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Oxygen cylinders?

N729LS

Well Known Member
Patron
Wasn't sure where to post this, but the classifieds are the most read, so...
I recently acquired a transfill adapter for my portable O2 bottle and now need to get a large oxygen cylinder for the source. Anyone have some advise on where to get such, and just what to get?
  • Is industrial oxygen OK, or do I really need to get aviator's oxygen?
  • What size bottle is reasonable? 150CuFt?
  • Should I buy a bottle or rent?
Notes: I don't go into the flight levels and keep the portable bottle in the cockpit, so I am not worried about freeze-ups. I would expect to refill not more than 1/year.
Thanks,
Andy
 
Welders Oxygen

It's been discussed in a couple other threads on here already, but if you work your way through these articles, you will have a pretty good idea of what you need. Basically, if you have the "small" setup for in the plane, get the biggest one you can afford or store for the "big" setup to fill from in the hangar. Usual safety caveats apply, but I have found it hard to work around the "medical" oxygen cartel and so went with the smallest "welders" oxygen tank that they would exchange without questions (ie, CGA540), and pieced the rest together from eBay. If you are really worried, try running it and breathing it for a few hours at your desk, if you keel over, it was the wrong gas :D

https://www.kitplanes.com/homebuilt-o2/

https://www.avweb.com/features/pelicans-perch-13getting-high-on-welders-oxygen/
 
Wasn't sure where to post this, but the classifieds are the most read, so...
I recently acquired a transfill adapter for my portable O2 bottle and now need to get a large oxygen cylinder for the source. Anyone have some advise on where to get such, and just what to get?
  • Is industrial oxygen OK, or do I really need to get aviator's oxygen?
  • What size bottle is reasonable? 150CuFt?
  • Should I buy a bottle or rent?
Notes: I don't go into the flight levels and keep the portable bottle in the cockpit, so I am not worried about freeze-ups. I would expect to refill not more than 1/year.
Thanks,
Andy

I bought a new 80 cf bottle off ebay for around $200 and a transfill adaptor for another $62. I use industrial oxygen. You can swap bottles or request to get your bottle back. Big bottles are hard to handle.
 
How many times do we have to say this? *All oxygen (other than laboratory grade) is the same*.

Welder's, industrial, medical, aviator's, whatever...it all comes out of the same tank, and yes, they all meet the mythical aviator's oxygen spec.
 
How many times do we have to say this? *All oxygen (other than laboratory grade) is the same*.

Welder's, industrial, medical, aviator's, whatever...it all comes out of the same tank, and yes, they all meet the mythical aviator's oxygen spec.

This is absolutely true today, in America anyway. 30-40 years ago that was not the case, but now it is. The only economic way to make oxygen now in the civilized world is the cryogenic process, which makes very pure oxygen and is used for all purposes other than special lab work. The hospitals get filled up from the same LOX truck that the welding supply houses use. Any plant not using the cryogenic process has long since gone out of business.
 
Locally, the tank rental is about $10 per month per tank for the 260CF. Purchase was $300 per tank. Made more sense to purchase outright in the long run. 260CF are the only size the welding supply (locally) deals with, since they don’t fill them on site. About $35 per tank exchange, full. With 2 tanks can get many fills, especially if you settle for a lower PSI, like 1200. Local FBO fill was $55, and filled the 2000PSI tank to 1800. Only did that once.

When you get the tanks, less information is better. If they press you, it can be for an Oxy-Acetylene setup. Was asked to leave the local air gas two separate times when I mentioned aviation oxygen.
 
When you get the tanks, less information is better. If they press you, it can be for an Oxy-Acetylene setup. Was asked to leave the local air gas two separate times when I mentioned aviation oxygen.

That only shows how ignorant they are of their products, but it's in line with all the other businesses that get nervous when someone mentions "aircraft" (HD, Lowe's, auto parts stores, you name it). They don't need to know any more than the color of my money. If pressed, it's for Nunya. Nunya business.
 
I got a fiberglass (or something like it) from Mountain High, years ago. Lighter than metal.

Used it to and from AirVenture, peacefully cruising above the clouds...
 
I have somewhere around 10 cylinders of various "process gasses" at multiple locations. We own all of them as opposed to lease just for accounting simplicity. I guess, if our shop was going through a pallet of welding gas per day, that would be different.

Being a flat lander, anytime I'm above 9k' for more than an hour, I turn on the good stuff. We spend so much time at 14.5k' with the -9 wing, I can't imagine being without it, or worrying about conserving. I love my Mountain High pulse demand.

