Burners 101

[George N. M.]

Thomas, as I think about it I believe we did have padlocks attached to the safety tags.  I had forgotten that until you used the phrase "locked out."

"By hammer and hand all arts do stand." 

[Mikey98118]

I agree with everything both of you have said, and it is balanced advice; not easily refuted

[pnut]

8 hours ago, George N. M. said:

I had forgotten that until you used the phrase "locked out."

I got on people's nerves at the rubber refinery with my obsessive adherence to lock out tag out procedure. I like all my limbs attached and unsqished. I actually had an argument with one of the old timers over it and yes, he was missing two fingers on his right hand. Time passes and some folks tend to get complacent I suppose. 

Pnut

[ThomasPowers]

I wasn't even supposed to be around the machinery but the safety officer said that EVERYONE would go through the training who would be on the 24x7 "fast switching test". There had to have a person onsite to hit the big red button if something went wrong.

[Frosty]

There was a lockout tag out board at work, each with a padlock, tag and unique key. The ONLY way to remove a padlock without the one key was cut it off. There weren't many places in the facility where one was called for but you should've heard some of the guys howl if they couldn't do something because it was being worked on. 

The electricians started putting two padlocks on panels they had to work on the circuit. The vote had to be unanimous before they'd energize a panel. The superintendent had the padlocks cut the one too many times so they started shutting the power off to the entire facility. He called the electric utility and complained to discovered cutting a lock out tag out lock was a felony and that was that.

He was not a well liked superintendent, real anger management issues. Not that riding herd on a State a department made anybody cheery but he wasn't in the right job. He had two retirement parties, the real shindig occurred the day after he left for good.

Frosty The Lucky.

[pnut]

At the rubber refinery all machine operators were issued their own lock and tag. It's strange to say it because it was such a dirty and hard job but I actually miss it. Truthfully I don't think my body could handle it anymore. I think the years I spent working there have a lot to do with the state of my back and joints today. 

Pnut

[ThomasPowers]

The oil patch was like that for me; 84 hour weeks continuously; but a lot of nice camping!  I saw job posts for mudloggers when my last job laid me off and my thought was that it would kill me fast nowadays; it's a young single guy's job!

[Mikey98118]

Sliding choke sleeves

The chokes on high-speed tube burners consist of a sliding sleeve running back and forth on the burner’s mixing tube, over its air openings; their sleeves may or may not have a slot and a braking screw. If the tolerances on both the mixing tube and the choke sleeve work out in your favor, you can take your choice between drilling and threading a hole in a loose-fitting choke sleeve, by using a screw threaded into the sleeve as a simple breaking mechanism, or drilling and cutting the choke sleeve to create a slot; allowing the sleeve to slide back and forth over a thumbscrew, which will then be drilled and threaded into the mixing tube.

    The advantage of the first choice is that it’s less work. The advantage of the second choice is a cleaner choke movement. Why would that be so? Both pipes and tubes tend to be slightly out of round, which means that, just because the choke sleeve will slide freely on the mixing tube in one position, doesn’t guaranty it will still move freely with a few degrees of rotation between the two parts. If your burner’s sleeve runs back and forth in a slot, you can decide the best spot to position it on the mixing tube for smooth performance. It’s simply a judgement call.

    Cut the choke sleeve 1/2” longer than the length of the burner's air openings, and after cleaning off all burrs from the sleeve and the burner’s mixing tube, ink a line the length of the choke sleeve, directly over any inside weld bead. try rotating the sleeve on the rear end of the mixing tube until the two parts slide freely together.

    If these two parts fit closely enough, some sanding can provide a sliding fit in one position on the mixing tube and enough interference with just a little rotation to act as a brake to motion; in this case, no braking screw is needed.

    When the choke sleeve is installed, you have a decision to make about what kind of choke action you prefer on your burner. If the sleeve isn’t modified any further, it will provide the maximum flame control. If a sixty-degree internal bevel is placed at its rear edge, it will provide the maximum heat flame heat.

