For all you high fliers out there...

[AdamFrisch]

Read about this product in Plane & Pilot. Apparently it concentrates oxygen by removing nitrogen and can deliver safe breathing up to 15.000ft. It's portable and can run off the internal power. Seems like a great device to have for longer routes when one wants to get above weather or terrain and don't want the hassle of oxygen etc. Or at night just to be safe.

Inogen One G2 Portable Oxygen Concentrator – Inogen One (http://www.inogenone.com/)

[stickandrudderman]

I wonder if the reduction in oxygen levels at altitude might cause this machine the same problem as it does humans?

[StavDav]

Hmmm, seems like it is good for pax in a pressurised environment. Not sure how well it will compress at 15k with a limited oxygen supply in the atmosphere.

[Maoraigh1]

"I wonder if the reduction in oxygen levels at altitude might cause this machine the same problem as it does humans?"
Is the % Oxygen any different at altitude? I am however very dubious about the practicability of this device.

[IO540]

There are several of these products now. I saw a data sheet on another one at Friedrichshafen this year.

I don't know how they work but it involves increasing the o2 % of the air, from the normal 21% or so, by some kind of compression process.

It doesn't make pure o2, but you don't need pure o2. If you can make air with say 50% o2, that is a big help.

A bit of an issue if it is aircraft powered (which I am sure it will have to be) and you get an electrical failure at altitude :)

Is the % Oxygen any different at altitude?

No; it is the same % all the way up; at least throughout the flyable atmosphere i.e. below 100,000ft.

[stickandrudderman]

The percentage is of course the same, but that's not what I asked/wondered.

I also wonder why a large percentage of contributors on this forum are obsessed with finding grammatical fault with other contributor's posts rather than understanding and responding to the intended meaning or essence of the post.
It's a sign of insecurity you know.
I'm not just referring to this thread, I concurr that there is a small degree of ambiguity in my post, but to PPRuNe in general.:bored:

There's a spelling mistake above, I wonder who'll be the first to comment on it.

[S-Works]

They use a denitrogenation membrane, commonly referred to a DNA system. Very common in diving, I have a DNA system for producing NITROX, oxygen enriched air. Safer process than adding oxygen under pressure. It works by removing nitrogen from the air. The downside is that it requires huge airflow.

It wont be very efficient at altitude due to the reduced partial pressure.

[Pace]

Diving has the problem of not only nitrogen being compressed but equally oxygen. Nitrogen causes fatal conditions such as the bends and nitrogen narcosis.
Oxygen compressed can cause oxygen toxicity and again death.
Every 33 feet of depth is the equivalent of one atmosphere or 14ps inch.
I use Nitrox. Normal air is roughly 21% oxygen, Nitrox is a mix where the oxygen percentage can be increased to 30 32 or 36%
This is mainly used to extend bottom time by having less nitrogen but has the drawback of limiting the depth you can go to without suffering the effects of oxygen toxicity so the higher oxygen percentage the less deep you can go.
Deep diving uses a further blend called TRI mix where helium is added and Nitrogen reduced.
Flying creates the opposite effect where pressure is reduced.
I cannot see how the percentages can be changed without blending and containement?

Pace

[BackPacker]

They use a denitrogenation membrane, commonly referred to a DNA system.

I was looking at the specs of this wonder machine and they're next to useless. Not that I'm interested in buying one of these (in NL you can't realistically fly VFR higher than FL65, or FL95 on weekends) but just out of curiosity, what are the typical performance figures of such a DNA system?

The O2% is normally 21. To what % can this be raised with such a system? Does that depend on the altitude? What flow rate can you achieve, and what's the power draw for that flow rate? Is there any maintenance required?

It wont be very efficient at altitude due to the reduced partial pressure.

Who cares about efficiency? As long as it works and produces sufficient oxygen, I don't care how efficient it is. (Unless the power draw is so significant that it robs the engine of all usable power of course - but realistically once you exceed approx. 150W you can't use the cigarette lighter outlet anymore and have to wire it in, and this becomes impractical wrt. certification requirements. But I doubt whether this device draws anywhere near 150W, considering the size of the batteries and their claimed capacity - 4 hours.)

