Another free vintage tank, what is it?

[Luis H]

Just for clarification on this. You are saying that an adaptor to convert a non scuba tank for scuba use is legit????

I wonder what PSI folks would say about a rig like this?

The DOT doesn't actually regulate the valves with the exception of the need for the burst disc. And I have never seen any regulation that prohibits the use of reducer fitting. That doesn't proof that some code or regulation doesn't exist, but if it does no one has being able to produce it.

The Compress Gas Association (CGA) does publish guides, standards, and recommendations, and some of the documents are invoke by the Codes of Federal Regulations (CFR). The CGA has established many of the valves interface standards, for example CGA 850 describes the interface dimensions for Scuba Yoke connections.

The use of reducer bushing and other fittings are common in industrial pressure vessels.

If my memory doesn’t fail me, I remember actually talking to Mark Gresham (Owner of PSI) about this subject a while back. It is really not a controversial subject, except for the issue with some dive shops based on their lack of knowledge.

Only licensed manufacturers can fabricate or modify a pressure vessel, but anyone can make their own valves or modify them. There is no regulation that prohibits the end user to have a valve threads machined down to a smaller tapered pipe thread.

 

[Eric Sedletzky]

Regardless of regulations concerning bushings, I see no problems or safety hazards whatsoever with bushings since they are threaded into the tank and the valve is threaded into the bushing. Nothing is going break or blow out or go anywhere and at 1800 psi it’s very low pressure.
My LDS has similar thinking and they will fill any tank with bushings because the guy who owns it has been around a long time and knows a thing or two.
Some schmuck somewhere that won’t even fill a regular steel 72 because they think they’re too old, those are the idiots you would have problems with.

 

[runsongas]

1800 psi is still considered high pressure per the DOT and in the industrial world. the only caveat with the bushing would be the pressure rating on them. SS from McMaster Carr ranges from 2500 psi to 3000 psi depending on 304 vs 316 SS. I would be hesitant to use a brass bushing only rated for 1000 psi though.

 

[Luis H]

1800 psi is still considered high pressure per the DOT and in the industrial world. the only caveat with the bushing would be the pressure rating on them. SS from McMaster Carr ranges from 2500 psi to 3000 psi depending on 304 vs 316 SS. I would be hesitant to use a brass bushing only rated for 1000 psi though.

I have to totally agree with that. Not all bushings are intended for high pressure. And yes, all scuba cylinders are high pressure.

The 1800 psi cylinder is just a bit over half what the highest pressure scuba cylinder runs in the US. That is nothing to discount as being insignificant.


Low pressure is what you operate for shop air, something around 100 to 150 psi. The 1800 psi cylinder is over 10 times that and I still have respect for the stored energy in my shop air cylinder. There is a lot of volume and stored energy in the compressed gas.

 

[rjack321]

1800 psi is still considered high pressure per the DOT and in the industrial world. the only caveat with the bushing would be the pressure rating on them. SS from McMaster Carr ranges from 2500 psi to 3000 psi depending on 304 vs 316 SS. I would be hesitant to use a brass bushing only rated for 1000 psi though.

That looks like a steel bushing to me but hard to be sure.
Part of me is like "well its lasted this long so it must be rated to close to 1800psi or more"
Part of me is like "I don't want to use unknowns components purchased from who knows where in a high pressure application"

I have some 1800psi lp50s with 3/4" NPS necks and I definitely don't think they are harmless or not capable of killing me should they fail. I recently had them hydroed, was their first since they were made in 1974. I was gifted them a few years ago.

 

[James79]

Assuming hydro goes well the bushing will get positively identified and or replaced if needed... No low pressure bushing for me (or, more importantly, for my kids).

 

[Luis H]

The Compress Gas Association (CGA) does publish guides, standards, and recommendations, and some of the documents are invoke by the Codes of Federal Regulations (CFR). The CGA has established many of the valves interface standards, for example CGA 850 describes the interface dimensions for Scuba Yoke connections.

Just as a side note:

The CGA codes and standards are only requirements and regulations when they are invoked by the Code of Federal Regulations (CFR). Otherwise they are industry standards or strong recommendations.

Let’s just say that if you are involved in a accident with some compressed gas and there is some legal action, you are going to really wish you had followed all the CGA codes and recommendations. But that is a different story and not where I am going here.



My point is that an example of a standard that is not always being followed is the CGA 850 interface standard. In order to accommodate the DIN convertible valves some valves are wider than the allowable range shown in the interface drawing. This has caused some interference issue with some yoke attachments.

For example, the heavy Conshelf yoke tappers and is narrower near the screw and it has to unscrewed some to fit on some convertible valves, especially on some of the convertible European valves.

The yoke that is shown in the CGA 850 drawing below actually looks very similar to a Conshelf yoke.

 

[John C. Ratliff]

I'm going to come down on the side of Luis H on this one, and say that this tank should probably be used only for display. While you can get any buoyancy problems taken care of easily enough, the age and the use of unknown bushings makes putting it back into service rather sketchy. At the very least, check with PSI/PCI at their website, and actually contact them and talk with them. Even these so-called LP cylinders have a huge amount of energy stored within them.

PSI-PCI - About PSI-PCI

SeaRat

 

[Luis H]

I'm going to come down on the side of Luis H on this one, and say that this tank should probably be used only for display. While you can get any buoyancy problems taken care of easily enough, the age and the use of unknown bushings makes putting it back into service rather sketchy. At the very least, check with PSI/PCI at their website, and actually contact them and talk with them. Even these so-called LP cylinders have a huge amount of energy stored within them.

PSI-PCI - About PSI-PCI

SeaRat

Well, that is not at all what I said on any of my post. Your statement about age on a steel cylinder is irrelevant.

I would never agree to retire structurally sound pressure vessel without proper factual reason. This is not about opinions. Show me some Objective Quality Evidence (OQE) that would indicate that this cylinder should be placed out of service.

There is no reason, not to use this pressure vessel the way it was intended, as a pressure vessel. Yes, it has to pass a hydro test and a visual. A proper visual should include the inspection of the bushing and replacement if needed.

It is totally incorrect to bring age by itself as factor on a steel pressure vessel. You could say that an older cylinder has had more chances of exposure to a fire accident or more time for the possibility of rust and corrosion, but either one of those can be ruled out by test and inspection.

If a steel cylinder is properly re-qualified with a hydro and visual inspection, then that cylinder has met the exact same requirements as a brand new cylinder fresh out of the factory. Age did not play any part on it.

The information I am providing about steel cylinders are facts that are easily verified.


Added: I did say that pressure vessels need to be respected, but I did not say anything about unsubstantiated irrational fear.
Lets not start a new shark frenzy.

 

[John C. Ratliff]

@Eric Sedletzky

Waste of time and effort

K MAG YOYO

Luis,

I was thinking this was you, but it was Sam. My mistake. I stand by the thought of talking to PSI/PCI about this though.

SeaRat