[Mikey98118]

Capillary tube & MIG contact tip gas orifices

1/2” burner orifices: The smallest MIG contact tip is made for 0.023” welding wire; its orifice is supposed to be 0.031” but can be as large as 0.033”. So, these tips will be barely adequate at best, and poor performing at worst in a ½” burner. 0.028” inside diameter and 1” long makes a much better orifice size, but diameters as small as 0.026” will work properly when tuned by slowly being shortened on #400 grit sandpaper. The desired orifice size of 0.026” to 0.028” can be provided by capillary from needle tips, or from1/16” annealed copper refrigeration tubing (0.028” inside diameter); available in some plumbing supply or hardware stores by the foot. 

 

3/8” burner orifices: Miniature burners (3/8” and smaller) bring up an instance where friction of the moving gas molecules down their tiny jet orifices become a major factor in gas flow. You will find cutting a 0.020” I.D. capillary tube 9/16” long,  or 0.023” I.D. tube 9/16” to 3/4” long, and mounting it within a MIG contact tip (drilled to match the capillary tube’s outer diameter, if necessary) will make a hotter output flame than a longer capillary tube, in these orifice diameters. Then, sanding the trapped tube down to a finish length in the MIG tip of .406” (13/32”) long with 0.020” I.D. capillary tube (or longer for 0.023” I.D. tube) will gain the best result in a 3/8” burner.

    Typically, a dispenser needle with an inside diameter of 0.020” will fit into a .023” MIG contact tip. MIG tips are designated by welding wire size. The actual inside diameter of such a tip is between 0.031” and 0.033”. If it turns out a little undersized, a wire file from a torch tip cleaners kit will adjust the tip opening in its soft copper easily.

In larger burners, the smaller the gas orifice diameter the leaner a given size of burner tends to burn, in even the longest available threaded MIG contact tips. So, in small burners, gas orifice length becomes a means of tuning the burner.

1/4” burner orifices: This size burner runs best with 0.015” I.D. capillary tube; this can be provided with needle tips, but an exact size is easier to find in 1/16” O.D. stainless steel capillary tube.

 

    Torch tip cleaners are made from a harder stainless-steel alloy than capillary tubes, but it isn’t so much harder that they can be successfully used to enlarge orifice sizes in stainless steel tube; they are perfect for getting rid of internal burrs, so that the holes where the gas inters and exits S.S. tube can be made round; a lighted magnifying glass is recommended to check that all burrs or gone.

    For building a gas jet from miniature tubing (thick wall capillary or thin wall hypodermic) and a MIG contact tip, I recommend using a (Tweco style) Tweco, Miller, Lincoln, or Radnor (1-1/2” long tip, with 1/4-27 thread). If you can get a tapered tip, that’s good; otherwise, you will have to spin it in a drill under a file or sandpaper, to taper it yourself.

    Just because there is a welding supply store in your town doesn’t mean that they will have the MIG tips you need in stock, or that they will bother to sell you one or two of them, even if they’re available. Your sale is hardly worth their paperwork. You can buy MIG tips online as few as five at a time for the same amount that they will cost at your local welding supply store. Chances are that the shipping charge will amount to less than the gas you may waste receiving a rotten experience, while trying to buy them locally.

    Radnor and Tweco Model 14T-052 (1-1/2” long) MIG contact tips have an approximately 0.064” orifice size. Depending on tolerances, 1/16” (outside diameter) heavy wall capillary tube will fit the orifice loosely or tight, but the work of mounting it won’t be much either way; these tips are available from amazon.com and eBay, and through online welding supply sites. If you can get a tapered tip, that’s good; otherwise, you will have to spin it in a drill under a file or sandpaper, to taper it yourself.

    Stainless steel 1/16” tube can vary from .060” to .065” outside diameters, depending on the manufacturer, and MIG tip tolerances can vary by up to .003” (oversize; never undersize). So, you may end up with an interference fit that requires little effort to mount. Or you may need to swage the MIG tip down around the capillary tube, or else silver braze the tube into the MIG tip, or you could even need to drill or file the MIG tip hole a little larger.

