Mikey98118 Posted November 4, 2016 Author Share Posted November 4, 2016 Where to position a burner's cross pipe and why It seems way late to worry about gas pipes with gas jet holes drilled in their sides, or MIG tips placed in their sides; about eighteen years late. Yet I still find such gas pipes used in commercial burners, and in home made burners too. Worse than that, I see these pipes positioned in totally wrong locations! You want the end of a gas jet to blast pressurized fuel gas across a gap of around 1/4" between orifice and mixing tube at a minimum, and 3/8" at a maximum; this is true of most burners; "T" burners being a possible exception. You may not be able to get that close in the case of a drilled hole for a gas jet, but you should at least try to. On the other hand you don't want a MIG contact tip projecting clear into the burners mixing tube for no better reason than you forgot to move the holes for the gas pipe to a accommodate it. You need to consider these things before drilling holes for a gas tube through the side of a reducer fitting A 3/4" size burner with a drilled side hole in its cross pipe can get by with a 1-1/2" to 3/4" reducer, but if a 1-1/2" long Tweco MIG tip is used for the gas jet, the reducer must be updated to 2" to 3/4". Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 7, 2016 Author Share Posted November 7, 2016 Circumstances do alters cases I like a "nine times" rule of thumb; that means nine times the actual inside diameter of the mixing tube, which for 3/4" schedule 40 water pipe is about 7/8"; equaling 8" from the forward end of a jet ejector burner's air opening(s), or where a linear burner's funnel shape joins the mixing tube, to the forward end of the mixing tube. Its called a rule of thumb for very good reason; how fast the gas/air mixture flow travels effects how much length is needed in the mixing tube. Presently, a Vortex burner needs fourteen times the mixing tube's I.D.; not for adequate mixing of the gas and air, but to slow down enough for good flame shape before exiting the the flame nozzle. Frosty like ten times the inside diameter to mixing tube length, which works out well enough on his "T" burners to melt steel. Eventually, I will use internal vanes near the nozzle end of Vortex burner mixing tubes to slow down the spin in the mixture flow, and may be able to shorten burner length more than any of these. The point is that you need your mixing tube the appropriate length for your burner's design perimeters; if those are known stick with them; otherwise, start way long and cut shorten an inch at a time, till you reach the burner's "sweet spot". The diameter of a gas orifice should be very close to right for the mixing tube's inside diameter; On a jet ejector style burner that would be between .031" to .038" if you are choosing between MIG tips (which means it would be a 023 or 030 tip (one a bit small and the other a bit large). If you are using a capillary tube source, like hypodermic needles, the orifice would be around .034". These are as close to ideal figures as you can get, without starting with the smaller tip and enlarging it with a set of torch tip cleaners. BUT, when it comes to burners, circumstances certainly do alter cases. I expect that on a typical linear burner , a MIG tip for 023 wire would be needed to offset lower air induction. Flame nozzle diameter and amount of overhang from the mixing tube also changes burner performance, and in turn is dictated by the speed of mixture flow down the burners mixing tube. A typical linear burner is best served with a tapered nozzle (about a total of 1/8" enlargement in 1-1/2" length). The effect of the nozzle is added to that of the mixing tube's wall thickness for the total effect on the flame. Some of the faster linear burners and most jet ejector burner can use, and in fact need, a more radical flame nozzle design. I call them step nozzles, because a spacing ring in the nozzle is used instead of a gradual taper to exchange flow speed for vacuum (actually a lowering of mixture pressure) in the nozzle area behind the flame. Again circumstances alters cases. Vortex burners need much larger flame nozzles. Is one nozzle better than another nozzle? That is beside the point. The right nozzle for your burner is what is best. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 8, 2016 Author Share Posted November 8, 2016 Hindsight How general principles apply to any given design varies; it even varies between one burner and the next of the same design. Your time is your own, and how much you want to spend of it insuring the best possible result, is a private decision. My burners are probably a lot touchier than most; yet I have seen some burner sizes vary much more than others. There have also been individual burners that ran better than others of the same size. There are even commercial assembly line products, like guns, who show such variance. So, are you trying for a "one of a thousand" burner, or just wasting time? The answer has to rest with you.I have always stressed doing the various recommended steps, such as beveling the front and rear edges of air openings one task at a time, monitoring performance differences as you go; especially on a new burner design. What you learn about your burner is at least as important as how well it runs. