rjs Posted November 30, 2015 Share Posted November 30, 2015 I came accross what appears to be a heat gun combined with a propane burner at this web site: http://www.onlygaz.com/pages/gas_torch.html Anyone know anything about these gizmo's? Articles posted on the site appear to be in french and all points of sale appear to be in France. They have an english users manual (pdf) it says that the unit preheats the air to 650 C and also preheats the propane some. The operating gas pressures are down around bbq levels ie very low. RJS Quote Link to comment Share on other sites More sharing options...
Charlotte Posted November 30, 2015 Share Posted November 30, 2015 The famous Sandia forge that was created in the Sandia labs used two stainless steel tubes that heated the air pulled by the burners in the forge. The plans may still be available from ABANA. The tubes were placed so that they crossed the dragons breath at the year of the forge. I haved use a similar set up to preheat the air going to my burners. It works well and can raise you forge heat without additional fuel. Adding heat with a heat gun etc. is a waste of energy and fairly futile. Redesign the forge so the exhaust blows over pipes that lead to the burners. Doing this naturally aspirated is difficult. With a blown system careful thought about where you introduce the propane will be required. No I will not tell you more about my design. The wrong way of doing it could blow yourself up. Btw a propane air torch supplied with compressed air amount to the same thing as the illustration. Quote Link to comment Share on other sites More sharing options...
rjs Posted December 1, 2015 Author Share Posted December 1, 2015 13 minutes ago, Charlotte said: The famous Sandia forge that was created in the Sandia labs used two stainless steel tubes that heated the air pulled by the burners in the forge. The plans may still be available from ABANA. The tubes were placed so that they crossed the dragons breath at the year of the forge. I haved use a similar set up to preheat the air going to my burners. It works well and can raise you forge heat without additional fuel. Adding heat with a heat gun etc. is a waste of energy and fairly futile. Redesign the forge so the exhaust blows over pipes that lead to the burners. Doing this naturally aspirated is difficult. With a blown system careful thought about where you introduce the propane will be required. No I will not tell you more about my design. The wrong way of doing it could blow yourself up. Btw a propane air torch supplied with compressed air amount to the same thing as the illustration. Thanks Charlotte, I have looked at the sandia forge info and while impressive it all seemed a bit much. If horrible freight were selliing a chinese knockoff of these for a reasonable price I would just get one and to play with but they are not. Oh well. rjs Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 2, 2015 Share Posted December 2, 2015 The ignition temperature of propane is 470 C; well below even the heated air figures, so I would not trust the safety of this tool. Quote Link to comment Share on other sites More sharing options...
rjs Posted December 2, 2015 Author Share Posted December 2, 2015 1 hour ago, Mikey98118 said: The ignition temperature of propane is 470 C; well below even the heated air figures, so I would not trust the safety of this tool. I think they are counting on it igniting the propane, the manual called for waiting for full electrical heat before turning on the propane. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 2, 2015 Share Posted December 2, 2015 I'm simply not that trusting of foreign made tools. An American manufactured tool exposes the manufacturer to devastating law suit losses, if the tool is defective and proves dangerous. But, try suing a French manufacturer in a French court "Yankee"! So, when I see normal safety concerns ignored by a manufacturer, who is beyond retaliation, I "just don't go there." Quote Link to comment Share on other sites More sharing options...
