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Oxygen - equipment, getting refills, refill hoses, safety, etc

Isn’t it funny how each and every thread about oxygen in general aviation sooner or later reaches this point?

Mainz (EDFZ) & Egelsbach (EDFE), Germany

I also use the Mountain High box and am VERY happy with it. Worth every penny alone in gas use and convenience.

Gas bottles, we have a neat exchange service here. You hand in the empty bottle, get a full one and pay only for the content. If you ever stop and hand the bottles in, they return your deposit I had to pay for them when taking them out.

Up to FL100 I usually don’t need it and also don’t feel any effects. Now that I do have oxygen, I use it if I go above FL100 as per the book, I have had short flights up to FL140 to avoid a danger area without it. Been up to FL170 which was a DA of >20000 ft that day with the Mooney and stayed there for 2-3 hours with the MH set with sufficient saturation and perfectly happy after the flight.

Last Edited by Mooney_Driver at 04 Apr 18:56
LSZH(work) LSZF (GA base), Switzerland

It is, but it is important to know what you get, that’s all. I know most use “regular” oxygen. The only thing is that shops that give a logbook entry for filling oxygen will use expensive oxygen. They can’t get away with “cheap” oxygen.

JP-Avionics
EHMZ

Isn’t it funny how each and every thread about oxygen in general aviation sooner or later reaches this point?

That’s because it has been repeated so many times in so many places. It is only now, 2014, that relatively few pilots in Europe still believe that GPS is evil (the USA moved on from that position many years ago). It has taken many years… On the UK sites, it was standard, and still happens now, that somebody would mention GPS and the discussion would end with a fight. And you still get people asking about which GPS to buy and then, to avoid a fight, they add “for a backup only, to be carried in a backback” etc.

That FAA leaflet (dated 2008) is mostly correct, technically, although the stuff about non-aviation gas being unapproved etc is simply nonsense. It may be the position of some FAA inspector who wrote it – you get the same with every European CAA where somebody inside writes some personal opinion.

Also portable systems are not regulated in the way installed systems are (via operating restrictions in the AFMS). For example the 18000ft limit on cannulas applies only to “fitted” systems, and it has self evidently been rendered nonsensical by devices like the O2D2.

All commercial oxygen is manufactured using the same cryogenic process. There is no difference between aviation, medical, food-fresh, and welding oxygen – the grades sold by British Oxygen for example. Only the paperwork differs. The water content is negligible in all cases. Curiously, welding is the process by far most sensitive to impurities in oxygen.

I use welding oxygen, because the other grades are more hassle for refills. I just take my old cylinder to a local BOC welding depot and they swap it for a new one. No questions asked. Sometimes I swap my argon cylinder at the same time (used for TIG welding) although on that one I have recently moved to buying a cylinder as it is a lot cheaper (I don’t think this option is available with oxygen, and anyway oxygen is cheap).

The only thing is that shops that give a logbook entry for filling oxygen will use expensive oxygen. They can’t get away with “cheap” oxygen.

Firstly the context here must be refilling an installed oxygen cylinder, not a portable cylinder (no logbook for that).

Secondly, of course the shop will go for the most expensive option, because they get a ~25% dealer discount. You can pay €150 for a refill from a jet service centre, for a tiny cylinder.

But we are here talking about a private pilot operating a portable oxygen system.

Last Edited by Peter at 04 Apr 19:37
Administrator
Shoreham EGKA, United Kingdom

Interesting… in the 10+ years I have been messing with this, nobody has ever before mentioned that an adaptor is needed for a DIN-fitting cylinder, to refill from a scuba shop.

For the rebreather systems they use this DIN G5/8" valve.

The scuba shop fills argon, helium and oxygen. They have hoses all using the same G5/8" connection.
I always check that they fill with the right hose :-)

I use two adapters: First from G5/8" to G3/4". Then G3/4" to 540 thread.

We already have a thread on “Aviation Oxygen” here: http://www.euroga.org/forums/flying/566-aviation-oxygen

Firstly the context here must be refilling an installed oxygen cylinder, not a portable cylinder (no logbook for that).

Agreed. But there a plenty of SEP with installed cylinder aswell (210, Saratoga, Bonanza). Could be included in discussion as well isn’t it. If your satisfied you might persuade fixed bottle owners to get rid of those, and get themselfs portable ones.

OT:
bq. Secondly, of course the shop will go for the most expensive option

Do you really think so? I think a good shop will go for the best possible solution for your needs. They would want a happy customer, instead of unhappy customer. Don’t you agree?
A happy customer will come back and bring more business.

Last Edited by Jesse at 04 Apr 21:09
JP-Avionics
EHMZ

The OP mentioned a C172 which implies a portable system.

