Oxygen Tank replacement troubles

[khedrei]

I can't seem to find a solution to this so I think I need some help.

Recent annual.  Tank is beyond it's life and needs to be replaced.  This appears to be much more complicated than I thought it would be. 

The built in tank in my 231 is a 76.x cubic foot steel tank.  Aerox and Mountain High both have composite models that can replace this one.  They appear to be a 77 cubic foot. There is a 115 cubic foot but would require larger bands.  Ideally I would go with this option.  Both tanks are significantly lighter than the steel tank that I have in there now and are available to buy but it seems that I have an issue with the regulator.  I talked to both companies at KOSH and they both said the same thing.  The current Scott regulator will NOT fit into the new composite tanks.  My understanding is that the regulator will need an overhaul if it is to be used again in a new steel tank, but it is no longer made.  They said they can sell me a new regulator that is made for the composite tank, but it is not altitude compensating.  So basically if I open the valve it will not give me a proper dose of oxygen.  At least thats the way I understand it. 

From what they told me, it seems like there are parts, fittings, or other system add ons that can make the system work but none of them are STC'd.  That is where my problem comes in. They said I can get a fiel approval (337) but those don't exist in Canada.  I was told by a mechanic that I can bring the plane down to the US and find a mechanic who can install what is needed to make the system work who can give me a 337 even though the plane is registered in Canada.  I guess this is because the plane was certified by the FAA so it's no issue.

Summary.

-I can probably get a new steel tank and overhaul the current regulator.

-Composite tank will require a new regulator that can compensate for altitude and I will need to find out more info for it to replace the system and have it function as is.  This is the idea option.  If anyone has experience with this, (particularly with a canadian plane) please let me know.

 

I am aware that there are other threads in here that talk about this and I have read through them and I don't see anything that covers the regulator issue.

 

Thanks all

[Fritz1]

Look at the precise flight demand conservers, they will do the altitude compensation, I use two of them, had them for 4 years, really like them, cuts your O2 consumption by 50% at least

[khedrei]

Do they just snap onto the canulas/masks of the onboard system?  or are they installed as part of the onboard system on the main tank/regulator?

[LANCECASPER]

9 minutes ago, khedrei said:

Do they just snap onto the canulas/masks of the onboard system?  or are they installed as part of the onboard system on the main tank/regulator?

https://preciseflight.com/product/all-in-one-tandem-solo-pack-x3/

https://www.mhoxygen.com/product-category/portable-pulse-demand/o2d2/

 

If you haven't talked to the Oxygen Lady yet, I would: https://www.aviationoxygen.com/about-aviation-oxygen/

She will know what tank, what regulator, etc.

[mike_elliott]

Scott Ashton at Aerox is my go to for all things oxygen..Great guy, great supporter of the Mooney community

He will steer you right

scott@aerox.com

full disclosure, Aerox is a sponsor of the mooneysummit

[Phil EF]

In the US, steel cylinders have a five year hydrostatic test requirement with no life limits. 
I have the same tank in my K. 
Is Canada more restrictive?

 

[PeteMc]

I was just going to say what @Phil EF said.  Did it actually FAIL the hydrostatic test or is someone telling you that it is "past it's life" and you need to replace it?

If they're saying "it is past it's life" they are WRONG.  (Unless... there's some Canadian Reg that gives the tank an End of Life date.)

Aerox Aviation bought Scott, who is the original installer of our 231 systems.  And they're in FL, so that might be the best option here in the US for you.  If for some reason they can't get you in, I had really good luck with C&L Aero in CA.

https://www.aerox.com/repair-station-and-support/

https://www.c-l-aero.com/

 

[Pinecone]

The Mountain High O2D2 does a better job of controlling oxygen flow than the altitude compensating valves.

[N201MKTurbo]

I thought all the steel cylinders had a 25 year life limit.

[Scott Ashton]

Here is the regulation on Steel Cylinders - 

§ 173.302a Additional requirements for shipment of non-liquefied (permanent) compressed gases in specification cylinders.

DOT 3HT cylinders. These cylinders are authorized for aircraft use only and only for nonflammable gases. They have a maximum service life of 24 years from the date of manufacture. The cylinders must be equipped with frangible disc type pressure relief devices that meet the requirements of § 173.301(f). Each frangible disc must have a rated bursting pressure not exceeding 90 percent of the minimum required test pressure of the cylinder. Discs with fusible metal backing are not permitted. Specification 3HT cylinders may be offered for transportation only when packaged in accordance with § 173.301(a)(9).

Scott

[philiplane]

2 hours ago, N201MKTurbo said:

I thought all the steel cylinders had a 25 year life limit.

3AA standard steel cylinders have no life limit

3HT lightweight steel cylinders have a 24 year life limit

Composite cylinders usually have a 15 year life limit.