rjs Posted December 2, 2015 Author Share Posted December 2, 2015 1 hour ago, Mikey98118 said: I'm simply not that trusting of foreign made tools. An American manufactured tool exposes the manufacturer to devastating law suit losses, if the tool is defective and proves dangerous. But, try suing a French manufacturer in a French court "Yankee"! So, when I see normal safety concerns ignored by a manufacturer, who is beyond retaliation, I "just don't go there." I hear that and I do not disagree. I took anofher look af the users manual and they do not rely on the hot air for ignition, instead they show some yoyo liighting it with a cigarette lighter. lol Certainly this is not a tool you could ever turn your back on and no one is suggesting using it as part of a forge. They do claim brazing heat with propane/air which I found interesting. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 2, 2015 Share Posted December 2, 2015 The Sandia forge is an effective "recuperative" design. "Recuperative" refers to recouping or "recovering" waste, heat in this case. As Mike points out propane has a relatively low flash temperature and it took the rocket scientists at Sandia (no fooling rocket scientists) some time developing the heat exchanger in their forge so it wouldn't get too hot pre-ignite in the mixing chambers. Another more effective recuperative burner is preheating the propane. There isn't the same limit to temperature there is preheating the air. Fuel preheat systems are the norm on hot air balloons. It's been quite some time since I really messed with improving my burners and a quick search isn't turning up any of the references I'm recalling though IIRC the ones I found most informative were by a British outfit. The ones I recall were preheating the fuel electrically to temps in the 1,000c range. The numbers they were charting were showing better improvement in combustion efficiency that using preheated air. When I say as I recall this was from before the accident so I'm working with sort of fragmentary memories. Still, I can't stop thinking about ways to wrap the copper supply line in the forge and this leads me to think I'm remembering rather than imagining. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
rjs Posted December 3, 2015 Author Share Posted December 3, 2015 44 minutes ago, Frosty said: The Sandia forge is an effective "recuperative" design. "Recuperative" refers to recouping or "recovering" waste, heat in this case. As Mike points out propane has a relatively low flash temperature and it took the rocket scientists at Sandia (no fooling rocket scientists) some time developing the heat exchanger in their forge so it wouldn't get too hot pre-ignite in the mixing chambers. Another more effective recuperative burner is preheating the propane. There isn't the same limit to temperature there is preheating the air. Fuel preheat systems are the norm on hot air balloons. It's been quite some time since I really messed with improving my burners and a quick search isn't turning up any of the references I'm recalling though IIRC the ones I found most informative were by a British outfit. The ones I recall were preheating the fuel electrically to temps in the 1,000c range. The numbers they were charting were showing better improvement in combustion efficiency that using preheated air. When I say as I recall this was from before the accident so I'm working with sort of fragmentary memories. Still, I can't stop thinking about ways to wrap the copper supply line in the forge and this leads me to think I'm remembering rather than imagining. Frosty The Lucky. Hi Frosty, another reason those guys preheat their propane is that they take it out of the tank and up to the preheater as a liquid. If they tried doing it the way we do it they would quickly cool their fuel tanks to the 0 psi level. the one I was just reading about had two burners each rated at 15,000,000 btu's and no more fuel tank capicity than a lot of us have running our forges. "twin JetStream Series II burners, produce a heat output of 15,000,000 Btu's per burner or approximately 4,390 kW" and no I do not think I want one of those in my shop. Years ago one of those things landed in a field across from my place, they hit the burners a few times on the way down and it sounded kinda like a carrier was doing cat shots out on the sound. rjs Quote Link to comment Share on other sites More sharing options...
Charlotte Posted December 3, 2015 Share Posted December 3, 2015 Recuperative builds are effective and efficient when you just recover heat by an exhaust gas incoming air heat exchanger. Does require a little experiment to get right. One problem that needs to be solved by the user is developing a burner system that allows stable ignition on cold start. The Sandia forge had an even greater problem in that they wanted high heat at relatively high altitude for the US. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 3, 2015 Share Posted December 3, 2015 41 minutes ago, rjs said: Hi Frosty, another reason those guys preheat their propane is that they take it out of the tank and up to the preheater as a liquid. If they tried doing it the way we do it they would quickly cool their fuel tanks to the 0 psi level. the one I was just reading about had two burners each rated at 15,000,000 btu's and no more fuel tank capicity than a lot of us have running our forges. "twin JetStream Series II burners, produce a heat output of 15,000,000 Btu's per burner or approximately 4,390 kW" and no I do not think I want one of those in my shop. Years ago one of those things landed in a field across from my place, they hit the burners a few times on the way down and it sounded kinda like a carrier was doing cat shots out on the sound. rjs Right, drawing liquid wouldn't drop the pressure and freeze the tank so quickly. Scratch that observation for an example of a recuperative preheating the fuel. Squirting liquid propane through an induction device is much more exciting than the average hot air balloon ride should be. Different application different effects. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 3, 2015 Share Posted December 3, 2015 rjs, They claim it can be used for brazing; by this we assume they mean hard brazing. What the American Welding Society terms braze welding and the Brits call spelter brazing. We assume this meaning because silver brazing uses much lower temperatures that can alredy be achieved by any air-propane torch. Since their claimed temperature of 4172 F is within hard brazing range, technically speaking it should be able to do so. But here's the catch: just because we can do a thing doesn't mean we can do it well. An oxy-propane flame is about 4800 degrees and it doesn't do braze welding well. You want at least an oxy-propylene flame (5200 F), and oxyacetylene is better (5800 F). We have all experienced the frustration of trying to overreach with a poor tool. If you want to braze weld and don't have an oxyacetylene torch set, I would recommend using a twin carbon arc instead. Quote Link to comment Share on other sites More sharing options...
