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Build your Own Oxygen Setup?

steve murray

Well Known Member
Took a short cross country the other day and came back at 13,500'. I loved the tail wind and the smooth air, now it is time to start looking for an oxygen setup. I have done some cursory pricing of the aircrafdt oxygen setups for about $500 and see medical oxygen tanks on ebay for less than $100.

Is it worthwhile, safe, cost effective to assemble my own portable system or should I just part with $500 and buy a system?:rolleyes:

Would also appreciate any mounting input for RV8'ers'

Steve
RV8
 
During the summer flying months when I do most of my long cross-countries I always carry oxygen with me. I rent a bottle and regulator from the local medical supply house. Cost is about $15.00/month plus o2 for about $19.00.
It would take a lot of years of renting to justify buying a system. Another expense that you have when you own is getting the bottle re-certified every 5 years or so. If it isn't re-certified nobody will fill it up. I can get up to 11.5 hours for two on the bottle that I rent.
 
Actually, you spend the equivalent of buying the system every 27 months - assuming you refill the bottles once a month. Hydrotesting the bottles can be done very easily and cheaply, I have several high pressure bottles tested per month for my air business at $22 per test. Metallic bottles only need to be tested every 5 years, and have an unlimited lifespan as long as they are undamaged and not exposed to excess heat. Carbon fiber or fiberglass wrapped bottles must be tested every 3 years and have a maximum 15-year life span. They are also more expensive, but less weight for the quantity of oxygen they can carry.

As far as filling them - and I'm not going to advocate for or against this practice, just use your own judgement - I know many pilots who have a pair of oxygen bottles from an oxy-acetylene torch setup with a transfill valve to top off their plane bottles. It reduces your oxygen costs to pennies per refill. Say what you want about the practice - but as an analytical chemist with a couple years of actual lab time working with it, I've personally run the tests to tell you that there is no appreciable difference between "medical", "aviation", and "industrial" grade oxygen supplied in the cylinders. There used to be, yes, but with todays modern air liquefaction plants there is no economic incentive for multiple grades of purity - all the oxygen comes from the same liquid oxygen supply at the liquefaction plant. The difference is in how much paperwork accompanies it to prove it's pedigree - just like experimental aircraft and engines. From an analytical purity viewpoint, you don't see a difference until you go to the expensive UHP (Ultra High Purity) gases used for Mass Spectrometry and some gas chromatographs.

And yes, once I have my bird flying, I will have onboard oxygen and I will roll my own and fill my own - but then again I've been working with high pressure gases for close to 20 years and I'm quite comfortable with them.
 
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DIY parts here

O2 is common for Western states glider pilots.

These guys cater to the glider pilots, and carry the various parts. Their web site has a lot of info...

http://www.wingsandwheels.com/page35.htm

http://www.wingsandwheels.com/page36.htm

I prefer this at the pilot end... saves oxygen, and a bargain at $30...:)

oxysaver.gif


gil A

Usual disclaimer - only a satisfied customer...
 
I have a 700L Praxair medical bottle and have considered adapting it to the plane. Anyone see any problem with that? Think I can get a regulator for around $50, then would need the cannulas, etc. Probably around $125 total. The tank is within the five year test period. Sure would beat the $500 systesm if there are no problems.

BTW, my father was a welder and used 2-4 bottles of O2 per week. Often they would be out of welding oxygen and would give him medical at the same price. They said they supplied welding grade to the hospital when they were out of medical grade. That was in the 60's and I'm sure it doesn't happen any more.

Bob Kelly
 
Looking out the back window of our hospital yesterday I saw the tanker hooking up to fill the hospitals oxygen tank. On the side of the truck it said...

WELDERS OXYGEN SUPPLY

When considering price you need to consider filling at an away airport and conservation.

O2 is pricey at those FBOs that have it and continuous feed systems rapidly deplete a tank.

If you plan on using it a lot I would consider a mountain high pulse demand system.

O2D2.jpg


I fill mine with 2 O2 bottles that I rent from a local welder suupply. 1 To fill tghe 2nd to top off the pressure.

Nothing wrong with using a medical bottle it doesn't know it is in an airplane instead of an ambulance.
 
Ah yes - I'll grow my own bottle, lines, and reg system, but the EDS system is one place where I will write a check. I love the idea of being able to conserve the oxygen in the bottle as much as possible. The oxygen is cheap (really cheap if you fill it yourself), but it's the hassle factor of removing the bottle, filling it, and reinstalling it. Also there is the question of a long high XC with passenger(s) sucking on it - there is just no scenario under which it makes sense to waste the gas you are depending on. You could end up getting bent over in a serious way trying to get an O2 fill at an FBO during a fuel stop on a trip somewhere, and about that time the small investment for an EDS starts looking pretty good. A 2-place with a good sized bottle could make a coast-to-coast round trip on O2 without a refill if you conserve it well.
 
