Hangar Project - Oxygen Filling Setup

[Z W]

@JoshK asked if I would post some pics of this in another thread, so here it is.

Background - I wanted to be able to fill the M20K's oxygen system in our hangar.  The goal was not so much cost savings as convenience and the ability to be sure to have a full oxygen tank for every flight if I want it.  I often found myself flying at lower altitudes to stay off oxygen just because, for example, it would be at 1/2 full and I wanted to save it for the flight home in case I needed to top weather.  At the same time, I wouldn't want to pay $100+ to have it filled while there's still 1/2 of a tank of oxygen left.  I also noticed I felt much better after flying with oxygen even at 9k or 10k feet and wanted to use oxygen more.  I got an O2D2 system that helps a lot, but filling in the hangar was the next step.  Here's what I did:

The 2-wheel cart and straps I already had sitting around in my garage.  The oxygen tank came from my local AirGas supplier, where I already had an account to support my welding and homebrewing habits.  I don't still have the receipt but I think it was around $120.00, which included buying the tank.  Refills will be about $25.00.  I purchased the oxygen transfill hose on Amazon for $115.00:

https://www.amazon.com/gp/product/B09GL4YN3G/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

It's designed to fill portable bottles and comes with this attachment for that, which I have not used because I don't have any:

It has CGA 540 fittings on both ends, which will fit the oxygen bottle, but not your plane.  You will need a CGA-540 to 9/16-18 Scott adapter.  I got mine here from Mountain High for $182.00:

https://www.mhoxygen.com/product/ta-916-s-transfiller-adapter/

The fill process is spelled out in the Mooney maintenance manual and is very easy.  You connect the hose to the fill port in the plane.  Open the oxygen bottle and transfill hose connections:

(note- the bottle says "Acetylene Gas Co." on it, as the manufacturer of the bottle.  This is in fact oxygen and not acetylene).

Then you open the oxygen valve by pushing the knob forward in the plane, and the pressure will equalize.  There are charts in the Mooney service manual that provide pressure limits:

 

This bottle came from AirGas with I think 2500 or 3000 PSI in it.  However, it only charged the onboard system to about 1600 before they equalized, on a 90+ degree day.  It seems the risk of over-pressurizing the system is very low.  I had someone sit in the plane and watch the gauge by the pilot's seat while I stood ready at the bottle to shut it off when we got to the right pressure, but it stopped beforehand.  Bonus - my local shop never filled our tank past 1250 PSI.  I'm happy to be able to actually get close to a full tank.

I'm not sure how many charges we'll get out of this bottle.  I had just about gotten it down to where it needed another recharge before the plane went for annual, and the onboard bottle was timed out, so we got a new one and they topped it up for us in the shop.  I will probably add a second transfill bottle to the setup.  Some do that so that you have one that you use to charge it up halfway, then you top it up with your higher-pressure bottle, and you can rotate them out that way.

A caution - I've worked with oxygen before.  If you haven't, do your homework and be safe, it's an extremely flammable gas that can self-ignite in the presence of oil.  You never want oil on these fittings and need to be careful in a greasy workshop and keep your hands clean.  Also stay away from open flames.  

I'm happy with how this turned out and would do it again.  I hope some of you might find it useful.

Edited September 10, 2023 by Z W

[N201MKTurbo]

You should have at least two supply bottles, or you will never get very full. You can calculate the final pressure when the two bottles equalize by knowing the capacity and pressures of each bottle. 
 

I have a compressor, so I can fill my bottles to full pressure a few times with one supply bottle. 
 

If you want to get a good bottle from the gas supplier, be waiting at the gate when they open in the morning. There are usually a few bottles that have just been overhauled and are freshly cleaned and painted. The early bird gets the worm.

[M20F]

If you are filling a portable bottle keep in mind it will get hot.  Have a plane to brace it while filling.  Obviously the built in tank gets hot as well but one doesn’t need to hold/maneuver it. 

