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Oxygen generators

Coming back to the oxygen concentrators, I believe they are the future for turbo (and turbodiesel) versions of SR22, DA40 and 42, C182, Bonanzas, etc…and some companies are starting to produce them (e.g. http://ainonline.com/aviation-news/ain-news-live/eaa-airventure/2013-08-01/zodiac-onboard-oxygen-generation-system-installed-cessna-206). They have been in use in military jets for decades (and still are because fighter jets are lightly pressurized to better resist artillery). The main advantages compared to the bottles are: you can fly high to places (e.g. south of Europe) where oxygen refils are not available or are VERY expensive (plus, in case of accident, you don’t have oxygen and avgas on the same plane!). Plus, you can set a very high oxygen flow above fl180 and keep using cannulas (oxyarm is great for comfort!) instead of masks. To avoid dry nostrils, they can have pulse mode (like O2D2) or have a water-rechargeable humidifier. Plus you can use VERY high flow and use diffusers (designed specifically for the oxyarm) that don’t touch any part of your face (very comfortable).

So far I’ve experimented up to FL220 with an Eclipse 2, the military version, certified to provide oxygen to wounded on medevac helicopters. It is possible to find brand new and “cheap” (1000-2000Eur) units from European military hospitals who upgraded to Eclipse Generation 3 (not a big difference with the 2, but you know militaries…always the best). You need to have a 200Watt plug in your plane: I commissioned an EASA-approved Minor Modification design to install a 24V/9Amp cigar plug in any SR22, which now is granted (arounf 1000Eur for license plus installation). The Eclipse has the size of a small backpack and sits on the floor between the rear passengers in the SR22 (almost unnoticeable, but in future Cirrus may install it in the tail). If plane electricity should go off, the unit continues to run on batteries for at least 1 hr. The high power plug can come handy for any application, not just oxygen generators (e.g. laptops).

Only drawback is that it can only generate a maximum of 3L/min continuous or 6L/min pulsed, so it can really serve only 2-4 people depending on the altitude and the type of cannula used (4 people at fl180 with mustache cannulas are ok). But more powerful models are coming in the market (the question is if the plane alternator can take it).

Please let me know if you have questions.

Thank you Valerio, very interesting. looks like the technology is now approaching a state where these generators make sense in SEPs.

You say

If plane electricity should go off, the unit continues to run on batteries for at least 1 hr

Does that mean it has its own battery?? I would want a generator without battery to save weight and space!

Also, would the generator be field-removable (for those flights where it is not needed)? If put into the tail, it won’t be I guess…

Mainz (EDFZ) & Egelsbach (EDFE), Germany

To answer Bosco, yes it has its own battery which can be removed (8.1kg with battery, 6.6kg without). And yes, the whole concentrator can be removed from the plane in 2 seconds (if it was fixed, one should get an STC, but for the plug you just need a Minor Mod EASA approval, which still required a fair bit of engineering effort from an Austrian design shop to dimension the cables and their paths around the Cirrus).

Have a couple of photos?

How about the paperwork for an N-reg.?

Mainz (EDFZ) & Egelsbach (EDFE), Germany

Unless I am missing something, the only “paperwork” involved here (FAA or EASA) is whatever is needed for the installation of the power outlet, which is the usual procedure whereby you choose a suitable aircraft bus and install a circuit breaker, install some sort of connector, and wire it up with a wire of the appropriate thickness.

What constitutes a suitable connector has been the subject of a huge amount of discussion on and off forums. Just about anything is better than the only connector approved on the Type Certificate – the crappy cigar lighter socket.

A fussy avionics shop will install something fairly robust and as per normal maintenance practice they will try to buy it with a traceability document (on a “release”) i.e. from say Adams and not from RS or Farnell even if it exactly the same item

For 15-20A the choice is fairly narrow and I would probably go for a milspec circular connector. There isn’t much choice in 2-pin high current and last time I bought some (for a 28V 40A ground power unit I built for the TB20, in 2002) I got some from FC Lane. Lemo also do some beautifully made and reassuringly expensive 20A connectors which I use a lot of.

What you then plug into that connector is nobody’s business. Obviously you want to satisfy yourself it is safe…

Administrator
Shoreham EGKA, United Kingdom

Less than a year ago Aviation Consumer had an article about the subject. There were (I think) four different makes. There conclusion was that it is a great product that needs a bit more time to mature.

It would be really interesting to see that article.

My “research” found very few units which worked at all at altitude e.g. 20k feet. The ones on Ebay etc usually claim to be ex military hospital equipment. The Sequal (Ebay) one is the best known one and definitely works to 20k but really only for 1 person, and having four of them in a 4-seater is not really viable. The Oxyfly is about the only solution for that.

There are dozens (at least) of units, mostly Chinese, some down to €200, which “work” but only to about 8k (airliner cabin). These are intended for the fairly large market in the West where many people need oxygen 24/7 (walk into any hospital outpatient dept).

Administrator
Shoreham EGKA, United Kingdom

My cylinder is overdue. What should I do? Replace it or go for this solution?

Is there no faa requirement that it should be an approved solution?

But above, Valerio said that the Eclipse 2 works at FL180, for up to 4 persons. So what is fact and what is fiction?

Mainz (EDFZ) & Egelsbach (EDFE), Germany

Mustache conserving cannula require 1/3 of the prescribed flow at any altitude below fl180. So, at fl180 one person requires 1.8l/min /3= 0.6 l/min. Multiply that by 4 people and you get 2.4l/min, which is easily produced by the Sequal Eclipse (actually it makes 3l/min). So I don’t agree with Peter claim and I back that with experience.
Please also refer to http://www.dg-flugzeugbau.de/sauerstoff-e.html for an interesting primer on oxigen use in planes.
These Eclipse units are really advanced pieces of technology. They have internal digital hour counters, so you can check if they are really new or used when you buy on Ebay. Plus the serial number on them and on the batteries contains the manufacturing date and if the model is the military version or not (the tipical seller on Ebay doesn’t know how to read these details, but the manufacturer does). They have solid state real time purity and flow sensors, so you are sure that you are getting the expected flow speed and the expected purity of oxygen.

Nothing on the market comes close to the Eclipse in terms of portability, flow volume, price and quality, and especially ability to work at altitudes (they all work at 8000ft, not many work above 14000ft….they literally stop working). Eclipses are built in hundreds every year and are the only used by militaries.

I tested other models since the UK representative at Intermedical was happy to lend me for free any model to test in flight, as he sees a commercial opportunity for the uk GA market, after RAF asked him to conduct the same tests for the army. I tested a very small Airsep unit which stopped working at 15000ft (I believe they have a pressure sensor that is supposed to sense if the air input is clogged, for example if the patient covers accidentally the air intake of the unit).

The Chinese versions on Ebay produce around 60pct purity oxygen (it is written in their specs), not the 90pct+ of the Eclipse or the other American brands (the rest being nitrogen).

hope this helps.

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