Then there is the hydro cert... Nobody out in the world will touch it if it is out of date. I've used the local wholesale fire extinguisher service co. with great success for hydro.
 
Two sources for hydro testing when you need it.

1) A scuba diving shop. They will be sending their air tanks out, and can get your O2 tank done too.

2) The last time I did it, it was not actually a hydro test. A soft-drink distributor had an ultrasound process for inspection. Meets the same 5-yr DOT requirement. And a big up-side is that you don't even have to vent the O2 out of the bottle!
 
Just got back from Airventure and talked to the Aerox folks.... “industrial oxygen”, “medical oxygen” and of course “welding oxygen” are grades but nothing you would notice. So you can use "welding" O2. In practice use a pulse oximeter to adjust your flow. You need a medical prescription for medical O2 which is 99.5% pure. I think welding is 99.2%. We NEVER use pure O2 with cannulas below 18K feet. The O2 is mixed with ambient and exhaled air. Only Jets with full face mask use pure O2 (because you need it at high altitudes). Again measure your saturation and adjust flow as needed.

The issue with filling are compatible fittings. A medical O2 bottle might have different fittings than a welding bottle. That is easy to fix... there are adapters. If you get a prescription you may be able to go to local medical supply and exchange bottles. It has been a while since I bought O2.... I stay below 12,000 mostly.

The bottle needs hydrostatic testing periodically. Most portable O2 bottles/cylinders are aluminum. For me "C" bottle is about right. You can pay for a full kit or try and buy your own bottle and regulator. In the end you need a good aviation cannula and flow meter. Keep in mind O2 after a few hours will dry your nasal passages out big time. Not pleasant.

Pilots can group together and rented a large tank from welding shop, and it kept in hanger to refill your bottle. Rental of bottle is not bad. If you go to FBO, but that could be expensive. Most RV's are not getting above FL180 routinely if ever. I only go to O2 altitudes if there are strong tail winds... Kind of cool seeing your RV doing 250 kts... ground speed.
 
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Just got back from Airventure and talked to the Aerox folks.... “industrial oxygen”, “medical oxygen” and of course “welding oxygen” are grades but nothing you would notice. So you can use "welding" O2. In practice use a pulse oximeter to adjust your flow. You need a medical prescription for medical O2 which is 99.5% pure. I think welding is 99.2%. We NEVER use pure O2 with cannulas below 18K feet. The O2 is mixed with ambient and exhaled air. Only Jets with full face mask use pure O2 (because you need it at high altitudes). Again measure your saturation and adjust flow as needed.

The issue with filling are compatible fittings. A medical O2 bottle might have different fittings than a welding bottle. That is easy to fix... there are adapters. If you get a prescription you may be able to go to local medical supply and exchange bottles. It has been a while since I bought O2.... I stay below 12,000 mostly.

The bottle needs hydrostatic testing periodically. Most portable O2 bottles/cylinders are aluminum. For me "C" bottle is about right. You can pay for a full kit or try and buy your own bottle and regulator. In the end you need a good aviation cannula and flow meter. Keep in mind O2 after a few hours will dry your nasal passages out big time. Not pleasant.

Pilots can group together and rented a large tank from welding shop, and it kept in hanger to refill your bottle. Rental of bottle is not bad. If you go to FBO, but that could be expensive. Most RV's are not getting above FL180 routinely if ever. I only go to O2 altitudes if there are strong tail winds... Kind of cool seeing your RV doing 250 kts... ground speed.

Lots of info on the intertubes; here's a pretty good summary http://www-personal.umich.edu/~lpt/oxlabel.htm

It's not the O2 itself, it seems, but the filling process that CGA uses to specify their grades.

The local group of RVers here all chip in to keep two big-@ss bottles from which to transfill our on-board tanks. When one gets low, somebody takes it across the street to swap it out for a full one with the local Airgas shop. Cheap, easy, legal and safe. And no fussing around with semi-bogus prescriptions for "medical grade" (unless that's the style of tank you want to use I guess).

To each his own, though :)
 
Somewhere in your area is a welding gas or industrial gas supply house. They will fill a 125 bottle for about $20. Dont go to the name-brand place they will want to own your bottle and charge high dollar for exchanges. Go to the welding gas supply house.

Also somewhere in your area is a company that takes new bottles, paints them, and sells them to industry. The most cost-effective thing is to purchase from the cylinder company a new bottle in the size you want (i.e. in a size you can lift) and they will usually paint it green and supply it tested, oxygen-clean, and ready to go. A 125 bottle is all I can lift safely by myself in and out of my truck. Last time I did this the bottle was $215 plus tax.

