice size and position of the jet pretty well, but a sliding choke may help a lot. You can make one from a piece of thin sheet metal. It doesn't need to move much to change the burn.

Now, the flame entry point:
Next, the flame needs the right path to enter the chamber without creating turbulence. Besides the right size port tube, the size and shape of the entry port matters. Normally, the end of the burner tube is about 1/2" to 1" back from the chamber wall. Additionally, the shape of the entrance hole changes things. A straight hole through the refractory (or just the burner sitting flush) will cause turbulence. Bits of loose refractory wool, and jagged refractory will make it worse. A smooth bell shaped entry ( called a flare) is better. I shape the hole in the wool to flare out and use satanite to make it smooth and have a nice bell shape. Some folks make a wooden or wax bell shape and use it as a forming mandrel as the refractory dries. Some folks put a slight flare on the end of the burner tube, which can help, too. You can either forge in the flare on a tapered mandrel, or use a slip-on flare. HTT&R sells these flares.

By moving the burner in and out in the burner port tube ... and keeping it centered ... you get the best position for smooth running. Adjusting the choke (if you have one) can tune the flame for a neutral atmosphere. It take some trial and error, and you have to go back and forth between the things that change the flame to get the perfect balance. Now, on word of caution - do all adjustments on a fully heated forge. Let it run 5-15 minutes before you make any fine adjustments. If you do it cold, you can pretty much guarantee that it will burn different when the chamber is heat soaked.
Click to expand...

Thank you for posting all this info Stacy! This is stuff I struggled to find with my weak google-fu... That's why I love visiting this forum. :thumbsup:
 
I meant to add that Charles uses pretty thick burner tubes ( which is good). There is usually a bit of extra metal flashing on the end where the pipe cutter cut it off. This can affect the burn by causing turbulence, and should be removed. Use a half round file and file this off smooth. A cylinder burr in a Dremel or flex-shaft will also remove it. Make the end a smooth chamfer from the inside to the outside. This acts like a mini flare and improves the smoothness of the flame. This trick is good on all burners.

Of course, if you have a pipe reamer, that will do the trick nicely.
 
Wow.. I have alot to think about on my forge. I have a 4-6 inch dragons breath, uneven opening around the burner, loose refractory at the entrance and more.

Thank you for the info Stacy!
 
I was not saying to go out and drill holes in your new burner. I was just saying it would help increase the air flow into the tube and help offset the “restriction” the gas orifice creates on air flow into the tube. It’s amazing how picky these ventury burners are with the air. I built one a little while ago and if you moved your finger within a few inches of the opening the flame would change. So anything around the entery point of the air will affect it.
 
Wow, sorry, I missed the last page of posts in this thread. Josh, is it still performing the same? I remember that forge model having all IFB, but I noticed some wool around the burner inside the chamber. Did you add this wool? If so, try removing it and make sure your burner is centered in the port. That should likely resolve the issues.

Charles
 
Charles I didn’t add the wool, it was there already. I coated everything in satanite after emailing you.
 
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