Adhamh Posted November 30, 2015 Share Posted November 30, 2015 Hi, I've been away for a while and now I'm back to utilize all the great knowledge here. A while back I built a new burner for my forge. I started using it again because my 3/4 burner was having trouble getting bigger pieces up to yellow heat in a timely manner. I think this bigger burner is too big for my forge. Here are the details: My forge chamber is about 300 cubic inches. My smaller burner is a 3/4" version. It uses a 1.25" x 1.25" x 1" T with an 8" long tube. I'm using a .035 mig tip for the jet. My big burner is a 1" version. It uses a 1.5" x 1.5" x 1" T with a 10" long 1" wide tube. The jet is also a .035 mig tip. When I run the smaller burner it will sputter a little but I can usually choke it or increase the gas to get it to stop. It seems like i have to turn the gas higher to get it to stop sputtering. On the big burner its more finicky than my wife's 13 year old cat. It sputters and sputters. I will crank up the gas and it will stop for a bit, but the hotter the forge gets the more I have to crank up the gas. Eventually the throttle is wide open and it seems to stabilize, but at this point I'm in danger of burning down my shed because flames are shooting out both ends. I just read a post that leads me to believe I need to make at least one adjustment. My jet has been aligned just above the throat. After reading the post I know now that the jet needs to be 3/4" or 1" behind the throat which puts it well inside the air intake. 33618-essential-gas-forge-formula. Besides that adjustments are there any others I should make? I'm still pretty happy with the size of my forge, the only change I would make at this point is to have it be an more of an ellipsoid than a cylinder. Thanks! Quote Link to comment Share on other sites More sharing options...
Frosty Posted November 30, 2015 Share Posted November 30, 2015 Where did you come up with the 10:1 dia to length ratio for the tube? More is NOT always better, not here for sure. The industry standard is 8:1. A 3/4" dia tube should be 6" long and a 1" tube, 8" long. This ratio isn't set in stone especially with home builds but it's a good number. You didn't increase the jet diameter when you increased the tube diameter. Try shortening the tube to about 8" and putting a 0.045" jet in it. The set back of the jet is a starting point at 1/2 the diameter of the tube. so you begin at 3/8" in a 3/4" burner and 1/2" in a 1" burner. These are definitely not set in stone, there are a LOT of variables depending on your location, etc. Please feel free to let me know if you have more problems. Oh yeah, there is one other thing. If you get a 1" burner tuned correctly in a 300 cu/in forge it'll melt the refractory right out of it. I don't know if you can turn it down enough to prevent damaging it. Get your 3/4" burner tuned it should be plenty, I forge weld in mine at will and the chamber is generally larger than that. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Adhamh Posted December 1, 2015 Author Share Posted December 1, 2015 And what if I WANT to melt my refactory? :-) I based my large burner on these directions: http://azblacksmiths.org/plans/Forge%20build.pdf. Maybe I missed a section where the talk about cutting down the pipe. What does the pipe length effect? For now I will cut down the small burner pipe to 6" and move the jet to the right location. I really don't want to use the large burner, its just too xxxx hot! Quote Link to comment Share on other sites More sharing options...
timgunn1962 Posted December 1, 2015 Share Posted December 1, 2015 In the first post, you say you've used the same size jet (.035 MIG tip) in the 3/4" and 1" burners. You will have a much leaner mixture in the big burner: more air for the same gas flow. Assuming the 3/4" burner was about right, upscaling to 1" should have the gas jet diameter increase in direct proportion to the pipe diameter. Try a .045 MIG tip and see if it's better. Quote Link to comment Share on other sites More sharing options...