rjs Posted December 3, 2015 Author Share Posted December 3, 2015 3 hours ago, Mikey98118 said: rjs, They claim it can be used for brazing; by this we assume they mean hard brazing. What the American Welding Society terms braze welding and the Brits call spelter brazing. We assume this meaning because silver brazing uses much lower temperatures that can alredy be achieved by any air-propane torch. Since their claimed temperature of 4172 F is within hard brazing range, technically speaking it should be able to do so. But here's the catch: just because we can do a thing doesn't mean we can do it well. An oxy-propane flame is about 4800 degrees and it doesn't do braze welding well. You want at least an oxy-propylene flame (5200 F), and oxyacetylene is better (5800 F). We have all experienced the frustration of trying to overreach with a poor tool. If you want to braze weld and don't have an oxyacetylene torch set, I would recommend using a twin carbon arc instead. after a number of years without access to my oxyacetyline rig I have recently aquired another one so my interest in the propane/air rig was largely theoretical however the portability of thie unt still makes it interesting on some level. Interesting you should mention the twin carbon arc approch. those things seem to have faded into oblivion as the years have gone by. Back in the fifties (yeah i was around back then) there were ad's for them in all the how to magazines. I always suspected (i have never used one) it was because while they might work for some things they could not come close to the finess/control you can get with an oxyacetyline rig. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 3, 2015 Share Posted December 3, 2015 rjs, Nothing but a TIG welder comes close to an oxyacetylene torch, and I never liked using TIG all that much. Twin carbon arcs didn't just fade away; they were quietly done away with by their own manufacturers back in the sixties; that was when weldors who had been using less than safe eye protection started showing up for eye surgery do to collective damage over the course of their careers; it was during that period that safety regulations on helmet filters were tighetened up considerably. Many old filter designs were removed from the market, and twin carbon arcs made by mainstream American manufacturers were quietly "dissapered" at the same time.l Why you ask? Because carbon arcs put out more UV than any other arc source, and companies like Forney were shaking in their boots for fear of potential law suites. For those of you who don't go back that far, a liberal revolution was going on in America back then. Today auto-darkening helmet filters have "come a long way baby" and can easily handle the increased risk from this tool. But, in the meantime, the American Welding Society has leaned on Uncle Sappy to get absurd safety standards put in place for carbon arc heating/welding. How do I know this? Because, at the same time carbon arc gouging, (an important industrial process $$$), which puts out exactly the same amount of UV for amps used has much lower requirements. I wrote to the department involved, and they answered that they "were just following AWS recommendations; on querying them, I was referred to their "safety standards commitee," and eventually to the single individual who wrote the recommendation. I asked for his justification, and never heard back from him. For those who don't know it, many welding experts have membership in the AWS (I suspect, in order to receive their magazine, which is excellent), but it is manufacturers and big time distributors who run it. There is a lot of money to be made selling TIG machines and supplies, and very little money to be made selling twin carbon arc torches, so even though the generation who might have sued over eye damage is long dead, it's still all about money. Isn't 'democracy' wonderful? "Truth, justice, and the almighty buck." Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 3, 2015 Share Posted December 3, 2015 What kind of oxy propane torch are you referring to Mike, things like the old Victor conversion tip junk? The oxy propane rig out in my shop outperforms oxy acet in every operation but gas welding of steel. Absolute temp is lower but BTU/sec is orders higher. The #5 heater tip will melt a cubic inch of steel in under 13 seconds while the equivalent oxy acet #5 rose bud hasn't run the temper color in the test coupon blue. Check out Harris alternative fuel torch and have a dealer give you a demo of the oxy prop rigs. