Oxygen concentrator

Continuing the discussion from Swiss torch/platinum tip/oxygen concentrator?:

Perfect timing for me, I was just looking into a oxygen concentrator to replace my O2 tanks. Cost me about $400 to rent a truck and refill my oxygen tanks. Where do I find information on how to use an oxygen concentrator. How do you hook it up to your propane? Do you just turn it on and suck air in? I know there’s got to be information about the transition somewhere? Right now I use a Smith little torch, propane and O2. Thanks Christina

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Look around the archives and recent discussions, lots of information about O2 concentraters and propane.

Rob is right, there is lots of info in the archives. As far as hooking up, you will hook up your propane tank as usual to your torch. The oxygen concentrator will have an threaded outlet which is usually hooked up to a brass fitting that ends in a hose barb. You may find one to fit to your torch hose directly. Otherwise, you will just have to exercise a little creativity and get some kind of (probably brass) fitting to go from the concentrator’s threaded outlet to your torch hose’s female nut. You will find a display board at your local Home Depot or similar with lots of brass fittings and adapters and you should be able to find something to fit. Bear in mind (see archive discussions) that you will probably want a check valve in the oxygen line, so that has to be plumbed in. I would not worry a whole lot about it, just get a concentrator and check valve and take them and your torch to Hope Depot or your local welding supply and someone will help you figure out what to do. You should be able to find a reconditioned or used concentrator for less than the $400 you paid to refill the oxygen tanks. I think I paid $350 for my reconditioned one. Less for a used one from a private party. There is an hours counter on the concentrator, so you can see how many hours it was used. It should be good for over 10,000 hours and it isn’t unusual to find one with just a few thousand hours on it. People who are rather sick use them and usually check out well before the equipment does… -royjohn

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Mine has a not-so-sturdy plastic fitting to attach the hose to. If yours does, over-tightening might strip the threads or possibly even break the fitting so be careful. Wrapping the threads with teflon tape might help.

A little leaking would not be a horrible thing - it isn’t a poisonous gas, its just the room’s oxygen going back where it came from. I’m not suggesting to be careless about it, just to not overdo the tightening and strip the threads if the fitting is plastic.

They are actually pretty simple devices. If the one you get does not come with a manual look for one online being sold to jewelers that does have a manual to download. Odds are it will serve well enough as a guide.

Neil A

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I’m a believer. A used oxygen concentrator was gifted to me. A friend who needs O2 to breathe let me observe his machine and how it works. He also gave me some of the used tubing - it’s replaced about every 6 months. Nothing wrong with the tubing, it’s just SOP. I’ve been using a 20# O2 tank with natural gas (NG).

So simple. Just push the tubing connector onto the machine’s connection, push the ‘on’ switch, and feel the gas rush out of the tubing. Since I didn’t need or want 50 ft. of coiled tubing, I cut it off at about 8 ft., and put it on the ‘oxy’ fitting of my Hoke torch. It fit snugly so the pipe clamp was unnecessary. My machine is rated at 5 liters. I operate it about 0.5 liters to mix enough O2 with the NG for a nice brazing flame.

The machine seems a little confused initially, but after a few minutes it ceased making beeps and light flashing. Quiet and constant O2 flow. No regulator, no pressured O2 bottle, no need to turn off the O2 when putting the burning torch on standby.

THANKS to all who have been encouraging about using an oxygen concentrator. Like those new LED shop lights I put in, WHY did I wait so long!!

Judy in Kansas, where Summer may have given us its swan song. No more temps in the 90s…YAY!