    With a plain (not tapered) MIG tip even thin wall tubing can be swaged into the MIG tip, but you must drill a hole in between two short pieces of 1/4” thick by 1/2” wide, by 1” long mild steel bar. Begin by drilling the hole, the same size as the outer diameter of your MIG contact tip, completely through the two flat bar’s widths. With them held tightly in place in a drill vice. Sand or grind a few thousandths of an inch from each bar’s drilled face, and sand down all burs.

    Slide the desired length of capillary tube into the MIG tip and place it within your new swaging die; tap its top of the swaging die with a hammer. Cut off the excess tube to within a 1/16” beyond the tip’s end, and hand sand it and clean out any internal burrs, with torch tip cleaners, to clean up the orifice from cutting.

    If the MIG tip’s orifice is only a little too small for the capillary tube, you can use torch tip cleaners to enlarge it a couple thousandths of an inch. You will find one round file in the set to be small enough to push back and forth within the soft coper MIG tip, while turning the tip slowly. Every few moments, you need to check the enlarging hole against the capillary tube, as its orifice gradually enlarges.

    Wire gauge drill bits can be hand spun in a pin vice to enlarge holes in MIG tips to within a couple of thousandths of an inch of your capillary tube; keeping the hand filing (with torch tip cleaners) from becoming tedious. Only increase the size of the orifice a few thousandths of an inch at a time, when drilling in copper.

    Don’t depend on your eyes for guidance. Pay close attention to the amount of tension felt in your fingers. Start drilling by barely touching the front of the tip’s hole. Stop frequently to clean burrs out of the drill bit, and blow them out of the MIG tip, from the hole’s threaded end. When you feel a sudden increase in tension on the bit, reverse its direction until the hidden inner burr in the hole is broken off, before continuing.

    Drill from the front end of the tip 1/2” deep. Because you don’t have a miniature drill press and drill vise ($$$), your hole is going to end up slightly oversize at its opening, and will taper down smaller as it gets deeper. You should be able to push up to a 1/2” long length of hypodermic or capillary tube into it with just enough interference to trap it in place with the help of a few light very light taps.

 

    Heavy wall brass or even copper capillary tubing, normally employed as electronic discharge machining (EDM) tubes, can also be used as gas orifices. Even thin wall stainless steel hypodermic tubing can be used, so long as both its inside and outside diameters are listed; it is available as dispenser needles, and as 3’ to 5’ lengths. MIG contact tips come in limited orifice diameters, as do capillary, hypodermic, and EDM tubing. You must begin your search for a convenient tube with the desired orifice size (inside diameter). Next, you try to find a MIG tip with as close a match to its outside diameter as you can. Saturn Industries, Inc. has been a practical source of EDM tube in the past.

    If a MIG tip’s diameter is within .005” oversize to the tube, it is easily swaged down to trap heavy wall tube in it; with a tapered MIG tip, you may be able to create a fit by running tape around its tapered end, and squeezing plyers around the thin tapered section.

    With a plain (none-tapered) MIG tip, even thin wall tubing can be swaged into the MIG tip, but you have to drill a 1/4” diameter hole into two 1/4” thick by 1/2” wide by 1” long mild steel flat bars; clamp them hard together in a vice, and drill a 1/4” hole completely through the bar, and then clean off all burrs. Power sand the drill faces of each half- hole a few thousandths of an inch, so that a ¼” O.D. MIG tip will drop freely into the drilled-out troughs and be squeezed down a hew thousandths when the die is struck.

    Slide the desired length of capillary tube into the MIG tip, and place it within your new swaging die; Tap the top bar with a hammer. Cut off the excess tube to within a 1/8” beyond the tip’s end, and hand sand it back to within 1/16” of the MIG tip’s face. Then clean out any internal burrs, with torch tip cleaners. Final shortening is done during tuning.

    If the MIG tip’s orifice is only a little too small for the capillary tube. You can use torch tip cleaners to enlarge it a few thousandths of an inch. You will find one of the wire files in the set to be small enough to push back and forth within the MIG tip, while turning the tip slowly. You need to frequently check the enlarging hole against the capillary tube, during filing.

