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An oxygen concentrator is a wonderful machine … when it works. Attempts to diagnose and repair a your concentrator when it fails can be very frustrating. But understanding just a few principles of operation may turn frustration to success.
Principle #1 Remember your sand box.
If you have ever played with a sieve in a sandbox, you already understand the science behind an oxygen concentrator. The air we breathe contains about 78% Nitrogen and 21% Oxygen. The other 1% is composed of a few other gasses. An oxygen concentrator is a sieve that lets Oxygen molecules through and holds back the Nitrogen molecules.
So you need to picture some poor quality sand with about 80% pea gravel mixed in. It’s nice and dry, so when you scoop some up in your sieve and shake it a bit over a bucket, you end up with some nice, beach quality sand and a sieve that’s still got a lot of pea gravel in it. Dump out the gravel into another bucket and do the same thing over again. Slowly but surely you fill your sand bucket with some nice sand. This is like the tank of oxygen you accumulate with an oxygen concentrator. The pea gravel dump pile is the Nitrogen that hisses out of the concentrator muffler. Take the muffler off, and you can get a better feel of the process.
Principle #2 – Respect the destructive power of moisture
Now, you might recall that when you get some wet sand in your sieve, the process doesn’t work so well anymore. You might need to shake it more and everything starts to clog up. Moisture causes lots of problems for an oxygen concentrator as well. Once it starts to condense in the sieve material, the sieve begins to break down. It would be like your sandbox sieve falling apart or getting rusty so that either everything just goes straight through or it gets completely plugged and nothing goes through. The sieve material in an oxygen concentrator is in the form of little clay pellets that are treated with zeolite. This material does a great job sorting out the Nitrogen from the Oxygen, but is very vulnerable to moisture.
If the sieve material has been exposed to moisture and has begun to break down, you will begin to see signs of this process with dust that starts blowing out of the exhaust mufflers. It is best to take care of the problem as soon as possible, because the dusting will only lead to more problems. It will begin to disrupt the valve operation and may even totally clog up the mufflers to the point where the Nitrogen can’t exhaust anymore. Chances are, by this time the sieve material is ruined and is not filtering out the Nitrogen anymore.
What to do. Unfortunately, if your sieve material is breaking down, your concentrator sieve beds will need to be rebuilt. The sieve bed needs to be opened up, old material dumped, and new sieve material put in. Sieve beds are typically in the form of two aluminum tubes with some screens and a spring to hold the sieve material in place. These need to be carefully cleaned, inspected for damage, and carefully put back together so that it is sealed up tight. If you’re not up for the challenge of rebuilding the sieve bed, you can send the beds in to us for a re-build.
Principle #3 Valves need to operate flawlessly.
Rebuilt sieve beds may not be the whole solution. There is a good chance that the dust from degraded sieve material has found its way to the valve set. The valves are your arms working the sieve in the sandbox: dig up some sand, hold it over the sand bucket, dump out the gravel into the gravel pile, do it all over again and again and again. If you’re sloppy, you’re going to get gravel in your sand.
In an oxygen concentrator, two sieves are at work together. When one is sifting, it is also at the same time helping to clean out all the Nitrogen being exhausted by the other sieve bed. The valves direct a certain quantity of air for a certain time into the sieve. Too much air, and it is like the sieve overflows and Nitrogen spills into your oxygen, diluting it. If the Nitrogen isn’t dumped properly, the next cycle is ineffective and disrupts the rhythm.
The valves need to open to let compressed air into the sieve for a certain time. Oxygen flows out the other side through an orifice and a check valve. As the air valve closes, it opens a second port to release the Nitrogen trapped in the sieve back into the surrounding air. A second valve lets compressed air into the second sieve. As it fills, some of the oxygen leaving the other end helps force the remaining Nitrogen out of the first sieve.
The valves are typically a spindle that slides back and forth to direct the gas flow. A solenoid pushes the spindle back and forth. When electricity flows through the coil of wire in the solenoid, the magnetic field generated pushes a plunger to move the spindle. The spindle needs to move freely. Dust or contaminants can interfere with its movement so that the air is not precisely measured or timed properly. A careful cleaning of the valve often will fix a sticky valve, but sometimes even when it seems to be operating smoothly, only a new set brings the precision needed for proper operation.
Principle #4 Check valves and orifices may seem insignificant, but they’re not.
What looks like little connectors for oxygen tubing are actually precision parts that work together with the air valves to direct the Oxygen and Nitrogen flow. Orifices are precisely sized holes that limit the flow of Oxygen. In a concentrator, they are often used to allow a limited amount of Oxygen to push out any remaining Nitrogen left after exhausting from the de-pressurized sieve. If it gets plugged, Nitrogen stays in the sieve and ends up contaminating your oxygen supply. The check valves prevent any excess oxygen from flowing back into the sieve. Make sure the oxygen hoses are clear of debris, you can blow air through the orifices, and the check valves work. You should be able to blow through one way, but not the other. They need to be oriented so that the oxygen flows to the oxygen tank and not back.