If you ask at the welding gas supplier they will usually know where to buy new clean cylinders.

You can create your own transfill system pretty easily buying oxygen-clean parts and hoses by Internet. "Western Enterprises" makes anything you want, delivered already clean and ready to use if you buy from the distributors. You can also scrounge but the cleanliness is up to you.
 
Oh, and the big bottles from industrial suppliers carry 10 year inspection periods, and they are re-inspected for about $20 every ten years. I would caution you to inspect your transfill much more often than that with a little Snoop.
 
RE: welding bottles
If a bottle is leased it will have the name of the company stamped into the neck. NO-ONE will fill a bottle branded unless it is branded with their company name on the neck. A "customer owned" bottle will not have the brand mark and anyone will refill or exchange that bottle. Just make sure if you exchange that you receive a NON branded necked bottle back or you will be out of luck next time if you try to go somewhere else. If you exchange the bottle vs have them fill it they will handle the hydro but you risk getting back a nasty looking bottle that wasn't as nice as yours. Some welding supply houses will only LEASE bottles while others will lease OR sell you a bottle. Either of them will fill/exchange your "customer owned bottle" if you have one. Leasing a bottle makes no sense for me so I purchased two from Craigslist for $150 a piece for 300CF tanks. These are the largest tanks that local shops will swap.

RE: transfiller
I got a nice setup from flea-bay. The listing was for a single bottle transfill unit so I sent an email asking if they could make a cascading unit for two bottles. This was not a problem for them and it came in the mail shortly thereafter.

Now EVERY time the plane leaves the hangar the bottle in it is full without exception.
 
How many times do we have to say this? *All oxygen (other than laboratory grade) is the same*.

Welder's, industrial, medical, aviator's, whatever...it all comes out of the same tank, and yes, they all meet the mythical aviator's oxygen spec.

Mostly true:

Air separation plants are all over the USA. Once the air is separated into the different gases they ship to "fill plants" in isotanks, or cryogenic liquid tanks as mentioned earlier.

yes, All Oxygen comes from the same tank as stated. Then as they fill the industrial, medical, aviator tanks they test for certain specs.

Medical oxygen is tested to certain specs before the certification label is installed. It has moisture in it because the people who need it are breathing it 24/7.

The big difference between medical and Aviator's? The aviator's is also tested for moisture content.

Don't want it freezing at altitude. Temps at altitude are quite cold, and the aircraft used to have plumbing from an un-heated part of the aircraft to the pilots oxygen supply. When flying in our RV's this isn't an issue because most have cabin heat where the oxygen cylinder is located.

Learned the difference between aviator and medical when going through military flight training.

Mike
 
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but I have found it hard to work around the "medical" oxygen cartel and so went with the smallest "welders" oxygen tank that they would exchange without questions (ie, CGA540),

https://www.kitplanes.com/homebuilt-o2/

https://www.avweb.com/features/pelicans-perch-13getting-high-on-welders-oxygen/

The CGA 540 is a valve and not a tank size. CGA stands for Compressed Gas Association. Different CGA valves are used for different gasses and/or different pressures for the same gas.

CGA 540 is an industrial oxygen cylinder while a CGA 870 is for medical/aviator oxygen tanks, they have pins designed to align the flow meter to the cylinder opening. Some medical oxygen cylinders have the CGA 540 valve, these do not have the pins.

Cylinder sizes for industrial oxygen are listed by the cubic foot.

One of the smallest you can get from a welding supply would be a 20cf, then 40cf etc..

Medical and aviator sizes are called size D or E for the small sizes that I use. Not sure what a size C is, but a size D is 14cf, and a size E 24cf. Bought both of these with a flow meter on eBay for real reasonable price.

If you fill from a industrial cylinder the bigger the better. If you fill a Size E using a 20cf industrial or welding cylinder, the E will not fill all the way and the pressure will equalize below the max pressure for the tank. You might end up with about 25% of the volume, give or take (example only no actual math was done). The welding cylinder will still have some in it as well. Both will be the same pressure.

Depends on the hydro test date stamp on the cylinder when it needs hydro tested.

Industrial cylinders will have several different markings.

See something that looks like a date? Does it have a STAR and a + sign near the date. This means the cylinder is good for ten years from the date, before needing the next hydrotest.

Medical and aviators do not use these symbols.

Caution when filling from an industrial cylinder, no way to know if someone emptied the cylinder completely and left the valve open. If they did this then moisture can get inside causing rust to form inside the cylinder, minute amounts can plug your breathing flow meter.