What you've got to remember is that this device is used for people with significantly reduced lung function, and is apparently OK to use in an airliner with a cabin altitude of 8000'. If your lung function is 100%, maybe you can use it up to FL150 or FL200?

[S-Works]

I cannot see how the percentages can be changed without blending and containement?

Blending is the classic way of producing oxygen enriched air. However the DNA type systems use a molecular sieve that removes the nitrogen from the air. To do this you have to push significant quantities through the sieve in order to be able to pull enough of the O2 from out. In the system we have for producing NITROX to fill a 10l cylinder with a 36% NITROX mix to 232bar will push nearly twice as much air through. The sieve is only good to about 45% mixes.

When we produce TriMix and Heliar we still do it by blending. Our system is big enough to use continuous blending where the Helium is added at low pressure and then compressed. Gives a better mix. The older system we used was partial pressure blending we would be the Helium in first to the required pressure and then add compressed air on top. It is rare to add O2 that mix as most TriMix is produced as a hypoxic mix although something like a 20/35 common in shallower CCR ops would be normoxic and require O2 adding.

However back to the original question.... I would think that device would struggle to produce anything useable in terms of O2 supply for crew in an unpressurised cockpit.

[lotusexige]

T-6A Texan II Joint Specialized Undergraduate Pilot Training - Gouge (http://www.t6driver.com/systems_oboggs.html) type thingie?

[jez d]

An interesting device but presumably a moot point for aviation. I believe that EASA are mandating the carriage of O2 systems for flight above FL100.

[The500man]

There's a spelling mistake above, I wonder who'll be the first to comment on it.


Are you sure there is just one? :)

[BackPacker]

I would think that device would struggle to produce anything useable in terms of O2 supply for crew in an unpressurised cockpit.

I've been reading up on this a bit more. Wikepedia writes this:

In high-altitude conditions, only oxygen enrichment can counteract the effects of hypoxia. By increasing the concentration of oxygen in the air, the effects of lower barometric pressure are countered and the level of arterial pO2 is restored toward normal capacity. A small amount of supplemental oxygen reduces the equivalent altitude in climate-controlled rooms. At 4000 m, raising the oxygen concentration level by 5 percent via an oxygen concentrator and an existing ventilation system provides an altitude equivalent of 3000 m, which is much more tolerable for the increasing number of low-landers who work in high altitude.

(Hypoxia (medical) - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Hypoxia_%28medical%29))

Extrapolating this... If you assume that FL100 is OK without oxygen, at the normal 21% O2 in the air, then each additional 5% O2 in the air will give you 1000m/3000 feet of extra altitude capability. So at 45% O2 you should have about 12.000 feet of extra altitude capability. That means that FL220 should be doable. (That is, assuming that that extrapolation works like that - it probably doesn't but even FL170 would be nice... The full article that Wikipedia refers to unfortunately requires payment.)

And of course the other assumption is that this little wonder device can provide the 45% O2 air at full breathing rate for all occupants, not just as supplemental air. Which sounds a bit of a challenge.

But I would not discount this device, or DNA technology in general, outright. Although it might take a while before the FAA/CAAs of this world would accept this as an equivalent to bottles filled with pure oxygen. But that's aviation for you.

On the other hand, another Wikipedia article claims that combat aircraft use molecular sieves oxygen concentrators to supply the pilot with oxygen at high altitudes. So clearly there is experience with these kinds of devices already.

Oxygen concentrator - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Oxygen_concentrator)

[IO540]

This issue interests me a lot because every trip I do out of the UK (apart from LTQ :) ) is done as high altitude IFR, and oxygen is a must. No o2 = no flight, no exception, because without o2 you have cut off most of your weather avoidance options. That is why for example I always carry two cylinders, because one can mess up and forget to shut off the valve after landing...

