Medical 'Homefill' Oxygen?

Jeff K

Jeff K

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Jeff King
I picked up a Invacare Home Fill oxygen system off Facebook marketplace for $220 and it included 3 cylinders with built in conservors. This system allows you to fill your own small tanks with Oxygen. The M6 tanks I got will last 6 hours. They even have transfill adapters for standard tanks.

Looked like a sweet way to get O2 in the plane on the cheap and easy. Even new and retail, about about $2300, it seemed like a good solution. But tons of these on craigslist and facebook marketplace. O2 concentration is >90% and these are medical system.

To my surprise I'm not seeing any mentions of this on any of the aviation boards. Am I missing something or just a good idea not yet discovered?

-Jeff


invcare.jpg
 
Aviation oxygen used for high altitudes MUST be moisture-free. Any moisture in the O2 could cause aviation oxygen systems to freeze up due to the low temperatures involved.

Medical O2 typically has moisture added to prevent drying of the nasal and breathing passages. Using medical O2 for flight could have catastrophic results if the systems froze up due to the added moisture.
 
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Zeldman said:
Aviation oxygen used for high altitudes MUST be moisture-free. Any moisture in the O2 could cause aviation oxygen systems to freeze up due to the low temperatures involved.

Medical O2 typically has moisture added to prevent drying of the nasal and breathing passages. Using medical O2 for flight could have catastrophic results when the systems froze up due to the added moisture.
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I see no issues if one uses a cannula directly from the bottle if the bottle is in the cabin with out.
 
I'd have no issues using that....but, my bird has a 115 cuft tank. :D

now....could I rig that up to fill my tank? o_O
 
Zeldman said:
Medical O2 typically has moisture added to prevent drying of the nasal and breathing passages.
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Oxygen from that machine has no added moisture as it's pumping. If you want moisture added you need to use one of these. It fits right there in the cubby hole where the black rubber band is.

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Zeldman said:
Aviation oxygen used for high altitudes MUST be moisture-free. Any moisture in the O2 could cause aviation oxygen systems to freeze up due to the low temperatures involved.

Medical O2 typically has moisture added to prevent drying of the nasal and breathing passages. Using medical O2 for flight could have catastrophic results if the systems froze up due to the added moisture.
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The moisture is added at the bedside at the hospital.

The oxygen is the same.
 
Cryogenically prepared O2 is very dry. This thing I'm not too sure about. Compressing the gas is going to cause some of the liquid to come out but how much?
 
FYI, this isn't aviation or medical oxygen. It is oxygen separated from the air. Whatever humidity is in the air will I presume be put in the tank, however that's worth looking into. It likely is moot since the tank is in the cabin.


Checkout_my_Six said:
now....could I rig that up to fill my tank? o_O
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From what I am seeing, yes. Transfill adapters are available and these are quite popular with the glassblowers to fill their oxygen tanks. You still might have a issue with humidity however.
 
Zeldman said:
Aviation oxygen used for high altitudes MUST be moisture-free. Any moisture in the O2 could cause aviation oxygen systems to freeze up due to the low temperatures involved.

Medical O2 typically has moisture added to prevent drying of the nasal and breathing passages. Using medical O2 for flight could have catastrophic results if the systems froze up due to the added moisture.
Click to expand...

All O2 (aviation, welding, medical) is the same. A supplier like Airgas provides all of them from the same source. Mosisture is added to medical O2 but not in the tank—it’s added at the point of use. So as long as this setup doesn’t add moisture to what it’s putting in the tank it seems viable to me.
 
But...isn't it like $50 at most for a refill of oxygen? $2300 will buy a lot of tanks of oxygen.
 
The standard that I am aware of concerning oxygen to be used by aviators is that the water vapor content must not exceed 0.02 milligrams per liter at 21.1°C and 1013 mb.
 
Jeff K said:
FYI, this isn't aviation or medical oxygen. It is oxygen separated from the air. Whatever humidity is in the air will I presume be put in the tank, however that's worth looking into.
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Did a bit of reading on the theory of operation, and while not definitive, I'm thinking the humidity is absorbed by the zeolite, which is hygroscopic, along with the Nitrogen. That is flushed on every cycle. The tanks are pressurized to 1500psi and I'm not hearing any water when I shake the tank. I'll get a humidty meter and see if the concentrator is dehumidifying the air.
 
bflynn said:
But...isn't it like $50 at most for a refill of oxygen? $2300 will buy a lot of tanks of oxygen.
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I paid $220 for it used with 3 tanks. I can refill in my hangar at 2am. I don't need (or have) a built in oxygen system in my plane.
 