[Fritz1]

I have a similar setup but I am renting the O2 tank, usually swap it 1-2x per year, typically when it its down to 1000 psi and did not know you could buy the tanks, do you have the swap tank delivered or do you have to go to the gas vendor to have your tank refilled?? renting the tank costs about the same per year as one refill, so I would rather buy a tank if I can

[kortopates]

I have a similar setup but I am renting the O2 tank, usually swap it 1-2x per year, typically when it its down to 1000 psi and did not know you could buy the tanks, do you have the swap tank delivered or do you have to go to the gas vendor to have your tank refilled?? renting the tank costs about the same per year as one refill, so I would rather buy a tank if I can

You swap out privately owned tanks just like leased tanks. This way you never pay for a hydro just like leased tanks. The difference is the privately owned tanks aren’t branded with a company name and you can take them to any industrial gas supplier- not just the company you leased them from.
Next time you go in, just tell them you want to purchase the tanks and i am sure they’ll be happy to exchange them for you. My advice is to buy +P tanks which allows overcharging the tank by %10 so that you can fill your onboard tank to full pressure more than once but you have to be careful not to over fill your onboard tank. The standard tanks have a max pressure same as your onboard tank.


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[A64Pilot]

Ideally you want to cascade two or more tanks, the more of course the higher the end pressure will be more often, but you have to balance that with expense of multiple bottles against frequency of use, but I’d want two. Of course start with the low bottle and use the high one to top off

The ideal is a Haskel which is an air driven compressor that will take your fill tank down to 200 PSI or so to fill your airplane, but you’ll never break even with paying for the Haskal unless you get a steal from a Scuba shop going under or something. A Haskal is what every tech diver wants, O2 is cheap, ultra pure Helium is not.

I’m sure you know but be extraordinarily careful with cleanliness with O2 fittings, even oil from your skin can ignite under pressure with pure O2. I’d put the hose ends etc in a plastic bag when not being used.

If your getting the fill bottle hot, slow down in filling, nothing wrong with it taking 5 min to fill a bottle. 

The attached picture is all you need to fill a portable, simple hose with a CGA 540 on each end, you don’t need gauges or anything else because the portable has a gauge on it.

That attachment in the bag you have I believe is for filling portable medical bottles, which I don’t think many use for flying, some might have home brewed something I guess.

‘I think you will be surprised at the money your going to save and at least as important you’ll be more likely to go on O2 now that it’s available and much cheaper.

 

[JoshK]

[mention=51817]JoshK[/mention] asked if I would post some pics of this in another thread, so here it is.
Background - I wanted to be able to fill the M20K's oxygen system in our hangar.  The goal was not so much cost savings as convenience and the ability to be sure to have a full oxygen tank for every flight if I want it.  I often found myself flying at lower altitudes to stay off oxygen just because, for example, it would be at 1/2 full and I wanted to save it for the flight home in case I needed to top weather.  At the same time, I wouldn't want to pay $100+ to have it filled while there's still 1/2 of a tank of oxygen left.  I also noticed I felt much better after flying with oxygen even at 9k or 10k feet and wanted to use oxygen more.  I got an O2D2 system that helps a lot, but filling in the hangar was the next step.  Here's what I did:

The 2-wheel cart and straps I already had sitting around in my garage.  The oxygen tank came from my local AirGas supplier, where I already had an account to support my welding and homebrewing habits.  I don't still have the receipt but I think it was around $120.00, which included buying the tank.  Refills will be about $25.00.  I purchased the oxygen transfill hose on Amazon for $115.00:
https://www.amazon.com/gp/product/B09GL4YN3G/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
It's designed to fill portable bottles and comes with this attachment for that, which I have not used because I don't have any:

It has CGA 540 fittings on both ends, which will fit the oxygen bottle, but not your plane.  You will need a CGA-540 to 9/16-18 Scott adapter.  I got mine here from Mountain High for $182.00:
https://www.mhoxygen.com/product/ta-916-s-transfiller-adapter/