BANAN Posted December 1, 2015 Share Posted December 1, 2015 Change only the nozzle greater. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 2, 2015 Share Posted December 2, 2015 A "T" burner will have completely different dynamics from one of mine, so most of the advice I can't comment on, but you definitely DO NOT use the same diameter gas orifice in two different burner sizes. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 2, 2015 Share Posted December 2, 2015 On 11/30/2015, 3:36:21, Adhamh said: And what if I WANT to melt my refactory? :-) I based my large burner on these directions: http://azblacksmiths.org/plans/Forge%20build.pdf. Maybe I missed a section where the talk about cutting down the pipe. What does the pipe length effect? For now I will cut down the small burner pipe to 6" and move the jet to the right location. I really don't want to use the large burner, its just too damn hot! How closely did you follow those directions? Sure its a modified sidearm burner but the basics remain the same. The difference tube length makes in the efficiency of the operation of the inducer. Too long and drag overcomes the benefit of increased vacuum induced in the tube. An induction device used as a burner requires sufficient time in contact before ignition for the air and fuel to mix. Unfortunately the longer the air fuel spends IN the tube the more drag is incurred by contact with the pipe wall. After a point the additional mixing passes the point of diminished returns so more complete mixing is offset by the lowered induction of combustion air. Meaning there isn't enough air for a neutral burn so it's worse than a waste of energy. THEN there's the reduced velocity of the air fuel mix to the point it's lower than the rate of propagation of the flame front and the burner back fires. Oh yeah. If you want to melt the refractory post pics please. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 4, 2015 Share Posted December 4, 2015 Frosty, I first encountered this as the nine diameters rule of thumb (in Ron's pages?), and through experimentation found that with my jet-ejector design it could be as few as eight diameters and as much as ten. With the shorter lengths producing a more powerful swirling flame and the longer lengths producing smoother flames (which are more desirable for brazing work). My vortex burners require fourteen diameters for a smooth flame. It seems likely that length to diameter ratios change according to burner design, and the "industry standard" is a little shaky, yes? Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 4, 2015 Share Posted December 4, 2015 The literature I had available and web searches before marketing made finding simple documents a PITA said commercial propane burners used the 8 diameters ratio pretty consistently. Commercial burners are tapered from the throat to the output though some have a short section of straight pipe for connections. Commercial burners typically operate under 1psi and develop serious output with little sensitivity to breezes and back pressure. I find straight tubes work fine at 8-9 diameters. Longer lengths need to enlarge or drag begins to be detrimental, 10 diameters and it's getting pretty unstable due to back pressure from friction requiring a smaller jet dia. and higher psi. I shared everything I had about burners with Ron but it was before scanners and attachments so I transcribed what I read. I didn't think of faxing him the data either. There's really nothing to figure out about the basic devices, they're been in use I believe since the 18th. century, probably earlier. Just not as burners but as air and water pumps in mines, later air supplies for smelters and furnaces driven by falling water. Early on I was searching patent servers looking for a forge burner and ran across drawings and descriptions very like Ron's EZ but it was old before 1890 the patent date and that patent was for a recuperative wall in the forge. The burner was just included to lend legitimacy to the design. Again, I never bothered to try making an air propane torch I only build forge burners that's where I need them to work well. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 5, 2015 Share Posted December 5, 2015 Okay, If we are talking about tapered mixing tubes, then I would think that 12:1 ratio might be more useful than 8 diameters, but on straight tube or pipe, a rule of thumb consisting of x many diameters for mixing tube length will end up variable according to mixture feed speed, internal pressure, and whether or not internal vanes are installed. So, exactly how many diameters of length are optimal is going to change for every burner design. Fourteen diameters are needed on my vortex burners only to deliberately provide more friction so as to slow down swirl in the exiting flame. But installing internal vanes in order to shorten mixing tube length would add another layer of complexity, which I don't want to introduce to "the discussion" at this stage of the game. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 5, 2015 Share Posted December 5, 2015 From the very beginning I did all my testing out in the open air, because I found that any naturally aspirated burner that works well in open air only works all the better after being placed in a forge or furnace. So, discovering the ability of these burners to be used as heating torches was a by product of testing procedures. During the years since publication canister mounted air/propane torches have improved immensely, but they still can't compete with a properly built and tuned homemade burner. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 6, 2015 Share Posted December 6, 2015 Frosty, To be fair, eight diameters always makes a good starting point during R&D, and most people would probably be perfectly happy with it as far as results go on most burners. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 6, 2015 Share Posted December 6, 2015 36 minutes ago, Mikey98118 said: Frosty, To be fair, eight diameters always makes a good starting point during R&D, and most people would probably be perfectly happy with it as far as results go on most burners. Mike: I don't usually talk to people who do proper R&D so I tailor my directions to simple and works. For example of why I keep it simple look how far this discussion has gone and the main players here have years experience tinkering the things to work. Tapering the burner tube at a maximum 12:1 ratio will allow you to make it almost any length up to the point the stream velocity falls below the flame front velocity of the fuel. This however is ONLY true when an ejector is used as a burner and that's a long way from their most common use. The aspirator on the faucet of the lab sink is an ejector with a tapered tube. The device that develops a strong vacuum in the storm drain cleaning trucks is a jet ejector powered by upwards of 150psi compressed air primary. The result though is evacuating a 8,000 gl tank strongly enough to suck 12" boulders and human bodies into the tank through about 25' of hose and ducting. We don't even want to get into "air amplifiers" and what they're used for. The underlying principle is exactly the same for all: A stream of air striking a curved surface at an angle accelerates and the pressure falls in direct proportion. We clever monkeys have come up with all kinds of cool and useful things to do with it. Anyway, after all that longwindedness I use the 8:1 dia to length ratio because it's the most reliable departure point to make a T type NA burner. It simplifies tuning and requires the least adjustments. I'm not trying to develop something new, just help folks make a tool that works. