The great DIN question

[Av06]

I am a pretty new diver with 21 dives and have just recently run into the world of DIN. This was brought about by the fact that I just bought a used cylinder which turned out to have a DIN valve on it. So after doing some research I decided to switch my reg over so I could use the new tank. My question is that I found the thermo pro valves which you can switch between yolk and DIN. I asked the dive shop owner who I got the tank from and he said that at almost 3500 using these tanks with a yolk just isn't safe and he doesn't reccomend it. Then I called up a shop in another city because I am renting tanks for a upcoming trip. They told me that the tanks I am renting have the pro valves and that it is fine to use them with yolk at full pressure because they use "new technology".

So the question is: is it really safe to use these HP cylinders with a yolk reg?

Thanks

 

[DA Aquamaster]

The convertible 232 bar DIN/K valve uses 5 threads rather than the 7 threads used on the 300 Bar DIN valve. This prevents you from screwing a 232 bar rated regulator into a 300 bar DIN tank.

The thing is there are basically no regs around that cannot handle 3500 psi. Whether a particular model can handle a full 300 bar or 4350 psi is another issue as many suffer from various design limitations at pressures over 3500 psi.

So in most cases at 3442/3500 psi the question is whether the yoke can withstand the pressure, not the reg. In my opinion, most heavy yokes in use today (Scubapro, Aqualung, etc) can handle 3500 psi as well as they can the 3300 psi they are rated for, so I would have no serious concerns with using a yoke reg on a 3442 psi tank.

That said, the shop that does not really recommend it is not wrong, as it is more than most yoke are officially rated for. In contrast, the shop that says it is ok as the pro valves use "new technology" is full of it as it is not a valve issue at all but rather a yoke issue.

The valve and the inlet on your reg need to maintain very close tolerances to create what amounts to a metal to metal fit with the o-ring contianed inside. If the yoke stretches due to excess pressure, this fit is lost and an o-ring extrusion and leak could occur. So the critical factor is the ability of the yoke to hold things together at the maximum tank pressure.

If you used an old, thin, 2250 psi yoke on a 3500 psi tank, the results would be more dramatic with a more or less immediate failure and with the potential for the first stage to be launched across the room, boat, into the back of the diver's head, etc if it fails suddenly enough.

In the end, erring on the side of safety is never a bad idea and you are better off with a DIN connection with a 3442 or 3500 psi tank.

 

[Mark Vlahos]

I am a pretty new diver with 21 dives and have just recently run into the world of DIN. This was brought about by the fact that I just bought a used cylinder which turned out to have a DIN valve on it. So after doing some research I decided to switch my reg over so I could use the new tank. My question is that I found the thermo pro valves which you can switch between yolk and DIN. I asked the dive shop owner who I got the tank from and he said that at almost 3500 using these tanks with a yolk just isn't safe and he doesn't reccomend it. Then I called up a shop in another city because I am renting tanks for a upcoming trip. They told me that the tanks I am renting have the pro valves and that it is fine to use them with yolk at full pressure because they use "new technology".

So the question is: is it really safe to use these HP cylinders with a yolk reg?

Thanks

The answer is either yes, or no, depending on your regulator.

I know that my reply is a little confusing. I intended it to be that way. The real deciding factor about the safety of any given yoke regulator at various different pressures is the yoke on the regulator and other regulator parts.

Here in the United States it is generally accepted that most first stages with yoke fittings are designed to operate well with the most common cylinder, namely the standard aluminum 80, which has a standard maximum pressure of 3000 PSI. There are of course exceptions to this, but generally that is the common practice.

The place for you to look is at your first stage regulator. Many regs have the maximum designed pressure clearly displayed right on the yoke itself. If yours indicates a pressure of 3442 PSI or higher you are ready to use your yoke regulator on a convertible valve safely. The metric equivalents for the 3442 PSI is just a little lower than 238 BAR.

Since you have already converted to the DIN fitting, and have an opportunity to use cylinders with convertable valves, I would suggest you leave everything DIN and just go with that.

Bye the way, the fitting is called YOKE, like various parts used to lift heavy items or attach a Horse or Ox to a wagon or plow. A YOLK is the yellow part inside an egg at breakfast.

Mark Vlahos

 

[D1V3R]

I put 4000 psi through a 1969 aqua-lung aquarius regulator
and dove with it to nearly 80 feet with no problems

call me crazy

 

[spectrum]

All good stuff so far...

For me the bottom line was that the vast majority of my diving was expected to be home based and with our own HP (3442 & 3500 PSI) steel cylinders. Experience has shown that upon occasion I may be blessed with fills considerably higher than those pressures so you can see that the safety factor of the yoke connection begins to erode quickly.

I've been an engineer working with fluid power for over 25 years. When I took up diving (2005) and was introduced to the yoke connection on a 3000 PSI scuba tank my reaction was, " you gotta be kidding". Granted that's the way a good chunk of the world dives and there have been users that have taken yokes to higher pressures. Being 100% in my own gear it just seemed to be the more robust solution.

Welcome to the world of DIN.

Pete

 

[SteFord]

My small "fleet" of steel tanks have convertible valves and are usually filled to 3500 psi. They're used about half and half yoke and DIN. Never had a problem DIN, but go through O-rings pretty regular on the yoke uses. I usually only have the adapter in the fitting when needed as I find water in there after use and rinses, etc. I pull the adapter plug for fills too.

 

[mark99]

So in most cases at 3442/3500 psi the question is whether the yoke can withstand the pressure, not the reg. In my opinion, most heavy yokes in use today (Scubapro, Aqualung, etc) can handle 3500 psi as well as they can the 3300 psi they are rated for, so I would have no serious concerns with using a yoke reg on a 3442 psi tank.

That said, the shop that does not really recommend it is not wrong, as it is more than most yoke are officially rated for.

Actually my Scubapro MK25 (yoke) is rated for 3442 psi. If you don't see it stamped on the yoke, the spec is probably in the user manual.

 

[BrianV]

FYI - my yoke CDX5 Oceanic first stage is rated at 3500 PSI. I've used it three times using HP80's rated at 3442, but they were all overfilled to about 3650. No problems, I'm sure a marginal degree of lee-way is built-into the yoke 3500 PSI rating, but I certainly wouldn't try anything higher than a 3442 (since many fills, especially when it's warm will go over by 200 PSI or so).

 

[DA Aquamaster]

Actually my Scubapro MK25 (yoke) is rated for 3442 psi. If you don't see it stamped on the yoke, the spec is probably in the user manual.

Older SP yokes were stamped 3000 or 3300, so I hesitate to give a blanket answer.

 

[Av06]

Thanks a lot for all of the answers. I did find that there was a 3500 stamped on my yoke. And a 232 bar on my brothers which is the same thing as 3500 I would guess because mine also said 232 bar. So I guess it technically could stand the pressure but I still don't think I would feel safe using something to the very edge of its rated pressure.