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Greg,

Good info.

But note that Norman seems to say he only uses O2 during the summer when he does long X-c's, so renting may make sense for him.
 
1 bottle = 2 people for 13 hours at 15,000 ft.

Ah yes - I'll grow my own bottle, lines, and reg system, but the EDS system is one place where I will write a check. I love the idea of being able to conserve the oxygen in the bottle as much as possible. The oxygen is cheap (really cheap if you fill it yourself), but it's the hassle factor of removing the bottle, filling it, and reinstalling it. Also there is the question of a long high XC with passenger(s) sucking on it - there is just no scenario under which it makes sense to waste the gas you are depending on. You could end up getting bent over in a serious way trying to get an O2 fill at an FBO during a fuel stop on a trip somewhere, and about that time the small investment for an EDS starts looking pretty good. A 2-place with a good sized bottle could make a coast-to-coast round trip on O2 without a refill if you conserve it well.

Greg...
The rebreather cannula is pretty good at conservation with a lot less $$$ than the EDS system.

Using a medical E bottle (28 by 4+ inches) or an aviators M bottle (20 by 5+ inches) - both are 22 cu. ft. - two people can safely fly for 13 hours at 15,000 ft.

That should cover a pretty long RV cross country....:)

The consumption chart is on the link I previously mentioned...

http://www.wingsandwheels.com/page35.htm

gil A
 
I've never flown with O2, but I thought that aviation (and medical) oxygen was dehumdified to prevent potential condensation freezing in the lines and cutting off the O2, and that welding oxygen was not which made it dangerous to use for breathing at altitude.

Is that just an urban myth?
 
As a certified welder, I can say that without quetion welding gasses are is good if not better than anything else. Lets say a batch of medical grade o2 gets contaminated with a tiny bit of nitrogen or CO2 or moisture...it is not going to be noticed by anyone who is brething it. When people are administered O2, it always mixes with the ambient air, you could never tell a tiny bit of impurities (assuming it not poison or something.) Welding gasses on the other hand, tiny amounts of impuritys get noticed in the weld color, weldability, arc behavior, etc. The real difference in Medical and Weld grade O2? The Medical tanks gets the fancy chrome valves :)
 
I've never flown with O2, but I thought that aviation (and medical) oxygen was dehumdified to prevent potential condensation freezing in the lines and cutting off the O2, and that welding oxygen was not which made it dangerous to use for breathing at altitude.

Is that just an urban myth?

It used to be based in some fact, but those days are long gone. All oxygen now sold in bulk is produced through air liquefaction, which requires removing all the moisture and carbon dioxide from atmospheric air before compressing and chilling the resulting air stream to -300 F at about 200 psi, where the oxygen and nitrogen (99+% of whats left in the air stream at that point) will liquify and this resulting fluid is sent to the fractional distillation tower (a supercold version of an alcohol still apparatus) to separate the oxygen from the nitrogen. The purified streams are then reliquified and stored for bulk sale. It all comes out of the same tap.
 
I ask the local o2 supplier what the dew point was of medical o2. He said it was -60c. I figured that I was safe. I won't be flying in those temps and if I am o2 won't be on my mind. You can quite often find good used medical regulators on e-bay. If you do go the medical route rent a regulator used on small children. You can get the flow rates down quite a bit more than the standard regulator.
 
Norman,

I use liquid N2 (occasionally O2) extensively in my lab at work and would be extremely surprised if the O2 would liquify even at -60C and even if it had a trace of water in it. Normal O2 will just barely liquify at -190C! But, as you say, if you are flying at -60, then you must be pretty high in the atmosphere and would really need that O2!

greg
 
I believe he meant DEWPOINT in the standard terminology, as in for water vapor in the gas - not the dewpoint of oxygen itself. Oxygen has a critical temperature of -118.5 C, meaning that no matter how much pressure you put on it, it won't liquify above that temperature.

The water vapor dewpoint of -60C is about right, they take atmospheric air and compress it, then chill it to about 34F to get most of the moisture to "dew" out, then chill it with an ammonia coolant loop to around -60C which causes the remaining water vapor and all the carbon dioxide to "frost" out onto the ammonia coolant loop. The remaining gas then gets routed through a molecular sieve bed to clean up anything left over and chilled further and sent to the turboexpander for liquefaction.