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 13, 2016 Author Share Posted November 13, 2016 The why-for of miniature burners Why construct miniature burners at all? There aren’t a lot of people longing for a micro forge or casting furnace, but there are a few. There are plenty of people who want to get more heat from air-fuel torches than is available from commercial models, and they tend to be in the same crowd that is looking to power miniature heating equipment. In the face of rising energy prices, many more people are looking to maximize equipment efficiency as much as possible. Naturally aspirated burners have large turn-down ranges. So, it would seem that a wide selection of burner sizes isn’t needed to accommodate heating equipment; and so far as it goes, that’s true. But, efficiency is about more than how well fuel burns. There is another factor to get control of, and that’s the velocity of a burner’s exhaust. It’s easy to see what goes wrong when there is too much or too little exhaust capacity available. It’s less obvious what goes right when you get superb control of the equipment’s internal flame velocity. That's because doing so involves balancing two separate combustion issues; they are flame and exhaust speeds. Fast flames burn hottest, but fast exhaust speed wastes heat. The reason burners are aimed on a tangent in compact heating equipment is to force their combustion gasses to swirl around in its interior, creating a longer distance from burner to exit. A longer exhaust path increases the gases amount of "hang time.” That seems quite obvious doesn't it? What isn't so obvious is that most of that increased time isn't made by the gases running a little farther at a given velocity; it’s provided through a considerable drop in velocity over that added distance. Two or three smaller flames will decelerate much faster than a single large flame. The smaller flames of a pair of 1/2" burners will drop velocity faster than a single 3/4" burner in a five gallon forge, increasing efficiency; because they can be turned up hotter without producing a tongue of fire out of the exit opening. But, what about the guy who wants to build a two gallon knife maker's forge? He is going to need two 3/8" burners, instead of a single 1/2" burner, to do the same trick. The guy how wants to forge hand tools in a coffee-can forge is going to need two 1/4" burners to do so with top efficiency. But why can’t a canister mount air-propane torch simply be stuffed into a miniature forge or casting furnace as is? Most of them have brass heads, which will melt when mounted within heating equipment. The few torches with stainless steel heads use very thin parts, which will rapidly oxidize away under those conditions. If the torch is kept safely outside of the equipment, its ability to heat anything falls off sharply. Finally, using one of these torches with propylene for brazing in the open air falls into the same traps, because of its much greater heat. Propylene can be purchased in regular industrial cylinders at your local welding supply store for about one-third more cost than propane, instead of three times propane’s price in 16 ounce canisters from the hardware store. Link to comment Share on other sites More sharing options...
Frosty Posted November 13, 2016 Share Posted November 13, 2016 Just a quick technical question Mike: What is the air fuel ratio difference between propane and propylene?As in tune it richer or leaner? Great thread Mike, thanks. Frosty The Lucky. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 14, 2016 Author Share Posted November 14, 2016 It would take a lot of of searching to stumble across that answer, as the only source for the product has no competition, and when I previously contacted the company about how they arrived at the B.S. flame heat figures for their last MAPP formulation, he suddenly stopped responding; even though my questions were ever so polite I never noticed much difference in the choke positions on my burners, but once the burner's flame nozzles were completely heated I always ran them wide open anyway, and used the regulator and needle valve to adjust flame temperatures. You could probably find an answer derived from the chemical composition, but it would probably be wrong. My best guess is not much difference... You probably would get your best estimate by looking at oxy-propylene torch recommendations, but I don't think it would translate well to air burners, because one of the things about propylene is that it simply mixes with air better than propane; that is also a guess, based on observation, so talk it with a grain of salt... Link to comment Share on other sites More sharing options...