[khedrei]

The above post got it right and match what I was told.  Mine has a 24 year life limit.

I appreciate the replies.  I will look into contacting the people mentioned above to see what I can come up with.  The reason I posted here is that all of these companies basically told me at KOSH this year that there is no composite solution available to me in Canada because there is nothing that is STC'd and we do not have field approvals here.  I would have thought they would have been itching to sell me a system.

As I said, I will send some emails out to the contacts above, but if anyone with a canadian aircraft found a kevlar solution I would be very interested in hearing what they came up with.

 

Thanks again

 

[kortopates]

The above post got it right and match what I was told.  Mine has a 24 year life limit.
I appreciate the replies.  I will look into contacting the people mentioned above to see what I can come up with.  The reason I posted here is that all of these companies basically told me at KOSH this year that there is no composite solution available to me in Canada because there is nothing that is STC'd and we do not have field approvals here.  I would have thought they would have been itching to sell me a system.
As I said, I will send some emails out to the contacts above, but if anyone with a canadian aircraft found a kevlar solution I would be very interested in hearing what they came up with.
 
Thanks again
 

I am pretty sure the IPC list multiple options including the composite 115 cu ft i have in my 252. you can use any of the listed ones in the IPC applicable to your airframe.
Changing out the larger holding bands is not an issue and shouldn’t be very expensive.
C&L aero can IRAN your 1st stage and functionally test your second stage- or find you an exchange if it’s not working properly. I am pretty sure they can also supply the tank and holding bands as well. They do everything wrt to Oxygen systems.

Some will say the tank vendor needs to have a STC for your airframe but many IA’s will consider it a minor mod. All the tanks are made to the same DOT standards.


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[khedrei]

Alright, I think some of you guys might like this.

I have a few replies now.  Two people from Aerox have told me that I CANNOT change from steel to composite.  The Oxygen Lady also told me basically the same thing and that there is a ton of paperwork but even then it might not be able to be done.  So it looks like I have to go with a new steel cylinder and they can test my old valve, if it fails I need an overhaul $$$$

I am open to any suggestions to get around this.  Of course the 20lbs of weight savings would be nice especially since I have to replace it and the cost difference will be minimal between the two types of cylinders.  

Any mechanics on here willing/able to sign off an installation of a composite cylinder on a Canadian registered aircraft?

[kortopates]

Is this a Canadian specific issue?


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[PeteMc]

18 hours ago, khedrei said:

Any mechanics on here willing/able to sign off an installation of a composite cylinder on a Canadian registered aircraft?

Didn't you just say Aerox told you that you could NOT change from steel to composite?  And aren't they now the STC holder after buying out Scott?

 

[Scott Ashton]

2 hours ago, PeteMc said:

Didn't you just say Aerox told you that you could NOT change from steel to composite?  And aren't they now the STC holder after buying out Scott?

 

Scott was purchased by Avox, now Safran.    We bought Sky-Ox, and own the Sky-Ox STC for thier installed systems, which go back several decades.   We are actually looking at those STC’s to see if there is a way to update them but it’s going to be a while to got through that process.   Even supporting the old Skyox parts is next to impossible because of parts availability.
Scott

[khedrei]

5 hours ago, PeteMc said:

Didn't you just say Aerox told you that you could NOT change from steel to composite?  And aren't they now the STC holder after buying out Scott?

 

Sorry, might have not explained it properly.  It's not an easy switch.  Obviously people are using these units.  If someone is willing to sign a field approval and do the paperwork it seems it can be done.  Aerox are not AI's they are distributors so I was looking for someone who had experience doing the install.

[JohnB]

On 8/12/2024 at 11:25 PM, PeteMc said:

I was just going to say what @Phil EF said.  Did it actually FAIL the hydrostatic test or is someone telling you that it is "past it's life" and you need to replace it?

If they're saying "it is past it's life" they are WRONG.  (Unless... there's some Canadian Reg that gives the tank an End of Life date.)

Aerox Aviation bought Scott, who is the original installer of our 231 systems.  And they're in FL, so that might be the best option here in the US for you.  If for some reason they can't get you in, I had really good luck with C&L Aero in CA.

https://www.aerox.com/repair-station-and-support/

https://www.c-l-aero.com/

 

I love this topic, as I have the exact same issue right now. My built-in oxygen tank has recently reached it's service life (15 years). I was told that since it has reached it, it cannot be hydrostatically tested and needs replacement. Looking for replacement options,  I may just get a small portable tank I can take while its being serviced or as a backup. Searching for places that can quote replacement onboard cylinders, if anyone knows a company that is good for supplying an onboard system and certifying the regulator, would like a pirep. I emailed the oxygen lady, thanks @LANCECASPER! 

[PeteMc]

1 hour ago, JohnB said:

My built-in oxygen tank has recently reached it's service life (15 years).