Sidenote to Greg - if you take a reservoir of atmospheric pressure liquid nitrogen and run oxygen through a tube immersed in the nitrogen at atmospheric or slightly higher pressure, the oxygen will readily liquify. The boiling point at 1 atmosphere for oxygen and nitrogen is only about 13 degrees C apart.
 
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Medical regulators

My medical regulator goes down to 2 lpm. Is this low enough if I use the OxySaver cannulas?
 
It's OK...

I would say no. Going off the chart at http://www.wingsandwheels.com/page35.htm
it appears it uses .25 lpm at 10k feet and .48 lpm at 15k. You would be flowing between 4 and 8 times what you need.

It probably is OK.... the regulator in this case just reduces the pressure to a manageable amount (30 psi?) that can be handled by Tygon tubing..

You still need a flow meter in the system, and this comes with a throttle valve. See this Aerox picture...

AERPX%20flow-needle-valve.gif


The regulators on the Wings and Wheels site are not adjustable. The flow rate is set by the flow meter.

gil A
 
Took a short cross country the other day and came back at 13,500'. I loved the tail wind and the smooth air, now it is time to start looking for an oxygen setup. I have done some cursory pricing of the aircrafdt oxygen setups for about $500 and see medical oxygen tanks on ebay for less than $100.

Is it worthwhile, safe, cost effective to assemble my own portable system or should I just part with $500 and buy a system?:rolleyes:

Would also appreciate any mounting input for RV8'ers'

Steve
RV8

Steve,
Come by my hanger, Ill show you my tank refill from welders ox setup so you can see one in action. Ill also show you the pressure mask to fly in the 20's if you see fit. Your welcome to try mine out. Ive tested mine to 30k' in my 8. Doubt you will make it that high in your though. But you should comfortably make the low 20's.

Best,
 
Sorry for the confusion the dew point of -60c was for the water content not the o2. I also meant the temperature of the cabin in the aircraft getting down to -60c. If it gets that cold I would be a block of ice and not needing oxygen.
A regulator with a minimum of 2 litres per min is way too much o2. Maximum you will need is 1 litre/min. By the way the highest I got in my RV-7 in a test was 25,400ft and that was has high as I could coach it. At 20,000ft it was still climbing at 500ft/min. It made the guys here in ATC sick. He said he had trouble getting that out of his Cessna at sea level. The ATC had a bet on how high I could get it with each other. Don't know who won. They also figured that I was making 500ft/min at 20,000. Standard carb. 0-360 and dual LS. I normally do my long trip across the continent between 13 and 17000ft. When I did the climb test it was in the middle of July here on Vancouver Island (CYYJ).
 
pulse ox meter

A handy addition to your ox system is one of the available mini pulse ox sensors that stick on the end of your finger and read the oxy levels in your blood (which is why you need suplimental o2 at alt). They are relatively cheap nowadays and allow you to adjust down the flow to minimum necessary. Also some people may be suprised at how low an alt you can be hypoxic, and benefit from suplimental o2. The pulse ox keeps you in the know.
 
Thanks Mike

Thanks Mike, I am going to be out of town for a week or so, but will stop by your hangar next time I see you out there. I would like to take a look at your Oxygen refill setup and get some contacts for your tank\oxygen supplier.




Steve,
Come by my hanger, Ill show you my tank refill from welders ox setup so you can see one in action. Ill also show you the pressure mask to fly in the 20's if you see fit. Your welcome to try mine out. Ive tested mine to 30k' in my 8. Doubt you will make it that high in your though. But you should comfortably make the low 20's.

Best,
 
O2 in an RV-8?

I'm building an RV-8 and I'm having trouble finding a good spot for the O2 bottle. Where are you guys mounting it and how are you plumbing your systems? A few pic would do wonders for us builders!
I've got a couple of C medical bottles that are about 14" to the top of the valve, and the obvious spot behind the pilot's seatback, might interfere with the back seater's shins. I figure the O2 capacity should last at least the fuel range...or do you think it should be 2 or 3 fuel tanks worth?
I would like to be able to open the bottle valve in flight, so I could be free to decide when to charge the system.
About regulators: they control flow rate by adjusting the regulated pressure, which then flows thru a control orifice. If you use one of those bubble flow indicators like the Aerox that Gil posted, you don't need to worry about the medical regulator flow rate. Just set it up so the needle valve on the flow meter will have enough pressure to give you the full range of adjustment.
About price: I got everything on 'Epay' including the CGA 870 to CGA 540 Filling Adapter, 2 bottles, 2 regulators, a flow meter, 2 oxysaver cannulas and a medical O2 mask for alittle over $100. Not one purchase, but a number of small bids and check later to see if I 'won'.
I just got an airline pilot 'quick don' O2 mask with internal mic, hose and cord, complete 'as new' for $12.99! (We'll see about that when it gets here)
 
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Do it yourself

I faced this a couple of years ago as well. I was going to purchase the Aero-ox system. A fellow RV'r showed me his set up purchased off of Ebay. I got a new D bottle, medical regulator and a 10 pack of cannulas. Total cost $103 (including the shipping). I later added a mustache type breather for $20.