The fill process is spelled out in the Mooney maintenance manual and is very easy.  You connect the hose to the fill port in the plane.  Open the oxygen bottle and transfill hose connections:

(note- the bottle says "Acetylene Gas Co." on it, as the manufacturer of the bottle.  This is in fact oxygen and not acetylene).
Then you open the oxygen valve by pushing the knob forward in the plane, and the pressure will equalize.  There are charts in the Mooney service manual that provide pressure limits:

 
This bottle came from AirGas with I think 2500 or 3000 PSI in it.  However, it only charged the onboard system to about 1600 before they equalized, on a 90+ degree day.  It seems the risk of over-pressurizing the system is very low.  I had someone sit in the plane and watch the gauge by the pilot's seat while I stood ready at the bottle to shut it off when we got to the right pressure, but it stopped beforehand.  Bonus - my local shop never filled our tank past 1250 PSI.  I'm happy to be able to actually get close to a full tank.
I'm not sure how many charges we'll get out of this bottle.  I had just about gotten it down to where it needed another recharge before the plane went for annual, and the onboard bottle was timed out, so we got a new one and they topped it up for us in the shop.  I will probably add a second transfill bottle to the setup.  Some do that so that you have one that you use to charge it up halfway, then you top it up with your higher-pressure bottle, and you can rotate them out that way.
A caution - I've worked with oxygen before.  If you haven't, do your homework and be safe, it's an extremely flammable gas that can self-ignite in the presence of oil.  You never want oil on these fittings and need to be careful in a greasy workshop and keep your hands clean.  Also stay away from open flames.  
I'm happy with how this turned out and would do it again.  I hope some of you might find it useful.

Awesome write up, thank you!!

@apache64 thank you for the comments on the portable whip too. I appreciate it


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[philiplane]

Keep the local regulators and the fire department happy while you're at it. You'll need a chain or strap to secure the tank/cart to the wall to prevent tipping while stored. 

And you have to post an NFPA compliant oxygen placard on the hangar door so the fire department knows you have oxygen tanks inside. 

https://www.mysafetysign.com/nfpa-sign/nfpa-placard/sku-nfpa-0007?engine=googlebase&keyword=NFPA+Signs&skuid=NFPA-0007-RE-6x6&gclid=Cj0KCQjw0vWnBhC6ARIsAJpJM6f9PSh6ltByiUSfz7m4kiPX_bbHXdGyIhLJnRIimay5tlLeNYNTNEAaAjV0EALw_wcB

A lot of guys are getting tripped up by these things as airport managers look for something to do. But it's good practice anyway, so the tank doesn't get knocked over and become a projectile when the regulator snaps off.

[JoshK]

Ideally you want to cascade two or more tanks, the more of course the higher the end pressure will be more often, but you have to balance that with expense of multiple bottles against frequency of use, but I’d want two. Of course start with the low bottle and use the high one to top off
The ideal is a Haskel which is an air driven compressor that will take your fill tank down to 200 PSI or so to fill your airplane, but you’ll never break even with paying for the Haskal unless you get a steal from a Scuba shop going under or something. A Haskal is what every tech diver wants, O2 is cheap, ultra pure Helium is not.
I’m sure you know but be extraordinarily careful with cleanliness with O2 fittings, even oil from your skin can ignite under pressure with pure O2. I’d put the hose ends etc in a plastic bag when not being used.
If your getting the fill bottle hot, slow down in filling, nothing wrong with it taking 5 min to fill a bottle. 
The attached picture is all you need to fill a portable, simple hose with a CGA 540 on each end, you don’t need gauges or anything else because the portable has a gauge on it.
That attachment in the bag you have I believe is for filling portable medical bottles, which I don’t think many use for flying, some might have home brewed something I guess.
‘I think you will be surprised at the money your going to save and at least as important you’ll be more likely to go on O2 now that it’s available and much cheaper.
 

Where did you get the CGA 540 female female whip? Did you make it?

I spec’d a Haskell out as part of the system my buddy was helping me with. By the time he got done it was touching on 10 grand for the way he suggested building it.

