Burners 101

[Frosty]

We've never agreed completely Mike, we just have decent working models. I don't think it really matters if one or neither of us is right we can make the things work. We've gained our basic information from different sources and built from there. My initial understanding and data is from a bundle of sales brochures from manufacturers to companies who used the devices. Jet ejectors to draw vacuums, linear inducers to supply a flow and air amplifiers to transport material from gravel to milling grain. The Dyson line of products use "air amplifiers" of one sort or another. 

Starting with that I spent time in libraries until I hit a point of diminishing returns. I'd make cites to back my opinions but I'm not going to go spend that much time in the library again. Some of the info was in weird places.

Don't worry about trying to figure out what I think. Just the thought scares me. 

Frosty The Lucky.

[Mikey98118]

I rarely find myself cast in the role of Doubting Thomas, but when you're there you're there

What is best about you/me is that we rarely agree completely; I find that valuable and think it is good for this group. If we should start agreeing too much I would have to provoke you; I'm much too old for that...

[Frosty]

Ah, if you weren't a skeptic your burners wouldn't be as effective as they are. Something I value in people when I find it is their being skeptical of what they know. I'm almost never sure I'm right though I do state my best opinion strongly. 

I learn more from folk who don't agree, a different perspective is good. If I start feeling you need a little provoking I'll get hold of one of the guys I know who just LOVE trolling and sic em on ya. 

I do know a couple few trolls I just don't associate, live or online. Heck at least one is a relative,  I think he lives in Everett! 

Frosty The Lucky.

[Mikey98118]

11 minutes ago, Frosty said:

Heck at least one is a relative, 

I outlived all of mine, but it sure took a long time; unfortunately, the good ones went away too.

[Mikey98118]

Tapered MIG tips; yes or no?

You will hear people like me saying to use a tapered tip in your burner, and others saying not to bother; who is right? It depends on the burner design; a tapered tip is a waste of effort in a "T" burner; this is because of the burner's flow dynamics. In most burner designs it does matter; how much it matters depends on the size of the burner. In a 1-1/4" burner; not much at all. In a 1/4" burner, tapering the tip is critical; it's a sliding scale between the two.

So, why do I always recommend installing a tapered tip? The problem is a newbie's tendency to overreact when judging a new burner's flame. Being over critical in judging a burner's performance is easily corrected because the victim usually asks for help. But a more serious problem comes from the builders "happy talking" themselves into believing a mediocre flame is just fabulous. If details like using a tapered tip, and correctly positioning it in the burner's "sweet spot" is seen to, to begin with, then the happy builder has a lot more chance to be right about his "fabulous" burner's performance.  

It isn't always convenient to find a tapered tip; in some tip brands, it isn't even possible. But anyone can mount a plain MIG contact tip into a hand drill, and revolve it under a file; if you do so, remember not to taper it completely. Leave a small amount of flat around the tips orifice (otherwise the soft copper will give you grief). Make the taper about three times as long the tip's diameter.

[Howling dog forge]

Hey guys I have a burner situation I would like to discuss and this is the best place I know for an intelligent conversation about such things. 

The Dog box has a few hours on it and it is everything I asked for but it seems to be a bit large for what I am doing right now. Yea I know "350in³ too large, How will you ever forge a cutlass in that?". I have been working mostly with tools and trinkets and can see having a long term use for something in the 150in³ volume. I am very fond of the "T" burner, it is so simple and elegant I can't see using anything else but the question is, am I overpowering the small volume box with a 1/2 in "T" burner??  

[Frosty]

A 1/2" T is a good size for a 150 cu/in chamber provided it isn't too long and narrow. You can always turn a burner down if it's too much but it's a real PITA to turn one higher than max if it isn't enough.

Frosty The Lucky.

[Howling dog forge]

kind of thinking 5x5 by 7" long with diagonal burner placement. sliding doors both ends. pretty much the same as the dog box only smaller. 

[Frosty]

Just now, Howling dog forge said:

kind of thinking 5x5 by 7" long with diagonal burner placement. sliding doors both ends. pretty much the same as the dog box only smaller. 

Should work a treat for you. That's a nice size and shape forge, I like it. Pics in operation please.

Frosty The Lucky.

[Mikey98118]

And please give us a flame photo of the 1/2" "T" running, please; we don't have one, so far.

[Mikey98118]

Capillary tube must be cut to the right length for your burner; that will vary according to burner design and exact inside diameter of the pipe or tubing you find to make your burner from. Cutting will create burrs that need to be eliminated, inside and outside the gas jet. Very fine sandpaper (#400 grit works best) will eliminate all external and most internal burrs, Torch tip cleaners will eliminate the rest.