Mike
 
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Wasn't sure where to post this, but the classifieds are the most read, so...
I recently acquired a transfill adapter for my portable O2 bottle and now need to get a large oxygen cylinder for the source. Anyone have some advise on where to get such, and just what to get?
  • Is industrial oxygen OK, or do I really need to get aviator's oxygen?
  • What size bottle is reasonable? 150CuFt?
  • Should I buy a bottle or rent?
Notes: I don't go into the flight levels and keep the portable bottle in the cockpit, so I am not worried about freeze-ups. I would expect to refill not more than 1/year.
Thanks,
Andy

The 150cf is good choice, small enough to move around, but plenty of refills in it before you need to get another. The Aviator would be the better choice.

Are you buying brand new? If not be sure to look for a date and then look for a STAR and a + next to it. That means the tank is good for ten years from the date before needing a hydrotest.

If your local welding supply exchanges the cylinder then this isn't an issue. But if they fill you will have to have the hydrotest done on your dime.

It is safer to buy a new cylinder if you can find one: Then only go to a place that gives your cylinder back to you.

If someone emptied a used cylinder that is for sale, and left the valve open, rust can form inside the tank.

When emptying the cylinder most welding supply will say to leave at least 50lbs of pressure in the tank so it doesn't let moisture in.

Most welding supply stores sell all of the mentioned types. Medical will only be sold to licensed medical facilities, while you can get the larger size aviator cylinders and same size industrial welding cylinders by asking.

Mike
 
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Medical oxygen is tested to certain specs before the certification label is installed. It has moisture in it because the people who need it are breathing it 24/7.

Ask any nurse where the moisture in an O2 line comes from...it doesn't come from the portable bottle or hospital-wide O2 piping system. It's added at the point of delivery with a humidifier (to keep the dry O2 from dessicating mucous membranes and such).
 
Mostly true: Not? :D

Medical oxygen is tested to certain specs before the certification label is installed. It has moisture in it because the people who need it are breathing it 24/7.

The big difference between medical and Aviator's? The aviator's is also tested for moisture content. Mike
Fake news, disinformation. :D Ha ha. I use to think the same thing Mike. You may be right about testing but the moisture is not a big factor.

In the distant past I was told do NOT use medical O2 for aviation where it could freeze in the lines. I talked to the Aerox guys at Oshkosh last week. They said not true. I followed up with some internet searches. You may be right about Specs, but moisture content between grades makes no difference.

There is little to nil difference in moisture between grades. Pure 02 is pure O2. There is less than 0.5 to 0.7% "other" gases. There will always be some impurity or variation, but not you would notice. Our Atmo is 78 %, 21% oxygen, 0.9 % argon, and 0.1 % other gases. As we go higher O2 becomes less and our ability to absorb it also goes down.

In the 1980's and 90's the medical field used in-line humidifiers to add moisture to the O2 given to patients, after the supply tank. That fell out of favor after studies showed it made little difference for people sucking supplemental O2 24/7. Also it was a great place for bacteria to grow. In general practice H2O in O2 tanks is not a factor. Humidifiers are still around just not used routinely in medical field. For home use people have humidifiers for the whole house; winter air is dry. In summer AC dry's the air.

For aviation at altitude (where ambient moisture is less) using supplemental O2 (which is always dry regardless of grade) you will dry out. It is just going to happen. Medical O2 is not "wet" vs other industrial grades, at least to make any difference. It use to be "common" knowledge it was a big deal, but it's not true.

Fun fact is we are blowing in way more O2 up our nose with cannulas at altitude then we use. Most of it is lost or does not physiologically get absorbed. The higher you go the less O2 can be absorbed at ambient pressure. At high altitudes you need a 100% pressure mask. That is why when one airline pilot gets up in fight for a break, leaving the other pilot at the controls, that pilot has to put on a mask at FL350 or higher. Above FL250 you need quick donning masks are required. It gets serious up there as we saw with Paine Stewart and Helios Airways Flight 522.

Don't fly with out a pulse oximeter and use it. Some smart watches have built in O2 blood saturation. Mine is fairly accurate but I rely on the finger type. These oxygen saturation devices or oximeters use the know difference in light absorption of Oxy-Hb and Deoxy-Hb and the ratio of the two. (Hb = hemoglobin).
 
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Fun fact is we are blowing in way more O2 up our nose with cannulas at altitude then we use. Most of it is lost or does not physiologically get absorbed. The higher you go the less O2 can be absorbed at ambient pressure. At high altitudes you need a 100% pressure mask.

