Determinant of a pressure rating on a tank valve

[Hoosier]

What is a determinant of a pressure rating on a tank valve?
Burst disk, Plug and seat assembly, Thread, or What?

I just rebuilt and O2 cleaned Thermo 3180psi and 3442psi valves today.

Except a number of threads, I can't see any difference in the internal parts.

Ironically, 3180psi valve has about 7-8 threads compared to 5 threads on 3442psi valve.



Any expertise?

Thanks in advance,


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From Diveriteexpress....

Is it safe to use a 200 bar SCUBA valve on the new 3442 psi SCUBA cylinders? Yes, it's fine for use with DIN regulators and modern Yoke regulators. We have seen a few yoke regulators with the yoke assembly marked for 3000 psi max service (or unmarked), and we do not recommend using the yoke adapter with those yoke regulators on the 3442 psi cylinders. While 3442 psi is approximately 230 bar, keep in mind the '200 bar' term is meaningless so far as the pressure rating of the valve outlet itself is concerned, it is a DIN 477 #13 valve outlet and the outlet itself does not have a pressure rating. Because of confusion about the 200 bar slang description for the valve and the 3442 psi cylinder pressure, we have noticed that some literature has taken to referring to the DIN 477 #13 valve outlet as '230 bar', even though the valve outlet is unchanged.

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[SparticleBrane]

The 3180 valve is 300bar due to it being for 3180+ HP tanks (rated to 3498psi). Valves coming from 3442 tanks have 5 threads (200-bar) since they aren't "true HP". There is no difference in the strength of the valves themselves.

 

[Lead_carrier]

The 3180 valve is 300bar due to it being for 3180+ HP tanks (rated to 3498psi). Valves coming from 3442 tanks have 5 threads (200-bar) since they aren't "true HP". There is no difference in the strength of the valves themselves.

It's amazing how those 50 psi come into play. Espcially if your pressure gauge is 2% off. Then that 3442 becomes 3510.

 

[WD8CDH]

It's what part of the valve that has the lowest rating, hopefully the burst disk. By convention, the DIN fitting with 5 threads (often called 200 bar, 230 bar or 232 bar) is usually used up to 3442psi and the deeper one with 7 threads (often called 300 bar) is used for 3500psi and over but most valves can handle quite a bit more. For example, OMS rates both their "200 bar" and "300 bar" valves for 4500psi working pressure.

Cousteau even used yoke fitting valves at 5,000psi and I have personally used DIN valves at 7,500 psi.

 

[DA Aquamaster]

200(232) bar versus 300 bar valves has nothing to do with the strenght of the valve. The purpose of the deeper 300 bar DIN connection is to prevent a regulator rated for only 200 bar to be attached as the shorter 200 bar male connection will not seat and seal in the deeper 300 bar valve - leaving it I susppose with a bad case of DIN envy.

The thing is that there are now almost no regs that are not rated to the 3500 psi where 300 bar (4350 psi) valves are considered mandatory.

That arbitrary 3500 psi distinction goes back to Sherwood's introduction of a 3500 psi HP tank and a perceived, but more or less conveniently created, need for a different valve design using 7/8" tank valve threads and a 300 bar DIN connection.

7 threads versus 5 makes no real difference as unless the threads are machined with extreme precision, you probably don't have more than about 3-4 threads in solid contact anyway at any given time.