    Wire gauge drill bits can be hand spun in a pin vice to enlarge holes in MIG tips to within a couple of thousandths of an inch of your capillary tube; keeping the hand filing (with torch tip cleaners) from becoming tedious. It is easiest to only increase the size of the orifice a couple thousandths of an inch at a time, when filing copper.

    Don’t depend on your eyes for guidance, when drilling in copper. Pay close attention to the amount of tension felt in your fingers. Start drilling by barely touching the end of the tip’s hole. Stop frequently to clean burrs and dust out of the drill bit, and blow them out of the MIG tip, from the hole’s other end. When you feel a sudden increase in tension on your drill bit, reverse its direction until the hidden inner burr in the hole is knocked loose, before continuing.

    Drill from the front end of the tip to 1/2” deep. Because you don’t have a miniature drill press and drill vise ($$$), your hole is going to end up slightly oversize at its opening, and will taper down smaller as it gets deeper. You should be able to push up to a 1/2” long length of hypodermic or capillary tube into it with just enough interference to trap it in place with the help of a few lite taps on the tube.

    Ink mark the tube at 9/16”. Cut the capillary tube 1/16” beyond the ink mark. Tap the tube into the MIG tip, and screw the tip into place in place on the gas pipe. Tap the whole assembly against a metal surface (ex. one of the pipe parts), until it comes within 1/8” of the MIG tip’s front face.

    Use a circular motion on very fine emery paper (#400 grit) to reduce it down to within 1/16” of the tip’s face; use the torch tip cleaners to remove the tube’s internal burr. During tuning, try the burner to see if it has a satisfactory flame; keep sanding the tube a few thousandths shorter at a time, until it does.

    It is important for the outside of MIG contact tips (in small burners) to be tapered for proper flow of incoming air, as it passes by the gas orifice, on its way from air intakes into the mixing tube area of the mixing tube. How important? How small is your burner? The smaller the burner the more important it becomes. On this burner it is fairly important, and will matter ever more as you build ever smaller burners.

    Although capillary tube can be made to serve as proper gas jets in small burners by varying their lengths to match output velocities of different gas orifice diameters, lengths and diameters will remain a matter of trial and error, because of tolerances; plus or minus .001" of an inch is a lot of difference when the orifice is between .020" and .023”. ¼” burners have smaller orifices; increasing the problem.                                                                                                                                                                                                                                                                                                                                                                                                                                                     Remember, the mounted capillary tube should be closely inspected under a lighted magnifying glass to make sure all burrs are completely eliminated from the tube’s orifice; it needs to be completely round; not jagged. Otherwise, the gas stream won’t be smooth.

 

Silver brazing capillary tubes: Most air/propane torch-heads have gas orifices that can be removed, drilled, and silver brazed, in order to mount a capillary tube in place directly within it. While this involves hot work, it is also more tolerant about drill alignment in small burners, as the capillary tube can be easily bent into alignment after the jet is replaced in the goose neck (gas tube), if your hole wasn’t drilled quite parallel to the part’s axis.

 

“Gluing” capillary tubes: If you mistakenly bought the hardening type of Threadlocker, or gasket sealant, to seal your MIG tip in place, it can be used to help trap the capillary tube in the MIG tip.

 

Most gas tubes on old air/fuel torches contain a spongy looking section at the entrance, which is meant to act as a fuel filter; unfortunately, it ends up doing a fine job as a clog maker. Drill or grind completely through the sponge; it has no value. Following this method enables you to re-task nearly any old air/propane torch-head.

    While there are a variety of sources for capillary tube, the easiest way to find any particular orifice size you need, still remains blunt end dispenser needles; all of which are stainless steel. Most easily available heavy wall capillary tube, or thin wall hypodermic tube, is stainless-steel.    Stainless requires the use of brazing alloys that contain 50% or higher silver content (the higher the percentage of silver the better it wets part surfaces), and flux that is rated for use with stainless steel; most of these are black flux. I recommend Harris white flux for use on stainless thin wall tubing, rather than black flux, which is likely to be too aggressive for thin wall tubing. For heavy wall tubing, you can use the black flux.