A couple of things, 1) This is not as fancy as the Aero ox or others, but who cares? You may have to buy a T fitting if you have passenger and plug it when not in use. No big deal.

2) Regarding medical vs. welding, one of my neighbors is a doctor and Flight Surgeon. He said if you were breathing welding O2 for many hours every day you might experience some nasal dryness, but for GA use, the welding stuff is fine. I've used it for up to 5 hours in one day without issue.

3) Filling the tanks. The best is the cascading system to get a complete fill but a welding tank will get you enough. Another method is to check with your local fire department. Everybody knows somebody in public safety. In many cases they will fill your tank for training purposes.

4) I use an Oximeter to track O2 blood levels and the Ebay system works just as well as the high dollar units.

There simply is no reason to spend $500+ on an oxygen system that you can get for $100 or so on Ebay. Use the savings for fuel.
 
Save-a-buck

I just got a regulator on Ebay for 99 cents!
It's a Precision PM-168708D and only weighs 7.4 ounces.
It flows .25 to 8 LPM, and fits on a medical square post bottle. It's small too.
So now I have 2 sets: C bottles with regulators and oxymiser cannulas.
My RV-8 isn't flying yet, but we have a Cessna 172 and fly the Cascades alot. The Mrs is a CFII so we switch flying. Now we have 2 redundant systems to throw in the back seat with the flight bags.
I guess I'll use a Tee to 2 flow meters in the RV, and only carry one bottle because there isn't much room.
For two people, 8 liters per minute might not be enough for an altitude record attempt, but below IFR altitudes it should be OK.
 
A quick note about tanks - make sure they've hydro tested the tank recently, preferably with a visual inspection as well. There's a wide range in the tanks available on eBay, from those in great condition to those in terrible condition. Buyer beware, since having a tank valve blow off has punched holes in the side of more than one vet clinic, and I'm pretty sure their walls are thicker than the sides of aircraft. :)
 
Thanks Norman;
I wasn't sure what the flow rate per altitude is, I haven't found a chart for conserving cannula and/or mask vs altitude, Just those spendy graduated flow meters.
Khelmar;
I agree, get the best you can, I enjoy getting the good stuff as cheap as I can.
 
Here.... and altitude compensated

Thanks Norman;
I wasn't sure what the flow rate per altitude is, I haven't found a chart for conserving cannula and/or mask vs altitude, Just those spendy graduated flow meters.
Khelmar;
I agree, get the best you can, I enjoy getting the good stuff as cheap as I can.

The chart for altitude vs. time available for various altitudes has already been posted....

Here is one with the oxysaver rebreather cannula....

http://www.wingsandwheels.com/page35.htm

Halfway down the page... can't paste it since it is an HTML table....

Simple mathematics will turn time into a flow rate since the capacity is known....:)

However, are the pressure regulators (medical) that have calibrated flow rates actually pressure compensated? Will the flow rate be anywhere near accurate at 17,500 ft.? I'm fairly certain the hospital equipment specifications do not cover high altitudes...

At around $50 each, I like the certainty of a flow meter that actually measures the O2 flowing, as opposed to some system with a possibly unknown calibration.... but YMMV....

gil A - been using the rebreather cannulas since they came out in the 80's...

This picture of a Nelson flow meter shows the large difference in required flow rates. The oxysaver scale on the laft, and the stadard mask on the right.

10a.jpg


UPDATE... I couldn't remember the FAA required flow rate for masks, but found it here on the Mountain High web site. It is 1 Lpm per 10,000 ft (hows that for mixing metric and english units....:)...)

This is MH's flowmeter, similar (bought from?) the Nelson one... and the price is $55...

MH4-dwg.jpg
 
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Lazy me

Gil;
Your right about calculating the flow requirement from the advertised duration on the bottle duration chart.
I was just hoping I could copy some official FAA chart that give direct flow rate VS altitude for cannulas and masks.
I was hoping to print it out and laminate it, the add it to the checklists in the plane.
 
