An oxygen concentrator might be one of the options to consider when buying a brazing outfit. For those not familiar with them, they are the units that supply patients (usually elderly ones) with nearly pure oxygen when their lungs are no longer working at full capacity. They are a small machine about the size of a suitcase that separates out the nitrogen and carbon dioxide in the air to supply nearly pure oxygen (pure enough for brazing anyway). They have a clear plastic hose that runs to a patient’s nose. They are heavily regulated in the medical industry and cost thousands of dollars if buying them outright or rent for hundreds a month. However there are used ones sold on the open market at modest prices for non-medical purposes like glass flame-working or brazing. They are popular with those that make jewelry.

Someone might consider this option is for reasons of safety, convenience and cost. Because it is not a highly pressurized tank, it isn’t going to turn into a missile or bomb if something goes wrong. There is no need to transport them to the store for refills (only possible during open hours) and the cost to run them is only the electricity they use and an occasional filter change. Because they have a built in flow meter, they don’t require a regulator saving that expense. Their biggest disadvantage is that they have to run for a minute or 2 before they produce enough pure oxygen or it will blow out the flame.

Probably the biggest market for concentrators is for people that live in big cities where the purchase and transport of oxyacetylene tanks are restricted or are a long way from a welding supply store. Furthermore some rental or home insurance policies are not friendly to potentially hazardous tanks. This unit solves those problems.

They are made with various amounts of oxygen output. The smallest ones at 5 liters per minute work fine with torches usually used for brazing. Their units of life is measured in hours used and designed to run for several years continuously.

There are many companies that sell refurbished ones. I bought mine from M&M Medical Repair in Beaverdale, Pennsylvania. They have all kinds of makes and models in stock. They are a supplier to other retailers as well. A 5 lpm unit costs $300 and comes with a 3 year warranty. I paid $30 for shipping to Michigan. The Rio Grand Jewelry company (they have online sales) sells a brazing version for $425. DotMed.com is an auction house for all kinds of medical equipment including concentrators with hundreds advertised at various prices. It is common to find them in the classifieds for $75 to $200.

Oxygen concentrators don’t typically need to be modified for brazing. On mine, the oxygen output has a brass size B fitting. All I need to do is plug it in, screw the end of my hose onto the fitting, turn it on and wait a minute or 2. After I light the flame, I adjust the flowmeter so its output matches the orifice size of the tip.

Concentrators differ a bit on what kind of fitting is at the end of the output. They have some kind of plastic barb to hold the clear hose that carries the oxygen to the patient. On my Devilbiss unit that plastic barb unscrews from a brass B fitting. The same fitting that is on the output of a oxygen regulator. On other models that only have a plastic non-removable barb, one would have to make a transition piece to convert the plastic ending into a brass A or B welding hose fitting. That could be done with a brass unit from Western Enterprises that has a barb on one end that fits into a short piece of clear hose and an A or B fitting on the other to connect to a hose going to your torch.

I want to be clear I’m not suggesting a concentrator is the best way to go for everyone. What I am saying is that it is a very good option to consider for safety, convenience and cost reasons. It combines nicely with propane that can be chosen for the same reasons. We are all different in what we like or don’t. And our choices can be influenced by where it is most convenient to buy what we want.

Doug Fattic
Niles, Michigan