Whose moronic idea was it to stamp the cylinder crown?

[clownfishsydney]

Recently I visited an address to purchase a cylinder which the owner was selling. It had about 3 stamps on the crown which looked quite dodgy. I questioned why they were there and he said it was part of scuba safety standards. I asked him is that everywhere. He told me the UK was 3 years, the US was 5, China was 3 and Thailand was 7. I asked him why such a discrepancy. He just told me I was lucky I don’t dive in Australia where they purposely punch holes in your cylinder so as to make you purchase a brand new one every few years. I declined to buy the cylinder on grounds I wanted a second opinion.

I live in Australia and I have never known of anyone having a hole punched in their tank. I have been diving for 36 years and have at the moment 10 cylinders so I think I know what I am talking about. By the way, the various standards (eg Australian and international) all dictate where the stamps need to be put.

 

[clownfishsydney]

What is the history of cylinder markings? Who came up with the idea? Since PADI was the first commercial operation in existence, who made it compulsory? Don't answer if you don't know the answer.

Relates to ALL cylinders which have something inside under pressure, air, CO2, O2 etc. All need to be tested and stamped, the time period depends on use and country. Predates scuba diving that is for sure.

 

[pisauron]

I don't think PADI was involved in early tank markings. This is my oldest and it predates PADI by a few years.View attachment 847422
View attachment 847423

Awesome are they still in use?

 

[boulderjohn]

Tell me what sciences and history is behind Scuba standards?

I assume you don't really mean the entire science behind scuba standards, because that would require a book. In the context of this thread, I assume you are referring to the standards for the hydrostatic inspection of scuba cylinders. The answer is simple. There are no scuba standards for the hydrostatic inspection of scuba cylinders. The standards and rules for those cylinders apply to ALL cylinders, only a fraction of which are for scuba, so there really are no scuba standards for them.

 

[lostsheep]

Tell me what sciences and history is behind Scuba standards?

I would suggest you take a deep dive into phrenology to better understand these markings.

 

[Tracy]

Awesome are they still in use?

That particular one is not. It has no DOT/ICC markings as it predates both of them. It still passes test at its rated pressure, but it can't legally be put into service. There was a very large window after the ICC standards were formed where you could stamp the old cylinders and grandfather them into current service requirements. I have many old pre war oxygen bottles that had the cylinder pressure stamped into them at a later date. It is easy to spot as the size and font don't match on the service pressure. That was legal to do for about 50 years. During that time, this bottle was never restamped and it is beyond the window where it was legal to do so. Now it just sits there as a piece of history.

 

[Tanks A Lot]

[...]There are no scuba standards for the hydrostatic inspection of scuba cylinders.[...]

That is not quite correct and depends on the region one looks at.

In the European region BS EN 1802-2002 stipulates the inspection period for aluminium cylinders and BS EN 1968-2002 + A1-2005 the periods for steel cylinders. Both have explicit intervals set for SCUBA cylinders, due to nature how these are getting used. Contrary to industrial cylinder fleets, SCUBA cylinders are in the hands of thousands upon thousands of individuals, none with strict corporate policies and guidelines in place with regards to cylinder handling. Damage and neglect like wet fills are far more likely in SCUBA cylinders, hence the shortened inspection intervals.

As for the original question, BS EN ISO 13769-2018 - Cylinder Stamping lays out quite nicely where and how cylinders shall be marked.

 

[tursiops]

For the record, dive ops gloss over the tank hydro stamps extremely fast in training.

Because most of their tanks on the boat aren't up to date. The last thing they want, is noobs checking the stamps.

This whole post is madeup nonsense.

 

[lexvil]

This whole post is makeup nonsense.

Except my confession!

 

[Edward3c]

For the record, dive ops gloss over the tank hydro stamps extremely fast in training.

Because most of their tanks on the boat aren't up to date. The last thing they want, is noobs checking the stamps.

Wherever I’ve dived, in the Caribbean, Mediterranean or the far east all operators have had in-test cylinders. In Egypt the authorities visit every dive operator and check cylinders, regulators and BCDs are sercices/tested every 12 months. If an operator doesn’t have a current CDWS certificate the police can arrest the manager/owner.