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Thread: acetylene vs propane

  1. #301
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    Default Re: acetylene vs propane

    bambuko- I have some concerns about using quick disconnect fittings like shown for O or A gas. My experience with these fittings on the many air lines (fed by a compressor) is that many will develop leaks with use. It's one thing to get a few PSI less in one's tire but it's all together a different possibility to allow a combustible gas and/or a strong oxidizer collect (remember that P will settle onto the floor) with an open flame nearby while one's focus isn't on the floor. Andy
    Andy Stewart
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  2. #302
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    Default Re: acetylene vs propane

    Quote Originally Posted by bambuko View Post
    One thing that I lacked when deciding whether to follow the usual torch recomendations here, or whether to stick with what's readily available locally was side by side comparison.
    There are plenty of photos of Victor, Harris, Uniweld, Meco, etc, etc but none of them side by side with typical "lightweight" torch in UK.
    So here it is (for the UK guys):



    As you can see the lightweight shank is almost exactly the same length as Uniweld 71 (freshly arrived from US).
    Both knobs are suitably chunky, although Uniweld ones are not colour coded.
    Close proxiemity of the knobs on lightweight torch is PITA and often causes propane to be knocked out of adjustment when using oxygen knob (and vice verse).
    Uniweld (and similar) torches seem very much better in this regard.
    The weight of Uniweld is 185 grams and lightweight torch is 275 grams - not much in it afaic.
    The shape of the handles - I've never yet used Uniweld in anger so it will be interesting comparison, specially since I got used to flat handle of my old torch.
    Main decider is easy and plentiful availability of fittings - I am finding now how expensive is having to buy everything from US...

    One solution is Harris 15-4GB (i.e. old Harris 15-3 with UK fittings. The only such combination available for sale, as far as I know)
    As to the act of brazing, I prefer flat torches. Meco Midget, Meco AV-Jet, that sort of thing. No doubt I'd like the feel of the UK torch you posted and I doubt I'd have any issue with the valve placement; I think I'd like it actually. Round torches want to spin in the hand of you hold them by the cylindrical body, which I don't. I moved away from my absolute favorite Meco Midget and back to my original AW1A with 1/4" hose and BB fittings (I grip the torch by the AB adapters which emulates a flat torch and prevents rotation) simply because I needed a cutting head and wanted to minimize the amount of equipment I have. I also like the tool-less tip changes but it wasn't a deciding factor. And having lost two sets of Smith Kevlar hoses to holes I'm a dyed in the wool regular rubber hose guy. No light weight hoses for me ever again. 3/16" T rubber with BB fittings would be my choice if someone stole my 1/4" ones.

    At the risk of being labeled a heretic I'll note that I spent WAY too much time in the search for the perfect torch. I think that's a common endeavor. It just doesn't matter much, assuming we aren't talking about crazy huge stuff. I'd be perfectly happy with a larger torch. If I was in the EU I'd be using EU stuff, not going to the expense and trouble to import US iron. None of my torches improved my results. Neither did switching to LP. Spending more time brazing did.

  3. #303
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    Default Re: acetylene vs propane

    I built a decent number of frames with a torch the size of my forearm. So pretty much any torch is the perfect torch. Although I really like the A1WA.
     

  4. #304
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    Default Re: acetylene vs propane

    Quote Originally Posted by Andrew R Stewart View Post
    bambuko- I have some concerns about using quick disconnect fittings like shown for O or A gas...
    And that's why I didn't buy airline connectors... but proper propane/oxygen connectors - different design.
    Chris Kaminski

  5. #305
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    Default Re: acetylene vs propane

    I’ve continued to collect information about propane brazing equipment since I started this thread. This is a kind of recap with a little new information so someone doesn’t have to read the entire thread to get started. Originally I learned how to use propane instead of acetylene because we started to make bicycle frames in Ukraine as a mission project. Then I discovered that my framebuilding class students who lived in bigger cities needed a fuel they could purchase locally and conveniently without being in a business location. Also propane is much cheaper than acetylene. There was also a period of time a few years back when 1 of the 2 acetylene factories in the US closed down for awhile because of an accident and supplies for a bit became scarce. Using propane as a fuel gas with an oxygen concentrator makes a lot of sense for someone starting out.

    When I started brazing with propane I used made-for-acetylene equipment using a variety of torch handles. Standard acetylene tips with propane work okay except they can blow out easily from back pressure when the flame is close to the work. It takes just a small puff from your breath to blow out the flame. Next I got made-for-propane mixers, elbows and tips. On the end of the Victor UN-J (on the end of a J-28) and Smith AT-61 mixer/elbow (attached to a AW1A) are threads for a small screw-on tip. These are an improvement. These mixers have bigger gas line holes and the tip ends are recessed to help keep the flame attached to the tip. The best available propane option between the Smith AW1A torch handle and the Victor J-28 or Victor compatible Uniweld 71 is using the Victor UN-J mixer/elbow with their TEN series of tips designed for propane. These take a medium puff of air to blow out their flame. The problem with some of these TEN series of tips (particularly the larger ones like the 3-TEN and 4-TEN) is that the flame pattern can be kind of blunt and not as sharp (I often but not always prefer a thin sharp flame). This depends on who is making them (Victor, Gentec or G-tec). Unfortunately within each brand are better or worse tips for a given size. In other words the Gentec 2-TEN has a better flame pattern than the Victor 2-TEN but the Victor 3-TEN produces a sharper flame than the Gentec 3-TEN. The screw-on tips for the made-for-propane Smith AT-61 mixer elbow are not recessed so they don’t stay attached as readily and blow out more easily and the flame pattern is short and blunt. Smith used to make a series of all-in-one mixer/elbow/tip for the AW1A handle that were designed for propane. These are the AW400 series (AW405, AW407 and AW409). They have a nice sharp flame tip and work great except there isn’t a place to buy them anymore unless you get lucky finding some old probably used ones.

