Medical vs Aviation O2 systems?

[A1Topgun]

Aviation legal issue. I have a oxygen bottle that is stamped with a DOT date over five years ago. Most shops won't refill it if the date is not within three years. To get a five year static check I will need to send the bottle out to a "Aviation Certified" shop. The cost of this is over three hundred $, just to get the bottle refilled. If memory serves me right that is about what I paid for the whole shebang when I first bought it. It is cheaper to buy a "new" dated bottle than it is to legally refill it.

 

[455 Bravo Uniform]

Aviation legal issue. I have a oxygen bottle that is stamped with a DOT date over five years ago. Most shops won't refill it if the date is not within three years. To get a five year static check I will need to send the bottle out to a "Aviation Certified" shop. The cost of this is over three hundred $, just to get the bottle refilled. If memory serves me right that is about what I paid for the whole shebang when I first bought it. It is cheaper to buy a "new" dated bottle than it is to legally refill it.

That 3 year arbitrary number makes no sense, unless that’s just that shop’s policy. And a DOT test stamp is all you get, not some aviation special stamp...that sounds like BS from a shop.

 

[Checkout_my_Six]

Nope....a DOT shop can do the recert. Most dive shops can do a hydro test for $30. This one of the few non-aviation cheap things.

Aviation legal issue. I have a oxygen bottle that is stamped with a DOT date over five years ago. Most shops won't refill it if the date is not within three years. To get a five year static check I will need to send the bottle out to a "Aviation Certified" shop. The cost of this is over three hundred $, just to get the bottle refilled. If memory serves me right that is about what I paid for the whole shebang when I first bought it. It is cheaper to buy a "new" dated bottle than it is to legally refill it.

 

[GaryM]

Hydro tests are due every five years, not three, if I'm not mistaken. SCUBA tanks are definitely every 5.

 

[A1Topgun]

My mistake, I type three while thinking five.

 

[MikeS]

I suggest you look at the Inogen Aviator unit, then acknowledge your error... the spec and demonstrated performance is definitely above 90%, up to the FAA endorsed 18,000' equipment ceiling.

Perhaps you're thinking of the medical units, but failing to qualify your comment?

If you'll look into the actual specs of the unit - which is nothing more than a re-badged Inogen One G5 medical unit, you'll find it's maximum saturation capacity is 90%. You apparently are taking your information from the intro splash screen at the website where they sell these re-badged Inogens as "Aviator" concentrators. Yes, the machine will function up to 18,000 feet . . . it'll probably continue running up to 50,000 feet . . . but the highest saturation the machine is capable of is 90% at sea level.

As I've mentioned somewhere else, if my oximeter is indicating anything below 95% I would turn up the tank regulator a notch. If at sea level, 90% saturation is an indication that there's something wrong with your pulmonary function - which is exactly the target market for these things. People with COPD or other breathing difficulties. 90% is the best these machines can do . . . any of them, not just the Inogen One. For years I've been interested in replacing my oxygen tank/regulator/cannula with a concentrator running off the plane's DC power. They're expensive so I kept putting off buying one. Eventually I stumbled across the information that these concentrators can only produce 90% saturation at sea level. At altitude, you can bet they'll be putting out even less. Way less.

 

[PaulMillner]

you'll find it is maximum saturation capacity is 90%.

That is not correct. The oxygen *concentration* coming out of the concentrator is in the low 90's... I've measured 94% on my unit. But saturation is a different phenomenon. You do *not* need 100% oxygen concentration to achieve 100% blood saturation, or we would all be dead by now... as I write this and you read it, we're breathing in air that has only 20% oxygen concentration, and yet our lungs and feisty red blood cells are achieving 97% to 99% *saturation* which is an entirely different concept. You seem to be merging concentration with saturation, but they're not the same thing at all, and our bodies are very good at turning lower concentrations into high saturations.

the unit ... nothing more than a re-badged Inogen One G5 medical unit

That's not correct... the one I have looks like a G3, but back when we did the June 2017 Aviation Consumer article on oxygen concentrators, the Inogen Aviator folks assured us that both the software and the zeolite, the medium inside the unit that actually accomplishes the separation, are different in the aviation unit. The aviation unit also has a different power supply, which accepts either 14 volt or 28 volt ship power input.

the machine will function up to 18,000 feet... it'll probably continue running up to 50,000 feet

No, it will overheat long before that. Remember, it compresses the ambient air to about 50 psia, and that heat of compression becomes significantly greater as ambient pressure is reduced at altitude. In fact, if you don't place the unit somewhere where the air can circulate around it, it can overheat and shutdown at even lower altitudes.

the highest saturation the machine is capable of is 90% at sea level.

Not true. The concentrator does not have a saturation specification. It has an oxygen concentration specification. The resultant blood O2 sat of the user depends on how one breathes, your physical condition, etc. I can report that my G3 reliably helps me maintain >90% sats to 18,000' or even slightly above. I think I've worn it to FL190 a couple of times.

If at sea level, 90% saturation is an indication that there's something wrong with your pulmonary function. 90% is the best these machines can do

You are incorrectly merging together the oxygen *concentration* of the machine's output with the user's blood O2 saturation... very different concepts. I invite you to try one. Assuming your body is functioning well, you should be able to maintain your 90%+ sat high into the teens, even if you're breathing only 90% concentration oxygen.

Eventually I stumbled across the information that these concentrators can only produce 90% saturation at sea level

I don't know why you think that. It is plainly not true.