Modern oxygen: (confirmed in my neck of the woods where I visited the supplier and saw them fill tanks, discussed with them)
Welding oxygen = Medical oxygen = aviation oxygen
It all comes from the same bulk tank.
Historically it was not that way.
I have breathed welding oxygen from my gas supplier's O2 for years. Zero evidence of moisture. Someone said in one of the O2 threads that welder's oxygen might have oil in it. No way. (Boom.)
 
I've wondered about the use of O2 concentrators in flight. I would think they'd struggle at altitude. I hadn't considered using a concentrator to fill O2 bottles on the ground. Hmm...
 
I wouldn't be concerned about the moisture aspect for an in-cabin setup. If it's below freezing in the cabin, you're going to be very cold, too.
 
I would say give it a try. Have a bottle of aviation O2 handy and use a pulse ox just in case I guess...
 
labbadabba said:
I would say give it a try. Have a bottle of aviation O2 handy and use a pulse ox just in case I guess...
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Dittos on all that. My plane is NA so not often at altitudes that legally require it, but when I did have O2 in my other plane, I did use it to reduce fatigue. 10-11K is what I like to do my long cross countries at.

The reason for the post was more why hadn't I seen this system mentioned before. Thanks to you and others for the input.
 
Thanks for starting the thread,some good info,in The replies.
 
azblackbird said:
Oxygen from that machine has no added moisture as it's pumping. If you want moisture added you need to use one of these. It fits right there in the cubby hole where the black rubber band is.

View attachment 62320
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Thanks for the info. I saw the words medical and oxygen and assumed it had moisture.

I have had oxygen hoses freeze twice, usually close to the fitting. The temp in the plane was light jacket comfortable.



https://www.avweb.com/news/pelican/182079-1.html
 
Sounds like a lot of aggravation and time to me for what will end up not being that great of a savings. The sales documentation on the invacair system is not very good. I'm just wondering what the upkeep is like. Are the ops manuals any better?
 
bflynn said:
But...isn't it like $50 at most for a refill of oxygen? $2300 will buy a lot of tanks of oxygen.
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These systems are for people dependent on supplemental oxygen due to lung or heart disease. They need oxygen for years and years. The alternative to this kind of home-fill station is the Airgas truck stopping once a week to top off a LOX tank and to replace a rack full of portable bottles.



The reason you can buy a $2300 system used for $500 is because patients who are oxygen dependent tend to die within a few years and there is no good secondary market for durable medical equipment. Medicare/Insurance either leases the equipment from a service provider or they buy it and it becomes property of the patient (or his estate).
 
PaulS said:
Sounds like a lot of aggravation and time to me for what will end up not being that great of a savings. The sales documentation on the invacair system is not very good. I'm just wondering what the upkeep is like. Are the ops manuals any better?
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I didn't read the documentation until after I had already filled a bottle. The only thing I was confused about was the O2 concentration low light being on when I first hooked it up... but by the time I did a web search it had gone off and the bottle was filling. It turns out it takes ~3 minutes for the sensor to warm up.

My mom has had a concentrator going on 5 years now. That's all this is + a high pressure pump. She just recently replaced the Zeolite columns. If she had paid for it it would have been about $150.

Weike is spot on.... it's the used market for these that makes them so attractive.
 
tsts4 said:
All O2 (aviation, welding, medical) is the same. A supplier like Airgas provides all of them from the same source. Mosisture is added to medical O2 but not in the tank—it’s added at the point of use. So as long as this setup doesn’t add moisture to what it’s putting in the tank it seems viable to me.
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We're not talking about cryogenic o2 from a supplier. We're talking about his oxygen concentrator unit.
 
flyingron said:
We're not talking about cryogenic o2 from a supplier. We're talking about his oxygen concentrator unit.
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I know. The first part of my post was in response to medical O2 having moisture. The next part addressed using the concentrator.
 
tsts4 said:
I know. The first part of my post was in response to medical O2 having moisture. The next part addressed using the concentrator.
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But your initial post is INCORRECT unless you're talking about commercially produced (cryogenic) oxygen. His concentrator will not necessarily produce dry oxygen. In fact, moisture screwing up the concentrator itself is a big problem with these things. Depending on the humidity of his ambient air, the bottles may indeed have moisture in them. Your statement about the unit "not adding" moisture isn't the issue....it's already there.
 
https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Oxygen_Equipment.pdf

To shut y'all up. FAA says in this PDF that Oxygen separators are okay for use in aircraft oxygen systems.

AOPA evens says in their documentation that you can use any form of Oxygen supplier that you wish. If you do choose to use welding Oxygen it's on your head if you end up with a contaminate batch.