This is true, but necessary. What matters in pushing O2 into the blood stream is not the total ambient pressure, but the ‘partial pressure’ of O2. And the easiest way to increase that is by increasing the fraction of O2 in the air. As pointed out, when high enough even 100% oxygen does not have a high enough pressure, and you need to go to breathing oxygen at above ambient ptessure.
 
Cylinder Markings

Depends on the hydro test date stamp on the cylinder when it needs hydro tested.

Industrial cylinders will have several different markings.

See something that looks like a date? Does it have a STAR and a + sign near the date. This means the cylinder is good for ten years from the date, before needing the next hydrotest.

Actually the Star and the + denote 2 different things. The Star denotes an addition of 5 years to the standard 5 year retest period. The
+ denotes that the cylinder may be filled to a pressure 10% higher than the stamped pressure. The cylinders might have either symbol, or both.

Skylor
 
Ask any nurse where the moisture in an O2 line comes from...it doesn't come from the portable bottle or hospital-wide O2 piping system. It's added at the point of delivery with a humidifier (to keep the dry O2 from dessicating mucous membranes and such).

True. Usually only added for higher flows. Added at the bedside, as stated.
 
Pulse demand game changer

Scott

I picked up the Pulse system you and Tanya used after that west coast trip you wrote up last year. What a difference in usage over the freeflow systems. I turned one of my buddies with an RV4 onto it and he only used 200lbs coming back from Osh this year and he was over at least 4.5 hours above 12500.

Thanks for the tip!
 
Fun fact is we are blowing in way more O2 up our nose with cannulas at altitude then we use. Most of it is lost or does not physiologically get absorbed. The higher you go the less O2 can be absorbed at ambient pressure. At high altitudes you need a 100% pressure mask. That is why when one airline pilot gets up in fight for a break, leaving the other pilot at the controls, that pilot has to put on a mask at FL350 or higher. Above FL250 you need quick donning masks are required. It gets serious up there as we saw with Paine Stewart and Helios Airways Flight 522.
[/COLOR]

Fun fact, the requirements to Don the mask at FL350 and above when one pilot leaves the flight deck went away with covid. Not saying it isn’t a good idea, but they said we no longer are required to do that anymore.
 
Scott

I picked up the Pulse system you and Tanya used after that west coast trip you wrote up last year. What a difference in usage over the freeflow systems. I turned one of my buddies with an RV4 onto it and he only used 200lbs coming back from Osh this year and he was over at least 4.5 hours above 12500.

Thanks for the tip!

I’ve also got the pulse demand Mountain High system in my little jet, and it is shocking how efficient it is. I have a tiny little bottle, and use it any time I am above 12K (which is probably 80% of all my flight time), and only fill the bottle about every ten flights. Pricey - but if you have to pay for fills, it can balance out on a cost basis. I have a three-bottle cascade in my hangar, so do my own fills, which means cost really isn’t my driver - it is overall endurance on a fill. Two years ago, I went all the way to Oshkosh on one fill!
 
Scott

I picked up the Pulse system you and Tanya used after that west coast trip you wrote up last year. What a difference in usage over the freeflow systems. I turned one of my buddies with an RV4 onto it and he only used 200lbs coming back from Osh this year and he was over at least 4.5 hours above 12500.

Thanks for the tip!

Yup! Been using it for my O2 addiction since day 1 over 14yrs ago.
 
I’ve also got the pulse demand Mountain High system in my little jet, and it is shocking how efficient it is. I have a tiny little bottle, and use it any time I am above 12K (which is probably 80% of all my flight time), and only fill the bottle about every ten flights. Pricey - but if you have to pay for fills, it can balance out on a cost basis. I have a three-bottle cascade in my hangar, so do my own fills, which means cost really isn’t my driver - it is overall endurance on a fill. Two years ago, I went all the way to Oshkosh on one fill!

Revealing! 3 bottle fill is most (cost and O2) effective (confirmed by the numbers), best to have flight bottle full for each mission, small bottle = weight efficient, home/self fill is most practical, maybe 28 fills to break even, so not really the cost, but personal effort-a real time saver. After all it is limited.

OK - I had all these questions and this pretty much confirmed my conclusions.
 
I'm certain we've long since paid for our O2 cylinders in the hangar (disclaimer, not the CFO). I've been operating a 2 bottle transfill with the biggest cylinders that you would want to move by hand. When we start traveling more (current plans), I'm confident the third cylinder will be a welcome addition.
We fill one hangar cylinder at a time. High gets swapped to Low... etc. Something about cost optimization that I don't understand at $30 a pop :). The local mom and pop welding supply co just backs up to the hangar and asks no questions. Granted, we sometimes have an eclectic mix of gas cylinders from all kinds of processes.