A maintenance shop, asked by the customer to do an oxygen refill (on an installed cylinder, or on a portable cylinder) is going to use a gold plated “aviation” process – nothing else. If there is a jet refill facility, and they can find an adapter, they will use that. The installed cylinders can often be refilled with the pressurised-aircraft emergency oxygen refill trolleys – I see these where I am hangared (they service TBMs etc there). For a portable system, they might take it to an aviation gas specialist – happened to me once when without thinking I asked the dealer (Air Touring) during an Annual to refill my then tiny Aerox cylinder and it came to about 150 quid. That is about what a TBM or KA owner gets billed for servicing his emergency gaseous oxygen.

The customer can’t argue with this – it is the “proper” process. But that doesn’t mean it is value for money. Paying £150 for filling a cyilnder which will last 1 person 5hrs at FL170 is rubbish value for money. In those days that was about the cost of the avgas… It is totally uneconomical and no private pilot would bother.

Already, many private pilots (with IRs) fly at low levels (often, “VFR” in solid IMC) because of this and I am certain that some of them have been killed pointlessly as a result. One was based in “my” hangar – N2195B. His whole family gone.

Personally, due to difficulties with scuba shops, I rent a cylinder from BOC and, very roughly, I get about 200 man-hours of oxygen (at FL170; vastly more if flying lower) out of that, with a refill cost of about £25. But even a scuba shop refill (probably about 5x more expensive than what I pay) would be vastly cheaper than using aviation oxygen from a traditional source.

Refilling installed cylinders is harder because they are big and very heavy, so need to be refilled in situ, so unless you can keep a refilling cylinder in the hangar, or can refill from a mobile pack like they use for TBMs/KAs etc, you are going to pay €€€.

Last Edited by Peter at 04 Apr 21:38
Administrator
Shoreham EGKA, United Kingdom

Seems, that O2D2 is the best option for me. Peter, you’ve mentioned, that you’re using exchange service. Does that mean, that you bring them the cylinder you’re using in airplane or you just take another bigger cylinder and then refill from it (as many scuba centers do)? I also do not completely understand “anatomy” of first stage regulator. How is it refilled? Do I need to disconnect upper part with oxygen line connectors and find some kind of DIN connector below?

EVCA

Does that mean, that you bring them the cylinder you’re using in airplane or you just take another bigger cylinder and then refill from it (as many scuba centers do)?

I take the partly empty cylinder back to the BOC welding gas depot. They give me a full one, stick my BOC account number into a computer and that’s it.

Unfortunately I have just sold my car and the trailer so I will have to find somebody to help me next time, because the cylinder is far too heavy for me to lift, and won’t go into my car.

BOC will also deliver but they charge for it. One of their drivers told me they won’t deliver to a private house but I suspect that is an isolated case because lots of people work at home making stuff like jewellery. I keep the cylinder in an outbuilding.

When the cylinder is swapped it is only partly empty because once the pressure falls below about 1000psi I don’t get a useful refill out of it. The solution to that is a pump which costs a few k…

I also do not completely understand “anatomy” of first stage regulator. How is it refilled?

The 1st stage reg is just a little thing which screws onto the cylinder and drops the 2000+ PSI to about 20 PSI. Here are two of them; the left one is Aerox and the right one is MH

I prefer the MH connectors.

The 1st stage reg remains screwed onto the cylinder, until the cylinder needs refilling.

Do I need to disconnect upper part with oxygen line connectors and find some kind of DIN connector below?

See this pic

In there I have the 1st stage reg, and two of its four output positions are used, and these feed the two O2D2 regulators, each of which can feed two cannulas.

Normally I have just one cannula plugged in (my one), because “the other person” is variable and they need to be given a fresh cannula.

One needs to exercise care when handling oxygen equipment (see the notes in the writeup) and particularly you must keep everything clean and free of grease and other contaminants. So e.g. when the 1st stage reg comes off, it goes into a zip-seal plastic bag so no dirt or spiders can get inside it. A plastic cap goes onto the cylinder thread immediately so that remains clean. The 1st stage reg needs to be screwed on most carefully because if it is cross-threaded (feels tight but is held on by only one or two threads) it will fly off at about mach 3 when the cylinder valve is opened, and will kill you.

I would suggest that a person who has no “technical” capability remains clear of all this. But then such a person is going to have difficulty learning to fly, not killing themselves, etc So probably most people are fine. However I do know of one pilot who is unable to drive a car with a manual gearbox. He has lots of money and got as far as a King Air and a ME PPL. He kept failing the IR. So it’s a personal judgement…

Last Edited by Peter at 06 Apr 06:31
Administrator
Shoreham EGKA, United Kingdom

Thank you for explanation. Fortunetely, seems, that I have supplier just few kilomoters from my home airfield. Now I’ve contacted them to get technical details and prices. What is recharging process looks like? I mean – you have special hose with connectors on both sides?

BTW, Mountain High also sells convinient cannulas: http://www.mhoxygen.com/index.php/face-masks/cannulas/82-ez-breathe-ii

Last Edited by pshz at 06 Apr 10:10
EVCA
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