HP tanks and their effect on regs

[mike_s]

Can you please tell us where you can get a 5,000 psi yoke setup including reg and tank?

If this isn't something that is readily available to the diving public than this is a mute point to the question and a complete waste of time.

don't worry.... there are very few places that you can get a 5,000 psi gas fill, so it's a mute point.

that and not that many 5000psi tanks sold out there either.



For the sake of adding to this discussion, I've got a yoke that is rated to 4,000psi. So not sure why it couldn't be used with a Yoke HP tank. (However, I much prefer the DIN connection and never use this reg anymore).

 

[WD8CDH]

It's not a totally moot point. Cousteau used unmodified yoke regulators on commercial manifolds at 5000 psi for many years. Only the tanks were not available to the public. I have personally used unmodified Poseidon and US Divers regulators on yoke valves at 4500 psi using AGA tanks which were sold in the US in the early 80's. Sherwood has been selling K valves that have been rated to 4000psi for over 25 years. Only the burst disks are hard to get.

The point is going from 3442psi to 3500psi won't make your yoke suddenly fail or invoke any law requiring 300 bar DIN. .......but personally, I prefer "232 bar" DIN to either yoke or "300 bar" DIN.

All of the dive shops near me can fill to 4500 psi and 2 of them will fill to 5000 psi (they do paintball tanks too). Of course they only fill to that pressure tanks that are rated to that pressure.

 

[WD8CDH]

For the sake of adding to this discussion, I've got a yoke that is rated to 4,000psi. So not sure why it couldn't be used with a Yoke HP tank. (However, I much prefer the DIN connection and never use this reg anymore).

I also have at least one Conshelf regulator that has 4000psi cast into the yoke and the yoke to DIN adaptor that my Poseidon came with is rated to 4500psi but surprisingly to most people, it only has a "200 bar" DIN fitting on it.

"200 bar" DIN is really only a slang term for the 5 thread DIN connection. Other terms often seen are "230 bar", "232 Bar", "240 bar" and "250 bar" DIN, all for the same 5 thread configuration. In Europe, the informal standard is usually using the 5 thread DIN up thru 250 bar (3626psi) and the 7 thread DIN above 250 bar.

 

[spectrum]

Contrary to popular belief, a 3500psi tank doesn't have to have a 300 bar DIN valve (or any DIN for that matter). It's just in this country, almost all 3500 psi tanks have 7/8 - 14 threads and none of the available 7/8"valves come in anything other than "300 bar" DIN.

Cousteau and others have used yoke SCUBA fittings at 5,000 psi.

That may be and actual regulations DOT or otherwise have escaped me. As for Cousteau, cave divers and the like that may demonstrate something but that does not make it permitted.

If there is no true taboo on a 3500 PSI yoke configuration why did PST, Worthington, and others shave a few atmospheres down to 342 when introducing the convertible valve?

BTW I recognize that the went from 7 to 5 thread DIN in the process but lets focus on the yoke issue.

Pete

 

[WD8CDH]

That may be and actual regulations DOT or otherwise have escaped me. As for Cousteau, cave divers and the like that may demonstrate something but that dose not make it permitted.

If there is no true taboo on a 3500 PSI yoke configuration why did PST, Worthington, and others shave a few atmospheres down to 342 when introducing the convertible valve?

BTW I recognize that the went from 7 to 5 thread DIN in the process but lets focus on the yoke issue.

Pete

As has been stated before, THERE IS NO DOT, CGA OR OTHER FEDERAL REGULATION LIMITING YOKE SERVICE PRESSURE to 3000psi. A valves service pressure is based on the manufacturers rating of the valve itself, or the burst disk installed, which ever is LOWER.

Many convertable valves, for example OMS, are rated to 4500psi with the proper burst disk installed.

Some history:
There is no technical or legal reason for the current HP tanks to be 3442psi rather than 3500psi. With the desired stress on the particular strength of steel used, anything between 3000 and 4000psi would have given a tank with desirable buoyancy characteristics. Near the middle of that range matched most of the installed compressors at the time and gave more capacity than similar sized aluminum tanks. Most of the first HP tanks were actually made in europe where they used exsisting tank designs that when the service pressure was converted from Metric to Imperial, it ended up being 3442psi.

The tanks were made with 3/4" NPS threads rather than the 7/8-14 UNF threads used by the older 3500 psi tanks for at least 3 reasons.

1. The 7/8" threads were generally disliked by the SCUBA industry for being different and harder to VIP.

2. 3/4 NPS threads could be put in the tanks with no change from the tooling used to make Euro spec. tanks except for the tap itself.

3. 4000psi rated yoke valves were easily available from several manufacturers that fit 3/4" NPS neck threads. Valve selection in 7/8" UNF thread size was (and still is) much more limited.

 

[Leadking]

While the manufactures can stamp various ratings on their yokes the CGA and ISO actually set the standards. DOT says to use the CGA standard or any other "RECOGNIZED STANDARDS" for outlet configurations. CGA does not recognize the Yoke configuration above 3000 psi, ISO recognizes it to 230 bar @15C/which has been temperature corrected to 3442 psi@70F for the US..

 

[WD8CDH]

CGA recognizes the ISO 12209 standard. They even sell it on their website.

CGA has a connection, CGA 850, which is rated to 3000psi for SCUBA. That connection is probably what is often sited as the limitation of yokes being 3000psi in general. The CGA 850 connection is an ancient fitting dating back to the '60s or even earlier, but it's not the only recognized SCUBA yoke fitting. CGA calls CGA 850 a "Limited Standard". The face width is only .875" wide, much narrower and somewhat weaker than modern SCUBA yoke valves. Fortunately, both the DOT and CGA recognize the stronger and mechanically interchangeable "International Yoke" which is what most modern valves are made to. ISO 12209-1 specifies the dimensions of the modern SCUBA yoke. I doubt if there has been a valve made to the CGA 850 spec in decades.

So to the original poster, if your valve is made to ISO 12209 and your regulator is made to ISO 12209 or otherwise rated to 3442psi or more, you are fine.

 

[Codyjp]

And to answer the original question in post #1.

NO.