Converting to Oxy/Propane

Education Welding
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I can’t get registered on velocipedesalon, so I’ll ask here:

  1. Propane tank from a local store
  2. Propane regulator with 2 gauges for both line and tank pressures with CGA 510 tank fittings
  3. 5 LPM Oxygen concentrator (it does not need an oxygen regulator)
    a) or an oxygen tank from a local welding supply store
    b) They come in 20, 40, 60, 80, 125, 150 and 251 cubic feet sizes with prices from $75 to $350
    i) which requires an oxygen regulator. It is preferable to get one with the least wide oxygen pressure settings (like 0 –40 psi instead of 0 – 100)
  4. Type T 3/16" hoses (the smallest) with B fittings on each end (probably 12 foot length – 25 or 50 ft. is also an option)
  5. “B” size flashback arrestors to connect the 2 hoses
  6. Smith Kevlar 10’ hose with A and B fittings ($70+) (Smith part # 14779-4-10) (this is optional since you can run a T hose to the torch)
    a) or TM technologies light hose (item # AWS-0052) ($45)
  7. “A” size check valves that stop the back flow of gas but not a flame (can be optional).
  8. Uniweld 71 “airline” torch handle
    a) or the Gentec or Metalmaster 140T or the Victor J-28
  9. Gentec 881 elbow (the equivalent to the Victor UN-J) (Victor part # 0325-0101) (this unit also needs a separate screw-on TEN tip)
    a) with Gentec 883TEN-2 screw-on tip (the equivalent of the Victor 2-TEN tip – Victor part # 0311-0485)
    i)one might also want a size 3 and maybe a 4 (Gentec 883TEN-3 & 883TEN-4) or (Victor 0311-0486 & 0311-0487)
    a)Another elbow tip all in one option is the Uniweld 17-2 all fuel brazing tip (one might also want the 17-3 size)

Is this still a good setup for oxypropane brazing?

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Just one thing to add, two gauges on the propane regulator doesn’t hurt, but it doesn’t add much info. Single-gauge for the line pressure is all you need, since the tank pressure doesn’t change except from temperature. The bulk of the propane in the tank is liquid, and the pressure of the gas on top of the liquid is just whatever the vapor pressure of propane is at that temperature. It’s hardly varies at all from full to empty, so the tank pressure doesn’t tell you how much you have left.

In fact a lot of people have gotten by just fine with propane regs with no gauge at all. Just turn the line-pressure knob to get the flame you want.

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That said, my propane reg has two gauges because that’s what I was able to buy cheap used on ebay (or was it Craig’sList?)

Be careful using acetylene regs, which sometimes work perfectly, but some are not rated for propane. Like Grade R hoses versus Grade T, some acetylene regs have diaphragms that can be degraded by propane. That’s what I’ve heard, but I don’t know how likely that is. Maybe they’re all good for propane now? But I’d confirm that.

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123

Put the tank on a scale I guess to determine what’s left? Good to know though, the propane regulator that came with my oxy concentrator just has one gauge.

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Thanks!

I’ll put together a specific list of what i get once i get it to make it easier for folks looking for a buy list.

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Exactly. USA tanks have the empty (“tare”) weight stamped into them. Maybe not all of them? But the three I have all do, “TW” followed by the weight in lb. If you make a note of what it weighs full, then you have the whole gamut from full to empty.

It’s linear, so if it weighs halfway between the empty and full weights, it’s either half full or half empty, depending on your philosophy. Or if you’re of a scientific bent, it’s always 100% full, just some of it is liquid and some is gas. (Not helpful!)

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126

Hi Luis, today I received the 3/8” BSP LH to 9/16” LH adapter, I assembled and tried the torch.
It happened the same thing that it happened when I had the acetylene setup. Almost 50% of the times, when I turn of the torch (first Oxygen then Fuel) a small flame remains and :boom: a small bang! Which is really annoying and I don’t know why is happening.
Here is how the setup looks.
Anyone knows why this might be happening? Is very annoying (possibly dangerous?) I do have flashback arrestors on the torch and on the tank.

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Wait, they always told me to turn off the torch by turning off the gas first, then the oxygen.

What I end up doing is turning UP the oxy so the flame extinguishes and then I close gas first and then oxy.

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Why do you have so many flashback arrestors in your lines ?
One is enough at the regulator.

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I think everyone learned it different. I’m just following what’s in the Uniweld manual.

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Hello again,
I’ve been playing around with the Oxygen Concentrator and Propane setup and I can’t seem to get a stable flame. The flame seems to be “breathing” somehow. The cone grows slightly bigger and then smaller again every few seconds. Did anybody here face a similar problem when working with an oxy concentrator? My research suggests that it could also be a problem with the propane regulator. I bought a fairly cheap one with only one gauge, maybe the regulator doesn’t work very well under 0.5 Bar?

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I have noticed a change in flame after a minute or two of usage, I have to slightly adjust it after that but then no changes.
I have attributed it to either the O2 concentration changing or maybe the tip being hot and chancing the flow slightly or simply the pressure regulator on my O2 is not as precise and it changes a bit.