I had to remind him “this isn’t for a 9-9’s electronics facility”


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[A64Pilot]

The guy from Airgas that brought our Argon dewers gave it to me, took it off the truck. My assumption is something they use regularly.

Did a quick google for cga 540 fill whip, many are out there, this one for $50 looks good on Ebay, it even has a gauge

https://www.ebay.com/itm/194020471334?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1qik4p5CrR9W8hVc-Qc0Atg57&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=194020471334&targetid=1585159290171&device=c&mktype=pla&googleloc=9011535&poi=&campaignid=19894961968&mkgroupid=148855406073&rlsatarget=pla-1585159290171&abcId=9307911&merchantid=6296724&gclid=Cj0KCQjw0vWnBhC6ARIsAJpJM6dKPzOnNVw2oNZazOZ49j3OOoQn8ZRU8aaHX7OR0-v-9vPKArKvTKcaAuilEALw_wcB

Super Deluxe for $100  

https://www.ebay.com/itm/224854850813?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20201210111314%26meid%3D621a7b0e50514c7983cc5e31a80fb1af%26pid%3D101195%26rk%3D2%26rkt%3D12%26sd%3D194020471334%26itm%3D224854850813%26pmt%3D1%26noa%3D0%26pg%3D4429486%26algv%3DSimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V2V4ItemNrtInQueryAndCassiniVisualRankerAndBertRecallWithVMEV3%26brand%3DPrecision&_trksid=p4429486.c101195.m1851&amdata=cksum%3A224854850813621a7b0e50514c7983cc5e31a80fb1af|enc%3AAQAIAAABUPqB0EgCndAssfMWNy0AT0GytGzF9%2By0G%2BlcW69DgBK3Qlz4BjwJQqPkN4K8I7qz9GoVciN1QNWqyS8EeqYS8rZRsDvyvw34m3N%2FyJKokwCTIIc3RNym2SNW8ARudP72DyiwgIY0dfUnIr5%2BMZDTaoutPD9lro52dRI3vCtiZn6tDj2GEG1AHwBk%2FyCSjmojLn8VHVhHd%2BPf8bsf01qxGK6XpgWUWYl1cPsPYHOeQ3ryGGQnAAHTIq94PI7A47Mk5HufyM%2FX5m7dz3bF2lMIY2DfF%2FL9976ugqW9t3iGMmVhzD%2FxB5kYwOPtL7C7G7hgZHcVNZ59xQcRDovxfH%2B6B9wmjtwk91Nqn2bAlrg%2BhaZa4jYmTEJSGv5rWimPfSABZJvHfXAooC5UWIZgDc4hLlyVqalSlmDwef1OvXyEWamVn7ydnwDopuZDKEduovWAfA%3D%3D|ampid%3APL_CLK|clp%3A4429486

[N201MKTurbo]

1 hour ago, JoshK said:

Where did you get the CGA 540 female female whip? Did you make it?

I spec’d a Haskell out as part of the system my buddy was helping me with. By the time he got done it was touching on 10 grand for the way he suggested building it.

I had to remind him “this isn’t for a 9-9’s electronics facility”


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I picked my Haskell up on eBay for $600. But I looked for a year before I found the right deal on the right Haskell. And that was 20 years ago. New, they are about $7000 for a single action, last time I checked.

[DonMuncy]

Don't lose the adaptor for the portable tanks. Soon someone will want you to fill their portable tank for them.

Remember that you can never fill a tank completely. It only fills until the pressures between them equalizes. You will have to refill the big cylinder when the pressure goes below the minimum you will tolerate in the plane. You may only get 3 fills before needing to replenish. With a two cylinder cascade system, it gets better, but you still have a limited number of fills available.

As to calculating the amounts of O2, I don't worry about it. I keep re-filling until it gets down to my minimum and re-fill.

Also, it is very important to remember that when filling, if you hear a "rattling" sound, quickly shut down the tank valve until it stops. That is the sound of the valve on the tank in your plane "bouncing" on its seat, and will quickly ruin it. They are expensive and a pain to replace.