Frosty Posted November 14, 2016 Share Posted November 14, 2016 I was thinking they were pretty close seeing as the same Bernzomatic torch will run either. When it comes to chemistry I know mixing a base and an acid makes a salt that's about it though. I also figured if there was anybody handy who'd know, I'd ask you. Close enough as makes little or no difference work for a working handle. I'll have to check with the local welding gas company next time I need a bottle. Thanks. Frosty The Lucky. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 14, 2016 Author Share Posted November 14, 2016 I bought the cylinder; I use everything way too slow to do well with demur-age charges; I seem to remember it was only a little bit higher than the same size propane bottle. Mikey loves cheap ever so very much Link to comment Share on other sites More sharing options...
Frosty Posted November 15, 2016 Share Posted November 15, 2016 I own all my bottles, demurrage isn't for me either. My last name may be Frost but there's more than a bit of the Scot's thriftiness in me. I'll have to call around and find out what's available, I'd rather not have to drive to Anchorage. I stay out of Anchorage as much as possible anymore. Frosty The Lucky. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 15, 2016 Author Share Posted November 15, 2016 I know you have the sense to cut your burner down enough to keep from damaging the forge from the added heat, but for the new guys... Caution: Propylene is so much hotter than propane that you need to reduce your burner's flame to keep from damaging your forge and/or melting your burner's flame nozzle. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 16, 2016 Author Share Posted November 16, 2016 The "Tweco 14T MIG Contact Tip" Modification Replacing the side hole in a transverse gas pipe in old burner designs with a long MIG contact tip results in a powerful modification. Instead of drilling a small side hole for a gas jet. a much hotter burner is achieved by drilling and tapping a hole to take a 1/4-28 thread for a Tweco 14T copper MIG tip for wire feed welders, available at your local welding supply store; these are 1-1/2" and come in several different hole diameters. The designation “T” denotes a long tapering shape. With this arrangement you can easily experiment with various tip openings simply by switching them as desired. Once you determine which tip performs best for your particular application. The way the tip works is twofold; to begin with the tip allows the incoming gas to accelerate much than any hole could; secondly it allows the orifice of the “gas jet” to be closer to the mixing tube entrance; both of these things induce more and faster air flow. To get the maximum benefit from this change, requires changing out the bell reducer for a larger diameter. The increased suction created by this tip modification will require that you increase the intake side of the reducer on a 3/4” burner up to a 2" diameter from the usual 1-1/2”, or you will not get enough intake air to achieve a balanced burn. There are other brands that provide long 1/4” diameter tips, but you will need to spin the tip in a hand drill, under a file to get it tapered; they may also have different thread then the Tweco brand. The tip has to be threaded into place in the cross pipe with it already in place within the reducer fitting; the easy way to to that is drill a 3/16" hole a little way into a wooden peg, shove the tip into it, and use it to turn the tip within the fitting through its small opening. The MIG tip modification speeds up airflow enough to allow the updated burner to allow "a step nozzle" to replace the older "flared" flame nozzle design, further improving burner performance. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 16, 2016 Author Share Posted November 16, 2016 Or, if the cross pipe is placed too low in the reducer fitting, a short MIG tip will have to do. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 23, 2016 Author Share Posted November 23, 2016 Are smaller jet ejector burner hotter? They can be, but smaller burners are touchier too.; the reason for them being touchier is easy too understand. The smaller the burner the harder getting gas jets to match up right to burner tube sizes are to accomplish, and the greater a difference of two or three thousandths of an inch is. Also, the more exaggerated changes made by variances, such as amount of over hang of flame nozzles to mixing tubes are. Centering and axial alignment becomes harder to maintain, while bad effects from less than perfect positioning becomes exaggerated. It is much harder to maintain maximum performance in a 1/4" than in a 3/8" burner. For most guys wanting to mount the smaller turner size naturally aspirated burners, I would recomend of a linear design, to get a larger turn-down range than they are likely to achieve in a jet-ejector model. Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 28, 2016 Author Share Posted November 28, 2016 One of the many things I like about both “linear, and jet-ejector" burners that are based on, threaded parts, is that they can be updated easily, by changing out a fitting or, pipe nipple, other part, rather than the whole burner being replaced. All of the best small burners feature a capillary tube trapped in a MIG contact tip, which is mounted in 1/8” schedule #80 threaded pipe nipples; This makes the most effective and simple gas jet possible. Schedule #80 pipe is not going to be available in most hardware stores. Furthermore, as with all other things, the quality of pipe parts vary, and it is far better to pay more for at least mediocre parts; even if you have to pay for shipping to get them. Pipe nipples come in both “seamless” versions, and crude types with an internal weld bead; choose seamless. Many low grade pipe fittings have thread that is out of alignment with the part’s axis; don’t settle for such junk! Whether you construct a Zoeller “Z” burner, a Frosty “T” burner, or an old Aussie burner with the MIG tip addition; any of these burners can be made quite powerful in a 1/2” or 3/8” size, and more powerful in a 1/4” burner, because it can be turned up higher than a “Mikey” burner; this may seem odd, but ironically, it is their generally weaker performance that allow these burners to work so well in their smaller sizes. Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 15, 2016 Author Share Posted December 15, 2016 the last lesson about gas jet pipes (probably) It is wonderful to see how long the obvious can escape me What is a 1/8” IP thread? 1/8” IP or IPS (iron pipe, or iron pipe standard) thread dies and taps can be used to make lamp rod thread (1/8-27) on the outside of 1/8” water pipe (designated size; actual outside diameter of 1/8” pipe is .405”). This is parallel thread, and is not to be confused with the tapered 1/8” NPT (national pipe thread--which is tapered); this is used on the ends of pipe nipples to mount your gas fitting or needle valve to. This means that your gas jet can be easily installed on your burner, with a flat washer for a choke included. Be sure to use an "S" letter drill bit; not an "R" bit, which is recommended for tapered thread; not parallel thread. Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 16, 2016 Author Share Posted December 16, 2016 That would be 1/8-27 NPS Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 17, 2016 Author Share Posted December 17, 2016 Not one of you has a comment? What this thread being available means is that a tap can change over a pipe fitting's 1/8" standard tapered hole to accept a variable position gas pipe on all those jet-ejector burners that we have been fitting up the hard way, or a threaded hole can now be placed directly into a "U" shaped flat bar, to mount over a concentric reducer, thus making linear burners the new EASIEST to build without a drill press. Link to comment Share on other sites More sharing options...
Latticino Posted December 17, 2016 Share Posted December 17, 2016 Had no idea that NPS pipe thread existed, so that does sound like a good work around for the various compression and/or set screw type systems I've seen for properly positioning the gas nozzle in a NA burner. Of course, if you are threading the outside of a pipe yourself, and tapping a carrier cross-member, you could always have just used standard taps and dies of the correct diameter I guess, but I've never tried to do that. As always, thanks for the tip. I've not been commenting on this thread as it has gone past my skill level in constructing of NA burners some time ago. Will have to make up a mini-ejector burner when I can source a lurelock orifice though. Need a mini travel forge for hammer-ins. Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 17, 2016 Author Share Posted December 17, 2016 You're welcome,Latticino: Even this thread, which was invented to provide running thread on 1/8" water pipe, will only prove adequate to combine exterior mounting thread and interior thread for a MIG tip on the same pipe nipple, if it is schedule 80. Otherwise a guy would pretty much need to use a lathe to do the trick; this would leave most novices out in the cold. I have tried to introduce Luer lock needles because of the variety of orifice diameters that are consistently available for them. But the truth is that heavy wall stainless steel gauge tube, and heavy wall copper or brass EDM tube can be trapped in MIG contact tips to more easily make small burners; its just that finding the the right orifice size can be more problematic when hunting up the desired capillary tube that way, and most newbies just don't have the patience for that. Unfortunately, the smaller the burner the tighter the tolerances for a given gas orifice must be. There is a fix for this, in that oversized orifices can simply be made longer and undersized orifices can be shortened in small burners to adjust for that, but than everything starts getting so complicated that most people's eyes glaze over. Fortunately, if a guy just wants to make something like a 1/2" Reil burner with the MIG tip update, a 14T Tweco .023" wire tip will work as is...although, slipping in a 1" long capillary tube with a .028" inside diameter orifice will ensure every last scintilla of temperature... Seriously though, only a crackpot like old Doc Frankenburner would go to that extreme, right? Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 20, 2016 Author Share Posted December 20, 2016 Contact your local propane dealer or the Propane Association on line to see what safety codes require. Link to comment Share on other sites More sharing options...
