Hi everyone, I hope this is the right place to ask questions. I haven't posted one before so here we go

I have just bought a Skyox O2 system. I found someone in Canberra to fill it with Aviation O2 at a cost of $103. Does this sound right and what is the difference between aviation O2 and medical O2. Can I use medical O2. I am only attaching 2 oximizers to a .6 litre bottle. As I understand, the moisture content required for normal aviation O2 is not necessary when using oximizers. Look forward to opinions on this

Stuart

aviation oxygen = dry medical oxygen
I use medical oxygen all the time, it's easier to obtain and has the same spec.

Thanks Ned. I figured that may be the answer but I had one particular airline who offered to fill my bottle tell me that Medical O2 would not suffice, and given I would be at flight levels, I did not want to find out that they were correct.

Stuart

Stuart,
Can you please let me know who at Canberra does oxygen filling. I recently had to have my tank hydrotested - only place that I could find was at Bankstown and it cost $350 for the test and fill.
John

Oxygen is another one of the great cons that afflict us in GA. In Australia, ALL oxygen comes out of the same process. Some moisture is added to the gas in hospitals because pure oxygen over a long period dries out mucous membranes and causes discomfort to patients.

You can safely use oxygen from ANY source - your local garage has the same stuff as the oxygen you will pay $100 for at an aviation filler. Oxygen used by the air force for 100 per cent supplies to pilots at very high altitudes, under pressure, is filtered to a slightly higher standard. This needn't worry you.

After being comprehensively ripped off by Uncle Tom Cobley and all, I now get my SkyOx unit filled by a friend in one of the local gliding clubs, which use it all the time. I pay $25 over the bar for drinks.

The other option is to get a number of people together and simply rent a large cylinder from one of the industrial suppliers. You can download refills from this into your aircraft bottle via a range of connectors available from Mountain High. You will hear a great deal of bullshit about how dangerous it all is and how skilled you have to be to refill a small cylinder. Simply follow a few simple rules and it's not a problem. If you're worried about your competence to do the job, just have a look at the knuckle-draggers who do it at "approved" shops!

Good luck and easy breathing,

Tony Rees

Hi Stuart,

$100 to fill a small O2 bottle sounds extortionate.

I pay around $100 for a refill to my 115 cu ft tank which typically takes around 45min of labour, although on one occasion it cost me just a carton of beer.

I believe some owners with access to medical O2 fill their own bottles.

Hi John

I had my O2 filled by Bridabella Airlines for $103. They did not test the bottle, only filled it

Hope this helps

Regards

Stuart VH - ERS

I fill mine from my workshop (welding) bottle. turn the tap very slowly to prevent heat build up. Only problem as the bottle is used up you don't get a full fill as the pressure is reduced. This probably happens at an aviation refiller also.

Got a fitting from the local industrial gas supplier and the other end made up on a lathe. cost all up under $100.

John has the perfect solution. That's what we should all do.

Peter is perpetuating the myth that "medical" oxygen is required. It isn't.

Regards,

Tony

I believe the strort regarding Aviation Oxygen versus medical oxygen stems for the USA. Over there you need a doctors prescription to buy oxygen. To save pilots calling ito the GP on the way to the airport the FDA (not FAA) made a rule that said "aviation" oxygen didnt need a script to get around the 'other' rule that said it did. The oxygen is exactly the same.

Now, I dont know about the difference between medical and industrial oxygen but what I can say is that I tried to buy industrial stuff and they refused to sell it to me when I said I wanted to sniff it not burn it when welding. $350 for a barometric test every 3 yrs with a fill is what I pay and for a fill alone it is $120 - 80 for oxygen and 40 for labour. I dont have a big bottle at the practice because my aircraft bottle runs to 3000 psi and I cant get that pressure for long out of a single tank. The LAME has a few hooked up in parallel to maintain pressure for longer

From a LAME's perspective, and for the record I don't drag my knuckles around the hangar floor, legally we have no choice but to use only 'certified' aviators oxygen. It is likely, as with a myriad of other things in aviation, that there is no difference between it and other oxygen available. Unfortunately though I get audited for what I have in stock and so have to have the 'certified' stuff available. As far as I am aware there is only one shop authorised to carry out the tests on G.A. oxy regulators etc and that is John Cameron in Bankstown.

Cheers Hamish

For what it is worth, I have a bottle of Aviators Dry Breathing Oxygen. I appreciate that the gas is he same, but the Aviators O2 comes in a much higher pressure cylinder than a normal "G" size bottle (this is the bottle that stands about 5' tall). This means that you can fill to full pressure many more times before the cylinder pressure is below the max. bottle pressure in the plane. The gas is similar price to any other O2 (litre for litre), but the major cost is usually the cylinder rental. We managed to strike a "deal" on that as we use about 20 cylinders of various industrial gases through our factory per week. I use the proper high pressure regulator which means it is not possible to over pressure the tank in the plane.

Two other shops that do hydrastatic test of GA oxy bottles and overhaul of associated regulators are
AEOS is sydney www.aeos.com.au
Plane Support at Sunshine Coast www.planesupport.com

Some interesting points.

Michael: Never volunteer information! The pressure problem is pretty well insuperable unless you connect them in parallel, which is hardly a proposition for occasional sniffers like us.

Hamish: Your obligations to CASA etc make no difference to the fact that the oxygen in your approved cylinder is precisely the same as that in John Kelman's workshop. The law, as you suggest, is an ass, but you have no option but to comply with it. As far as tests on cylinders and regulators are concerned, an oxygen breather would be insane to trust anyone but a certified shop. Your knuckles are another matter entirely, and I withdraw unreservedly any imputation that they have ever made contact with the hangar floor!

Andrew: Sounds like you've got the ideal set-up - high-pressure oxygen at a reasonable price. Well done!

Cheers,

Tony

Having has some experience with Oxygen plants I know that if you do not start with very dry, very pure oxygen/nitrogen mix from the ait with all the extra things removed by a "molecular seive" you will not distill oxygen from the air. Oxygen is separated from nitrogen by the same process that distills fuels and distills whisky. It has to be so pure to do the distillation that it is very pure oxygen. This liquid oxygen is used for all purposes. One plant I worked on had a tap through which you could drain liquid oxygen (and another for liquid nitrogen). I have long thought that you could use this, take some off in a thermos flask, then using a length of pipe of small diameter (withhold pressure far safer) fill it with an amount of liquid oxygen, connect it to your cylinder then as it evaporates it will charge your cylinder to what ever pressure you want. Best to have some pressure relief in case your maths is bad. Use mass = pressure times volume divided by R (Oxygens gas constant) and also divide bt the temperature (degrees Kelvin). You probably learnt the formula in school as PV=mRT. Hospitals and Universities usually have liquid nitrogen facilities if you do not have access to a smelter or steel plant liquid oxygen plant.

I know its not very practical, but I always wanted to prove it could be done.

Geoff
NWF (no oxygen system)