You need to order the cleaner set, and mic the files, so as to understand what the set number actually been before ordering capillary tube because the set's wire files are sized to match up with torch tip holes; not as a progression of hole sizes, as in a drill bit set. If you don't make sure that the inside diameter of your capillary tube matches up to one of the wire files (with an additional .002" for working room), you will end up trying to find the right size piano wire to work with. A little forethought beats a lot of cussing here 

The smaller the jet the greater the friction it generates. Too much friction will steal the force a gas jet generates; the right length trumps longer every time.

Stainless steel tube is harder to work with than brass or copper capillary tube; it is also much easier to make a working gas jet with because of that.

Use a magnifying lens to assure that the finished jet has no burrs or mar to its roundness to wreak performance.

The smaller the diameter of the capillary tube the greater the exact length of this part plays on burner performance; in a 1/4" burner you get down to 1/32", so fine tune the gas jet's length with sandpaper.

[Mikey98118]

The easy way to find regulators and gas hose

Input "QCC-1 braided hose" on Amazon.com to bring up two pages of the best deals on adjustable regulators and braided stainless steel propane hose at one shot, instead of spending days trying to locate a good deal on these products.

[Mikey98118]

Soft flames

There is a lot to be said for a flame that is hot enough but also is soft. A soft flame doesn't need to be precisely positioned in order to impact away from the center of the forge floor to avoid burning the heating stock. Loads of guys find that to be a valuable contribution to forge building.

I have spent years promoting the hottest hardest possible flames because they save fuel and burn clean; the downside of this is the need to build the forge as exactly as the burner. Most people don't want to work that hard; especially on their first forge.

What I consider to be a mediocre burner can make a comfortable fit with a more relaxed forge build. where do we draw the line? Look at the exhaust gases; it should be expected that some of them are blue in this forge. Blue exhaust flames indicate fuel still burning. You can bet that such an exhaust is producing carbon monoxide; a small amount can be handled by a powered exhaust system or by using the forge outdoors. A lot of Co will present a health hazard whatever you do; don't go there.

•  

[Mikey98118]

Burner performance is enhanced by being in the forge

I had not agreed with Frosty's view that a burner should be tuned within its forge. His burners make soft flames, while mine make very hard flames. Also, I have always tuned mine in the open air, so the method is "tried and true" in my world. While it is also true that all burner designs work better within their forge than out in the open, I didn't see that fact as affecting my preferred tuning method.

However, recently one of the members here attempted to build a Mikey burner; he generally did a fine job, but the mixing tube portion of his burner was way short of the length needed, and the resulting flame was disappointing...until he mounted the burner in his forge. Then suddenly the flame transformed into a perfect example of single wavefront combustion.

This is the first time I've seen this happen, but if it only happens one time in a hundred times, or if someone figures out why, it makes his point.

[Frosty]

Minor point Mike but my view is, "tune the burner for where you're going to use it." This approach means I don't have to be nearly so picky building them which suits my lazy nature and filled the goal of making them as tool and skill minimal as possible.

I remember the change in your tone when the too short burner turned out to work so well. That's how I felt when the NARB turned out to be so stable. 

So long as there's something new to tinker with and figure out I guess I'll stick around.

Frosty The Lucky. 

[Mikey98118]

The facts must rule over my druthers...no matter how long it takes me to see them

Your minor point is noted and pertinent.

[Mikey98118]

 

This is how I mount MIG tips directly into copper refrigeration tube on Vortex burners; there are some tricks that could prove valuable for mounting MIG tips in other burners too.

 

Mounting the gas line and gas jet in an aluminum mounting plate: You will be ordering about one foot of 1/4" fully annealed refrigeration tube, which has an inside diameter of 0.190”. You may only use four or five inches of it, but hardware stores simply aren’t interested in cutting it off the roll in less than one foot lengths. The section of 1/4" refrigeration tube is going to hold a MIG tip (part for a gas jet at one end and a gas-tight fitting on the other end.

Note: 1/4” refrigeration tube has an I.D. of 0.190”. MK brand MIG contact tips have 12-24 thread, which has a nominal minor diameter of 0.1722” and a nominal major diameter of   0.2160”(I have measured them at as low as 0.2110”); MK series #621 tips come in short (1”)  and long length (1-1/2” beyond the thread); Praxair carries them, and they can also be ordered online. You would probably want to silver solder an inch long section of 3/16” refrigeration tube inside to help to help form thread.

Or, you can use a Tweco 14T series MIG contact tip for the gas jet; they are available online and at most welding supply stores. Spin tips in a hand drill, under a file, to turn down the threaded end, and braze the tip into the refrigeration tube. Or, you would want to silver braze an inch long section of 5/16” refrigeration tube on the 1/4” tube’s outside; this thickens the tube to provide enough material in the tube wall for forming thread, should you choose to tap the refrigeration tube for 1/4-27 thread.

