Hi Luis, I got a 19-6 Harris torch with these check valves.
I also have these tips:
I have a flashback arrestor on the propane bottle and one for the concentrator as well.
Honestly I have never had an issue with it so far. I didn’t check about compatibility and I’m still here.
I got it from this shop as far as I remember
https://www.as-welding.de/
But probably you can get it somewhere else.
Given the package size it would be quite easy to buy the torch in the US and have it shipped. Most likely you will be able to find it used, if you have any friend that are vacationing here you can also have them bring it back. Just some extra options.
Flashback arrestors are good safety devices to have at the regulator. If a flashback or some sort of errant fire travels from the torch tip backwards through the hoses, a flashback arrestor will stop the flashback or fire from continuing on towards the gas tank. Thus, it prevents the gas tank from potentially becoming a full-on bomb. So, it’s good to have flashback arrestors at the regulators for safety. The downside is that is also suppresses the regular forward flow of gas from the tank onwards to the torch. The drop in flow varies. On the smaller tanks, I’ve measured a drop of, at least a couple of PSI. Not much to make a difference since what we, as framebuilders, use for acetylene or propane brazing is low PSI compared to a guy using acetylene or propane for cutting metal. However, most people that use an oxygen concentrator won’t use a flashback arrestor or a regulator coming off an oxygen concentrator. I’m sure it doesn’t hurt to put a flashback arrestor on the oxygen concentrator. It’s just not really as necessary to do since the oxygen concentrator isn’t a tank that could potentially become a catastrophic explosion in the event of a flashback.
About torches and hoses… Most hoses in America have “B” or “A” fittings to connect to American torches. Also, American torches (Victor, Smith, Harris, Uniweld, etc.) also have either “B” or “A” fittings on the end of the torch to connect to American hoses. If you use an American torch in your country with non-American hoses in your country, you would have to use an adapter that may be difficult for your local welding supplier to locate, or you would have to modify your non-American hoses to get the American torch to fit with non-American hoses. For that reason, I suggest you just purchase the welding hoses in your country which will NOT have the American “B” or “A” fittings. Then,buy an international Harris torch in your country. Harris installs the correct hose fittings on the torch end to connect to hose fittings that are regularly available in that country.
Sorry if this is a dumb question because I’m new to this, but how would a flashback into a propane tank cause an explosion?
In my mind, in theory at least, there is no oxygen in the propane tank so there could be no combustion right? In the lines I understand there could be some residual air if they were disconnected, but with the tank I don’t really understand the risk. Is it something that actually sometimes does happen because reality rarely perfectly matches theory?
Omg I found an oxygen concentrator complete with hoses and a gas connection (and stationary torch for glass blowing) within cargo bike distance!
Can anyone tell me if I can buy this and just replace the stationary torch with a handheld torch?
The price is crazy low though but maybe there’s just not much of a market for oxygen concentrators that aren’t fit for medical use and the rest of this stuff.
If it seems good to anyone with more knowledge about this I’ll send the guy an offer asap.
300 Euros seems super steep to me but other than that, all seems good.
This particular model seems to go up to 5lpm judging by the scale on the front, that is plenty, I never go over 3lpm on mine and lately I stay just over 2.
The connection is also standard, you will either have to use an adapter for your hose like this person is doing here or if you are lucky it will just screw in once you remove that green adapter, mine came with the adapter like in the picture but once removed the connection was the same as my hoses.
You most likely won’t need any tools like those, just the oxy concentrator.
If you try it, make sure oxygen comes out, there should be leds and audible notification of any issues.
Mine takes 30-45 seconds once started to go to an “all green” status but only if the oxy flow is open, if there is no flow it will start beeping, remember, this was designed for human use, if there is no flow it’s a problem so, not all “alarms” are bad for us, some simply means that the flow is not open.
On mine I just disconnected the wire to the buzzer, problem solved!
But yeah I leave the O2 knob on the torch open at least a little all the time, to avoid that period of time after you turn it on when it’s not making high-purity O2 at first. Shutting the valve briefly probably doesn’t harm it but who knows, they’re not meant to be shut off like that ever, so maybe safer to just leave the valve always open.
Not claiming to be an expert about this, everything I know I learned from Doug Fattic.
