Tanks meeting CE and DOT standards

[Schwob]

Disclaimer: This thread is not started to lament the fact that no scuba cylindets meeting both DOT and CE standards are being sold. It is started in the hope of finding out why exactly that is, driven by the desire to understand.
In that sense, I am going out on a limp and state that if a tank manufacturer really wanted to make tanks that would pass both standards, they could. Other than the fact that they do not do that, does anyone know why they do not? Is it all a market separation and preventing grey market import things (pending on which way exchange rates swing) ... or is there actually something in either standard that really would make meeting both unpractical? If so what?

 

[Leadking]

Each country has there own standards, kind of a legacy thing. That said there was an attempt to create a United Nations (UN) standard. I do not know where that is now, as I left the industry almost 10 years ago. 49 CFR 178.71 - Specifications for UN pressure receptacles.

 

[rjack321]

Disclaimer: This thread is not started to lament the fact that no scuba cylindets meeting both DOT and CE standards are being sold. It is started in the hope of finding out why exactly that is, driven by the desire to understand.
In that sense, I am going out on a limp and state that if a tank manufacturer really wanted to make tanks that would pass both standards, they could. Other than the fact that they do not do that, does anyone know why they do not? Is it all a market separation and preventing grey market import things (pending on which way exchange rates swing) ... or is there actually something in either standard that really would make meeting both unpractical? If so what?

You need to convert the USA to the metric system for starters. Every US DOT specification is written in imperial, the reverse for CE.

 

[Bob DBF]

You need to convert the USA to the metric system for starters.

They started the conversion when I was a kid in the '60's', but it has not caught on very well. The up side is for tool manufacturers, since now they sell you two sets of tools to work on equipment now.


Bob

 

[redacted]

Where is the demand that would justify such a manufacturer expense? Who travels between CE and DOT destination and takes their own tanks?

 

[Schwob]

Well, if you know that there is an expense that there needs to be an upside to, could you elaborate please?
What precisely is it in each standard or in each testing requirement that suggests selling tanks under two sets of approval markings is costlier than selling them with dual approval? Does anyone in the community know the actual difference? Do we know the tanks are in fact different other than the approval marking? Please accept that I am not stating there is no difference, I just aim to learn what the actual difference is that is driven by the requirements - if there is one. So I am ideally hoping for a reply from someone that is or was involved in the design of cylinders with a manufacturer that serves both markets. Someone who knows indeed. I fail to see how past discussion and many opinions valid as they may be could aid in answering the original question. Are there any in the industry active or formerly active pressure vessel engineers out there? Someone not in a position to loose a job could over it hopefully?

 

[RhodeDiver]

if you don't want an answer from us common internets folk. You could try emailing a tank manufacturer.

 

[Schwob]

Rhode Diver, my intent was not to put anyone off. It was to focus the thread back to what I asked. Speculation as much as I like to engage in it myself (while I am into engineering, I am common folk myself and have nothing to do with pressure vessel design, or design for diving at all) ... speculation won't really answer the question. Am I wrong in trying to focus the thread? Maybe. Am I wrong in hoping to find someone here really in the know and also in a position to share? Maybe. But manufacturers often have reasons not to share, or reasons to share something other than the real core reason behind something.
And (prior to posting) I did contact one manufacturer of rebreathers and they sell small (diluent) tanks I think under their brand brand name (for either CE or US approval), but they did not reply. So I thought I ask here. But why would me having or not having asked a manufacturer have to preclude me from asking here on the tanks forum anyway?
I would not have tried to refocus this thread had I not started it. I can only hope it would be OK to seek the answer here. If indeed not, I am willing to delete my posts to the matter.... but haven't looked into how to do that. But why would you suggest there is no space for me with my question on this forum?

 

[rjack321]

All the metallurgical specs are written differently. Steel and aluminum have to be tracable back to the lot tested by an approved testing source etc.

You can't get m25 valves with burst disks and you can't get 3/4" neck valves without burst disks either. So its not just the tanks which are unique.

What does it matter anyway? Other than tiny little CCR bottles, cylinders are too heavy to fly. If you are moving just sell your used ones and buy other used ones at your destination.

 

[Schwob]

rjack321: Thanks. Some info and thought in there.
Still doesn't mean a tank could not meet both specs for all technical spects of the specs, but I guess I can see how it might get difficult for the bureaucratical profing and traceability aspects and which burocracy trusts which testing and certification enterprise to certify what and to trace what...
Does it really matter in any way. No, not really. Fair point.
I just want to understand better. But it does not really matter.
If someone ended up explaining what the actual specs state and what it means and where the differences are and why and what and... I might be happy as a clam to understand and then even I could talk about it... and it still would not really matter. Very fair point you make there.
But it does not really have to matter in some deep way or otherwise - or?
Anyway, I refer to the first sentence of the first post in the thread.
That's all I am trying to do. No deeper purpose...