Following back on this now that everything is here for a test fill I started with a bone empty 15ft portable cylinder and empty 115ft tank in the Rocket The links to the whip and adapter that are in this thread work perfectly and the parts arrived in about 10 days all total. I used 200ft Oxygen cylinders for the first fill, I will swap to 300’s when I swap them (same price, local place didnt carry 300’s so they’re special order) First stage starting at 2300 psi brought the A/C tank to 1400psi. Then 1400 in the first stage brought the 15ft portable up to 1150ish Second stage starting at 2300 brought the A/C to 1750 where I stopped it. Bottle still has 2000 in it. I topped the portable up to 1750 as well and near as I can read the gauge I think stage 2 is 1850-1900 I didn’t touch stage 3 yet The system is kludgy right now, I have to make the time to build a rolling rack. Bottles are currently stored laying down and chocked into a corner. When in use I stand one up and strap it to a hand truck to stabilize it while filling. I will refine more as I fill more however I think the following is my go forward: Get the 300ft bottles to start A single bottle isn’t bad but 2 is better, looks like 3 will be optimal for a hangar setup for a single airplane. The Aviation adapter for CGA540 to Scott 9/16-18 is substantially more expensive than buying the fittings off Amazon and assembling yourself. No surprise, I just didn’t know the fittings were standard so I pod the $205 or so for an aviation one instead of a welding supply one. I am looking for an off the shelf solution now online, I can find one that comes preassembled I will post it. Other than that, everything else is off the shelf sourced from Amazon. This is easy. Fill slow, be clean and careful, and you can be independent on your oxygen. Sent from my iPhone using Tapatalk