It does not happen every few seconds.

If your regulators are not keeping up, I would maybe have a higher pressure out of them and then regulate it down at the torch, sort of building a little pressure in the hoses to make up for any lost one.
It’s totally possible that for such low pressures your regulator has a hard time regulating correctly

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Some oxycons “pulse” – larger machines have two zeolite chambers that they alternate between to produce a smooth output, while smaller (portable) machines may only have one chamber that cyclically gets pressurized and emptied, producing an inconsistent flow. What kind of machine is yours?

Alternatively, I did recently have a similar problem with a propane tank that I suspect is nearly empty. I couldn’t maintain a stable flame, and the pressure gauge on the regulator was behaving oddly. I switched to a different tank and that solved the problem.

-Jim G

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If it wouldn’t be too difficult or expensive for you, get an O2 bottle and reg, even borrowed temporarily. That would settle the issue of where the instability comes from. If it’s still there when using bottled O2, then your P reg is the cause. (or something else on the P side, bottle or hose or flashback arrestor or…?)

If your concentrator has two sieves (as do all the ones I’ve tried) and one gives more flow than the other, it could be time to have it reconditioned. Unless it’s just a badly designed unit, and that pulsing is normal for it? Did you say what make/model it is?

I’ve never had one reconditioned, no idea what it costs, but there are businesses that do that, and sell reconditioned units. They cost more than a Craigslist score of unknown history, but still way less than a new one. Doug Fattic has told us about at least one such business.

Or maybe educate yourself on how to rebuild it yourself. I’ve heard the sieves can be repacked with fresh zeolite, doesn’t sound like it needs any fancy equipment. Rebuilding the compressor might also be needed. I saw a Youtube of a guy overhauling his, he had a rebuild kit from the manufacturer, and the skills and tools needed were basic. I wouldn’t expect that kind of pulsing from the compressor though, sounds more like a sieve problem. Or a leaky hose connected to one of the sieves? That would be nice to find since it’s an easy fix.

Or just dive back into the cesspool of CraigsList/OfferUp (or local equivalent if you’re not in the US) and roll the dice on another one. I’ve bought three used ones (sold one, have two currently) and all 3 have worked fine. The last two were $75 each, so they aren’t worth a lot of work to fix, if I can just find another cheap one. Maybe not so easy for you, I’ve heard they aren’t as plentiful everywhere, or I got lucky.

But there’s honor (or karmic cleansing) in rebuilding things rather than throwing them away. Oh yeah definitely don’t throw it away — even one that pulses like yours will still be of value to someone, a lampworker maybe, or for parts to someone who rebuilds 'em.

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Thank you for all your input!

Since I’m working with a Devilbiss 525 that has only about 300 hours of runtime, I figured that it probably wasn’t the cause for the fluctuation since I’ve seen that a lot of you are using this machine. After “researching” for a couple of hours, I landed on a couple of lampworking forums where people described this exact behavior, and it almost always turned out to be a problem with the propane regulator. Now the cheap one that I bought is only rated for 0.5-4 bar (7.3-58 PSI), and that apparently means that for pressures under 0.5 bar the diaphragm of the regulator can’t keep up with tiny changes. I went out and bought a good regulator, and the problem has disappeared.

Now I still find it very hard to adjust the flame to be neutral. Doug has written in a different forum that as one ads oxygen, the color of the flame will change from greenish to light blue and then to purple, but I’m really struggling to see these colors in the flame. No matter how I adjust the flame, I keep burning the flux on my practice pieces even before the metal has a chance to get up to temperature for bronze brazing. Do you have any advice for me?

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What flux are you using?

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This is the flux I am using. It’s the only one I found that I can buy here in Germany as a non-professional.

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Ah OK, I just wanted to make sure you weren’t using silver flux.

The temperature limit of 1100° C on yours is a bit low compared to fluxes I use that are rated to more like 1200-1300° C, but it should still be in the ballpark.

Is “in the ballpark” an expression in Europe? Probably not! I just mean close enough, probably adequate.

Framebuilder Supply sells Gasflux brand bronze brazing flux, used by most US FBs. They might ship to you, (you could ask), but I imagine shipping cost would make it not worth it.

But back to your flame: I don’t think it’s all that critical in terms of keeping the flux alive, though oxidizing is worse than reducing, so maybe err on the side of to much fuel.

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I’ve had the exact same experience with this flux. Ended up aquiring the pro stuff through the company I work for:

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@bulgie We don‘t have this exact expression in German but since I grew up watching English shows and YouTube I am familiar with it :smile:

I think importing flux would be too much of a hassle though and would probably also mean that I would need a license to import it. There must be some European made flux that’s up to the task.

@Luniz82 That is good to know! I guess that is the route that I will need to take.
Any reason you went for the powder instead of the paste?

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At the end of the day, it is the same stuff. I figured I can get more bang for the buck if I buy the powder but ultimately I don’t think it makes a big difference…

1 Like