Burners 101

[Greg in Maryland]

8 minutes ago, Another FrankenBurner said:

This is my interpretation so far:

Appreciate the help.  A much better and more accurate representation than my attempt.  Thank you very much.

[Mikey98118]

Why build small burners at all, why high-speed?

If you want to produce extremely intense flames—without the expense of adding oxygen, or acetylene fuel—that will likely come from accelerated flame speed; this begins with the switch from laminar to turbulent air/fuel gas flames, and continues through levels of matipulation.

    So, what about burner size? Few of us desire a micro forge or jeweler’s furnace, but there are many who want more concentrated heat from their air-fuel torches. A large burner makes a clumsy hand torch; thus, the need for 1/4” and 3/8” burners with compact flames. A 1/2” torch is the largest an average person can handle comfortably.

    But these are primarily equipment burners. So, understand that heat management only begins with how hot flames get. The reason burners are aimed on a tangent, is to cause their combustion gasses to swirl around equipment interiors; creating a longer distance from flame tip to exhaust opening.   

    Obviously, a lengthened exhaust path increases the amount of its hang time. Thus, depositing more combustion energy on internal surfaces. What isn't so clear is that the heat gained isn't added by hot gases blowing an extra foot or two at high speed; it’s mainly due to their continuing drop in velocity over that added distance.

    Combustion gases begin to slow as soon as they leave the flame envelope, but the hot exhaust from small flames decelerate quicker than that from large flames. The flames of two 1/2" burners will use the same amount of fuel to produce an equal amount of heat as a single 3/4” burner; but they will drop velocity much faster in a five-gallon propane cylinder forge; increasing efficiency, because they can burn faster/hotter without creating a wasteful tongue of fire out the exhaust opening.

    When heating small parts, further efficiency can be gained by placing a temporary partition in equipment interiors; separating them into twin spaces, and shutting down one of the burners. This is something that can’t be done with a single large burner that is centrally located.

     Fuel cost may seem to be a minor concern in miniature equipment, but faster heating times, and increased portability remain obvious advantages. Portability? Yes; equipment isn’t all that portable, if it must be fed from a large fuel cylinder.

    Do multiple flame burners (Giberson ceramic burner heads, or homemade ribbon burners) take flame deceleration even further? Certainly; unfortunately, the burners and ceramic heads themselves tend to be quite large. Over time, compact multi-flame burners will be perfected, but first there must be a lot more interest in doing so. Since this kind of burner provides the most advantage in larger equipment, we could have a long wait.

 

[Mikey98118]

Notice of a better way to buy a 3" angle grinder

12V 3" angle grinders are on sale at Harbor Freight Tools for $35; this is as low a price as they ever get. I have seen it matched once on Amazon, with free shipping. However, if you buy your grinder at at a local Harbor Freight Tools store, you can exchange a lemon, should you get one, without hassles, which is what you will get from a drop shipper selling through Amazon.

[Greg in Maryland]

On 2/25/2023 at 5:03 PM, Greg in Maryland said:

Results from jet change.

First picture:  Schedule 40 nipple with .035.  15psi.

Second picture:  Schedule 80 nipple with .030.  15psi.

Below:  Schedule 80 nipple with .025 tip.  15 psi.  The previous settings allowed for a wide range of choke adjustment (burner would keep running with choke wide open).  The .025 tip choke range is only 1/3 of the air slot.  Any additional exposure (towards wide open) makes the flame go out.  Thoughts?

[Mikey98118]

My own burners vary from burner to burner as to how far the choke can be open, until the flame retention nozzle warns up to orange incandescence. Some of my best burners could only have the choke open 1/4" during warm up; that is out in the open air. In a forge, the game changes again. I have other burners that could started just fine with the choke wide open 

As to the flame, you are almost there. Lots of guys would call this good enough; I hope you won't stop short of the prize. Normally, I would advise you to go for an 023 tip. But, I suggest you play with the burner a little bit, before making further changes. Yes, you will make them, but spend some time along the way, getting familiar with your burner. And, yes, I believe you will get the magic flame from the 023" tip. The 025 tip is perfect in my burners, but this design always ran a little different. I had hoped, with the bevels it would support a slightly larger tip, but apparently not. Have you played with the amount of nozzle overhang, with this tip? If not, try shortening it a little bit, to see what happens.

[Mikey98118]

So, It might help if I made things a little clearer about what is different in this flame. Why do I state that "you're almost there" anyway? What is different than an any of the other photos?

