Scuba accident in a swimming pool close to my house

[Bob DBF]

Good IMCA summary off the DGE site:
https://www.divegearexpress.com/amfile/file/download/file/166/product/6641/

What is interesting is that the marking on the valve is printed on it not stamped, so it could wear off

 

[Fibonacci]

What is interesting is that the marking on the valve is printed on it not stamped, so it could wear off

Likely to be laser etched into the nickel or chrome plating so would be pretty durable...

 

[SlugLife]

Good IMCA summary off the DGE site:
https://www.divegearexpress.com/amfile/file/download/file/166/product/6641/

Thanks for that! That article specifically only references M25 x2 and 3/4 NSPM. There are other thread types I discovered, including 7/8 and 1/2, which are more common on steel cylinders.

at the marking on the valve is printed on it not stamped, so it could wear

It varies greatly from one valve to the next. Some are engraved. Some are superficial. Some have NO marking at all. Based on my unofficial survey of random valves I did earlier, around 50% have no marking indicating threading.

I actually ran into this problem yesterday when trying to buy valves online, and verify if they're 3/4 or 7/8.

 

[Bob DBF]

There are other thread types I discovered, including 7/8 and 1/2, which are more common on steel cylinders.

There are two 1/2 " thread types, the 1/2 NPT that was the SCUBA industry standard, and 1/2 NPS which was used by a manufacturer, for a short time, before the 3/4 NPS won the bid as the new industry standard. When you put your SCUBA museum together, let me know, I think I have a 1/2 NPS valve in a bin around here somewhere.

 

[DAJ]

It can be easy to get them mixed up if you don’t verify the thread pattern before using them. I keep a few of the M25x2 valves for spare parts if needed for the 3/4 NPSM valves. While an M25 will fit easily into a US cylinder, you won’t generally get the cylinder filled to it’s rated pressure before it blows off.

 

[BoltSnap]

I keep a few of the M25x2 valves for spare parts if needed for the 3/4 NPSM valves.

Not sure I get you, are you saying that you would use the M25X2 valves in place of 3/4NPSM valves on tanks that are supposed to be made for the 3/4 NPSM valves???

 

[DAJ]

I keep the M25X2 valves in case I need parts from them to work on the 3/4 NPSM valve. They are identical except for the thread pattern so the M25 valve can not be used on US cylinders. The 3/4 NPSM valves are very difficult to find. The M25X2 valves are still available outside of the US.

 

[DandyDon]

Meanwhile, in the US: "The Special Permit (SP) is expired as of 9/30/22. This means that any cylinder stamped with that SP9791 or E9791 is no longer valid for use, fill or transport in the US by law. It means that regardless if the cylinder still contains gas, or is still within its current hydro or inspection period, it is still not valid for fill, use or transport."

Scuba Cylinder Alert: Status of Special Permit 9791

Industry Bulletin: Status of the Special Permit 9791 By PSI-PCI October 23, 2022 PSI-PCI (Professional Cylinder Inspectors) would like to provide the following information related to the expiration of Special Permit 9791 ...

californiadiver.com

 

[Bob DBF]

It means that regardless if the cylinder still contains gas, or is still within its current hydro or inspection period, it is still not valid for fill, use or transport."

In commercial use, which is what DOT controls, one probably won't get fills from your dive shop.

 

[ChrisDee]

Pg 76

DAN Annual Diving Report 2020 Edition - NCBI Bookshelf

Thanks go to Kosta for the original link.

https://www.ncbi.nlm.nih.gov/books/NBK582510/pdf/Bookshelf_NBK582510.pdf