Here's the Aviation Consumer article I wrote in 2017:

https://www.dropbox.com/s/2u2r2itl8wje3jf/AviationConsumer_O2_Concentrators.pdf?dl=0

Paul

 

[PaulMillner]

I have an oxygen bottle that is stamped with a DOT date over five years ago. Most shops won't refill it if the date is not within three years.

According to DOT regulations (not FAA), metal bottles, steel or aluminum, must have had a hydrotest in the past five years, or they can't be filled. Fiberglass bottles must have had a hydrotest in the past three years, or they can't be filled. Fiberglass bottles also have a finite life, something like 18 years after manufacture. So that date applies as well.

To get a five year hydrotest, I will need to send the bottle out to an "Aviation Certified" shop. The cost of this is over $300.

No, you don't need to do that. Any DOT approved shop will work. The least expensive places I've found are fire extinguisher companies. They're doing dozens of DOT hydrotests a day, and are happy to add your oxygen bottle to the gang. It's usually less than 24 hour turnaround, too. I pay under $20 for that. Then, I take the bottle to the oxygen supplier for a refill.

It is cheaper to buy a "new" dated bottle than it is to legally refill it.

You need to stop doing it that way, Ron!

Paul

 

[PaulMillner]

Is the Inogen Aviator a re-badged medical unit.

They say not... they say the software is different, and the zeolite inside, that actually separates the oxygen and nitrogen in the air, is different.

A buddy in Arizona tried a consumer unit in his airplane, but it overheated and shutdown ~10,000 feet. That's not conclusive, of course, but consistent with Inogen Aviator's story.

 

[MikeS]

Well if my understanding is wrong I appreciate the corrections. Mixing concentration with saturation is apparently a thought malfunction on my part. So many responded I'll agree I may very well be all wet. I see references however to 90% saturation somehow being acceptable. If my saturation drops to 95% I turn the regulator up a notch. 90% is not something to be crowing about. That's barely alive. That's life support territory. 100% concentration is optimum and if these things do 90% at seal level, I still very much doubt they're putting out anything serviceable at altitude. Anyway . . . 95% saturation is the lowest I want to see. If one of these machines can maintain that at 11 -14K I'll take back all my misconceptions.

And I'l re-read the 2017Aviation Consumer article. I've read it earlier but apparently missed or mis-remember whatever I read. Thanks for the link. Great publication.

 

[Matthew Rogers]

Well if my understanding is wrong I appreciate the corrections. Mixing concentration with saturation is apparently a thought malfunction on my part. So many responded I'll agree I may very well be all wet. I see references however to 90% saturation somehow being acceptable. If my saturation drops to 95% I turn the regulator up a notch. 90% is not something to be crowing about. That's barely alive. That's life support territory. 100% concentration is optimum and if these things do 90% at seal level, I still very much doubt they're putting out anything serviceable at altitude. Anyway . . . 95% saturation is the lowest I want to see. If one of these machines can maintain that at 11 -14K I'll take back all my misconceptions.

And I'l re-read the 2017Aviation Consumer article. I've read it earlier but apparently missed or mis-remember whatever I read. Thanks for the link. Great publication.

You still don’t understand correctly.

The o2 concentrator takes input air with 20% oxygen and produces an output air with 90% oxygen. This is the air that you are breathing - 4.5x more oxygen than regular air. 90% O2 and 10% N2. The functional difference between breathing 90% O2 and 100% O2 is quite small.

Saturation refers only to blood O2 concentration. It has nothing to do with the O2 concentrator machine or it’s function. It is a value that is measured from your blood and the factors that determine it are your physiology, altitude, exertion, etc. If you get Covid you could have a blood O2 of 70% even while breathing 100% oxygen.

 

[flyingron]

To amplify what MattR says, the thing that drives the perfusion is the partial pressure of O2. As we go up in altitude the atmospheric pressure goes down and since the percentage of oxygen remains the same, the partial pressure of O2 goes down. There are two ways to fix that: raise the pressure (pressurized aircraft or a pressure mask) or increase the percentage of oxygen. Somewhere around 18,000 feet or so, even 100% oxygen doesn't yield enough partial pressure.

That gets you past the membranes in the lungs, as he also points out there are other physiological effects that can decrease the O2 actually perfused.

 

[AlphaMike]

This is an interesting article. I've been back and forth about getting the G5 version. I just can't find many reviews. They say it works well for 2 people up to 17000 but I can't find anyone to confirm it.

 

[WDD]

Interesting technology. Many years ago we rented an O2 concentrator when we went to CO for family vacation. Wife has problem with altitude, so we got it for her to use at night. Noisy, gasping, and wheezing - the machine, not the wife. Sounds like they've improved things so much since then.

I think we'll get an O2 system for when we fly 8-10k feet to keep the headaches away. But for our use, we'll probably just need the bottle system - I don't see myself flying higher that 10,000 let along high enough the legally need O2.

 

[Matthew Rogers]

Interesting technology. Many years ago we rented an O2 concentrator when we went to CO for family vacation. Wife has problem with altitude, so we got it for her to use at night. Noisy, gasping, and wheezing - the machine, not the wife. Sounds like they've improved things so much since then.

I think we'll get an O2 system for when we fly 8-10k feet to keep the headaches away. But for our use, we'll probably just need the bottle system - I don't see myself flying higher that 10,000 let along high enough the legally need O2.

And just look for a used medical bottle and regulator on Craigslist. The bottle will likely be new (with current hydro test), aluminum, and you can upgrade the regulator if you want for $50 on ebay to a pulse demand. Getting it filled is easy at the welding shop with/or without a prescription. My primary doc wrote me a prescription for free that just says "O2 for high altitude flying". The welding shop made a copy and could not care less about it.