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I'll go first: I have a trans-fill setup at KBAZ New Braunfels in my hanger. Set up for the standard CGA 540 fitting like on my Aerox bottle. Drop me an email and if I'm in town, I can meet a fellow RVer and help fill your aviation bottle for a donation ($10?). |
I would sign up on a list where RVers could arrange a free fill at my hangar...
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weld tank to Areox bottle
Read a lot on forum and probable listed somewhere. Prefer hose and fitting as an assemble but sure I can put items together. I've seen what I think I need but big money / small wallet.
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Cascade system for Dummies (aka me!)
After reading through this and other threads on O2, I'm not finding the details I'm looking for (or simply don't understand what I'm reading). So for the sake of argument if I wanted to build a 2-tank cascade refill system, what would I specifically ask for at my local welding supply shop with regards to the tanks and refills?
-- What size tanks? -- Do you sign up for some kind of O2 service for refilling? -- Is it better to buy or rent the tanks and does that have an impact on getting them refilled? Oh and is there anything I shouldn't do like say to the welding folks "Oh I don't want to weld, I need the tanks so I can refill my aviation O2 bottle", or something to that effect? I realize that I'd also need a transfill and an intercoupling kit but those parts seems pretty straightforward. |
Todd, I am not sure if I would bother to cascade. A large single bottle... will refill the flying bottle many many times. It may not be up to full capacity after a while.... but it usually lasts a long time. Easy fills right at your hangar make it convenient and inexpensive. I purchased a really large bottle of oxygen and then took it to the welding shop. They just exchanged for a full one and noted in my account that it is not a rental tank.
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Assembly cleanliness, lubes, leaks etc would concern a vendor as they might be concerned about liability by just selling parts to a novice. They might give you some training and then sell an assembled unit, though. They are just trying to stay in business and keep people alive. They really want to sell gasses and be helpful. Surprised an Auburn guy doesn't know this stuff. ;) Oh - I mentioned that a full K tank filling a JD (21 ft3) flight tank can refill it 5 times from 300 psi before dropping below 1500 psi on both. That is 72% of capacity in terms of moles and hours at chosen altitude. That is 4X the rated tank flight hours. I have not done numbers for a 4K tank. A little more complicated for the calculations. |
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Wait, do I hear Vlad's plane starting up? :D |
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As an aside, oddly enough I'm quite familiar with the dangers associated with high pressure air (3000+ PSI). Back in the day I was an ICBM launch officer and our launch control centers (LCC) had 4 shock isolators that suspended the LCC from the surrounding structure. The isolators used high pressure air. |
I see the tank prices vary widely based on location. The cheapest I could find rental tanks 250CF was $30 per month per tank in my area. At those prices, the $300 per tank to purchase sounded better. Exchange for a full one is supposed to be $32, although I have not had to do that yet. If I could rent for $30/ year, would have gone that route.
I was asked to leave an Airgas location when I finally admitted I was going to use industrial gas to fill my tank. He wanted to sell me "aviation oxygen" for twice the price listed above. I said I was under the understanding that there was no difference. That location sells medical, aviation and industrial oxygen, and he admitted to getting the supply from the same source, delivered in the same tank but the aviation gas was certified for moisture content. Told him I don't care about the paperwork. He said what if the line freezes. Told him the tank was right behind me so if it freezes, so do I. Could not win that one... |
My research
I've done a bit of research over the past few days, too. One local industrial gas supplier is AIRGAS. I can order Aviators' oxygen from them. They do not keep it in stock. Price is $62 for a 200 cubic ft. sized refill (actually a cylinder trade, empty for full), not including the cylinder.
Rather than use welding oxygen, some may want to spend that $62 rather than the $31 welding O2 costs and have the piece of mind that comes with knowing that the aviators oxygen can be tracked by lot # and you can get a certificate of analysis for it if requested. That is what I was told the difference is. They do not normally provide paperwork unless asked for here, because they have to get it from their distributor. I does not come with the shipment. Disclaimer: I'm not sure they can't do this with all of their gas cylinders no matter what the content. In today's litigious society it would seem like a good idea. They also sell veterinarian oxygen. So, I talked to my vet nephew after church, today. He doesn't use enough quantity to buy the big cylinders. What he uses is about the same size as what most of us have in our planes. I asked him if there was any difference between it and medical O2 and he said none that he knew of but if I try it and start mooing I couldn't blame him! Anybody else want to volunteer? :) I am managing a small airport so I checked around the web on what I could install a fill system for and found these links with system prices. http://www.deltaoxygensystems.com/id115.html and http://aviationoxygen.com/aviation-o...e-systems.html It would never pay to have even the smallest fill system unless you have traffic that used oxygen. I've never even had one request for an oxygen fill in the 4 years I've been manager. Well except for one unnamed RV'er. There is only one other piston airplane on our field besides mine that is equipped with oxygen. The jets and turbo-props are pressurized and their emergency bottles are serviced elsewhere. p.s. If you want to hear some horror stories about breathing the wrong gas, catch me at Oshkosh. In a previous life I worked at a chemical refinery where we separated gases via cryogenics. You can also ask me at Osh what I use in my RV7 oxygen bottle...;) Joe |
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