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Operating an Oxy/LPG torch.

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  • Operating an Oxy/LPG torch.

    My home gas kit which I use for brazing and heat treatment of tools etc is Oxy/LPG.

    LPG in NZ is 60% propane and 40% butane (more or less).

    I am on a rather slow learning curve to get the best out of this! For starters, can anyone please suggest pressures to set?

    General tips on how to set it up and adjust for best flame and any other insights greatfully accepted.


    John

  • #2
    I just set it like a regular acetylene torch tip by the drill size of the orifice.
    Now our propane is a different mix and your heating values will be different, maybe lower? It also will take a while to learn the speed to travel. As I have a tendency to out run the preheat.

    This is what our propane tips look like on the right.
    You have to move slower, preheat longer and the cut kerf edges will be rougher. I use the plasma, for most cuts.

    Here are a couple of I beam chops.
    I use it mostly for bending and heating.
    See following post for more photos of the tip.
    Glen
    Been there, probably broke it, doing that!
    I am not a lawyer, and never played one on TV!
    All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only

    Comment


    • #3

      A propane tip on a regular torch body



      The two part propane tip, front,inside,and back.
      Glen
      Been there, probably broke it, doing that!
      I am not a lawyer, and never played one on TV!
      All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only

      Comment


      • #4
        Originally posted by PTSideshow View Post
        I just set it like a regular acetylene torch tip by the drill size of the orifice.
        Now our propane is a different mix and your heating values will be different, maybe lower? It also will take a while to learn the speed to travel. As I have a tendency to out run the preheat.<<snip>>
        What you interpret as outrunning the preheat is too low a setting on oxygen pressure. Sometimes the same result is due to the oxygen valve on the main handle not opened all the way. The preheat is unnecessary once the cut begins. Oxygen actually burns the iron and the exothermic reaction releases enough heat to keep the cutting action going. Many industrial cutting machine operations turn off the preheat once cutting begins.

        The charts that you have are a good staring point for setting up the torch, but are just that... a starting point. It is important to use the correct size tip, as the cutting orifice size is critical to good cuts and is directly related to material thickness. The cutting speed is also critical. Too fast and you outrun the exothermic cutting action, to slow and you end up re-welding the cut with the preheat flame.

        In the case of acetylene it is easy to set up the torch without any gauges on the regulator at all. Open the fuel gas valve on the handle about 1/2 to 3/4 turn and then start bring up the fuel pressure while trying to light the fuel gas. Continue increasing the pressure until the flame 'leaves' the tip. At this point, with the handle oxygen valve wide open and the cutting torch oxygen valve open 1/4 to 1/2 turn, slowly increase the oxygen pressure until you get a neutral flame. Then depress the cutting lever and increase the oxygen pressure until the preheat flame goes past neutral and balance the cutting torch oxygen setting and the regulator pressure until the cutting lance is sufficient to cut the stock. This last bit is something that needs to be arrived at by practice and experience... and this practice is brought about by needing to use a torch that has a damaged gauges. Sometimes the boss doesn’t care to hear excuses... just cut the pipe already...

        paul
        paul
        ARS W9PCS

        Esto Vigilans

        Remember, just because you can doesn't mean you should...
        but you may have to

        Comment


        • #5
          flashback arrestors vs check valves...

          PT, I saw that you have two in line check valves in your oxy/propane rig.

          I saw these guys at Fabtech a few years ago:
          https://www.youtube.com/watch?v=hH1xIWR5f8U

          I stopped using check valves and installed flash arrestors after seeing the video... contrary to what my wife says, I am trainable :>)

          The check valves that so many of us used to use are useless and only serve to reduce the available pressure at the torch. you can test the pressure drop by monitoring gas flow out of the tip (submerge the tip in water and watch for the bubbles) raise the regulator pressure and see how high the gauge rises before gas starts to flow. Adding more check valves only increases the pressure drop even more and if you are using the regulator gauges to set the gas pressure you need to factor these pressure drops into consideration when setting up.

          more info
          http://iigas.com/fba.htm

          paul
          paul
          ARS W9PCS

          Esto Vigilans

          Remember, just because you can doesn't mean you should...
          but you may have to

          Comment


          • #6
            Thanks everyone, some useful information there!

            Comment


            • #7
              Originally posted by ironmonger View Post
              I saw these guys at Fabtech a few years ago:
              https://www.youtube.com/watch?v=hH1xIWR5f8U

              I stopped using check valves and installed flash arrestors after seeing the video...
              +1 in favour of flash arrestors.

              It may be different now, but when I sought these out locally they were difficult to
              find. Vendors told me my usage didn't warrent them and to just settle for valves
              like everyone else. IOW - this is what we've got, so it's what you really need. Mine
              ultimately came from an online source.

              I've never seen a video demonstrating the difference. It isn't emphasized, but notice
              how at 0:10, he uses the quick connects to remove both hoses from a lit torch without
              consequence. Thanks, ironmonger.

              TAB, is the decision to use LPG instead of acetylene a gas cost/insurance retention matter?

              .