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted December 4, 2015 Share Posted December 4, 2015 2 hours ago, Frosty said: What kind of oxy propane torch are you referring to Mike, things like the old Victor conversion tip junk? The oxy propane rig out in my shop outperforms oxy acet in every operation but gas welding of steel. Absolute temp is lower but BTU/sec is orders higher. The #5 heater tip will melt a cubic inch of steel in under 13 seconds while the equivalent oxy acet #5 rose bud hasn't run the temper color in the test coupon blue. Check out Harris alternative fuel torch and have a dealer give you a demo of the oxy prop rigs. Frosty The Lucky. Totally agree with Frosty's experience. Mapp gas if you can find it was capable of steel welding; I learned to weld in the bad old days. Today I use propane for anything that doesn't require acetylene; The Turbo torch system using propane was good for high temp silver braze of stainless steel. I must say however that oxy/acetylene is still the best training for Tig. Tig is a great system but as others have noted not for the faint hearted or inexperienced. At 70 coming I find that I don't quite have the steadiness to do a really good job with tig these days, Not enough use and too expensive to practice I guess. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 4, 2015 Share Posted December 4, 2015 Remember that we are talking about braze welding; not silver braze "sweating." I've even braze welded with one of the burners in my first book (and wrote a short chapter on how to do so), and also remember that I stated "being able to do a thing doesn't mean we can do it well." Pinpoint heating is the key to professional grade braze welding, and that depends on a super hot flame. Some braze welding is even done with the arc from a TIG machine. Braze welding also used to be done with both twin carbon arc and single carbon arc "flames" for the same reason. MAPP gas isn't produced anymore; it has been replaced with propylene fuel gas since 2008; weather or not it could successfully be used for steel welding was a subject under debate. On the one hand a friend of mine used it for welding steel tubing. On the other hand It was not used for any certification tests, which suggests to me that it wasn't quite "up to snuff." If I were going to flame weld steel without employing acetylene, I would use a twin carbon arc, to supply the excess carbon from its flame, which can otherwise only be supplied by acetylene, for it is claimed that the carbon content transferred to steel from an oxyacetylene flame is the reason MAPP gas wasn't supposed to be used. I don't personally know whether or not the flame's carbon content was the actual reason, as claimed, that MAPP was no good for welding steel, or it was an urban myth. Back when I had ready acsess to the tools and materials to make these tests I was too busy making a living instead :-) Quote Link to comment Share on other sites More sharing options...
Charlotte Posted December 4, 2015 Share Posted December 4, 2015 Mikey98118 I said silver braze with deliberate intent. Silver alloy manufactured by STOODY for High pressure stainless steel tubing carrying hydrogen at 4000 PSIA with no failure of joint or leak for years. The Joints were only replaced with orbital welded autotig welded systems because of the requirement for absolute purity. Trust me on the MAPP It was a superior fuel but was shoved off the market by the stupidity of the supplier that retained control of it and tried to establish a monopoly. Blazer was close enough in function compete. A secondary problem is that petroleum chemists raised the pricing after they found other applications for methyacetylene/Propadiene which returned more profit. MAPP's real strength was in forehand horizontal welding. I know that MAPP was discontinued. I know I was there. I worked for the corporate entity that controlled MAPP though its holdings. When It went down I acquired several 25 gallon tanks that I shared with friends that need fuel for several purposes. There were a lot of crawfish boiled over MAPP gas In Louisiana. You should know that the international company that owned MAPP went out the cylinder gas business and sold all of its cylinder gas subsidiaries. Another case of corporations being run by people that have more interest in their own pockets than commitment to the products and the people that produce them. I sat in meetings with some of those Swinging D_____s and heard their thinking. