Using an Oxygen Concentrator/Generator for Soldering

Last updated:  4/21/22, 4/20/22, 4/9/22, 10/10/21, 10/01/21

Nancy LT Hamilton

Please see my Disclaimers page.

Please take care, work with a professional, and use due diligence to know your city, county, state, and federal guidelines/laws for the use and storage of compressed, bottled, or other types of gases in your home, studio, garage, outbuilding, etc.  You are responsible for your actions! This page is for entertainment purposes only.

I just finished my video on the oxygen concentrator.  It will be live on 4/22/22 at 6:00 am PST on YouTube.

I recently changed my soldering system.  After extensive research, I decided that it was too dangerous to keep my acetylene tank in my studio. I live in an area with a propensity for forest fires, and I was worried about injuring firefighters AND potentially blowing up my studio. I switched to a small, one-pound canister of propane with oxygen.  While I was researching new soldering systems,  and the reason I went with the smallest tank of gas I could reasonably use, was that I learned just how dangerous propane could be (see my torches page).  The oxygen for this system is supplied by an oxygen concentrator/generator.  (Either term works.)

A one-pound propane canister   

The Oxygen Concentrator

I purchased a refurbished concentrator (5 LPM) from Rio Grande (which is, as of this writing, out of stock).  It costs me about $450.00 + shipping.  Rio Grande also carries a full kit version for about $835.00 plus shipping – which is also out of stock, as of 4/21/22.  There were no instructions on how to use this machine (even though their site says it comes with them).  I eventually called Rio Grande’s helpful support staff because I had unanswered questions.  I share what I learned, on this page and in my video above.

If I was starting out,  I would probably purchase Stuller’s kit, below.  It has everything you need to get started besides the propane.  If Rio Grande gets them back in stock, you could purchase the kit there too (Item #:  500150, $834.75 for the kit [as of 4/20/22]).

Prometheus Concentrator

Items in Stuller’s kit:  “The Ready-Ox System includes the oxygen generator, a genuine Smith Little Torch with eight-foot hoses, 5-tips (sizes 3 through 7), regulator for disposable propane tank, propane tank bracket, spark lighter, reverse flow safety check valves, and step by step set-up and operation instructions.” (Quote from Stuller).   It costs about $827.00 as of 4/21/22 – shipping costs will be high due to weight.

Stuller only sells to businesses.  You’ll need a resale or business license.  See their requirements to open an account.  International and American accounts.

The Ready-Ox Oxygen Generator

Other places to purchase:

  • Bradshaw Oxygen Supply.
  • If you are in the United Kingdom, there is Tuffnell Glass.  They sell a reconditioned unit with the torch, hose, and safety glasses.  Not sure how many LPMs.  Contact them directly.
  • Invacare and other dealers carry them too. You could also check with your local health care shop that sells them.
  • And others.

There are 10 and 15 LPM concentrators available, although, for the micro-torch, that much oomph is not necessary.  If you are a glass bead maker, you’ll want a 10 or 15 LPM concentrator to power your larger flame.  Check with your community for more information.

If you are adventurous and want to make your own, here’s a video to watch.  I haven’t done this, so you are on your own.  Just thought it would interest you!

Ever wanted to tear apart an oxygen concentrator and see how it works?

Another video on the oxygen concentrator. Check out the video below.

Converting LPM to psi

According to the jewelry tech staff at Rio Grande, the 5 LPM concentrator produces about 7-8 psi.  This amounts to approximately (using the 8 psi number) 1.6 psi per LPM.  So, with my concentrator (when I tested it, it only went to 3.5 LPMs), therefore, I only get about 5.6 psi.  3.5 (LPMS) times 1.6 (psi) equals 5.6 psi.  Maybe my LPM meter isn’t accurate?

Here’s the formula I used:

5 LPM / 8 psi = 1.6 psi per LPM

How to see what your max LPMs are

To see your highest level of LPMs, remove your torch’s tip (I had to use a small plier to crack open mine initially)  and turn on the concentrator.  Open your torch’s oxygen valve and watch the clear gauge on the concentrator’s front.  There’s a ball in the bottom of the gauge.  That should move to the top of the gauge and end up on the 5.  If the oxygen at the torch is closed, the gauge will read 0.  Replace your torch tip and tighten well.

Concentrator Gauge with oxygen, at the torch, closed – reading 0

If not using a concentrator and a 1# propane cylinder, adjust your gas and oxygen based on your tip size – for the Smith Torch.  Here is Smith’s chart which explains which tip to use and the related psi.  The chart below is merely for reference for a concentrator and small propane cylinder system with the Smith Little Torch.  See your torch’s directions or contact the manufacturer directly.

With a disposable tank and an oxygen generator, you do not generally adjust the psi but instead, adjust the amount of gas and oxygen at the torch.  Once you get your concentrator set, you shouldn’t have to adjust it again.  But, you could fuss with it and use the formula above whenever you change tips if you wanted to.  If your flame keeps blowing out and the gas flow is set accurately, lower the psi on the concentrator.

(Above) The Smith Little Torch Chart for which tips to use with which gauge.  (Essentially, the tip size equals the psi.

No. 2 tips are for acetylene only.  Both the No.2 and the No. 3 are very difficult to light.

    I use a small, pen-like, butane torch to light my Little Torch.  Others have used alcohol lamps (be sure to put it out when you are done soldering!) and candles (ditto!).  I have not had success with my electronic lighter.

Generally, 5 psi is sufficient for the other micro-torches.  Set your concentrator to somewhere around 3.5 LPMs.  Experimentation will guide you.