              Comment


              • #8
                EddyCurr, LPG I can buy from the hardware store but acetylene requires me to rent a cylinder at exorbitant prices (or I could buy a cylinder but there is no local filling point).

                Renting the oxygen cylinder is plenty expensive enough.

                If I find out more about compressed air/LPG for heating I might switch to that.

                I only want to do brazing and heat treating tools, for welding I have arc and mig and for cutting I have a plasma set.

                Comment


                • #9
                  Artful

                  Keep an eye on craigslist for an oxygen concentrator. I found one locally a few years ago, and it came with a 2000 psi portable cylinder filler compressor. It makes about 5 LPM, and is quite happy to run unattended. You can then try to find an oxygen cylinder that some one bought and never recertified and fill that, you will never have to take it in for another refill.

                  In the states many gas suppliers charge rental based on the length of time that you have the cylinder, which makes refilling theirs a problem, but even if you could I would never refill a cylinder that I didn't own, as the O2 form the concentrator is only 95% or greater oxygen, but it is not 100% as the cylinder is supposed to be. My torch has never complained about the lack of purity :>)

                  I use it mostly to fill my little R cylinders, which are about 6" in dia. and about 16" tall. Handy but really expensive to fill commercially.

                  paul
                  paul
                  ARS W9PCS

                  Esto Vigilans

                  Remember, just because you can doesn't mean you should...
                  but you may have to

                  Comment


                  • #10
                    Originally posted by ironmonger View Post
                    Artful
                    Keep an eye on craigslist for an oxygen concentrator. I found one locally a few years ago, and it came with a 2000 psi portable cylinder filler compressor.
                    What make/mode is the cylinder filler compressor? I already have a concentrator I use for a glass torch, it would be nice to be able to fill cylinders with it too.

                    bob

                    Comment


                    • #11
                      I have 2 oxygen concentrators that ran 15 bay muffler shops, on my to do list to hook one up & use with LP. Also have a moterized torch cutter & was amazed how smooth a cut can be when not done by hand.

                      Originally posted by ironmonger View Post
                      Artful

                      Keep an eye on craigslist for an oxygen concentrator. I found one locally a few years ago, and it came with a 2000 psi portable cylinder filler compressor. It makes about 5 LPM, and is quite happy to run unattended. You can then try to find an oxygen cylinder that some one bought and never recertified and fill that, you will never have to take it in for another refill.

                      In the states many gas suppliers charge rental based on the length of time that you have the cylinder, which makes refilling theirs a problem, but even if you could I would never refill a cylinder that I didn't own, as the O2 form the concentrator is only 95% or greater oxygen, but it is not 100% as the cylinder is supposed to be. My torch has never complained about the lack of purity :>)

                      I use it mostly to fill my little R cylinders, which are about 6" in dia. and about 16" tall. Handy but really expensive to fill commercially.

                      paul

                      Comment


                      • #12
                        Originally posted by
                        [URL=http://s35.photobucket.com/user/ptsideshow/media/Tools/WElding%20equipment/DSCF0010.jpg.html
                        [/URL]
                        Here are a couple of I beam chops.
                        I use it mostly for bending and heating.
                        See following post for more photos of the tip.
                        Can't blame process gases for poor technique. Most commercial cutting is done with oxy propane as it actually heats faster and more evenly for less cost. BTU's per cubic foot is about double that of acetylene. Surface finish is excellent.

                        Acetylene is for welding. Inner flame has all the heat which makes it easy to use as a very concentrated heat source.

                        Comment


                        • #13
                          Anyone ever use the gasoline & oxygen cutting outfits? I've only see youtube vids but the look impressive.

                          Comment


                          • #14
                            Originally posted by kf2qd View Post
                            Can't blame process gases for poor technique. Most commercial cutting is done with oxy propane as it actually heats faster and more evenly for less cost. BTU's per cubic foot is about double that of acetylene. Surface finish is excellent.

                            Acetylene is for welding. Inner flame has all the heat which makes it easy to use as a very concentrated heat source.
                            Have to agree, I've been using oxy/propane for cutting heavy steel sections (5/8"-2") for years and have always gotten very nice smooth cuts using this combo. Now with plasma for anything smaller I don't even need an acetylene cylinder any more.
                            Although I do miss oxy/acetylene welding.

                            Below a link to a short video showing the cut produced from a machine guided oxy/propane torch in a very thick section of steel.

                            https://www.youtube.com/watch?v=Zy3g4-D1ZeA
                            Home, down in the valley behind the Red Angus
                            Bad Decisions Make Good Stories​

                            Location: British Columbia

                            Comment


                            • #15
                              Originally posted by rowbare View Post
                              What make/mode is the cylinder filler compressor? I already have a concentrator I use for a glass torch, it would be nice to be able to fill cylinders with it too.

                              bob
                              They were using one of those for my grandpa too. It was a compressor unit that sat on top of the oxygen concentrator, the bottle laid down on top of it and had a quick release that went on the side of valve assy. I dont know who made it though. He does not need it anymore.

                              Comment

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