I used a diving shop to fill it up. The first attempt didnt work since the O2 bottles have a residual pressure valve
An adapter may be needed to fill with DIN. I had to buy this part on top. Note it pushes the checkvalve out, otherwise you can’t refill…
Adapter to fill cylinders (DIN-477) with a residual pressure valve.
Last re-fill I know of (owner did it) was at Aero Entreprise / Trimaille , Ovation 3 large composite tank: 75€
I take my portable unit to a Glider Club and get it filled for free ! 
I went into a scuba shop yesterday to get some (air) cylinders filled up and the guy said to me that DIN is the way everybody is going and the “A-clamp” will go away.
Most of his cylinders were used with A-clamp 1st stage regulators but all the ones he looked at were actually converted from DIN, with that screw-in insert shown above. The way you can tell there is a screw-in insert is from the allen key hole
So anyone buying oxygen cylinders would be well advised to buy them with DIN and not 540 fittings, for filling from any scuba shop which carries oxygen and is willing to sell it to you. You will still need the adaptor above but at least most of the work is done.
I’m looking for where to get Oxy cylinders periodic Hydrostatic testing done ?
Try Atelier Bigata in Bordeaux…
I got a replacement cylinder for my Mooney including hydrotesting as well as IRAN of my altitude compensating regulator…(built-in system)….
Excellent, thank-you @AnthonyQ.
I don’t think any of the relevant fittings are BSP, but it’s not impossible.
You can’t really use those fittings for high pressure cylinders. In aviation use, the first stage regulator screws directly onto the cylinder so the 150 bar pressure is never “exposed”.
Can I ask what you are trying to achieve? Are you trying to mount the first stage reg remotely from the cylinder?
Obviously you need to be extremely careful with high pressure fittings. If something comes off, it will be doing approx mach 3 (an AK47 round is mach 2.5) and will go through a brick wall. The first stage regulators in both aviation and scuba go directly onto the cylinder. The only time, in aviation, that the high pressure goes somewhere is in fitted oxygen systems where a very tiny internal diameter type goes off to a pressure gauge in the panel (because the cylinder is in the back and the pilot would not see a pressure gauge mounted on it).
There are new oxygen DIN valves. The ones from MH are still old and can be easily refilled.
For newer ones, you need a DIN/DIN adapter as they have an additional valve which is shown frm Vref.
With scuba shops you have to be careful. You need to find one which fills oxygen into rebreather kit. Rebreather always used DIN 477 connectors, the A connectors were for compressed air only, which is useless. Rebreather oxygen tanks have a female thread, whereas normal oxygen tanks (for welding) and MH tanks have a mal tread, so you need a connecting hose with 2 female threads at both end to refill.