First is the shape of the primary flame envelope; that is the very light blue (with a very faint green tinge) flame front coming out of the flame retention nozzle. Some people would suppose that the primary envelope is the shorter darker blue area before it; but that is actually a clear void. What you see in that area is actually the thinning rear of the primary flame. Why does this area look darker blue? Because you are seeing both the near and far side of the flame envelope. If this area was white, it would be a primary flame front, and a very undesirable one at that.

Next, there is a darker blue secondary flame, which is about equal in length with the primary flame.

Finally, there is plum colored tertiary flame, that is only a few inches long.

The next change will be the tertiary flame folding into the secondary flame, which will become very short, or both secondary and tertiary flame will both simply fold into a perfect blue primary flame; if that happens your fun begins and mine ends (I like it better when a burner fights me every step of the way).

The clincher is that very short tertiary flame; it tells me that you nearly have your fish in the boat

[Jake18]

sorry, pretty off topic but where do you get your schedule 80 1/8 in pipe? i cannot find it, at least not in smaller quantities. And thank you mike for the detailed flame report. I've been trying to get better at reading the flames and that helps.

[Mikey98118]

Look for 1/8" schedule #80 pipe nipples on line.

 

And it is not off topic at all

[Mikey98118]

1 hour ago, Jake18 said:

I've been trying to get better at reading the flames and that helps.

So, your question and this comment indicates that you are either building or modifying a burner?

All questions are welcome here. Your problem may seem minor to you, but there are always many others with similar questions.

How burner flames look, and what that means, is one of those things in life that appear complicated in the beginning, and are utterly simple looking back at it. Unfortunately, their learning curve, while simple, makes people very tense, in the beginning.

One of my earliest students, who was an airline pilot (so no slouch), spent his first month certain that he would never get his burner flame right. I helped him do the final tuning and invited him to light it up. Bingo; out came textbook perfect flame. You'd have though he'd just learned to flap his arms and fly! He never had a real problem; just wanted the result to hard to believe

[Jake18]

all of the above . I have a forge i've been working with but it is not working how i would like so i am going to try and modify it to work better so i can keep using them. I will probably be asking quesstions about it later. I haven't used them in a while so i do not remember what the flame was like but i have a good idea of some modifications it could use after reading this. Other than that i will likely be building some mikey burners sometime soon and then expirementing with some other designs. I definitely can't get all that done if i dont know what a good flame looks like. Glad to hear it will get simple though after a while. looking forward to those days lol. Wow! yeah i can understand that, i can't wait to get my first good flame. In the coming months ill definitely have plenty of questions when i get time to really test this stuff and expirement. College has me pretty busy at the moment.

[Mikey98118]

Take a little time to look over other burners on IFI, too. "One shoe doesn't fit all" is especially true with forges run off ribbon burners.

It all depends on what you want to do with your forge, and what size and shape forge you decide to build. The more sweat equity you invest in you forge, the more you get for your money. The more research you  do, before building, the more you will get for your sweat

[Jake18]

That is pretty much the stage I am in now. Without the time to put anything together i am spending time studying these forums and other reputable sources i can find. right now i am planning on a D forge, or actually, a box with a D on top of it and using two 1/2 in burners to heat a 6x6x10 or 12 box with an undetermined arch size. After spending time on the 3-D printed burner thread, i am currently expirementing with trying to create a design as efficient as the one created by AnotherFrankenburner.  At the moment i am trying to get a better understanding of flame nozzles and how they work and when to use what style cause that is where i am most lacking in knowledge.

[Greg in Maryland]

16 hours ago, Jake18 said:

sorry, pretty off topic but where do you get your schedule 80 1/8 in pipe? i cannot find it, at least not in smaller quantities. And thank you mike for the detailed flame report. I've been trying to get better at reading the flames and that helps.

Grainger has them.

[Mikey98118]

 

sorry for the slow reply; apperently I didn't send the first try, and then typed over it.

So, trying again: The answer is simple. Input 1/8" schedule #80 pipe nipple, and up will pop a few ads for them.

The Bauer 20v 3" cutoff tool (available from Harbor Freight Tools for $50 (but the battery is another $50); this is a burlier version of the 12V 3” angle grinders (whether they are called grinders or saws is just an advertising choice; they are all used for both tasks). You trade handiness on delicate tasks for extra power; This is one of the latest models of stronger 3” angle grinders. DeWalt, Works, and other brands are also selling 20V 3” cordless angle grinders.

