Mikey98118

Burners 101

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Frosty,

May I suggest that the  pilot bits and taps each be partially embedded in individual wine corks.

The size can then be written on the body of the cork, and the bits will not bang around and become dull.

SLAG.

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GADZOOKS!  Mr. Mikey,

You are astute.

Hic.

Regards,

SLAG.

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      I have changed mixing tubes in my burners to increase efficiency:

       The mixing tube is a 12” long section of 3/4” schedule ten, #304 stainless steel pipe (part #928 at Onlinemetals.com. Use the part number to bring this material up on their website); it costs $6.01. and shipping, cut to length (enter 12 in the pop up cut window). This pipe has a 1.050” outside diameter, and an 0.884" inside diameter (sixty thousands larger inside diameter than typical schedule #40 mild steel pipe (which works properly with a 0.030” MIG tip used as a gas jet), with superior roundness (closer to tubing). So why not use tube? For this burner size, the inside diameter of the stainless steel pipe will end up a little larger than that of the nearest tube size, which doesn’t lose too much wall thickness for sound construction. Also, the nearest equivalent in stainless steel tube would cost $27.24 (SS pipe is generally less expensive than SS tube.

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Now you are just cheating.  Stepping away from thick walled iron pipe nominal sizing.  What if people want to hang their body weight from the burner sticking out of the side of the forge?  Maybe hang a hammer/tong rack from the burner tube?

Why not push further?  Currently on Amazon, for $11, you can get a 12 inch length of 1 inch OD, 0.93 ID tubing in 316 stainless. (Search for "stainless tubing") Almost in 1 inch pipe ID territory.

Higher volume, lower velocity.  A slower shorter flame.  If enough extra air is induced, a larger jet for higher output.

There will be less mass to conduct heat away from the business end is the only maybe downside I can see.  I am using refractory nozzles so it has not been a problem.  

I am sticking with normal pipe sizes for the inducer heads because people like to use pipe and build their own thing.  I have been playing with thin wall pipe/tube for my own personal burners.

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Thanks Mikey; that item from McMaster is $20, though their shipping tends to be more reasonable than most. (McMaster says there is a weld bead on the inside, which seems preferable to avoid.) McMaster's stainless tubing is about the same price, with a smooth bore.

I ordered a piece of plain-steel tube from McMaster, 0.87" ID, 1.00" OD (0.065" wall); $3 for 1' or $7 for 3'. 

Thanks for the Amazon item AFB; I just ordered one of those too.

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All excellent replies, and helpful for others. The point is that the more we pay attention to the inside diameters of our mixing tube choices the more we can get out of our MIG tip gas jets.

DThat will hold ture no matter what kind of burner why design.

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Thank you for sharing all of the information Mr. Mikey.  I wonder how many burners are burning hotter/cleaner because of your contributions.  

No problem jwmelvin.  Report back whatever you are building over there.  I enjoy seeing everyone's burners.

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Mikey, I find it funny that you posted a 0.030" mig tip works properly with my burner mixing tube, I was pondering the other day and I noticed that my burner either was really lean or rich and I already had a 0.030" mig tip so I threw it in this evening before seeing your post just to experiment and lone behold the flame it made looked similar to the flame from the previous 0.023" mig tip at 20 PSI but was running at a much lower 5 PSI.

Living at sea level so close to the ocean I often get fluttering with my burner what I mean by that is that my burner with go from lean to rich in a split second, wind can be a problem for naturally aspirated burners due to the induction being such a low pressure when an equal to or greater than pressure collides it can render the Venturi effect inert causing your burner to gasp for oxygen, I had only noticed this issue more because the larger jet stream produces a weaker vacuum due to less pressure.

I plan to fashion a dog cone style funnel attached to the top of the choke to help prevent the interruption of flow.

Picture: 5 PSI burn after few minutes of warm up.

Thanks, Corey

Screenshot_2019-04-11-22-53-15-437_com.miui.gallery.png

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I see nothing wrong with the flame.

It is best to keep wind currents away from burner intakes.

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i feel i should know this, but...

Does more gas mean hotter?

will three 1/4" burners match the output of a single 3/4" burner?

will four 1/4" burners be hotter than a single 3/4"?

Ive been in garden mode.  missed alot here

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Fun line of questions.  I look forward to seeing other's answers.  

My current understanding of things:

More fuel contains more energy, yes.  There are some caveats though.   More energy may not mean higher forge/flame temperatures.  Heat loss, fuel max temperature, etc.

  • If more fuel is introduced and it causes the flame to burn less cleanly, the flame temperature could reduce.   The flame temperature depends on how clean the flame is burning.
  • If more fuel is introduced by increasing velocity and the extra speed pushes heat out the doors of the forge, the extra heat produced is heating your work area instead of the forge.  
  • If the burner(s) output volume is/are too much for the forge volume, the same blowing heat out the doors can occur.

As far as comparing smaller mix tube burners to larger tube burners, it all depends on the burners being compared and the forge they are in.  Ease of construction typically makes a single 3/4 burner a better option then multiple smaller burners.  I am a fan of the 1/2 inch burner size but I like 150-300 in3  forges and my burners may be outputting more heat then the typical 1/2 inch.  The golden standard burner for a long time now has been the 3/4 inch burner.  Easy to build, decent heat output, not too large in size.  