I tried to phone that Inogen firm re cost but they are not working yet :)

The biggest issue with previous continuous delivery has been the cost. With the system I saw (some 10k euros IIRC) there is no way to make it pay in any private GA context.

If you look at the kit described here (http://www.peter2000.co.uk/aviation/oxygen/index.html) and here (http://www.peter2000.co.uk/aviation/oxygen2/index.html) and look at the cost of that (around £1k), and throw in the cost of keeping a huge British Oxygen cylinder in a shed (c. £80/year rental plus c. £20 for swapping it for a new one say every 2 years) there is no contest. A cylinder-based portable o2 system wins by a huge margin.

If the air is enriched from 21% o2 to say 50% o2 then doubling the gas flow rate would make it equivalent to a cylinder-based o2 system which obviously delivers 100% o2. Whether one could deliver double the required o2 via a cannula (which a lot of people find less than comfortable already) is another matter. Obviously at say FL120 there is no problem because the gas flow is very low but at FL180 (the highest practical level for cannulas, and the highest level at which cannulas are authorised via the AFMS in fitted o2 systems) it could be a problem because you are on the limit of effective cannula delivery already. I have flown at FL200 and one has to really concentrate on breathing up there, and that is with the gas flow turned right up well past the "FL200" setting. That is why one uses masks up there, but the o2 demand goes through the roof then.

The Inogen spec tells one exactly zilch about the performance, but the product shown at Friedrichshafen was said to be fine for FL180 so the 50% drop in the available air at FL180 seems to not be a fundamental issue to the technology. And any medical product has to work at airline cockpit altitude (FL080) anyway.

BP - you are right for a system where all the air inhaled is thus enhanced. This is not the case with a cannula where - at a guess - only a few % of the inhaled air comes from the cannula.

Also FL100 without o2 will tire out most pilots after a few hours - regardless of what they think :)

I thought that military jets (fighters) use chemical o2 generators. Much more compact and you can get tons of flow.

[AdamFrisch]

I think I saw the article mentioning something around $2K for the Inogen thing. I can't find that issue now, but it was in one of the last 3 ones. There was also some talk about a FAA approval of some sort, but I could be remembering wrong.


IO540 - with the kind of flying you do, you should really try to get a pressurised single. For not much more than you would get for your TB20, you could have a P210 or a Malibu. Or if you tag a multi engine rating on, a Cessna P337 is as cheap as it gets for a pressurised twin. You can get them for $70K today and they're very capable. Not everyone's cup of tea admittedly, but their performance and value for money is hard to beat.

[IO540]

There was also some talk about a FAA approval of some sort, but I could be remembering wrong.

An FAA approval is not needed for portable o2 kit, and in fact an FAA approval (of any legally meaningful sort, in the private flying context) cannot be obtained for portable equipment (other than transmitting equipment such as ELTs etc).

It's like all that stuff about an "approved Ipad". It's a meaningless concept - except on AOC ops.

with the kind of flying you do, you should really try to get a pressurised single. For not much more than you would get for your TB20, you could have a P210 or a Malibu. Or if you tag a multi engine rating on, a Cessna P337 is as cheap as it gets for a pressurised twin. You can get them for $70K today and they're very capable. Not everyone's cup of tea admittedly, but their performance and value for money is hard to beat.

A P210 is an old dog today. A C337 likewise. Any ageing piston twin is likely to be a black hole for money, which is why they are so cheap. A Malibu is a good long distance tourer if that is all you do and you can deal with the engine issues. I stick with the TB20 because it does nearly all of what I presently need, at a cost I can easily afford. The logical step-up would be a Jetprop (which I know pretty well) at around 2x to 3x the operating cost, but one would still lose a lot of flexibility (e.g. no grass). If your mission profile is entirely high altitude then I agree re pressurisation, but you pay for it one way or another.

[BackPacker]

There was also some talk about a FAA approval of some sort, but I could be remembering wrong.

Probably in the context of being approved for a passenger needing supplemental oxygen in an airliner. Not for supplemental oxygen for flight crew in unpressurized aircraft above FL100 or thereabouts.