The fire marshal in Dallas, will not tolerate O2 bottles in the hanger unless you pay a yearly fee. When he comes to inspect, my FBO folks tip me off in advance, so I can go bring my cylinders home until after the inspection.

 

[N201MKTurbo]

18 minutes ago, DonMuncy said:

.

The fire marshal in Dallas, will not tolerate O2 bottles in the hanger unless you pay a yearly fee. When he comes to inspect, my FBO folks tip me off in advance, so I can go bring my cylinders home until after the inspection.

 

They are the same at our airport, unless they are in the plane. When they schedule an inspection, I just put them all in the plane. They are just portable bottles, so easy to put in. I have the refill cylinder at the house. Nobody cares if I burn my house down.

[DonMuncy]

1 minute ago, N201MKTurbo said:

 I have the refill cylinder at the house. Nobody cares if I burn my house down.

Great for portable cylinders. Not so great with an on-board tank like K models. I have to keep my refill cylinder in the hangar, or carry it back and forth.

[N201MKTurbo]

15 minutes ago, DonMuncy said:

Great for portable cylinders. Not so great with an on-board tank like K models. I have to keep my refill cylinder in the hangar, or carry it back and forth.

Yea, I know. 

[N201MKTurbo]

Down at the MSC, which is airport property. He has his cascade on a cart, not chained to a wall. Maybe if you paint your cart blue and write ABO on it, it will be approved.

Admittedly, his cart is quite heavy and can’t tip over, but where are the specs for an approved cart? I think the conventional wisdom is, if it was bought at a military surplus auction, it is approved.

[JoshK]

Down at the MSC, which is airport property. He has his cascade on a cart, not chained to a wall. Maybe if you paint your cart blue and write ABO on it, it will be approved.
Admittedly, his cart is quite heavy and can’t tip over, but where are the specs for an approved cart? I think the conventional wisdom is, if it was bought at a military surplus auction, it is approved.

A simple welding gas cart is all you need. And every weld supply, harbor freight, and Lowe’s carries welding carts that hold 2 bottles (oxygen and acetylene) but nothing says you can’t put to O2 tanks on it instead of O2 and C2H2

Many thanks to you guys, I cropped down the system assembly costs by about 8x total. I ordered everything tonight and ought to have a small cascade in my hangar within 2 weeks


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[Pinecone]

Yes, strapped to a cart meets the requirement to be secured.  If not in the cart, then secured to the wall or in a cage.

Minor point, Oxygen is not flammable.  It supports combustion.  And, under pressure can cause ignition of flammable materials, such as oils or grease.  Even the oils on your hands.

My K had a 115 cubic foot tank.  The standard O2 tanks, like shown, are about 4 feet tall and hold 120 cubic feet of oxygen.  So, a single bottle will fill my tank once to half full (120 split into two tanks).  The next fill will be very short, about 1/4 full.  So you need a 2 or even 3 bottle cascade to fill.

 

For my use, I am getting about 6 months of flying or more off a fill.  My shop fills it as part of the annual, so at most I have to pay for one fill per year.

[wombat]

I'm really happy about this thread; I've got a portable bottle that is nearing empty (900 PSI) and while the built-in bottle on my rocket is at about 1,500 PSI.

Since many of my flights are at relatively high altitude (> 10,000 MSL) and between places that don't have oxygen service or at times when O2 won't be available, this is a great thing for me.   I've been wanting to do this for a while, so thanks for the pointers and tips on what I need to buy.

 

One note though, I think the price you mentioned for buying the bottle is maybe way low.     I don't think you can get any bottle of any size for oxygen for $120, let alone one of that size.

[N201MKTurbo]

17 minutes ago, wombat said:

I'm really happy about this thread; I've got a portable bottle that is nearing empty (900 PSI) and while the built-in bottle on my rocket is at about 1,500 PSI.