Me personally I'd be looking up the spec sheets on those tanks you got with the system. You need to make sure they are either DOT approved or can withstand the pressure changes at altitude.
 
ARFlyer said:
https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Oxygen_Equipment.pdf

To shut y'all up. FAA says in this PDF that Oxygen separators are okay for use in aircraft oxygen systems.
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Did you actually read the article. The article says NOTHING of the sort. It just identifies it as a type:
Molecular sieve oxygen generators (MSOG). The air that we breathe contains basically 21% oxygen, and the remainder is inert gases that play no major physiological role in the body. MSOGs take ambient air and separates oxygen from inert gases, using that to supply oxygen to the aircraft. The military has used this system for many years, as well as medical patients who need a portable oxygen system. Civil aviation hasn’t embraced MSOG, but it may be more in vogue in future aircraft​
Furhter, he's not running the MSOG in the plane, he's running it on the ground to fill a compressed tank. There's no assurance that the MSOG is fully removing the water.

AOPA evens says in their documentation that you can use any form of Oxygen supplier that you wish. If you do choose to use welding Oxygen it's on your head if you end up with a contaminate batch.
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AOPA, again, is talking about commercially obtained oxygen. All commercial oxygen these days is cryogenically separated and hence dry and pure. "Contaminated" O2 is an immense safety hazard even if you aren't trying to breath it.

Again, we are not talking about commerical (cryogenic) oxygen here.
Me personally I'd be looking up the spec sheets on those tanks you got with the system. You need to make sure they are either DOT approved or can withstand the pressure changes at altitude.
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This would be the last of my concerns. These bottles are filled to 1500PSI. The 10 psi difference you're likely to see at altitude isn't going to mean a whole lot.
 
Ted DuPuis said:
I wouldn't be concerned about the moisture aspect for an in-cabin setup. If it's below freezing in the cabin, you're going to be very cold, too.
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The temp doesn’t have to be below freezing. As the gas expands it lowers the temp. But to your point it won’t be much colder in the cabin than it would be in grammas house.
 
flyingron said:
His concentrator will not necessarily produce dry oxygen. In fact, moisture screwing up the concentrator itself is a big problem with these things. Depending on the humidity of his ambient air, the bottles may indeed have moisture in them. .
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Moisture "screws up" the concentrator because Zeolite is hydroscopic, meaning it removes moisture from the air (along with absorbing Nitrogen). This occurs before the oxygen is output. The presumption, which I will try and confirm later this afternoon and post my results, is that it is dehumidifying the air to some extent.

If there was significant moisture in the output of the concentrator, which I don't believe there is, it would be streaming out of the compressor in some fashion as there is no user accessible water trap.

Again, this is in the crew compartment. My plane's heat works. There isn't significant cooling on the concentrator assembly or value when in use (this is a pulse system).

flyingron said:
Did you actually read the article. The article says NOTHING of the sort. It just identifies it as a type:
Molecular sieve oxygen generators (MSOG).
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That is what this is.

https://en.wikipedia.org/wiki/Oxygen_concentrator#How_oxygen_concentrators_work

flyingron said:
Civil aviation hasn’t embraced MSOG, but it may be more in vogue in future aircraft
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flyingron said:
Furhter, he's not running the MSOG in the plane, he's running it on the ground to fill a compressed tank. There's no assurance that the MSOG is fully removing the water.
Click to expand...

In fact, Civil Aviation does have a MSOG option now. The Inogen G2 aviator Certified to 18,000 feet using identical technology. That's how this whole thing started with me. At least in the used market, the homefill is a far cheaper solution that I can share with my passengers.

http://www.inogenaviator.com/products.html

But stay tuned, I'll measure and post how much the unit dehumidfies later tonight.
 
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ARFlyer said:
https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Oxygen_Equipment.pdf

To shut y'all up. FAA says in this PDF that Oxygen separators are okay for use in aircraft oxygen systems.

AOPA evens says in their documentation that you can use any form of Oxygen supplier that you wish. If you do choose to use welding Oxygen it's on your head if you end up with a contaminate batch.

Me personally I'd be looking up the spec sheets on those tanks you got with the system. You need to make sure they are either DOT approved or can withstand the pressure changes at altitude.
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you do realize the pressure change from sea level to 19,000.....is like 7 psi. o_O
 
Jeff K said:
The tanks are stamped and certified just like any other O2 tank. I believe this occurs ever 5 years.
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The problem with the home-fill tanks is that nobody checks whether they are due for hydro. If you bring a timed out tank to a gas supplier, they are not going to fill it for you.

But then, 1500 is probably a fraction of what the vessels are rated at.
 
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