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 6, 2015 Share Posted December 6, 2015 Frosty, I more agree than disagree with your viewpoint. And, at any rate try not to let the mad scientist part run away with the rest of me, lest I can no longer lure victims down to the deep end of the pool Doctor Frankenburner Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted December 7, 2015 Share Posted December 7, 2015 Just what we needed, knife makers and burner builders leading us innocent smiths astray... Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 7, 2015 Share Posted December 7, 2015 I didn't want to sound like I was taking exception Mike I love what you do. Heck that's where Ron and I drifted apart, he was into refining his design till it was as perfect as he could get and I just wanted something that works so I could beat hot steel. I had a number of ideas but had a paycheck job that kept me out of town 3 weeks a month for 20 years, literally, 6/10s was my normal work week. I spent more time forging in a camp fire on rocks and later a rail anvil than in a "real" forge. I retired in 07 and landed a nice retirement job 10mins from home delivering equipment and soil maybe 25 hrs. a week Good pocket money. I was finally off and running on my shop dreams, I got the shop building up and weathered in but the tree got me before I got it wired or insulated, Heck not even a good work bench. So, I never got into milking burners for what I could get out of them I spend more time teaching others to forge and build forges and burners. I'm a lucky guy though, seriously lucky. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 7, 2015 Share Posted December 7, 2015 Frosty, I don't think you and Ron so much drifted apart as that he got very involved in his web pages, and of course later he darn near got swallowed whole by one set of troubles on top of another. First he was required to re-certify when his teaching credentials were threatened, and then about a six month siege of pneumonia. He and I had a falling out about then over Rex Price, and quit speaking to each other. Later, I heard he had a series of heart attacks. Talk about being retired with a thump! Like me, Ron did seem to be in love with tools...but he spoke well of you when I knew him, and he was definitely impressed with your "T" burner. He used to hint about it like it was classified material. You'll be pleased to know he never discussed a single detail of its construction with me though. You should try to get back in touch with him, now that both of you have more time. Yes, Charles: My absolute favorite thing is to hand somebody an idea that excites him so much he can't sleep. When I was Writing Gas Burners ideas would wake me up at two or three in the morning and not let me rest until they were written down. Passing that excitement on to others feels sublime. And of course there is that magic moment when a student lights up his first hotrod of a burner, and I can see his own inner mad scientist gloating and making plans; yummy! 1 Frosty, after some consideration it seems to me that a mixing tube that is tapered, could be the naturally aspirated burner fan's answer to fan-blown ribbon burners, if they get too uppity about them you may have to complete your experiments, just to keep the competition going :-) Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted December 7, 2015 Share Posted December 7, 2015 Good to see a wicked sense of humor to go with a very active mind. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 7, 2015 Share Posted December 7, 2015 I am getting SERIOUSLY TIRED OF IPS!!! Yeah, long reply disappeared of course. Back later. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Latticino Posted December 7, 2015 Share Posted December 7, 2015 8 hours ago, Mikey98118 said: after some consideration it seems to me that a mixing tube that is tapered, could be the naturally aspirated burner fan's answer to fan-blown ribbon burners, if they get too uppity about them you may have to complete your experiments, just to keep the competition going :-) The classic Ransome industrial NA burner has a tapered mixing chamber, as described. These are used extensively in the glass and ceramics world for firing furnaces and kilns. One of the best ways to use same is with a Giberson style cast high alumina refractory burner nozzle. These are round, or rectangular in cross-section and have multiple small openings for the mixture to exit the burner (remind you of anything?). You can check them out on this site: http://www.joppaglass.com/burner/mini_square.html. Note that he even has a small forge design to go along with his burner/burner tip assembly. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted December 8, 2015 Share Posted December 8, 2015 latticino Thank you for the information It follows along with an experiment that I had planned. That is a very interesting link and will give a great boost to this discussion/ Quote Link to comment Share on other sites More sharing options...
Latticino Posted December 8, 2015 Share Posted December 8, 2015 Glad to help. For what it is worth, I used Giberson burner heads on blown, low pressure, natural gas burner assemblies for 10+ years. They are quiet and supply a nice soft, hot flame. Have to be careful regarding thermal shock, but that is the case for any type of refractory. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 8, 2015 Share Posted December 8, 2015 Latticino, Yeah, Giberson practically invented home brewed hot glass work, but I had three problems with his burner heads: (1) They cost a lot of money (2) They are vulnerable to damage from rapid thermal cycling; this is no problem for day tanks, but is a real sticking point for metal working hobbies. (3) They are not supposed to be used in a sealed port, which will cost a lot heat lost from uncontrolled secondary air ietrainment. The ribbon burners have none of these weaknesses, so I'm thinking about trying out a cast refractory burner head mated to a fan-blown ransom type burner, and also to a Vortex burner (just to be thorough). Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 20, 2015 Share Posted December 20, 2015 Charles, By the way, thank you for the most enlightening compliment I've ever received. "...to go with a very active mind." Lot of food for thought there... Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted December 20, 2015 Share Posted December 20, 2015 Just welcoming you to the "club" lol Quote Link to comment Share on other sites More sharing options...
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