Well unfortunately this is the first time I’ve ever seen an oxygen concentrator for less than €350 here in Belgium so €300 and an included propane regulator is probably the best I’ll find here. And it being super close by is a bonus.
Yes I looked up the model and it does go up to 5 lpm which is what I’ve seen people recommend.
Okay nice hopefully this will be the same then.
I’ll send the guy an offer but ask to test it first.
Okay so I just picked it up, for €300 I got a companion 590i oxygen concentrator, a propane regulator and a Nortel minor benchtop glass working torch. (And hoses but the guy said this setup had been sitting for 10 years at least so I’ll be replacing those)
The companion 590 needs to have a couple of brittle hoses replaced but other than that she purrs beautifully.
Thanks for all the replies!
I’m probably overthinking this, but interestingly the tips that you have are injector style tips and the Harris catalogue specifically mentions oxygen pressures of 1-1.8 bars for the different sizes. An unmodified concentrator only produces about 0.5 bars. Obviously it works nonetheless as you have used this setup for brazing but I’m still a bit confused. Do you adjust the concentrator to the full 5l/min and then adjust the flame on the torch itself? What propane pressure do you use?
Yes I crank it up to 5l/min and then adjust the torch, Propane I think I´m using 1.2 bars, but I´m not sure, I need to check.
Maybe what you say is valid for Acetylene, with propane honestly I have never had any issues.
What Torch did Doug recommend? When I took a class with him more than 10 years ago, he recommended the Uniweld 71 handle with a couple of different tips. This is what I got back then. I used it when I started with acetylene, but then I switched to propane + oxy concentrator.
I used to have that exact same machine. Be warned – it’s an old machine – long since out of production, so getting spare parts can be problematic. Open it up and make sure the hoses haven’t solidified and started cracking. I have PDFs of the manuals if you need them.
-Jim G
Hi Jim, yes I’ve opened it up and read production date '97 / '98 on some parts, she’s (slightly) older than I am!
The clear/white oxygen hose that goes to the output did go brittle and cracked but luckily that seems to be the easiest one to find and replace, the others are still nice and flexible.
I’ll keep it in mind if I ever have an issue I can’t figure out, thanks!
That’s the exact torch that Doug recommends in the velocipede forums for brazing with propane and oxygen. Just out if interest, where did you take that class with Doug?
Since you didn’t have any problem with your injector style tips I went ahead and bought a Greggersen Ergomax setup. It’s made here in Germany and it’s super common, so I won’t need any adapters for the hoses and finding parts is as easy as visiting the closest welding store.
I found a couple of posts in German forums about brazing with propane and an oxygen concentrator and someone mentioned, that most concentrators have overpressure valves that one can adjust to up the pressure of the machines. I fiddled around with that a bit and managed to get 1.3 bars of oxygen pressure out of my DeVilbiss 525. That’s right around the pressure that the 2-4mm Greggersen tip calls for. With this setup I can adjust the oxygen flow to
around 1 liter/minute and the propane to ~0.1 bars and I get a stable flame that I can adjust very finely. Now I only need to learn how to braze. 
Maybe this information will be helpful to someone without easy access to US torches in the future. 
Hi Luis, thanks for the info. I will try to get some tips for propane, I think these ones are for Acetylene only, and I´ll give it a try. I remember I had some trouble finding adapters for the different threads. It is quite a nice torch to be honest, small and with the flex hose was super nice to use it.
I will look around to see if I can get higher pressure output out of the Philips concentrator. What I´ve read is that you can get higher output but lower oxygen concentration, sometimes less than 90% but this is just forum talks.
This is the Forum post I’m referencing. Doug compiled a list of everything that one needs to braze with oxy/propane. He specifically mentions the Victor TEN tips for propane and the Uniweld 71 torch. So you should be ready to go!
And since the Victor mixer should be of the equal pressure type, you don’t even need higher pressure out of the conecntrator.
Cool! I thought everything I have was for acetylene.
I must say I was happier when I was an ignorant, now that I know that I could have blown up I’m very concerned 
FYI I’m using 0,5 bar with Propane, I’ve just checked my setup, forget what I said about 1,2 Bar 
I was about to tell you to get some Paige Tools tips but it seems they are gone.
Does anybody know if Paige is still operating and/or what happened?
Looks like the owner has possibly passed away.
Another one, between him and TinMan we are losing a lot of good small local companies