I haven't fired the Oxy Acetylene torch in many years. Go fly and use the O2 freely. You'll show up much happier.
 
A quick question which I don't think I've seen addressed in this thread or in previous threads on this topic...

There are home oxygen concentrators which have the capacity to fill medical O2 bottles. The fill rate is not hugely fast, I recently was told 6 hours to fill a cylinder (sorry, the conversation didn't cover that level of detail).

Has anybody used a home oxygen concentrator to fill O2 bottles to use in their aircraft? If so, I would very much appreciate you sharing any details around the make/model of concentrator and the method/experience of filling O2 bottles with it.

Thanks in advance for any details you might care to share.
 
I have checked out a few concentrators; some are rated for aircraft use. But I have never seen any that pump the O2 up to anywhere near a typical tank pressure.
 
Having seen the results of a scuba tank exploding while being filled, you do not want anything that produces that kind of pressure in your plane. The oxygen generators only produce the pressure needed for each breath, not for storage.
 
Having seen the results of a scuba tank exploding while being filled, you do not want anything that produces that kind of pressure in your plane. The oxygen generators only produce the pressure needed for each breath, not for storage.
I interpreted the remarks as meaning, can one use an oxygen concentrator to facilitate filling a bottle for flying use? Short answer is, yes after adding much complexity, cost and hazard. You'd need a very specialized oxygen safe compressor (big $$$) and all the associated O2 safe plumbing with your concentrator. And then the result would be an air - oxygen blend in your tank.

I looked at a compressor installation for transfill and pressure boost of my flying oxygen bottles, and quickly gave up. Safely handling 100% oxygen at those pressures is expensive and very hazardous if not done properly. I use two ea 250 cf bottles for my transfill operation. When the low one gets to 8-900 psi, I exchange it for a full and it becomes the high pressure bottle. The best trick I've found for boosting the pressure is to set the fill bottle in the sun and let it heat up a bit. Gives me noticeably more pressure in my flying bottle.
 
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I... The best trick I've found for boosting the pressure is to set the fill bottle in the sun and let it heat up a bit. Gives me noticeably more pressure in my flying bottle.

The only way i see this working is if the fill bottle is in the sun, and the aircraft bottle is kept cool. The same thing can be done if the aircraft bottle is put in the frig while filling, or even just chilled before filling. PV=nRT
 
The only way i see this working is if the fill bottle is in the sun, and the aircraft bottle is kept cool. The same thing can be done if the aircraft bottle is put in the frig while filling, or even just chilled before filling. PV=nRT

Yep. That's how I did it. I believe I did put the flying bottle in the refrigerator before. Recall seeing ~~300 psi improvement after.
 
I interpreted the remarks as meaning, can one use an oxygen concentrator to facilitate filling a bottle for flying use? Short answer is, yes after adding much complexity, cost and hazard. You'd need a very specialized oxygen safe compressor (big $$$) and all the associated O2 safe plumbing with your concentrator. And then the result would be an air - oxygen blend in your tank.

I looked at a compressor installation for transfill and pressure boost of my flying oxygen bottles, and quickly gave up. Safely handling 100% oxygen at those pressures is expensive and very hazardous if not done properly. I use two ea 250 cf bottles for my transfill operation. When the low one gets to 8-900 psi, I exchange it for a full and it becomes the high pressure bottle. The best trick I've found for boosting the pressure is to set the fill bottle in the sun and let it heat up a bit. Gives me noticeably more pressure in my flying bottle.

Poor wording on my post. I didnt think there was any way it would produce enough pressure to fill a tank - at least that is what I was trying to say! The reference to scuba tank was to show why you didnt want anything in your plane that could produce enough pressure to fill a talk. I admit- poor example. Do a search on scuba filling explosion's. That is why they put the tanks in water when filling.

I have a 2 tank filling system in my garage that sometimes even gets used for welding!
 
What I Did

My reference to CGA540 regarding size (I realize that is a valve standard, not a size standard) is that when I called the local welding supply place, they basically said anything smaller than around 20cf would be considered "medical size", even with a CGA 540 valve, implying lots of questions would start being asked. In addition, the smallest size you could walk in and just swap out (with a CGA540 valve) is a size called "Super D". They told me I could bring in my own smaller CGA540 tank, or any tank I specifically wanted to keep, and they would refill it, but because it can't be swapped, it was generally a 1-3 week turnaround to go out to the main refilling hub and then come back to the local welding supply place. I also got the impression that any hint at all of this being for anything other than welding would have immediately terminated the phone call.