    What then is the point of this particular tool? After all, there must be a point to it, if competing brands are proliferating, right? Not necessarily. Lots of power tools don’t last the test of time; I don’t think these will either. their point is supposed to be sufficient power to be considered a practical workman’s tool, but light and handy for cutting; this is why some ads call them a cutoff tool, and not an angle grinder. All of these new power tools are used for both jobs. While it is considered hard to make an angle grinder too powerful (a view I totally disagree with), it is easy to make a saw overpowered and unsafe; this is because of the danger of severe kickbacks from overpowered hand-held saws. But high torque hand-held saws have been used for over seventy years, right? Yes, for cutting wood--not steel. The difference is positioning. If you plunge cut steel with a chop-saw, it can be done safely. If you put a friction blade on a circular saw, you can cut steel safely, so long as you keep its shoe (the flat rectangular metal base) flat upon the work surface. But surface cutting is done free hand; this is likely to create kickback. During this kind of cutting, too much torque in your tool is likely to be paid for with blood.

[Mikey98118]

What do different turbulent air/fuel gas flames seem to indicate?

" seem to indicate" must be stated right up front, because I'm no combustion engineer; just an amateur who has been playing with these toys, and finding out what I can, for a very long time.

What I state as fact, has been gleaned from the writings of those who teach combustion engineering. But I could have misremembered.  What I suppose is so, is from observation; a pinch of salt is needed there

Uncontrolled gas flames are usually described as flammable gas explosions. A controlled gas flame, only issues from a gas orifice, and is in fact a controlled series of multiple tiny explosions, which proceed from the outside of a gas column that is mixed or mixing with air. It is important to understand that combustion begins at the periphery of the flame, and proceeds inward from all areas of the periphery, constituting a LAME ENVELOPE. These are the facts as best I understand and remember them.

All controllable air/gas flames fall into the category of laminar or turbulent. Laminar flames, such as those found on Bunsen burners are laminar. Most other air/gas heating equipment use turbulent flames to increase heat output.

Looking at various flames, you may find a single light blue flame envelope (one of the different ways of describing a flame front); this appears to be the ideal configuration, presently. Flames should improve shortly after someone recognizes what that takes; these are only an armature's suppositions.

The worst flame to see has a white primary envelope exiting the flame retention nozzle; it will usually be followed by secondary and tertiary flame envelopes: This is observed facts. My supposition is that the white flame is made by heavy carbon combustion in this flame, followed by secondary envelopes that are mostly combusting hydrogen molecules, with oxygen. I suspect that the tertiary flame is the combustion of carbon monoxide formed by incomplete combustion in the primary and secondary flames.

Above are only examples of the various forms that unbalanced gas combustion can take. A primary flame with anything from a green tinge, to one followed by a green secondary flame is just as probable; this indicates too little inducted air for the amount of fuel. A dark blue to purple primary flame indicates varying degrees of too much air (oxygen source) to fuel gas.

Usually, the smaller the gas orifice to burner size the higher the gas pressure must be turned up. The higher the gas pressure the faster the gas column. The faster the column the more air is inducted in a naturally aspirated burner. So, usually, the smaller the gas orifice, to burner size, the the leaner the flame. However, if taken far enough, this tendency will may be reversed, with a fuel rich flame! What the heck? My supposition is  that some of the molecules in the gas column starts outracing the incoming air. However, I only suppose...

Take what you  gain here and run with it

What you don't get, or don't dig, speak right out about.

 

 

[Greg in Maryland]

4 hours ago, Mikey98118 said:

Take what you  gain here and run with it

What you don't get, or don't dig, speak right out about.

Appreciate your input into the quest for the perfect flame.  My knowledge has increased since joining this thread ( I recognize now how much I didn’t know about combustion).  I haven’t played with the nozzle overhang yet.  Will report soon.  The .023 tips are on order.

[Mikey98118]

There is never any need to wait on parts, when experiments can be done, and plans, plans, plans, can be thought about

[Jake18]

I got a question now. I’ve been using my buddy’s forge since I was not happy with the one I built and am working on making a better one, and his gets pretty hot but having an issue with “backfire”. The flame will go back up to the nozzle but only for a moment before going out. There is a lot of dragons breath coming out from it even at low psi. Which to me says that it is running rich(or it could possibly be from the burner only being about 4 inches from the floor of the forge?). Anyways, my guess is that the orifice is too big, creating a very rich flame at too low of a speed to pull in enough air. I’m also thinking maybe this can be improved by drilling out the holes into fill slits to allow more air. I’m not sure though. Before I just dealt with this cause it still works but realized it’s a learning opportunity so here we go.