    Just before brazing, use fine grit emery paper to break up surface oxide, and to scratch up the tube’s smooth surface, wherever you want the silver braze alloy to flow. Equally as important is to keep the flux well away from areas you don’t want the filler alloy to overrun, like the end of the capillary tube. Handy Flux Type B-1 is for brazing stainless steel, nickel, tungsten, and super alloy; its effective temperature range is from 1100 to 1700 °F (593°–927°C)

    65% silver content brazing alloy #3101100 from Rio Grande Jewelry Supply, is excellent and inexpensive; it is especially recommended for small parts, such as stainless needles and capillary tube It is best to add flux to a length of tube (but short of the tube’s end), and push it into the contact tip, leaving excess tubing protruding from the MIG tip’s end; then cut, sand, and deburr the tube to fit, after brazing.

 

Note: the higher silver content (50 % or more), which helps joining alloys to wet stainless steel, nickel, and tungsten, also does a superior job of wetting copper, brass, and mild steel.

 

Brass or copper EDM tubing can also be used to provide the right size gas orifices, by combining them with MIG contact tips with close to the correct orifice sizes. Various diameters of Drawn brass and copper tubing are available through Saturn Industries, and through eBay; heavy wall brass EDM tubing with 0.019” and 0.020” orifice diameters are commonly found there. Brass tubing can simply be soldered into copper MIG tips.

    If you have the choice, I recommend heavy wall capillary tube (AKA gauge tubes, or instrument tubes) over thin wall hypodermic tube, if you can find them in the orifice diameters desired (as they are far less inclined to be partially dissolved by flux, should you be a little slow in your braze work). Different companies have various orifice sizes available; one of them well stock tube in 0.020” inside diameter, and another will stock 0.018” or 0.023” instead.

    My favorite way to make a gas orifice for a 3/8" gas burner, is to insert a 1/64" OD by 0.020" I.D., by 9/16" long stainless-steel heavy wall capillary tube in a 14T (for tapered) Tweco MIG tip for .052” welding wire, and to sand the end back somewhere between 1/64" and 1/32" shorter, during final tuning, to dial in its performance. 1/16” OD stainless steel instrument tube is strong and has been around long enough to have an abundance of standard 1/16” compression to pipe thread fittings easily available for it, if you want to go that route. The tube description is usually given with its1/16" (0.0625”) OD given first, followed by its 0.020" (or.5mm) ID, and then followed by its length.

    The gas orifice chosen for this burner is a 1/16" (0.0625”) OD x .020" (.5mm) ID stainless capillary tube (AKA instrument tubing). But you can find thin wall capillary tube used for dispenser needles easily enough. The heavy wall tube is more convenient to employ. MIG welding contact tips can be used to provide low-cost orifices for larger burners, but capillary tube is the key to building efficient burners in 1/2” and 3/8” sizes. The most convenient way to attain that tubing is in the form of blunt tip dispensing needles or heavy wall capillary tube, either of which can be mounted in MIG contact tips. Heavy wall stainless steel capillary tube (AKA gauge tube, or instrument tube) only comes in limited orifice choices (ex. 0.005”, 0.010”, 0.015”, 0.020”, 0.025”, and 0.030” or typical) This difficulty can be partially offset by using shorter, or longer tube lengths. Or to get a sufficient variety of orifice sizes, you may employ stainless blunt tip dispensing needles; which you choose is simply a matter of convenience. I would suggest:

 

[Mikey98118]

What; no questions?

There are also capillary tubes that are thinner wall stainless steel or brass, that aren’t 1/16” outside diameter, which can still be press-fit or silver brazed into MIG contact tips: Amazon.com: 2pcs of 1.2mm (0.047”) OD x 0.5mm (0.0197”) ID by 400mm (15-3/4”) long #304 Stainless Steel Capillary Tube; $6.30 and $1.50 shipping. MIG welding contact tips for .040” wire are supposed to have a 0.048” orifice. Making this a perfect fit silver brazing into one; their actual orifice size will vary. But you can use torch tip cleaners, or solder to accommodate tube to tip.