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 4, 2015 Share Posted December 4, 2015 I can only agree with Charlotte. My three favorite examples of corporate bonehead thinking are a little yellow 150 amp gasoline powered welding machine that could be lifted by one person and had a true hundred percent duty cycle. The manufacturer was bought out by Lincoln and shut down, so it wouldn't compete with their 150 amp piece of junk welding machine. There used to be a rubber welding gasket sold which wrapped completely around welding helmet light filters, covering their edges on three sides; it totally prevented light leaks, cost two bucks, and lasted for years. The manufacturer was bought out and production shut down; thereafter we all got to replace our one dollar (but you needed one on each side of the filter) oil impregnated paper gaskets about twice a year, and light leaks were a constant problem. Finally, a well known manufacturer of auto-darken welding helmets came out with a model that had a green LED light just above its lens. When the auto-darkening filter was in rest state, it was the equivalent of a #4 green light filter, and the LED would provide just enough green light, which the filter did not interfere with to allow the operator to change position before starting another weld. The flaw in this system was that they forgot about weld berries, which over time would destroy the LED. Rather than provide a protective clear plastic filter for the LED, incorporate it into the auto-darken filter (where it would have been protected) or sell quick installing replacement lights (after all LEDs are cheap), the company discontinued the helmet! So, if you want a high production capacity helmet for short welds, you must build your own. When I was a working stiff, all this stuff just made me grin; after all, work was dog eat dog, and everything bad only tended to cripple my competition, while I did workarounds. The working man's world is still dog eat dog, but I'm out of it; so don't mind teaching "them as listens." Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 4, 2015 Share Posted December 4, 2015 I used MAPP in the shipyards for years; it was superior to anything else for torch cutting, heat bending, and silver brazing. I listened to both sides of the debate among welders as to whether it was good for flame welding carbon steel for years, but my interest was low because my employers were the ones paying out big bucks for acetylene on special pipe welds. After the shipyards closed, I spent another sixteen years working in small boiler shops and ship repair projects for the fishing fleet; both kinds of employer mostly used oxyacetylene. By the time I was personally concerned about the efficiency and cost of supplies, MAPP gas was a memory. However, propylene gas could be purchased for only a third more cost than propane from welding supply dealers, if you bought your own D.O.T. approved cylinder, and while both fuel gases were way cheaper than acetylene, they also both use three to four times as much oxygen in the flame. Now, oxygen in many places is reasonably priced, but Seattle isn't one of them. If you're an industrial customer, its cheap here. If you're a hobbyist or small business owner, get ready to be sheared... Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 5, 2015 Share Posted December 5, 2015 Charlotte, You stated that "MAPP's real strength was in forehand horizontal welding." I can only picture forward flame welding in the horizontal position as appropriate for for either a root pass, or multiple bead finish passes; when I wanted good single bead shape on a finish pass I welded back hand. Give with the details; us ex welders wanna know! Quote Link to comment Share on other sites More sharing options...
Charlotte Posted December 5, 2015 Share Posted December 5, 2015 Alas, I can't give more details. I was given that advice by the Company vendor rep when I learned to weld with gas. Most of my gas welding was doing small ornamental assembly and repair. On the half dozen times I gas welded anything bigger than 1/16 I slavishly followed that recommendation. Since my divorce, when I lost half my stuff, I've used acetylene for welding and propane for cutting. I was never a big time job weldor. A lot of what I know is from being in the industry and insisting that if I was responsible for some of it I should have hands on knowledge. It is much easier to QC results if you understand on a physical level what the technician had to do and how the product/equipment works. All I remember of the conversation was that___ since you are using a bigger tip than you would for acetylene and generating more total BTU at a slightly lower temperature you need to make use of the heat to get the job done. These days I use mig for the same jobs and now that I have finally gifted my self a tig will retire the acetylene cylinder unless I find some one that insets I repair something where it sits. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 7, 2015 Share Posted December 7, 2015 Alas, with "scratch arc" TIG for shipboard small pipes, gas welding is nearly gone. I loved doing it, though, and am sorry for that little bit of progress. BTW, you are sooo right about an inspector needing to know, first hand, how the weldor goes about doing things; they didn't at Boeing, and some of us played with them shamelessly Quote Link to comment Share on other sites More sharing options...
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