Note: do not attempt to substitute 1/4-28 thread in copper tube; that only works as thread in steel tube and schedule #80 1/8” steel pipe.

The refrigeration tube should be inserted through a side hole drilled in the mounting plate, forcing the tube from within center hole to beyond the plate’s edge. This side hole should be drilled out to run parallel to one of the fan's supporting ribs; the rib that the fan wiring runs under. So, you can't drill the side hole without having the fan for comparison.

Support ribs on most fans bridge the gap between rim section and center section at an acute angle rather than at ninety degrees, and it will become obvious to you that the gas tube will have to be bent in two places for the tube to end up in the center area immediately below the fan motor in the center section. You can’t easily adjust the gas tube’s centering after those bends are made.   

Keep two things in mind before allowing yourself to become discouraged by this task: In the first place, you can use another fan rib to lay out the gas tube on for visual comparison, before insertion; secondly, annealed copper tube is easily bent and re-bent so as to adjust the tube’s position perfectly; use the centering rod through the burner’s mixing or coupling tube (needed for silver soldering the tube in position within the aluminum plate) to help provide assurance that you can eventually stumble over the victory line, no matter how clumsy your efforts might seem at this point. LA-CO aluminum flux enables copper tube to be soldered with tin/silver solder to aluminum alloys.

The first bend is made after mounting the MIG tip. Ideally, you want the tip to end up about 1/4” to 3/8” short of the mixing tube or coupling tube’s entrance at the funnel’s small end. However, linear burners are more forgiving than jet-ejectors, about whether or not your tip’s end is placed in the “sweet spot” for distance from the mixing tube entrance.

After the gas jet (MIG tip) is installed in the 1/4" refrigeration tube and the first bend is made, it gets pushed and pulled through the side hole in the mounting plate. Then, it is kept centered and aligned while the tube is being hard soldered into permanent position within the mounting plate by use of a wood centering rod; which you need to sand to the right diameter for a slip fit within the funnel’s mounting collar. Drill a 1/4" + hole in the end of the wood. plastic, or metal rod used to trap the gas jet's refrigeration tube centered and aligned to parallel with the tube axis.

Note: The centering rod only needs to be a few inches in length (3” to 4” is fine). Afterward, you pull it out of the collar. On burners without collars the rod must be a couple of inches longer than the full length of the mixing tube. Be sure to keep the centering rod for checking alignment during maintenance work, later on.

La-Co aluminum flux and one of the tin/silver solders (ex. 95/5) is suggested for permanently affixing the refrigeration tube into place within an aluminum mounting plate. All other connections should be silver brazed, but can be silver soldered if you’re careful to make good joints. You must prep, bend, and fit the refrigeration tube, and then solder it into position as soon after drilling the side hole through the aluminum plate as possible; this means that you'll want the MIG tip mounted and the refrigeration tube’s first bend made before you even begin drilling the side hole. The reason for all this haste is that aluminum immediately begins forming a new oxide layer after drilling; the longer between drilling and soldering the more work your flux has to do to overcome that layer.

Once the gas tube is fitted into position within the mounting plate, but before soldering it, the other end of the refrigeration tube gets a threaded fuel hose fitting, or a 1/4" hose barb silver brazed on (compression fittings aren’t recommended; they don’t need brazing, but have their own complications).

[Mikey98118]

Gas jets

The simplest way to make a gas jet orifice in a burner is to drill a small enough hole in the side of a small pipe or tube, and mount the tube across the path of incoming air on the burner. Linear burners used this method for decades; many of them still do (sigh). Then I decided that since the point of that little hole was to help high pressure fuel gas to exchange potential energy of compressed gas to be transferred through the hole into kinetic energy in the gas jet,

the small bore in a wire feed welder's (AKA MIG welder's) contact tip would exchange more energy, provide a lot of work already done in a low cost easily available part, increase efficiency since the gas pipe and bore would now be inline, and allow the jet to be placed exactly at the right distance from the mixing tube's opening, it should replace holes.

Note: Frosty, unowned to me already had been using MIG tips in a similar manner on his "T" burners.

Larry Zoeller made the happy discovery that schedule #80 1/8" pipe allows threading for MIG tips directly into the pipe just in time for the flood of complaints from people who cannot or will not use long MIG tips to be successfully exchanged for short tips because, In the absence of the right tip, that short tip can be made to serve by increasing flow inside the gas pipe to tip interface. Change out the locale equivalent to 1/8" schedule #40 pipe to 1/8" schedule #80 pipe. The increased streamlining of gas flow at the joint will permit the shorter tip to serve.