I only need O2 for the occasional XC, and I didn't feel like investing the time, space and money into having a transfill setup when I might only need a refill once a year or six months. So, I went with a CGA540 pediatric regulator and oxymizer cannulas from eBay, and the smallest CGA540 tank available at the welding supply store that can be swapped, and figured at 27$ per refill/swap (taxes and fees etc included), it would take a while to justify having the full setup. I haven't really had a chance to use it all yet though, since I didn't get my parts in time for Osh, so maybe I will discover I should have gone the other route so I can have that sweet sweet O2 flow all the time.

I have heard of getting a prescription easily from your AME or whatever, but it wasn't clear that this would make it any easier or cheaper if you are going the just-swap-it-out route vs having a transfill setup. The upside on the medical type setup (ie CGA870), is that the bottles are lighter, and come in much smaller sizes, so you could save some weight and size according to the mission at hand. However, I reasoned that if I was out of town, and really wanted or needed O2 for the next leg, the courtesy car in Randomville Nowhere USA would get me to a welding supply place easier than a medical oxygen place.

In the end, you kind of have to do it like you do your plane: plan it out, find what works best with what _you_ actually have access to, your budget etc, and then build it and use it. I am not more than 200$ into the setup, and it get's me going, and can expanded/upgraded/modified. I think overall consensus is that having O2 available at almost any XC altitude is a big plus and worth the investment.
 
Fill port

I have a MH built in system in my 10. Went to fill it for the first time at a buddies hanger who has fill set up with his own tank. Mine has an AN-800-3 valve and he has a Scott filling set up. Does anyone know where to get a direct adaptor? I called MH and they don't have one.
 
Wow, for a bunch of folks who pride themselves on being on the leading edge of technology it sure doesn't take much deviation from strongly conventional thinking to cause one to be shot down in flames. Now I know how the alternative engine folks feel! ;)

My question regarding the use of an O2 concentrator to fill tanks met with some, to put it politely, uninformed responses.

As an example of the equipment to which I was referring, Invacare makes a concentrator/compressor stack - see attached photo and description below.

This is the type of equipment which might be handy for an aviator to own rather than running a bunch of big welding bottles and transfilling at high pressure. The price isn't totally over the top and the tank fill times aren't unreasonable if one has more than one cylinder and can keep a spare cylinder available to be topped off at home. Heck, one might even leave this unit in the hangar and fill bottles while working on the airplane.

If one doesn't want the hassle of hiding the truth from welding gas suppliers, this might be a decent way to go. Or not. That's why I was asking the question, in hopes that perhaps some fine soul already had gone down this path and was willing to share their experiences here.

Perhaps from this new baseline we might get some better-informed feedback.


=====================

HomeFill II Oxygen Compressor - The Invacare HomeFill II complete home oxygen system will revolutionize ambulatory oxygen by allowing patients to fill their own high-pressure cylinders from a concentrator. The HomeFill is a multi-stage pump that simply and safely compresses oxygen from a specially equipped Invacare 5-liter or 10-liter concentrator into oxygen cylinders in size ML4, ML6 and M9(c).

Features

Connection and controls are designed for ease of operation
Fill cylinders while patient continues to receive oxygen from concentrator
Virtually eliminates the high service costs of frequent deliveries of cylinders and-or liquid oxygen
Gives ambulatory patients greater freedom and independence
Small and lightweight

Specifications:
Electrical:120 VAC +- 10% at 60 Hz
Power:Consumption: 200 watts
Rated Current Input:2.0 amps

Pressure:14 - 21 psi

Oxygen:Output from concentrator: 0 - 3 lpm (while filling cylinder)
Input: 0 - 2 lpm
Dimensions:20.25"W x 15"H x 16"D
Product Weight:33 lb
Cylinder Filling Times:M6: 1 hr 25 min
M9: 2 hr 20 min
 

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What I read is ‘pressure. 14 - 21 psi’. For most aviation uses that is nothing. Am I not reading it correctly?
 
Well, I apologize. I have never seen anything like this. It would be perfect for my needs - except for the cost. I can get a lot of refills at fbo prices before this investment makes sense.
 
Pressure

This is not a bad idea if you could figure how to connect your tank to the unit or in my case the fill port on in the plane. I looked it up and it fills tanks to 2000psi.
 
It looks like an interesting unit, for sure. I'd say just get well educated as to the long term costs and maintenance and expected lifetime of the system. If it all checks out, could be a good way to go. 2000psi is adequate. You can get more with a cascade system, however.