3D printer nozzles can be threaded into smaller gas tubes, are cheap, and usually come in assorted orifice sizes; they are too short to work out well in 1/2” burners, but are just fine in 3/8” and smaller burners. Because they are short, you need to make sure that the gas tube’s end is at true right angles with the tube’s axis, and that the thread tap is kept parallel to the tube’s axis.

 

Hoke torch tips are small, and the cheapest make of torch tip available online and through jewelers’ supply stores. Most Hoke tips are 7/8” long, made from 1/4” hex stock, with 3/16” long flats, are bluntly tapered forward, and have 3/16-40 by 1/4” long male thread. Orifice sizes go by fuel, with acetylene smallest, and propane or butane larger, and natural gas way too large. Each gas has three to four orifice sizes Extra fine acetylene flame tips, stamped #04, have a 0.010” diameter orifice, and are fit for 1/8" burners. Fine acetylene tips, stamped #03, have a 0.014” diameter orifice, and are fit for 1/4" burners. Medium acetylene tips, stamped #02, have a 0.023” diameter orifice, fit for 3/8 burners. These tips aren’t as short as 3D printer nozzles, you still need to make sure that the gas tube’s end is at true right angles with the tube’s axis, and that the thread tap is kept parallel to the tube’s axis.

The complete variety of Hoke tips are available at ottofrei.co.

Hoke Propane or Butane tips are also available at guesswein.com   

 

[Mikey98118]

 

Sliding choke sleeves

The choke on a high-speed tube burner consists of a sliding sleeve running back and forth on the burner’s mixing tube, over its air openings; the sleeve may, or may not have a slot and a braking screw. Depending on the tolerances of both the mixing tube and the choke sleeve, you might choose  between drilling and threading a hole in a loose-fitting choke sleeve, using the screw threaded into the sleeve as a simple breaking mechanism, or drilling and cutting the choke sleeve to create a slot; allowing the sleeve to slide back and forth over a thumbscrew, which will then be drilled and threaded into the mixing tube, or rotating the sleeve on the tube to stop motion without any screw at all.

    The advantage of the first choice is that it’s less work. The advantage of the second choice is a cleaner choke movement. Why would that be so? Both pipes and tubes tend to be slightly out of round, which means that, just because the choke sleeve will slide freely on the mixing tube in one position, doesn’t guaranty it will still move freely with a few degrees of rotation between the two parts. If your burner’s sleeve runs back and forth in a slot, you can decide the best spot to position it on the mixing tube for smooth performance. It’s simply a judgement call.

[Mikey98118]

  Flame Retention Nozzles

The name describes their main purpose, but they can also help prevent burn back into a burner’s mixing tubes, and they can promote air intake; how much and how well such nozzles, or simple restrictions or flares at the end of flame tubes, do each of these tasks depends on their shapes and dimensions. Flares, and bull-nose shaped restrictions may be part of a flame tube, or added as part of a flame retention nozzle. Stepped nozzles tend to be the strongest acting, but may not work well as a flare shape on burner designs with insufficient mixture flow. The first advantage of separate nozzles is that they can be replaced as they oxidize into uselessness.

    Stepped flame retention nozzles are usually designed to slide back and forth on the burner’s mixing tube; this allows them to be tuned exactly to match mixture flow, which varies somewhat with fuel pressure into the burner’s gas orifice. Any sliding nozzle can be tuned somewhat by increasing or decreasing the length of its overhang past the end of a burner’s mixing tube, since that changes the length to width ratio of the nozzle.

 All nozzles operate best when centered and axially aligned with the mixing tube.  

 

     Stepped nozzles are tube shaped, with a spacer ring at the rear of the nozzle; these parts slide back and forth on the mixing tube, held in place with three to six socket set screws, equally spaced apart in one or two rows.

    You need to cut the nozzle to a length equal to the mixing tubes width, plus 1/8”. Plus the length of the spacer ring; this should be at least o1”, but can be longer.  

 

[Mikey98118]

CORRECTION:  You need to cut the nozzle to a length equal to the nozzle’s inside diameter, plus 1/8”. Plus the length of the spacer ring; this should be at least o1”, but can be longer.  

