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Medical Oxygen Concentrator For Welding Oxygen


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  #1  
Old 04-17-2019, 11:50:05 PM
dalmatiangirl61 dalmatiangirl61 is offline
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Default Medical Oxygen Concentrator For Welding Oxygen

Came across this video a few nights ago and been wondering about it. Anyone here using one of these things, in this way? I'm wondering how long it would take to fill a full sized oxy cylinder, and the cost effectiveness of it. I see these as scrap on a regular basis, so cost there would be minimal. Bottle swaps in Nv are not cheap (double the reg cost) due to transport costs, and there is the whole pia drive to town thing, and they might be out till next truck shows up. Lastly, what are the safety concerns?
https://www.youtube.com/watch?v=GxclrM270gA
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Old 04-18-2019, 12:42:50 AM
Vanman Vanman is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

I've seen that one as well. It would be radically more efficient, energy wise, to skip the compressing and bottling step. Of course it's nice to have the capability for the option of portability.

There's a fellow on Youtube that makes vacuum tubes using a torch supplied with natural gas, and oxygen directly from a concentrator. I think his channel is Glasslinger. Repairs old radios and stuff too. Quite entertaining.

I can't see any safety concerns, so long as all of the usual precautions required in oxygen handling are followed.

Keith

Last edited by Vanman; 04-18-2019 at 02:04:49 AM.
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Old 04-18-2019, 11:04:37 AM
Pete Spaco Pete Spaco is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

I think that would be great for jewelers and others who do tiny work, but I wonder how long a full cylinder would last for doing even moderate sized work in a home fab shop.

Here's a page that describes medical oxygen tank sizes, fill and usage rates, etc.:
https://www.tri-medinc.com/page32.htm#R31081

I have a "farm size" oxygen tank that's about 125 cu feet. I probably only get about an hour or two of cutting out of it, using propane. So, it's hard to imagine getting very far with that tiny cylinder.
These days, I do most of my cutting with a Chinese Plasma cutter and use the oxy-propane or oxyacetylene outfit for general heating (with a rosebud) , for welding of smaller and putsy steel stuff and for cutting material thicker than about 1/2".

Still, I think it would be interesting to port the concentrator's output directly to a torch (with a low pressure regulator?) and see how much of a continuous output you'd get.

Then there's:
https://www.multiplaz.com/about
if you are looking for a way around buying gases.
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Old 04-18-2019, 01:32:10 PM
dalmatiangirl61 dalmatiangirl61 is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

Pete, I was thinking skip the little medical bottle and compress straight into a normal oxy welding cylinder. Of course downside there might be burning up the compressor because it was not meant for running 10 hours straight. Anyone know what the media is that absorbs the nitrogen? My other thought is to just build a larger unit, not really much different than a dual cannister desiccant drier, one cannister gets used till "full", then switch to other cannister and bleed some from that cannister to purge the other one, reverse when needed.

There are several vids where people use 2 of the medical units to feed a torch for brazing and gas blowing, they just feed straight from concentrators to torch, no compressor.

I don't do a whole lot of cutting or brazing, but when you need a torch its nice to have.
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Old 04-18-2019, 01:54:24 PM
Andrew Mackey Andrew Mackey is offline
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Question Re: Medical Oxygen Concentrator For Welding Oxygen

Dalmationgirl, how much do those scrapped units go for? I was interested in one for myself, but i don't see them here in NJ.
Andrew
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Old 04-18-2019, 02:14:03 PM
dalmatiangirl61 dalmatiangirl61 is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

I would have to weigh one to find out, standard price at local yard is .30c a lb, being there is a lot of plastic and media in that weight, + my "frequent shopper" discount, if a whole load of them comes in I can probably get a better price. I've seen them in 1's and 2's, and whole trailer loads. Probably available on CL too, no idea what people would want for one, scrap units might have problems, but if enough of same kind, there should be enough to mix/match and get one running.

Hmm, thinking some more, if you built a larger dual tower concentrator, then fed with compressed air from regular shop compressor, could you just run it straight to a cutting torch?
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Old 04-18-2019, 05:11:05 PM
DustyBar DustyBar is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

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Originally Posted by dalmatiangirl61 View Post
... Anyone know what the media is that absorbs the nitrogen?...
I believe the concentrateor has two containers of zeolite. It compresses air into one while using the oxygen enriched air stored in the other. I believe releasing the air from the charged zeolite container allows oxygen out first. At some point the nitrogen is released or purged. You can hear the machines switch between the two tanks. I also don't think this is 100% oxygen, rather just enriched.

https://en.wikipedia.org/wiki/Pressu...rption#Process

Last edited by DustyBar; 04-18-2019 at 06:37:51 PM.
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Old 04-18-2019, 08:57:57 PM
Thaumaturge Thaumaturge is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

From what I know of them, Dal, I think the biggest issue might be one of system pressure. Units are made to concentrate a large enough quanity of oxygen in use to avoid having to use big bottles. Full tank pressure is 2200psi. Not sure concentrator would be up to fully recharging a bottle. But then again you wouldn't need a full recharge for it to become economically useful.
Doc
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Old 04-18-2019, 09:11:21 PM
dalmatiangirl61 dalmatiangirl61 is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

Well I was going to correct you on the vermiculite statement, but I see you've already fixed that . Not really sure what the difference is between vermiculite and zeolite, only place I'm seeing it discussed is on a mushroom growing forum. Yes I did some reading on the process today to find out what is used. Dual tower desiccant dryers work the same way, kind of, active tower bleeds off enough into inactive tower to purge the moisture to atmosphere. I used to have 2 big dual tower desiccant dryers, sadly they were scrapped years ago because no one wanted them, now I could use one.