Years ago I had pretty interesting oxygen fire using a haskell booster system. I had filled oxygen and other gasses for years, but that one caught me off guard because it was all O2 cleaned. Suffice it to said, I have a lot more respect for adiabatic compression now. :) That was pre-aviation days for me.

I will say that I own a 4 large cylinder cascade system, and if you invest in such a system, and store it well, you can get a lot of time out of it for really nothing for maintenance other than a hydro test for any tank you send in that's over 5 years since previous. The transfilling adapter is a one-time purchase. And Oxygen is cheap. It used to cost me less actually to get a large cylinder full, than it did to get an aviation portable system filled at any FBO. These days I fill much less often, so my initial investment is not costing me any additional dollars at this time. When I finally send in my low cylinder, it'll cost me maybe $50 to get it all back and returned filled I'm guessing, and I'll get a few more years out of the system before spending another $50. I would say that if you can pool together with a small group of local pilots, just buying your own cascade system will be a great way to go.

Whatever you do, read and follow the safety recommendations for O2 filling, and you will probably have zero issues. Primary on the list is make sure everything involved is O2 cleaned and compatible. Right behind that is, open every valve slowly. If you do just those 2 things, you will have good success.

As has been said many times before, these days an O2 fill is an O2 fill. And, you don't need to justify anything to anyone. Simply tell the company you want to buy 3, or 4 large size welding O2 cylinders with valves. You can get 250cuFt cylinders for under $300 each. Probably can buy 4 and have them filled for $1200. If you're a sole user of such a system, my guess is that will last you 5-10 years if you use it as often as me, and from there on your costs are very low. Without doing any calculations, you're looking at I'm sure many dozens of fills before you need to pull a cylinder for top-off.
 
Just exchanged my large O2 welding tank for $40, I'm good for another 5 years or so.
 
Scott
Can you add the pulse demand system to the AerOx cylinder?
Figs

I am not Scott but I changed my AerOx system to the Mountain High pulse system years ago. The system was old and needed new connectors on the regulator as the ones I had were leaking. May have been as simple as replacing O-Rings in the connectors (could not get the connectors apart) but I changed to the Mountain High system instead. I needed to replace the connectors on the AerOx regulator to ones that worked with the Mountain High equipment and everything works fine.
 
As an example of the equipment to which I was referring, Invacare makes a concentrator/compressor stack - see attached photo and description below.
=====================

HomeFill II Oxygen Compressor - The Invacare HomeFill II complete home oxygen system will revolutionize ambulatory oxygen by allowing patients to fill their own high-pressure cylinders from a concentrator. The HomeFill is a multi-stage pump that simply and safely compresses oxygen from a specially equipped Invacare 5-liter or 10-liter concentrator into oxygen cylinders in size ML4, ML6 and M9(c).

Features

Connection and controls are designed for ease of operation
Fill cylinders while patient continues to receive oxygen from concentrator
Virtually eliminates the high service costs of frequent deliveries of cylinders and-or liquid oxygen
Gives ambulatory patients greater freedom and independence
Small and lightweight

Specifications:
Electrical:120 VAC +- 10% at 60 Hz
Power:Consumption: 200 watts
Rated Current Input:2.0 amps

Pressure:14 - 21 psi

Oxygen:Output from concentrator: 0 - 3 lpm (while filling cylinder)
Input: 0 - 2 lpm
Dimensions:20.25"W x 15"H x 16"D
Product Weight:33 lb
Cylinder Filling Times:M6: 1 hr 25 min
M9: 2 hr 20 min

So help me here, I looked up the specs and it doesn't read like an engineering document - - If I understand the concentrator is a separate unit from the "compressor" . . . and the compressor needs 14-21 psi inlet?

The concentrator is a separate unit and to be used by the patient directly most of the time or used to provide the 14-21psi source of O2 to the compressor for filling portable tanks for freedom of movement.

So for pilots, all we really need (me) is the "compressor"? Then I can suck my welding tank down (F, 240CF) to 200 psi before needing to refill and still 100% refill my J (647L) aviation bottle? I guess the input would have to be dropped from 300-2000psi to 24psi or it will pop a cork.

This whole discussion came up a few years ago and I did all the calculations and economics for a 1-2-3-4 bottle (F) O2 reservoir. I even got a few quotes for an oxygen qualified pressure booster pump (aviation company) around $5000. That seemed a bit much, but if this guy is $2000 it seems like a real price improvement AND it is electric. This means a used unit is likely available from a medical supply?

Can this be confirmed?
 
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