Since many of my flights are at relatively high altitude (> 10,000 MSL) and between places that don't have oxygen service or at times when O2 won't be available, this is a great thing for me.   I've been wanting to do this for a while, so thanks for the pointers and tips on what I need to buy.

 

One note though, I think the price you mentioned for buying the bottle is maybe way low.     I don't think you can get any bottle of any size for oxygen for $120, let alone one of that size.

I got a 180 CF overhauled bottle for $80 about 15 years ago. New bottles are a lot more, but not that much.

Here is an ad for a 250 CF new Bottle. less than $300

https://gascylindersource.com/shop/oxygen-cylinders/250-cuft-steel-oxygen-cylinder/?utm_source=Google Shopping&utm_campaign=shopping_us&utm_medium=cpc&utm_term=14675&utm_source=google&utm_medium=cpc&utm_campaign=17883930643&gad=1&gclid=EAIaIQobChMIupCEl5WjgQMVXGpvBB0eHgliEAQYAiABEgL53fD_BwE

 

If you want to make it an ABO cylinder, get some spray paint and a sticker.

[Z W]

Yeah, I honestly don't remember what I paid for the bottle.  It could have been $250-$300.

[N201MKTurbo]

For geeks like me:

 

[JoshK]

41 minutes ago, N201MKTurbo said:

I got a 180 CF overhauled bottle for $80 about 15 years ago. New bottles are a lot more, but not that much.

Here is an ad for a 250 CF new Bottle. less than $300

https://gascylindersource.com/shop/oxygen-cylinders/250-cuft-steel-oxygen-cylinder/?utm_source=Google Shopping&utm_campaign=shopping_us&utm_medium=cpc&utm_term=14675&utm_source=google&utm_medium=cpc&utm_campaign=17883930643&gad=1&gclid=EAIaIQobChMIupCEl5WjgQMVXGpvBB0eHgliEAQYAiABEgL53fD_BwE

 

If you want to make it an ABO cylinder, get some spray paint and a sticker.

I looked into buying like this, this is a good price.  Shipping is via freight and it's costly.  I have a freight dock at my shop so that isn't a problem but it was basically "pay for 4 bottles get 3" when shipping is factored in.

 

The local gas supply houses by me will not fill a customer owned tank, they will only swap it.  The nearest place I could find that would fill while I waited was almost a 90 minute drive each way.  

 

I decided to rent 3 bottles as I negotiated the price for 300cuft bottles to the same rental fee and fill cost as 200ft bottles since they only stocked 200's and I'm a local business.  The cost to rent was $66/yr, they waived the deposit (again, local business) and the tanks came filled.  With buying 3 tanks, shipping them here, then paying for a fill at the place 90 minutes away and driving back again I penciled it out that I needed to do a lot of filling before it made sense in money/time/hassle to own vs. rent.

 

The CGA 540 to Scott adapter arrives whenever MH Aviation decides to ship it.  The rest of the stuff is either on my loading dock or in my hangar already.  Total cost for a 3 tank cascade for 1 year appears to be right about $500.  Next year that price will be around $300 since I don't need to pay for the transfill and whip a second time.  All in all that's pretty reasonable as compared to the cost to hop to a neighboring airport and spend half a day for them to fill it up for $125 plus tax.  Convenience alone I would pay $500/y just to be able to do it myself.

[MikeOH]

2 minutes ago, JoshK said:

The local gas supply houses by me will not fill a customer owned tank, they will only swap it. 

I would think swapping your tank would be preferable as you would no longer have to worry about periodic hydro tests yet you 'own' the tank so no rent.

[N201MKTurbo]

I can rarely get my tank filled on the spot. I did once and it surprised me. I usually have to leave it overnight. It is cheaper to own, the hydro tests are a pain, but you only need to do it every 5 years. For me, it isn't a huge hassle, the Hydro test place is only 6 miles away. It helps when you live in a huge city.

All the fill stuff is outside, so the fill guys start way before the place opens for customers. So it isn't likely they will fill yours the same day.