Using 232 bar yoke on HP 130 steel tank

[keendiver]

Hi,
I have Tusa RS-340 and yoke is rated to 232 bar. I have also bought X8-130 HP steel tanks with working pressure of 232 bar 3442 psi. So as far as I can see there should be no problem using the regs with this tank. The small question is that 232 bar is not 3442 psi as 3442 psi convert to 237-238 bar. Is this difference of 5-6 bar a problem and how common it is that the tank would be filled a bit above the working pressure (by the shop) making this difference even greater? My understanding is that 232 bar/3442 psi is standard and that the conversion difference is not important.

Many thanks...

 

[Captain CaveMan]

Yes to a chart 232 bar is 3442psi, but that 232 stamped on the valve is its sugested max working pressure. So when you put that yoke on that HP130 your shortly weakening your yoke and valves over time. This is why HP tanks are most commly used with 300bar DIN valves. 300bar is 4351psi so that 7 turn DIN is not under its sugested max pressure. If I were you I would take off the 232 K valves and buy a nice set of 300bar DIN and get your regs turned into DIN.

 

[keendiver]

I agree and that was my thinking as well. I am not considering this to be an urgent issue. Do you agree?

 

[Luis H]

The 232 bar yoke will not be weekend at all by using it with 3500psi or even 3900 psi.
I use them all the time and there absolutely no visible flexing. Structurally it is not an issue.
Keep in mind that Cousteau used yokes with 5000 psi tanks.


Another common misconception is that the 7 thread 300 bar DIN is stronger than the 5 threads 200 bar DIN. The only difference between the two is to avoid compatibility.
Actually the 200 bar DIN is less prone to damaged if the valve is hit.
Take a look at this link:
Valves, Regulator Fittings, Cylinder Neck Openings -- More than you wanted to know

 

[Tienuts]

Yes to a chart 232 bar is 3442psi, but that 232 stamped on the valve is its max working pressure. So when you put that yoke on that HP130 your shortly weakening your yoke and valves over time. This is why HP tanks are most commly used with 300bar DIN valves. 300bar is 4351psi so that 7 turn DIN is not under its max pressure. If I were you I would take off the 232 K valves and buy a nice set of 300bar DIN and get your regs turned into DIN.

Not trying to start war, but damn near everything you just said here was inaccurate. Read the link Luis H put up.

There is no structural difference between 200 BAR and 300 BAR. Made from the same alloy to the same specs, with the exception of the thread lengths. The 300 BAR were designed so you could not use a yoke insert. Thats it.

Secondly, 200 BAR valves are far more common on HP cylinders. Trust me, I sell them - it's an economics thing - the 200 BAR are the same, and simply cheaper.

232 BAR stamp is not the valve's max pressure - it's more like a slang to ID the valve. If you look, the burst disks on the back of these valves are set to blow at the max testing pressure, which for 3442 PSI valves, should be 5250 PSI.

The only difference between DIN and Yoke regs, is the part which connects it to the cylinder. You can bring almost any yoke regulator into your shop and tell them to make it a DIN reg - all they do is remove the yoke and screw in a DIN fitting. That's it. The risk you have of using yoke is the o-ring on the face of the valve is more likely to blow with a yoke.

At the shop, we fill the HP cylinders to 4200 regularly with yoke vales. To the OP, it is better to use DIN, and if you plan to do any deco or overhead environment diving, change to DIN, but you will be perfectly fine using Yoke with your 130's.

 

[Stu S.]

Yoke is OK.

Although 3442 psi is a lot of pressure, the area of that pressure at the seal is a fraction of a square inch. So, you really have about 700 pounds of force on the yoke. That might seem like a lot of force, but it is well within the pull strength of the yoke. The bolts that hold your bed together are probably stronger than that.

If the yoke was a weakling, it would probably stretch enough to not seal. That weakling could never be tightened enough to seal. This does not happen, as the yoke is plenty strong. The weakest part of the yoke valve setup is the o-ring.

Most of my group is using 3442 cylinders and the yoke. We never broke anything. I never saw anybody else have a yoke fail either. As an engineer, I'll tell you that DIN is better. But, I don't have a need to make the change on what I use.

Stu.

 

[Luis H]

Yoke is OK.

Although 3442 psi is a lot of pressure, the area of that pressure at the seal is a fraction of a square inch. So, you really have about 700 pounds of force on the yoke. That might seem like a lot of force, but it is well within the pull strength of the yoke. The bolts that hold your bed together are probably stronger than that.

If the yoke was a weakling, it would probably stretch enough to not seal. That weakling could never be tightened enough to seal. This does not happen, as the yoke is plenty strong. The weakest part of the yoke valve setup is the o-ring.

Most of my group is using 3442 cylinders and the yoke. We never broke anything. I never saw anybody else have a yoke fail either. As an engineer, I'll tell you that DIN is better. But, I don't have a need to make the change on what I use.

Stu.

The interesting part is that both yoke and DIN use the same style face sealing O-ring.

IMHO most O-ring failures on yoke fittings are due to operator error. Occasionally it may be caused by damaged parts. The elastic flexing of the yoke is normally insignificant and is not a contributor unless some one is using an old undersized yoke for the higher pressures.

I started using DIN fittings well over three decades ago and I am convinced that the major reason for the lower failure rate on DIN fittings is because there are less around and the users of DIN fittings are more careful. That is why they are using DIN fittings (in the US)…tech divers, etc.

BTW, I use mostly yoke fittings now a day. I never liked screwing different threaded parts together all the time and the fact that it is hard to inspect the loaded side of the female threads…yes, I am also an engineer, but this is just a personal preference.

 

[Stu S.]

Luis, what is the diameter of a DIN o-ring?

 

[Jimmer]

Yoke face O rings are either 014 or 112, which will have an I.D. of .488 +/- about .005".

 

[Captain CaveMan]

I've read what you posted from DR but I still stand by what Ive said 100 percent. Over time 3442psi on a yoke reg will strech not enough to see with the eye but you will never know because you just tighten the bolt down just a little more. And if there is a defect in the steel it will start to crack. maybe 10 or more years or next week.
The more threads you have on a bolt the stronger is will be, this is why all engines are made with fine threads. ( the same with the DIN) More threads is more surface area more surface area the stronger it will be.
BOLTS AND TORQUE SPECS
look at 1/2 bolt grade 8

I will only use a DIN on HP tanks and a yoke on 3000psi or less.