Frosty Posted December 20, 2016 Share Posted December 20, 2016 The common name is lamp rod for this dia. and pitch threads. A good electrical supply will have taps and dies. Frosty The Lucky. Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 22, 2016 Author Share Posted December 22, 2016 Thanks for the tip, Frosty. I have just been using eBay, and am still waiting for a die from China (although the taps came promptly; go figure). Link to comment Share on other sites More sharing options...
wpearson Posted December 23, 2016 Share Posted December 23, 2016 hyd fittings come in nps Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 26, 2016 Author Share Posted December 26, 2016 For the last two years I have been growing in agreement with Frosty's views about keeping equipment as simple to build as good design will permit; during that time, several factors have harden my belief in the importance of promoting swirl as early in the air's journey down the burner as possible. These things have combined to reawaken my interest linear style burners, with concentric reducer pipe fittings on their ends. What I secretly disliked about them in the past was how clunky I thought they looked sticking out of a forge shell; of course that was in the larger burner sizes. In smaller burners, they look okay, and smaller burners are what I like to play with nowadays; which leads me back to how 1/8" IPS taps and dies are important to YOU. Once you have a red hot gas jet planned for your burner, it needs a convenient way to be installed on it, and accurately aimed at the mixing tube, from the perfect distant to it; oh by the way, we want to do so with as little fuss as possible; while we're at it, let's be greedy and insist on a perfect adjustable air choke with no extra bother; plus, we want it all for a twenty, okay? Well, that's about what all the parts and tools cost to do this trick; and you get to keep the tools to do the trick any time you want. Fun, huh? Of course you don't see how yet, because we haven't introduced the one item that stitches every word I've written on this subject together; a few inches of flat bar. Just take that bar and bend it in a "U" wide enough to drop over your reducer fitting, and long enough to provide plenty of length for the choke to be adjusted in, but to still leave room for two screws through each one of its ends to penetrate the bar and through the reducer wall. Now, drill a threaded hole for a gas pipe in the middle of the bottom section of the "U". Run your gas pipe, with its gas jet, through the hole; place the assembly on top of the reducer, and screw the gas pipe down until the gas jet touches the reducer's small hole. If you like, you can wrap tape around the MIG tip gas jet as a spacer ring, to keep it dead center in that little hole. Now, center the "U" shaped saddle on the reducer and drill & tap one, and only one, screw hole in one of the two top holes. Insert the screw, and, after checking that the saddle is still centered on the reducer; repeat the process on the opposite side of the reducer. Then, repeat the process on the two lower holes. The point of all this rigamarole is to keep you from messing up an easy construction task, and screwing up the gas pipe's aim; at which point you can throw away the saddle and reducer, and start all over again. I'm going to assume that building the choke from a convenient flat washer needs no instructions, right? What a minute; what happened to promoting air swirl good and early, huh? I could be wrong, but I'm pretty sure that the saddle will promote air swirl too...happy Holidays. Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 28, 2016 Author Share Posted December 28, 2016 You cannot use a standard set of torch tip cleaners with gas jets for 3/8" and smaller burners, which are .022" and smaller. Tip cleaners only go down to #72, with is .025”. Instead you need stainless steel piano wire for deburring and cleaning such small capillary tubes, by poking them through the cut and sanded end of the capillary tube from its finish end, and then running them back and forth until the cut end is smoothed: http://ziggystubesandwires.com/Wires Link to comment Share on other sites More sharing options...
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