I think the medical oxygen concentrators only go to 98%, but from the videos it looks like it works. Would that unknown 2% affect brazing?

Edit: Doc, some of them have a high pressure compressor too, but realistically its only designed to refill small bottles, not big ones. Further thinking on using shop compressor to feed the zeolite towers and realized I would most likely need a coalescing filter to remove oil before oxygen concentration.
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Old 04-18-2019, 09:13:49 PM
DustyBar DustyBar is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

They are totally incapable of producing 2200 psi. The oxygen enrichment process doesn't even come close to working at that pressure. You would have to provide a high pressure pump to fill the cylinder with only an enriched oxygen/nitrogen mix.
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Old 04-18-2019, 09:27:36 PM
Rod V Rod V is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

Medical oxygen concentrators take the oxygen out of the room air and through sieve bed canisters , to extract the oxygen There are none that make 100% pure oxygen. Most commercial cylinder oxygen is not 100% oxygen either. The only real difference in Medical Grade Oxygen and Commercial burning/welding oxygen is the testing that is required for the Medical grade (medical has to be 99.5% pure). I worked in the medical field for 29+ years with compressed medical oxygen and concentrators. The valves on the cylinders that fill off the concentrators are different then a regular O2 cylinder. There is only about 12CF of oxygen in one of the small cylinders, as obsessed to the "M" Cylinder with 125 CF and "H" cylinder 282CF. Most shops that do a lot of burning or welding now use Liquid Refrigerated Oxygen (less storage space with high volume of oxygen). I have seen people try to go directly off the concentrator to burn and has work just OK. I would not recommend that for anything that is a specific cut that needs to be straight and clean. Just thought I would throw it out there since I have worked with these machines for years.
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Old 04-18-2019, 09:30:47 PM
dalmatiangirl61 dalmatiangirl61 is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

Dusty, watch video in first post, according to that vid the compressor goes to 2000 PSI, and it is 94-96% oxygen. The concentration of oxygen happens at a lower pressure.

From what I've see so far, the main limitation on the medical units is that they do not produce enough oxygen to run a cutting torch directly, but they do produce enough to run a brazing torch. That limitation is what got me to thinking of larger towers, and just feeding them compressed air from a shop compressor, then feeding that straight to a cutting torch (regulated pressure), no high pressure compressor needed.
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Old 04-18-2019, 09:55:56 PM
DustyBar DustyBar is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

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Originally Posted by dalmatiangirl61 View Post
...according to that vid the compressor goes to 2000 PSI, and it is 94-96% oxygen. The concentration of oxygen happens at a lower pressure.

... just feeding them compressed air from a shop compressor, then feeding that straight to a cutting torch (regulated pressure), no high pressure compressor needed.
The pressure swing adsorption process only releases oxygen when the pressure drops. The zeolite is charged to some higher pressure and then allowed to drop so a continuous high pressure supply of air would have to be interrupted or cycled between two or more concentrator media tanks. I don't know how long the adsorption process takes. You most likely would need a second compressor to get it back to the 20+ psi you need for the torch.
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Old 04-18-2019, 11:43:36 PM
dalmatiangirl61 dalmatiangirl61 is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

Quote:
Originally Posted by DustyBar View Post
The pressure swing adsorption process only releases oxygen when the pressure drops. The zeolite is charged to some higher pressure and then allowed to drop so a continuous high pressure supply of air would have to be interrupted or cycled between two or more concentrator media tanks. I don't know how long the adsorption process takes. You most likely would need a second compressor to get it back to the 20+ psi you need for the torch.
I don't think that is correct, atmospheric air is pumped into the zeolite chamber, the zeolite absorbs the nitrogen leaving enriched oxygen, the oxygen then needs to be transferred to a reservoir, pressure released from zeolite chamber which releases the nitrogen, then nitrogen is purged back to atmosphere. Which is basically the same as a dual tower desiccant dryer, just need to speed up the valve switching

What I'm envisioning is 2 nitrogen scrubber/zeolite canisters, 8"-10" maybe 12" diameter and 4'-6' tall, and lots of valves. Or maybe it would be better to go with lots of smaller chambers?
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Old 04-19-2019, 02:05:09 AM
Thaumaturge Thaumaturge is offline
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

What the heck, go for it Dal! FWIW: surplus center has high pressure check valves for ~$9 ea. https://www.surpluscenter.com/Hydrau...350-9-8035.axd
Don't forget to rinse any oil out of tubes/valves.
Doc
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Old 04-27-2019, 07:01:09 PM
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Default Re: Medical Oxygen Concentrator For Welding Oxygen

I stumbled into a lot of medical oxygen concentrators at an auction some time ago. I have a pair of them set up with small torch that works fine for brazing and silver soldering. I've not tried welding - I think they run 95% ish oxygen, which I'd guess would be OK...
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