It depends upon which tank you have.  Some have an end of life date, others don't.  You just need to confirm which tank you have and find out what the story is for you.  

The other thing that gets people is when you have to do the hydrostatic test.  If you have a full tank of O2 and someone tells you that you have to send in the tank.  Have them show you the reg.  I understand it to be at the NEXT FILLING.  You don't have to pull the tank and send it in by date.  Now it may just be easier if the plane is in for its Annual to send it in then.  But that's your call. 

 

[MikeOH]

10 minutes ago, PeteMc said:

It depends upon which tank you have.  Some have an end of life date, others don't.  You just need to confirm which tank you have and find out what the story is for you.  

The other thing that gets people is when you have to do the hydrostatic test.  If you have a full tank of O2 and someone tells you that you have to send in the tank.  Have them show you the reg.  I understand it to be at the NEXT FILLING.  You don't have to pull the tank and send it in by date.  Now it may just be easier if the plane is in for its Annual to send it in then.  But that's your call. 

 

Interesting...

My problem is that logic suggests that "NEXT FILLING" doesn't make sense, for you could wait another year and still not have used all the O2.  Heck, I've owned my Mooney for nearly 8 years and haven't used my portable O2 tank once!  It doesn't seem like an IA should be expected to sign off on an installed tank that's multiple years past its test date simply because it hasn't been refilled.  BWTHDIK?

[PeteMc]

5 hours ago, MikeOH said:

My problem is that logic suggests that "NEXT FILLING" doesn't make sense, for you could wait another year and still not have used all the O2.

That's exactly my point.  No need to do a test when you have a years worth of O2.

And exactly what logic???   I do not believe there is an issue with a charged bottle suddenly going bad and it will explode.  If anything, it will probably just leak out at a weld.  What happens with the hydro test, as I understand it, is to overcharges the bottle to make sure there are no defects primarily from abuse.  Think welding tanks dropping off a truck.  But aging is also an issue.  But maybe someone with more experience can jump in, but I've never heard of a full aviation tank suddenly going bad.  More likely it would be the regulator or something in one of the lines. 

And I thought I had the documentation where it actually says it can be done at the next filling, but I can't find it right now.  I'll do some more digging tomorrow if I get some time.  

[Scott Ashton]

Here is part of the CFR reference for cylinders - https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-178/subpart-C#49:3.1.1.1.1.3.1.24

the PHMSA also regulates the manufacture of pressure vessels through a special permit process.   You can search it here - https://www.phmsa.dot.gov/approvals-and-permits/hazmat/special-permits-search.   The 15 year life on Kevlar wrapped cylinders for example, is a condition of the SP that is issued to the factory that manufactures the cylinders for us.

if you have a Kevlar wrapped cylinder it must be taken out of service at 15 year for the DOM.  That is a DOT/PHMSA reg and there is no leeway on it.   The steel cylinders have different lives depending on the thickness.   
 

Regarding hydro, it’s correct that you can go beyond the hydro date if it’s filled already, but needs to be hydroed at the next fill.   It’s not the absolute pressure that hurts a cylinder - it’s corrosion inside and the fill/empty cycles that do damage.   Cylinders are roll-formed from a single piece of material so there are no welds to leak, and the hydro test is measuring the amount of expansion in the cylinder, not checking for leakage.

we are an oxygen OEM,  not a distributor so anyone can call us with any technical questions you have - and I will be at Mooney Summit in a few weeks too!

Scott 

 

[Scott Ashton]

12 hours ago, JohnB said:

I love this topic, as I have the exact same issue right now. My built-in oxygen tank has recently reached it's service life (15 years). I was told that since it has reached it, it cannot be hydrostatically tested and needs replacement. Looking for replacement options,  I may just get a small portable tank I can take while its being serviced or as a backup. Searching for places that can quote replacement onboard cylinders, if anyone knows a company that is good for supplying an onboard system and certifying the regulator, would like a pirep. I emailed the oxygen lady, thanks @LANCECASPER! 

If you are in Long Beach just go right to CGS in SoCal, or you can send it to us and we can replace the cylinder.   If you went to the other woman, she’s just a repair broker and will send it to them or us for the actual work anyway.

Scott

[PeteMc]

6 hours ago, Scott Ashton said:

If you are in Long Beach just go right to CGS in SoCal, or you can send it to us and we can replace the cylinder.

So you work for CGS?  You guys bailed me out earlier this year when the (new to me) shop sent my tank and regulator to the shop they had always used.  Estimate came back WAY high and my regulator that was working perfectly and no unexpected loss/leakage suddenly had multiple leaks in both sages.  He got it back and I had gotten recommendations (from here) and send it to you. 

Still wonder if the regulator parts you received were actually the original ones that came out of my regulator at the other shop.  But we'll never know.