The advantages of multiple smaller burners are a splitting of the heat source for more even heat and shorter flame envelopes.  Shorter envelopes can shed their heat into the forge faster and are less likely to impinge on your work or the wall of the forge.

It is written here that each step down in size is a halving of the output so a 1/4 inch burner should produce a quarter of what a 3/4 burner produces.  Again, this would depend on the burners being compared but if it is true, you would need four 1/4 inch burners to match a 3/4 burner.  If we calculate out mix tube area, five 1/4 inch pipes would be less than a 3/4 pipe.  I would expect there to be extra losses caused by the extra surface area of the smaller pipes.

1/4 inch burners are not mentioned much as the smaller the burner, the more critical the dimensions become.  Even 3/8 burners don't come up often.

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34 minutes ago, Another FrankenBurner said:

My current understanding of things:

these were all of my thoughts as well.

I was also pondering the temp difference / efficiency of a burner with and without a ribbon head.

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Frankenburner has it right. If, you do a dandy job of building and mounting the smaller burners, than you could end up with better heat efficiency than a single large burner, and only than. If you try building something as small as 1/4" burners, you need to use a linear design; jet ejectors get too finicky at that size.

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I have "successfully"  built one1/4" Mikey burner; that is to say, it was able to produce a neutral flame in a single envelope; but it was not a practical burner, being too finicky and too much trouble to construct. It is quite possible that someone else may build a more robust version of this burner size in a linear design. However, duel fuel propane torches, with built in needle valves, and already set up for available hose fittings are a far more practical path. How much is our time worth?

If someone wants to build a 1/4" burner, just to prove he can, I say "bravo!"  But sometimes it is more practical to buy rather than build :)

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22 hours ago, Another FrankenBurner said:

No problem jwmelvin.  Report back whatever you are building over there.  I enjoy seeing everyone's burners.

I made the first flame today. I have been thinking a bit on the 3d-printed bellmouth and came up with something I wanted to try, so I have that on the end of the thin 316 tube (12" long, 0.93" ID). I have a 0.030" MIG tip in a brass tube (threaded the end) that I'm just holding in the mouth of the possibly-vortex-generating inlet. And for a nozzle I grabbed a piece of pipe that is 1.375" ID and extends past the end of the mixing tube about 1.75". It was hastily assembled just to see if it would sustain a flame. I'll be building a frame to hold the propane nozzle centered in the right place, and I will make a flame nozzle. Here are some pictures at about 7psi (I believe the flame was about the same but the lighting changed between the two flame pics):

IMG_0739.jpg

IMG_0736.jpg

IMG_0733.jpg

IMG_0724.jpg

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Careful.  It's addicting. 

I expect your blades are acting as paddles which hinder vortical flow more then help it.  Every time I have tried to force anything to happen, it reduced induction volume and usually reduced vortex strength.  You would have to print a model without them and test them both with smoke to see for sure.  Hopefully I am wrong.  

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Jungle671: Burner output is a function of the area of the mixing tube. A quick approximation I use for estimates is: 1/3 increase in diameter doubles output. Eg. A 1" burner is 2x the output of a 3/4", a 3/4" is 2x the output of a 1/2". So a 1/4" burner is half the output of a 1/4" of a 1/2" burner.

Without breaking out the calculator or scratching paper my dented head says it'll take eight 1/4" burners to equal one 3/4" burner.

Might as well build a multiple outlet burner, less work. Hmmm? 

Frosty The Lucky.

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6 hours ago, Another FrankenBurner said:

I expect your blades are acting as paddles which hinder vortical flow more then help it.  Every time I have tried to force anything to happen, it reduced induction volume and usually reduced vortex strength.  You would have to print a model without them and test them both with smoke to see for sure.  Hopefully I am wrong.  

That’s a good point, thanks. I do need a control. Especially since this is my first burner.

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Let's not throw out the baby with the bath water. That is a pretty nice flame coming out of a burner running sans flame retention nozzle out in the open air; obviously, something important is going on here!

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1 hour ago, Mikey98118 said:

Let's not throw out the baby with the bath water. That is a pretty nice flame coming out of a burner running sans flame retention nozzle out in the open air; obviously, something important is going on here!

That’s encouraging, thanks. It does have a nozzle (blew itself out without one) it’s just that the pipe I used for a nozzle is so long it swallowed the whole mixing tube. I’ll try to fashion a proper, adjustable flame nozzle and fixture the accelerator. I do have another inducer styled more like AFB’s to try too. 

Also:  what is the downside to a mixing tube that is too long ?

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I look forward to seeing more.

Extra mix tube length adds drag which could result in less air induction.  It may mix better if that is needed.  It can also result in a more laminar flow for a longer more pencil like flame which can be good for certain uses.  Longer in a forge is not generally desired.  

I tried an 18 inch mix tube just to see an extreme.  It produced a rich flame which was longer then a foot.

Too short and you deal with poor mixing and a bushy turbulent loud flame.

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