Using an Oxygen Concentrator/Generator for Soldering

Last updated: 4/15/24, 12/13/23, 4/21/22, 4/20/22, 4/9/22, 10/10/21, 10/01/21

Nancy LT Hamilton

Please take care, work with a professional, and use due diligence to know your city, county, state, and federal guidelines/laws for using and storing 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.

See my video: Why you Need an Oxygen Concentrator.

Contents

Oxygen Concentrator Problems and Solutions

Torch Flame Keeps Blowing Out

I just spoke to John at tech support for Rio Grande (12/13/23). I called because my flame kept blowing out when I added oxygen. The answer to my problem was that I needed to open the oxygen at the torch handle and run the concentrator for a few minutes. This allows the machine to purge air (not necessarily 02) in the oxygen line. John said there isn’t a reservoir holding the oxygen – which I didn’t know. He pointed out that when you run the 02 with the oxygen valve closed; the machine stops producing oxygen – even though it sounds like it’s still pumping away. He noted that the machine was designed to prevent oxygen buildup and a potential hose blowout if, for whatever reason, the hose becomes blocked or kinked. Remember that these machines were initially designed to supply oxygen to humans, and it wouldn’t serve them well if a kinked line caused an explosion or a blowout. It makes sense to me. It also worked! I love a $0.00 repair!

These days, I leave the oxygen valve open when I am done (not the gas!!!) When I start up again, I run the concentrator for two to three minutes with the valve open. Then I close it, and the torch doesn’t blow out the flame! I also start with a small amount of gas, add oxygen, and work up to a hotter, larger flame.

Torch Flame Keeps Fluctuating

If you are experiencing a fluctuating flame, there are a few things to check!

1. If your propane tank is low, switch it out for a fresh one. When the tanks are low, the gas takes a lot of pressure to reach the tip.

2. Check your torch tip’s cleanliness. Use a thin wire (obs, one that fits in the tip) or a torch tip cleaning tool to ensure no soot or debris is clogging the tip. Tap the tip afterward to knock out any debris.

3. Ensure that your propane tank is open all the way.

4. Make sure that the oxygen is turned up all the way.

5. If you still can’t get the flame to burn evenly and use a large torch, try switching to a smaller torch like a Meco Midget (Rio Grande) or the Smith Little Torch.

Draining the Torch When Shutting Down

John at Rio Grande also said, “Don’t burn off the propane/acetylene gas when shutting down for the day – leave it open (gas and O2 open) and unlit to drain into the ambient air.” John said this is because the flame can enter the torch handle and melt the Teflon packing when burning out the gas. Leave the oxygen side of the torch open, too, and drain it. After a minute or so, turn the gas torch handle off. I leave my oxygen knob open. Be sure to close it again before the next use! Have your ventilation running during this process

How to Operate an Oxygen Concentrator

Ensure that the gas is turned off at the torch handle.
Leave the O2 open at the torch handle. Start the 02 concentrator with the 02 side of the torch handle open.
Let the concentrator run for a minute or two.
Close the O2 at the torch handle.
While waiting for the concentrator to run, open the gas (propane or acetylene) at the tank and keep it shut off at the torch handle.
If you have one, adjust your fuel regulator to the required pressure for your torch type; otherwise, if you use a 1 lb tank, open the tank fully.
Once the 2 – 3 minutes are up for the concentrator, shut off the oxygen at the torch handle. Leave the concentrator running.
Turn on the fuel gas and light it. Start with a smallish flame.
Slowly add oxygen to the gas flame. You are looking for a sharp blue tip with no hissing.
Adjust to desired flame shape, size, and type.
At the end of the day, shut down your fuel container.
Turn off the oxygen concentrator. (Shut down can be in either order – concentrator first or fuel gas first).
Once both gas supplies are shut down, open the oxygen and your fuel gas knobs at the torch handle.
Let them drain. You can tell when they have finished draining, as you won’t feel any gas blowing out of the torch tip. Leave the oxygen knob open until the next soldering session.
Close the fuel gas knob at the torch handle. (See “Draining the Torch” above).
Go to bed! Haha.

Why I Changed My Soldering Setup

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

The Oxygen Concentrator

I purchased a refurbished concentrator (5 LPM) from Rio Grande. It costs me about $450.00 + shipping. Rio Grande also carries a full kit version for about $835.00 plus shipping. There were no instructions on using 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.

I would probably purchase Stuller’s kit below if I were starting out. 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]).

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.

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 healthcare 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. I 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), I only got 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 one-pound (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. See your torch’s directions or contact the manufacturer directly. Great information and charts from Miller Welds, who sell the Smith Little Torch.

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 want to change tips. If your flame keeps blowing out and the gas flow is set accurately, lower the psi on the concentrator. Also, see the section above titled:

A Problem With the Flame Blowing Out When Using An Oxygen Concentrator

(Above) The Smith Little Torch Chart shows 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 them out when you are done soldering!) and candles (ditto!). I have not had great success with my electronic lighter. Be very careful that the pen torch has the flame end facing out! A friend of mine burned herself severely by not having it facing in the correct direction!!!!!

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. Also, I wish that my LPM gauge worked.
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 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 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 for 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

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 decide 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 about using flashback arrestors and check valves with this setup.

From years of testing, many professionals have found that flashback arrestors and check valves are unnecessary if all safety practices are followed. Things like draining your hose (without lighting the flame – see above section titled: Important Update to Shutting Down an Oxygen Concentrator/Gas System – 12/13/23), 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, and 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 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 or it will stop producing oxygen even though it sounds like it is, AND your torch may not light. My setup does not have a flashback arrestor because of this.

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 considering purchasing check valves as they need minimal pressure to open 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.