If you also can't find the preferred gas pipe, then you can braze a heavy wall stainless steel "gauge" tube with an inside diameter of about .030" inside diameter into the tip to bring it up to the right length (1-1/2" length of bore) on 3/4" burners.

[Ted Ewert]

I haven't read the whole 45 pages of this thread, but I was wondering if blown burners would be allowed into the discussion? I've been experimenting with several different designs and would like to talk theory a bit. This is the only forum I've found which actually dives beyond " it lights up and it's hot...I'm good to go". 

 

Ted

[Mikey98118]

There are plenty of people on who prefer blown burners. Discuss away 

I will lead the loyal apposition by stating that blown burners have there place in the scheme of things.

[Ted Ewert]

I'll give you a little background where I'm coming from. I like to build things, and metal is my preferred material. I started off building a small anvil, then decided to put a harder surface on it and purchased a 1/2" thick  piece of D2. I knew D2 was tool steel but that was about it. I then discovered all about heat treating and figured I'd build a little HT oven. I built it out of standard firebrick and mortar. Then I learned all about refractory materials (do you start to see a pattern here?). So I have this brick and mortar boat anchor, and get the bright idea to turn it into a forge. Drill and cut a few holes in it and Bob's your uncle. I took apart an old propane burner I had for a still I made and used the nozzle in a few NA burners I fabricated. The regulator was junk, so while waiting for a new one I started messing around with blown burners, since I happened to have a blower. I went from 3/4" to 1" pipe, then to 2". This is fun! I made round flames, wide area flames (with a ribbon burner) and recently made long thin flames. 

I've studied a bit about fluid dynamics, am quite familiar with Bernoulli, Coanda and have read a lot of Victor Schauberger (among others). I don't, by any means, claim to know much about forges or burners, but I'm getting the hang of it. I'll post a few pictures tonight of what I've made so far and let you guys have at it. 

 

Ted

[Ted Ewert]

Here was the first burner I made:

Then added a new top with holes drilled at an angle to create some swirl

At this point I didn't understand the pressure / flame / size-length of pipe relationship (as you can see the flame burning up in the head). This was part of reason I went to a blown design. I could revisit this burner, and with a few minor modifications, make it work quite well. 

This was my first blown design. It worked all right, but with a 3/4 inch pipe didn't deliver a very hot flame.

 

Here's what it looked like in the forge:

 

 

This was my version of a ribbon burner. I packed Kaowool between the tubes and then put a 1/2" insulating board on top of that with holes for the tubes. It stayed pretty cool.

 

Here's a pic of it in the forge. I put some stainless steel screen over the tubes to keep the flame lit and up close to the top of the forge.

 

Somewhere in the mix I built this total failure. It has no compression / acceleration of the gas and as a result the flame burned up inside of it. But it was a good learning tool.

 

I then caught on to the compression /acceleration trick and built this head:

 

 

But, as you can see in the picture I still had the flame burning up in the head and getting everything hot.

 

I use threaded rod to provide turbulence. This slows down a portion of the mix and helps to keep the flame lit as the velocity of the gas increases.

The last head I made was a culmination of what I have learned so far:

The piece sticking out of the hole is the edge of an airfoil. Picture an airplane wing and this would be the trailing edge. The gas passes around it and gets compressed and accelerated on each side. This forms it into a thin, wide flame. BTW, this shape doesn't work without the airfoil. The bolts are there to adjust it in and out to see how it works with varied flows.

Here it is burning in free air. Notice how the flame starts at the threaded rod. I ran this for about 5 minutes and it was cool to the touch. It also burns the same in the forge.

I'm thinking of using something like this in the new forge I'm building. It would lend itself to a nice tangential burn in a cylindrical chamber, and create a decent swirl.

 

Ted

[Mikey98118]

The ribbon burner is probably putting out the most useful flame. I would rather see the last burner design heating a forge before saying yay or nay on it because its orange flame could either be from oxidation of the burner nozzle or a secondary flame envelope.

[Andrew Golabek]

That last nozzle reminds me of one used for flame emission spectroscopy

[Ted Ewert]

10 hours ago, Mikey98118 said:

The ribbon burner is probably putting out the most useful flame. I would rather see the last burner design heating a forge before saying yay or nay on it because its orange flame could either be from oxidation of the burner nozzle or a secondary flame envelope.

I'll take a picture of it in the forge tonight for you. The orange flame is due to a slightly rich mixture. 

I'd have to rebuild the ribbon burner, as I used tubes which were too large in diameter. I would also want to cast it; the tubes are a pain to insulate.

I got the idea for the last design from the Aerospike rocket engine. I watched a YouTube on it: 

This engine uses an inverted bell shaped nozzle to provide thrust over a wide range of atmospheric pressure. Although we aren't building rocket engines, a lot of the same principals apply.