# Is "medical" oxygen system suitable for part 91 aviation use?

I am, in a somewhat desultory fashion, considering obtaining an oxygen system (for use in the U.S. under part 91, perhaps sharing with some passengers).

An initial search suggests that one can buy a 15 cu-ft tank with the extras (regulator, tubing, cannulas) from an aviation supplier for around USD $700 I also see that I can get a medical system for about$125 (with just a single stretch of tube, basic regulator, (but no flow-meter) and cannula).

I know that medical oxygen is sometimes disparaged for perhaps containing too much moisture, but I figure I could simply refill it with ABO anyway, right? I also read that moisture is unlikely to be present in reality today, and further that for the kind of cabin pressures I would be flying (unpressurized A/C and below 15,000' absolute maximum) this is unlikely to be an issue. But perhaps I miss something.

So... is there a compelling reason to spend the extra? Or is it likely that I have completely misread specs on things. Am I absurdly off the mark with the pricing for an aviation system (did I look at the wrong supplier, perhaps!)?

• Welcome to aviation.SE! This question has some related information. Sep 7, 2021 at 18:56
• I saw that question when formulating mine, and I admit I'm really unclear as to the relevance of the whole part 23 discussion. Part 23 is aircraft certification, and this is not part of the aircraft. It's true that it does include a discussion of using portable oxygen to satisfy the requirements of part 23, and puts constraints on that. But I don't think that's relevant, as I'm not trying to satisfy part 23 using portable oxygen, I'm trying to satisfy part 91. And to be honest, I'm more interested in the pragmatic aspects of safety/usability. Though perhaps I should take a wider view. Sep 7, 2021 at 19:35
• Though to be fair, I missed the middle opinion on legality. Though that doesn't appear to offer much substantiation and doesn't directly address my dual topics of is it sensible, am I missing the pricing aspect. Sep 7, 2021 at 19:38
• It's generally well-understood that all the O2 comes from the same huge tank. While it might be labeled industrial-, medical-, or aviation-grade, if it comes from the same tank then it's the same stuff. That being said, if you are not using it to meet Part 91 requirements, i.e. time at altitude >= 12,500, I would think that it's as perfectly legal as breathing any other gas you care to. Sep 7, 2021 at 23:03
• Well, for myself as PIC, it would be for part 91 requirements, at least sometimes. And I would want the equipment to be "suitable" for my passengers comfort and health. I got altitude sickness one time from 90 minutes at 15,000' and I wouldn't wish that on anyone! Sep 7, 2021 at 23:44

Aviation equipment costs more as the market is small. Like any product you can shop for better prices. The only step change in price that I would pay for is a pulse system, and only if I intended to use it a lot as they can cost $800 per user just for the pulsing device. These release oxygen only as you breathe in, and so conserve the amount consumed for a given saturation. • Good point on the flow-meter. What I was looking at has a$25 regulator, but no flow-meter. Anyway, I suspect you've likely hit the key points (and yes, visitors here from the low parts of the country sometimes get altitude sickness just from going for a modest hike.) Sep 7, 2021 at 23:48