What torches to use with this setup

As far as I know, with the 5 LPM concentrator, you’ll want to use micro-torches.  There are quite a few brands.  I’m only going to list a few.

  • Meco Midget – Rio Grande (500700) has the torch and tips for $236.25.  They also sell just the torch, without the tips, for the same price? I don’t understand that.
  • Smith Little Torch – Rio Grande, (500090). Little Torch with tips for disposable tanks. $261.45
  • Gentec – Contenti. Gentec Torch for disposable tanks comes only with a #4 tip but, you can purchase more. Don’t bother with the 2 or 3 tips. 114-473 for $164.75. There are also knock-offs available.
  • Grobet Hoke Torch – (not easy for one-handed operation). Amazon: https://amzn.to/3L4fWg6.   $67.25. 4 tips, no disposable tank hookup for propane/Mapp Gas Pro. See Contenti for tips (below).
  •  Contenti – Grobet Hoke Torch. (110-407). $62.00, four tips. For propane/butane and oxygen. They also carry the micro-tips (110-410), (which makes it a micro torch), for $24.50.

Oxygen Concentrator/Generator Pros & Cons

Cons

  • Bitch one: the noise level.  It’s pretty loud.
  • No instructions came with mine
  • I wish mine went to 5 LPM.
  • Shipping is expensive, as is the equipment.

Pros

  • Safety!
  • Constant supply of oxygen.  You won’t run out until the machine dies.
  • Safety!
  • Much cheaper in the long run.
  • Not filling the landfill with tons of small O2 bottles – if you can’t recycle them – but it is still wasteful as you’ll go through many more oxygen canisters than propane – 15 to 30 canisters to every one-pound propane canister!  See MF MetalArts’ video below.
  • You don’t have to have a hoard of O2 containers stored in the house/studio/garage – wherever.
  • The initial setup costs are on par with setting up an acetylene/propane and oxygen system.  Purchasing regulators, hoses, torches and tips, flashback arrestors, tanks, gas, etc., will cost you almost the same as a micro-torch, a one-pound canister of propane, and the concentrator.

MF MetalArts video on the ratio of O2 to propane used:

The dangers of oxygen – even though it’s not flammable!!!

Oxygen is NOT flammable, but oxygen makes fire burn hotter. Oxygen is also an oxidizer.  Oxidizers intensify combustion.  Oxidizers also widen the flammability range of flammable gases and liquids and lower the flashpoints and ignition temperatures of combustible materials so that these materials are more likely to ignite.

Did you know that steel wool burned?  Watch what happens with oxygen.

The Firefighter Insider has some scary videos on oxygen combustion and a lot of good information on oxygen safety.  Watch this video on what oxygen can do to a flame!

Some information about propane

Propane should never be stored in a home, basement, or attached garage in any enclosed space.  See Propane 101 for information on propane storage.

Never refill small propane cylinders like the 1# tank or the smaller 14.6-ounce bottle. Refilling these containers is against federal US law and comes with a $500,000 fine and up to 5 years in prison (that’s not the same as “jail”!).

See the video below to see why you shouldn’t refill the one-pound propane canisters.

One way to protect yourself is with a propane leak detector.  Be sure the detector is installed near the floor, as propane is heavier than air and, therefore, sinks.

I found this video on removing the gas from a 1# cylinder so that it can (hopefully) be taken to a recycling center.  I have not tried this.   Remove the valve thingy outside and away from any potential flame source.  Do this at your own risk. For entertainment purposes only!

A tool similar to what he mentions in the video, the core removal tool, can be found here.

I’m not suggesting that you do this.

Flashback Arrestors and Reverse Flow Check Valves

Smith Flashback Arrestors @ Amazon

Here’s an article from Hobart Welder’s, David Pryor on my website.  David talks about the uses of the arrestors and

Here’s an article from oxyfuelsafety.com on the difference between flashback arrestors and reverse flow check valves.

Here’s an article from the Harris Product Group on The What, Where, and When of Hose Type Flashback Arrestors to help you make a decision on flashback arrestors.

A flashback arrestor also contains a check valve so you don’t need both unless recommended by a professional.

Speak with a professional regarding the use of flashback arrestors and check valves with this type of setup.

From years of testing, many professionals have found that flashback arrestors and check valves are not necessary if all safety practices are followed.  Things like draining your hose, opening the baffles on the regulators, and turning off the gas pressure at the tank when shutting down, do much to reduce potential dangers.  Checking hoses, not using broken regulators, storing your tanks correctly, keeping them free from dirt, oil, and grease – all these practices and more will help reduce the dangers of operating a torch.  Remember, most injuries are caused by operator error, through either a lack of training, negligence, and/or neglect, etc.  Check with a professional before you install your system.

It is recommended to use a flashback arrestor with an oxygen concentrator.  The arrestor would need to be placed at the end of the hose, on the regulator side of both the oxygen and the gas.  Understand, though, that the pressure is so low with the 5 LPM concentrator that it might not be sufficient to open the valve in the arrestor, so you may not get sufficient O2 or propane, and your concentrator’s pressure alarm may sound due to backed-up pressure, AND your torch may not light.

I have no experience with flashback arrestors or check valves for this type of fuel/O2 system.  Check with a professional like AirGas before proceding.  I do not have flashback arrestors or check valves on my soldering system, at this time, but that doesn’t mean you shouldn’t. I am looking into purchasing check valves as they need minimal pressure to open as compared to the flashback arrestor.

Here’s a link to the Smith Little Torch Manual.  Read it if you are using this torch.

Be sure to check out my Q&A Torch page, my Torch page, and my page on gases.  Lots to learn!

Thanks for stopping by.