    The very best tips for propane are multi-port tips. In the US, these are made by Meco, Paige and G-tec. The side ports around the main orifice stabilize the flame and make them easier to light and much harder to blow out. The flame pattern varies a lot between these 3 brands. My favorites are the Meco tips because the side ports are very small and don’t increase the heat pattern width but stabilize a very sharp pointed center flame. These are my favorite when fillet brazing. It takes a really strong puff of air to blow out these flames. Way more than the recessed tips. The Paige side ports are not round but are slits. They work well but have a little broader heat pattern because there are bigger flames coming out of the side slits. The problem with these Meco and Paige tips is that they only fit the threads on the end of the elbow on a Meco Midget torch handle. The handle is not round but shaped like a cigarette box. Some people prefer this shape but I am with the majority of not liking them. The G-tec multi-port tips have the same threads as Victor tips. The problem with these G-tec tips is that the side holes are fairly large so they act more like a rosebud with a fairly broad heat pattern. This works great in some applications like bi-plane fork crowns where I want a soaking broad heat rather than a pinpoint one. But normally for many situations (especially fillet brazing) I prefer a sharp rather than a broad flame.

    So, there is not one perfect combination of torch handle, mixer, elbow and tips (in the US). G-tec makes propane mixers for about every brand of torch handle. Their elbow screws into the mixer and their Victor compatible tips screw onto the elbow. Their elbows come in 3” and 6” lengths. One is a little short and the other a little long (unless using a huge flame) for my taste. I am used to the Smith and Victor 5” long mixer/elbow/tips. The G-tec elbows don’t have quite as sharp a bend either as standard elbows. It is more similar the bend on a Smith AT-61. This means that if you have a Smith AW1A you can use the G-tec mixer on it and whichever length of elbow you prefer with any of the Victor and compatible TEN series of tips. The G-tec propane tips are just like the Victor series except they are made of brass instead of copper. Copper is better because of its ability to withstand heat. For intermediate hobby use it doesn’t really matter.

    An important new development is that Paige is making 2 new copper adaptors so their tips (and Meco’s) will fit the Smith AT-61 and Victor UN-J threads. The Meco/Paige tip threads are 1/4” X 28 tpi (teeth per inch). The AT-61 treads are 1/4” X 32 tpi and the UN-J are 5/16” X 27. So their Victor adaptor would have female 5/16” X 27 threads on one end and Meco 1/4” X 28 male threads on the other. The Smith adaptor would be 1/4” X 32 and 1/4” X 28. They are supposed to be available in March. Before it wasn’t possible to use Meco or Paige multi-port tips on a J-28 or AW1A. Well without making an adaptor on a lathe. I modified the Paige MMH adaptor for Hoke torch handles so Meco tips could fit on a Smith AT-61. I cut off the threaded end and bore it out with an end mill and then tapped that hole with 1/4” X 32 threads so it would fit onto the end of the Smith AT-61. That allows me to use my favorite Meco multi-port tips with a Smith AW1A torch handle.
     

  6. #306
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    Default Re: acetylene vs propane

    Quote Originally Posted by Doug Fattic View Post
    I’ve continued to collect information about propane brazing equipment since I started this thread. This is a kind of recap with a little new information so someone doesn’t have to read the entire thread to get started.
    This is all really useful, thank you.
     

  7. #307
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    Default Re: acetylene vs propane

    How much Ventilation do you need if you using a Propane set-up in a Garage? Open the side Door? Open the Garage door - but then have to deal with the wind blowing the torch out?

    Industrial Air scrubbers needed or you will die from the fumes?
    Dane Morrison
    Bike Enthusiast
    Total Number of Frames built by my Hand = 1 on the Dave Yates Course

  8. #308
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    Default Re: acetylene vs propane

    Quote Originally Posted by morrisond View Post
    How much Ventilation do you need if you using a Propane set-up in a Garage? Open the side Door? Open the Garage door - but then have to deal with the wind blowing the torch out?

    Industrial Air scrubbers needed or you will die from the fumes?
    Ventilate the place. Minimally I would have your side and garage doors open enough to support a reliable, gentle air exchange via local winds or with the help of a fan if that's what it takes.

    As fuel gasses go I believe that by products of LP combustion aren't nearly as bad as some others. Still, I'd expect some carbon monoxide and that's not a good thing. And remember that the fluxes you're using are at least corrosive so presumably their vapors are; who knows what else is going on with them. Although I doubt (hope) you're not using cadmium based fillers, fumes from molten metal (and the alloys within) aren't real healthy either. If you're using fillers containing cadmium then you need to be serious about reliable, forced evacuation of the fumes from your breathing zone.

    For context: This is an exposure based thing. In a full time industrial setting there should be reliable, engineered, serious ventilation. But you're not. Lots of us (self included) have brazed with the workshop all buttoned up and we're still here. But I can smell nasty things and always get a funny taste in my mouth. I don't do that anymore, even for the lone braze-on. I open a couple of windows, fire up my 24" exhaust fan that's built into the opposite wall directly above my brazing station, and throttle the flow (with a shutter outside, on the discharge side of the fan) down to a gentle/adequate rate to exhaust the fumes up and away from me. It works well and the shutter (home made fan door with a cord and cleat for positioning) was a lot less expensive than a variable frequency drive. Photo during shop makeover here: Flickr

  9. #309
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    Default Re: acetylene vs propane

    Avoid the hard to escape heat plume off the piece. It carries a lot of flux fumes. Flux head won't kill you right away if at all. But it will leave you glad you stopped. Andy
    Andy Stewart
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