 

[Mikey98118]

. While the set screws normally are threaded through both nozzle and spacer ring, if the mixing tube is thin (ex. As with flame tubes on air/propane torch-heads), the spacer ring may be slit, and the screws threaded only through the nozzle, so that they press the spacer ring against the tube, instead.  

[Mikey98118]

The two most commonly available stainless-steel alloys are #304 and #316. Often you can take your pick between the two in a desired shape and size tube or pipe; when you have the choice, #304 tubes usually come with polished surfaces, and are a little easier to drill and tap. #316 usually comes with a dull finish and is harder to drill and tap then the #304 alloy; but #316 stainless has 2% Molybdenum in it, and #304 doesn’t: that addition makes the alloy a little harder to work with, but greatly increases its resistant to high heat oxidation. The one part in a burner that benefits from molybdenum is the flame retention nozzle’s outer tube; not its spacer ring.    

[Mikey98118]

What is the future? Where next?

Forges improve on several fronts, depending on advances in materials science on the one hand, and on burner advances on the other. Burners themselves improve aspect by aspect. We have all had plenty to say about ribbon burners. For me, it usually boils down to multi-flame burners versus multiple small high-speed burners.

So, how shall we have our cake and eat it too? How about looking into combining the two? Outrageous? I hope they will be quite successfully so

[Mikey98118]

    The reason burners, whenever possible, 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. A longer exhaust path increases the amount of "hang time” for combustion energy to be deposited on internal surfaces. That seems obvious, doesn't it?

    What isn't so clear is that the heat gain isn't added by hot gases blowing a few inches farther at high velocity; it’s due to an ongoing drop in velocity over that added distance. Combustion gases begin to slow as soon as they leave the flame envelope, but the flare from a small flame decelerates much faster than the blaze from a large flame.    Do multiple flame burners (ex. Ribbon burners) take deceleration even further? Yes, they sure do; unfortunately, ribbon burners, and Ransom burners with ceramic heads, tend to be large. Over time, compact multi-flame burners will be perfected, but first there must be a lot more interest in doing so; there isn’t much, because he apparent worth of such burners are thought to increase in direct proportion to equipment size; I don’t share that view, and consider them to be the future of heating equipment. /but their flame faces won't be cast in homemade burners; they will be drilled into high-alumina kiln shelves, and cemented into cast bodies.

[Mikey98118]

Linear chokes

Linear burners are also improved with chokes, Originally, these were flat plates, which revolved into place over burner entrances from a single periphery screw, and were mostly used to prevent chimney effect, after shutdown on homemade burners.

Some commercial burners feature double plates with openings that can enlarge or shrink, when the outer plate is revolved around a central screw over the openings on the inner plate; these are more practical for modifying flame performance than single plates with a periphery screw.

The best plate choke on linear burners runs up and down the threads of a center screw, to vary the distance from plate to burner entrance; this has  the ability to encourage swirl in the burner earlier than happens otherwise; a great improvement over the other two designs.

[Mikey98118]

Gas orifices for1/2” burners

The smallest MIG contact tip is made for 0.023” welding wire; its orifice is supposed to be 0.031” but can be as large as 0.033”. So, these tips will be adequate at best, and marginal at worst in a ½” high speed burner (this distinction is made because burners with slower internal flow speeds will need larger gas orifices). A gas orifice of 0.028” inside diameter and 1” long makes a much better size, but diameters as small as 0.026” will work, when tuned by slowly being shortened on #400 grit sandpaper. The desired orifice size of 0.026” to 0.028” can be provided by capillary tubes from blunt dispenser needle tips. Why the variance? Needle gauges go by outside diameter; their inside diameters will vary according to the needle’s wall thickness,

 

Stainless Steel 304 Hypodermic Regular Wall Tubing 19 Gauge .042" OD x .027" ID x .008" Wall x 60" Length (5 Pack for $10.34) is available through Amazon.com.  

    MIG contact tips for 0.030” welding wire are supposed to have 0.038” orifices, but may have as large as 0.040” diameter holes; either of which can be enlarged with torch tip cleaner wire files to 0.042”.