Principle #5 More O2 flow is not better
A simple thing to overlook when trying to figure out when the O2 purity isn’t what it should be is excessive oxygen flow. Bring back to mind the sieve in the sandbox. The sieve is only so big. It will only hold so much sand and pea gravel. If you exceed the capacity, extra material is going to fall over the sides and not go through the sieve. Try operating your concentrator at a flow rate that is lower than the maximum rating. If you get good oxygen purity at a low flow rate, but it starts to fall off as you approach its rating, you might have some oxygen leaks. An oxygen leak won’t be measured by your flowmeter. Use some soaping water to look for leaks and fix them.
We sell and service most brands of industrial oxygen concentrators, stock parts, and do all we can to keep oxygen concentrators healthy. We also sell and rent oxygen meters to determine the oxygen purity of a system. A diet of clean, dry air is proven to greatly extend their life. They are designed to handle a limited amount of moisture, but it is risky. Continuous use, just like regular exercise, will also extend life. Startup on a humid day will be hard on them. Hot humid air from the compressor is liable to condense in a cooler sieve and begin the cycle of damage. If the suggested remedies do not solve your concentrator problems, feel free to give us a call.
If you keep a pair of sieves as spares to be used when required, can they absorb moisture if unused for quite some time. If so how long can you keep them before use
Thanks
If the plugs on the inlet and outlet are in place the sieve beds are not exposed to ambient air and therefore would have a very long shelf-life.
What is the oxygen concentration of the exhaust air? 0%? Is it pure nitrogen?
The exhaust air typically still contains 2-5% oxygen + nitrogen + other inert gasses such as argon, helium, carbon dioxide, ect.
Joel, do you think an exhaust air from the oxygen concentrator of about 98% Nitrogen should be vented to the outdoors?
We all wish the oxygen concentrator was that efficient. Alas, it is not. The oxygen concentrator actually exhausts about 90% nitrogen, maybe as good as 95% nitrogen, but unlikely. Therefore, we do not vent this exhaust special, there just is not enough imbalance of nitrogen to oxygen to cause any offset in a normal room.
My wife complains of a headache and nausea at times when she uses her oxygen concentrator. I can’t smell any unusual odors, chemical or otherwise, but she says she sometimes smells what seems like natural gas. There are no gas leaks in our house. I’ve exhaustively checked that out. Having grown up in a WV natural gas storage field, it is a smell I can instantly detect. I do not smell anything in our room out of the ordinary. Is there anything in the sieves or the compression process that might produce a headache or nausea when she is sitting within a few feet of the exhausted Nitrogen, CO2 and inert gasses? Could breakdown of the materials in the sieves create what she smells. We live in Colorado, so the humidity is so low, there is little probability that moisture is causing the sieves to deteriorate.
I would suggest checking oxygen purity from the oxygen concentrator. My guess, is the oxygen purity is low. If it is low, the aid it provides to her health is compromised, but also, if oxygen purity is low, there are other gasses taking the place of oxygen. While you may not know what those are, that is not relevant. Repair the oxygen concentrator to regain 90%+ purity and you will likely be in good shape.
Rent a handheld oxygen purity meter at link below:
https://www.oxidationtech.com/products/rent-ozone/rent-ozone-monitor/maxo2-rental.html
I have an overflow 5L p.m. that runs for 10 minutes and then the red light and audible alarm come on you can shut it off and let it sit for a few turn it back on and it repeats the same sequence you run it for 10 minutes everything seems fine and then the red light and audible alarm come on can you help please?
It sounds like the oxygen purity is low. A build in oxygen sensor may be detecting low levels of oxygen and giving the alarm. Try running the unit at a very low flow rate. This will allow a weakened sieve bed to keep up and produce a high enough purity oxygen to delay or prevent the low oxygen purity alarm. The sieve beds have a granular zeolite material that can wear out if it is exposed to moisture. An oxygen meter https://www.oxidationtech.com/products/rent-ozone/rent-ozone-monitor/maxo2-rental.html will be able to measure the oxygen purity. When an oxygen concentrator is working well, it will produce 90-93% pure oxygen.
I like how you mentioned how breathing clean, dry air has been shown to significantly increase a person’s lifespan. Although they can withstand a certain amount of moisture, doing so is dangerous. Similar to consistent exercise, continuous use will also lengthen life. Given that he has been diagnosed with chronic lung disease and must continue his treatment even at home, where he requires the use of oxygen, this is something my cousin should consider. I’ll make sure to pass along these tips to him so he can choose the best one. Thanks!
Hi,
You have great educational content.
The question i have is:
On the exhaust side of my oxygen concentrator, how do I get 14% oxygen for altitude training.
What setting do I use on a 5 litter per minute
And on a10 litter per minute oxygen concentrator.
Thank you
Peter szonk
Peter,
14% is a lower concentration than ambient. The oxygen concentrator would only increase oxygen concentrations in air. Not sure this is the right tool for the job here.
In any case, if you are going to pursue this path, ensure you have a proper oxygen purity meter as increasing nitrogen content in breathable air can be dangerous.
Price and availablility of your max02 oxygen tester please. I am in Boksburg
Link to prices, purchase and rental option of these devices – https://www.oxidationtech.com/catalogsearch/result/?q=maxO2
i have a invacare platinum 10 liter oxygen concentrator when it is time for me to change the material in the sieve bed is that something i can buy from your company ? If so can you give me a rough idea on how much material i will need and what that material is . Thanks
Typically the sieve beds are replaced as a whole. Changing the sieve itself without precise instructions from he manufacturer and necessary internal parts is typically not effective.