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Christina…Sorry that my first post was so short. I was on my tablet and it is not typing friendly. All that others have posted is good advice and a repeat of much of what has been posted in the past couple years about O2 generators/concentrators. They can be found on craigslist and other similar places. The only precaution is that, if it has sat around for a long time, it may not work properly. The sieve beds need to operate on a regular basis to stay healthy. I would look for a local medical device reconditioning place where they get rebuilt. I am lucky enough to have one nearby where I can also buy replacement filters. Once you find a good unit, per royjohn, it should last a long time as they are made to run 24/7. Judy, please tell us more about running your Hoke torch on NG. Is it street pressure (less than 1 psi). I experimented with a very old Hoke torch and got it to run on street NG and O2, but it wasn’t a great experience. I often wonder if a new torch would work better. That being the case, I could get the 1 lb. propane cylinders out of my shop. An NG accumulator is on my list, but a long way down. Again, take a tour of the archives and you will find a lot about this subject…Rob

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The new Hoke torches are made in China and the quality is poor. People have especially complained about the quality of the needle valves.
The Hoke was the standard of the industry for many years. I trained and worked with them for decades. They worked with standard street pressure natural gas, though that is no longer legal in New York as commercial flashback arresters need higher pressure.
When I moved to a hobby studio set up in my apartment I went with a Little Torch on propane. I found an old, USA made, propane Hoke on ebay, though I haven’t set it up yet.

Thank you all for your replies, I have a better idea for what I’m looking for and how to set it up.

I got a used Ox concentrator for free. It is max 5 liters, which is fine for soldering, but not very good for melting metal for casting. Try to get a 10 liter unit.
I literally just plugged a clear plastic hose into the unit, put an arrester on the line, turned it on and started using it. If you turn the air flow off while it is running an alarm will sound, which will stop a minute or so once the ox flow is on again. I usually just turn off the gas when I am in the shop and leave the ox flow on. Seems to be ok. Good luck.

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I’m not sure why flashback arrestors are needed on the oxygen side when using a concentrator. There’s no oxygen to explode……

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I have no arrestor on my O2 concentrator, just on the Propane valve. I read that an arrestor can impact the already minimal but sufficient ( for most needs) pressure and flow of the Oxygen, but mostly it is not there because I do not see it as a problem.
I could be wrong.

I am relatively new to using a concentrator and small propane bottle, myself, having for over 45 years used full size tanks, and even piped natural gas and Oxy. None of my employers ever have any arrestors at all, but when I set up my home shop, I aimed to satisfy more stringent Insurance Co requirements for a home.

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I have run my torch with and without flashbacks/check valves and there is no difference in operation. This doesn’t make sense, since there is likely a pressure drop across them, especially a check valve. I added them in sequence, first the propane side then the O2 side, expecting some measurable reduction in capacity. You are correct that there is little O2 in storage, but I guess better safe than sorry. I have considered removing them to see if there might be an impact on my limited ability to melt brass and copper. Once I do this, I will report the results. I note that the system that Rio Grande sells appears to have at least check valves installed…Rob

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The flashback arrestor are there to stop a pressure wave/explosion to travel back into a tank/storage device and rupture something causing flammable gas leaking.

Gases themself are non flammable when there is no Oxygen available ref. the “fire triangle”
The amount of Oxygen needed to be combustible depends on the gas. Acetylene are the worst I believe, the others are more “benign” in that they are combustible only in a narrow range.
Thus an actual explosion of a tank/storage device is highly unlikely.

But a leak of flammable gas may cause catastrophic fires anyway.
A leakage of Oxygen do not pose the same amount of immideate danger, but if left unchecked, may contribute to a fire if it ever happens. I think we were thaught that a 1% increase on Oxygen doubled the rate/speed of burning.

The need for flashback arrestors, should not be neccessary on Oxygen concentrators. Because if there are a flashback that breaks anything on the Oxygen side, you should more or less notice it immideatly due to lack of oxygen at the torch.
You will then have ample time to take measures.

What regulatory rules may or may not say, that is a completely different ballgame :slight_smile:

Acetylene, even if it is good in many ways,
differ a bit from other flammable gases.
Because it can decompose catastrophically without Oxygen if sufficiently shocked or overheated.
Tanks should always be kept/stored outside if possible.