    MIG tips for 0.035” welding wire are supposed to have 0.044” orifices, but may have as large as 0.046” diameter holes; either of which can be swaged down to 0.042”. Are the capillary tube can be silver brazed into oversized holes.       

 

[Mikey98118]

Melting and oxidation of Flame tubes and nozzles

 

Flame retention nozzles and the ends of flame tubes will both melt if they are pushed too far into forge interiors. All that cools them is the refrigeration effect from liquified petroleum gas, mixed with incoming room temperature air. When kept away from swirling internal forge atmospheres, even stainless steel will slowly oxidizes away. So, enough thickness in doubler tubes over flame tubes, or flame retention nozzle walls are necessary, to keep your burner working a long time, before repairs are needed.  The rate of oxidation depends on what metal is used. Stainless steel is far better than mild steel, and #316 stainless is better than #304 stainless.

Screws keeping double tubes or flame retention nozzles in place must be made of stainless steel, becuase mild steel cannot be removed after a few heats.

Of course the future of burner nozzles belong to ceramic materials...

[Hefty]

Mikey, I have more ready access to 3d printer extruders than mig tips and I can get them in 0.2, 0.3, 0.4, 0.6, 0.8 and 1mm but they aren't as long (only about 1/2" long). Could I use a 0.6mm or 0.8mm in a 1/2" mikey burner for a torch or would their shortness render them unable to be tuned?

Cheers,

Jono.

[Mikey98118]

Friction losses make shorter lengths in gas orifices  an advantage in small burners. But larger burners benefit from the longer orifice sizes provided by MIG contact tips. 3/8" and smaller burners are best served by 3D printer nozzles 1/2" and larger burners benefit from the longer MIG contact tips as gas orifices. But you can use ether kind of orifice on any size burner, if you are determined to.

That said, a smaller diameter printer nozzle could serve well enough in a 1/2" burner by reducing orifice diameter. Of course, capillary tube can serve to extend orifice length, if you want the advantage of more orifice diameters available, or simply want to avoid needing two drills and taps involved in using both MIG tips and printer nozzles.

The methods I describe aren't "set in stone"; They are simple the surest paths I know to acceptable results. The more you learn the why of them, the easier it is to chose your own path

To answer your specific question, try various nozzles, to see which works best. If none of them satisfy you, mount a 1-1/4" long  capillary tube from a #19 hypodermic needle on a printer nozzle, and tune the burner by slowly shortening it on #400 grit wet/dry sandpaper, until it makes a perfect flame. Don't forget to use torch tip cleaners to clean the gas orifice from construction debris.

[Hefty]

I also have a question about inducing a vortex, prompted partly by your book and partly by AFB's 3d printed burners. Apologies if it has been answered elsewhere, I'm trying to get through all of "burners 101", all of "forges 101", all of "Frosty T burner Instructions", all of "3d printed plastic burner experiments" and your book in PDF form!

In your instructions in your book you talk about putting bevels on the interior of the leading edge and exterior of the trailing edges (lip of the reducer)of the air intakes to reduce drag while still guiding the air. Did you ever try complimentary bevels on the long edges of the slots as well, to further induce vortex? As in, say, the exterior of the left long edge of each slot and the interior of the right long edge of each slot? My thinking is that this might be a "poor man's version" of the helical aerofoils in AFB's burners?

Cheers,

Jono.

[Mikey98118]

Good question!

Over the years, several people have brought this up. I was never interested, because I felt it amounted to" gilding the Lilly." Another Frankenburner did much more than that, and his efforts have paid off BIG! If you can print burner parts, you should definitely go his way, and I make no bones about that.

If you wanted to do all the part shaping by hand, you could make your idea work. But very few people would try that, including me. If you want what his burner can do, you should pay the oeuxw and build his burner. Eventually, everyone will. I'm surprised the Chinese haven't copied it already.

[Frosty]

5 hours ago, Mikey98118 said:

pay the oeuxw

Lost me there Mike. 

Frosty The Lucky.