[Mikey98118]

First thing is, that exhaust flame is the kind of nearly opaque yellow that many of us have come to link with oxidizing of calcium binders in some refractory products, rather than heavily reducing burner flames; just a thought.

1 hour ago, Jake18 said:

his gets pretty hot but having an issue with “backfire”. The flame will go back up to the nozzle but only for a moment before going out.

The first thing that comes to mind is tarry wax buildup in the gas orifice. You need to cheak for that with a set of torch tip cleaners.

However, one thing does not exclude the other; his forge could have both problems.

 

Or rather, both symptoms, since oxidizing calcium binder is only distracting; not problematic

looking again at your photo, the right lower corner shows something orange; if that something is exhaust flame, then oxidizing calcium binder simply becomes all the more likely.

[Greg in Maryland]

On 2/28/2023 at 7:44 PM, Greg in Maryland said:

Below:  Schedule 80 nipple with .025 tip (Lincoln) 15 psi.  The previous settings allowed for a wide range of choke adjustment (burner would keep running with choke wide open).  The .025 tip choke range is only 1/3 of the air slot.  Any additional exposure (towards wide open) makes the flame go out.  Thoughts?

Below:  Schedule 80 nipple with .023 tip (tweco) 15 psi.  Observation:  The .030 tip in the post at the beginning of this page is a tweco.  The .025 directly above is a Lincoln.  The tweco tips are longer.  I also noticed the choke adjustment range retuned to the same as the other tweco tip.  It sure appears the shorter Lincoln tip is adding a variable.  Thoughts?

[Mikey98118]

1 hour ago, Greg in Maryland said:

It sure appears the shorter Lincoln tip is adding a variable.  Thoughts?

That is because it is giving your burner more variance; however, that increased variance is because the shorter tip is de-tuning the burner somewhat. You are headed in the wrong direction. Not being able to open the choke completely, is an interesting data--not a problem; it only means that your burner is able to draw in too much air, which doesn't mean you have to. Too little air; now that's a problem.

What is the distance between the end of the MIG tip, and the forward end of the air openings? How much overhang does the flame retention nozzle have past the end of the mixing tube, and what is the inside diameter of the nozzle? Something is going on with your burner that doesn't make since. Therefore, I suspect that we are missing something obvious.

[Greg in Maryland]

All testing:  1.5” flame retention nozzle overhang.  Tip .5” past the forward air opening.  15 psi.

First photo:  Schedule 80 nipple .025 tip Lincoln (actual orifice .031)

Second photo:  Schedule 80 nipple .023 tip Tweco (actual orifice .028)

Third photo:  Shorter tip is the Lincoln.  It is 1/4 shorter than the Tweco.

Thoughts?

 

[Mikey98118]

1 hour ago, Greg in Maryland said:

Tip .5” past the forward air opening.  15 psi.

You're telling me that the end of the MIG tip is 1/2" beyond the forward edge of the air openings?!? If this is the case, please move it 7/8" of an inch rearward, and then we can begin tuning again.

[Mikey98118]

19 hours ago, Greg in Maryland said:

Schedule 80 nipple .025 tip Lincoln (actual orifice .031)

Second photo:  Schedule 80 nipple .023 tip Tweco (actual orifice .028)

This is interesting. For decades Tweco MIG tips for .023" welding wire had actual orifice diameters of .031". and the newer .025" tips were .034". I got used to larger diameter through holes in imported tips, but smaller diameter hole sizes makes absolutely no sense at all.

[Greg in Maryland]

3 hours ago, Mikey98118 said:

This is interesting. For decades Tweco MIG tips for .023" welding wire had actual orifice diameters of .031". and the newer .025" tips were .034". I got used to larger diameter through holes in imported tips, but smaller diameter hole sizes makes absolutely no sense at all.

I don’t have pin gauges so I used a set of tip cleaners and a micrometer.  I am fairly confident that I am within .001.  To clarify:  The tweco style tips are made by American Torch Tip.

Test:  .025 Lincoln tip.  1.5” flame retention nozzle overhang at 15 psi.  Picture sequence:  Mig tip beginning 7/8” rearward of the forward air slots and moved in 1/8” increments towards the forward end of the air slots.