Steve,
Come by my hanger, Ill show you my tank refill from welders ox setup so you can see one in action. Ill also show you the pressure mask to fly in the 20's if you see fit. Your welcome to try mine out. Ive tested mine to 30k' in my 8. Doubt you will make it that high in your though. But you should comfortably make the low 20's.

Best,

Kahuna
Can you give some more information about the pressure mask. I have used a pressure breathing system in a chamber but only above 38000 feet. It is only practical to use pressure breathing for very short periods and you tire very rapidly. Also talking/communication impractical whilst on pressure breathing.
In military only used till can get down below 38000ft where 100% non pressure O2 is sufficient.
Regards
John
 
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Ill try and remember to take a look at it at the hanger and get you a model number.
Perhaps pressure mask is the wrong words to describe.
Its a mask that covers both nose and mouth and straps on your head. Mic built in and delivers 100% o2. ~rubber material. I was able to keep >90% ox level with it at 30k'

I dont know the model and type off hand. It was given to me my a Mooney Ovation 2 owner. It came with his plane and he never used it.
 
Your right about calculating the flow requirement

Make sure when calculating duration to treat it like fuel and have an adequate reserve especially when flying IMC. Probably not a good thing to be on top, running out of 02 and having an hour to go before starting your approach. Especially over the Rockies.
 
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I finally got around to taking some pictures for ya Steve.
Here is the tranfer device that is the heart of transferring from a welders O2 tank to a portable O2 tank.

o2-1sm.jpg

o2-2sm.jpg

o2-3sm.jpg
 
I have used the Mountain High system works great.

Looking out the back window of our hospital yesterday I saw the tanker hooking up to fill the hospitals oxygen tank. On the side of the truck it said...

WELDERS OXYGEN SUPPLY

When considering price you need to consider filling at an away airport and conservation.

O2 is pricey at those FBOs that have it and continuous feed systems rapidly deplete a tank.

If you plan on using it a lot I would consider a mountain high pulse demand system.

O2D2.jpg


I fill mine with 2 O2 bottles that I rent from a local welder suupply. 1 To fill tghe 2nd to top off the pressure.

Nothing wrong with using a medical bottle it doesn't know it is in an airplane instead of an ambulance.
 
Kahuna

Ok I'll bite.....Could you please tell us how you got to be at 30k in your 8?..:)


Secondly, I see you only have a single welding cylinder...I thought you needed at least two to top the pressure off...Does not the single cylinder start bleeding down pressure wihting a couple of fills?

Thanks

Frank
 
Ok I'll bite.....Could you please tell us how you got to be at 30k in your 8?..:)


Secondly, I see you only have a single welding cylinder...I thought you needed at least two to top the pressure off...Does not the single cylinder start bleeding down pressure wihting a couple of fills?

Thanks

Frank

First question, I just went.

Second question, It does start bleeding down, but not till after many fills. I frankly dont know how many I get per tank As long as I can top to the green on the pressure indicator (2kpsi) then I keep filling. I also never run the little guy to zero either. I get a good dozen tops before refill of the big one is required. Thats a swag cause Iver never counted.
 
NEW ANGLE....

I know this isn't quite in with this thread BUT... I have found that the fittings used for oxygen quick connects can be modified and used for latches for hatches. Does anyone have a source for large fittings? :eek:
 
I finally got around to taking some pictures for ya Steve.

Hi Kahuna.

Thanks for the pictures and report.

I've got one (maybe dumb) question though. All of the oxygen cylinders I'm familiar with are green. I go through several every couple of weeks at work, which are all green (along with compressed nitrogen, which is delivered in black tanks). The welding oxygen tank in the hangar I share is also green.

A little googling tells me that cylinder color codes aren't universally applied, but it makes me nervous to see a blue supply cylinder. I'm assuming there is a clear label on the cylinder.

I'm aware of at least one fatal accident resulting from compressed air being substituted inadvertently for oxygen.
 
Yeah its O2.
I dont rely on what the tank says, I rely on what my pulse ox sensor tells me Im doing.
Good eye on noticing that and checking on me.
Ill have to double check what the tank says. Its been a couple years since I filled it up and I dont recall anything about it.
 
I'm aware of at least one fatal accident resulting from compressed air being substituted inadvertently for oxygen.

WOW! You guys really need to read that report -- it's very interesting. The airplane suffered an in-flight break-up and the female passenger lived to tell about it. Cause of death in the man's case was hypoxia. Wow, terrifying story.
 
Frank, go to one of Kahuna's posts, look under his name in the sig block, click on the "S8".

Sit back, and enjoy reading:D
 
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