Steel tanks, Yoke valves, DIN valves and the lot?

[MechDiver]

Th reason HP steel tanks need 300 bar valves (i believe) is because the 1st stage regs need to be able to handle this high pressure and the 200 bar valves don't have enough threads to securely tighten the reg to the valve. It was found that the yoke connection made to a 300 BAR valve using an adapter had a high rate of failure.

A yoke will not fit over a 300 bar valve as a safety measure. Also, as far as a mechanical fitting, the two extra threads don't make much difference in HP tanks used here. For true 300 bar tanks (4350psi), it would provide more safety.

I have no problem putting 3500 psi throught my 232 bar manifold.

MD

 

[headhunter]

This is simply a 200bar DIN valve with the insert. The 200bar version is pretty much the maximum limit for the E-series tank pressures. A 300bar has 2 more threads, and is too long for an insert. Sure, you could make an insert, but the yoke fitting would not normally be long enough to fit the valve.

Many divers will use 200bar valves with 300bar DIN reg fittings. This way the reg will fit all DIN valves regardless of their rating. I personally use 200 on my single tanks, and 300 on my doubles. If I should use a yoke only tank valve, then I simply put an adapter on my 300 DIN reg fitting. The "official" rating of 200bar pressures is 2,900psi, so the E-series is a bit of a stretch on the valve. I realized that the ECU was going to a 232bar rating when the Mares yokes started displaying that rating some years back. Low and behold, the new PST ratings are almost identical. The 300bar is for up to 4,350, which should meet the needs of those needing shall we say, "higher fill pressures".

Greg

I believe you're right Greg.

The PSTs are rated to 3442, but I think this is a 200 bar DIN valve I'm talking about. I was not aware that the difference between the 200 and 300 bar valves included 2 more threads for the 300. I know that my old yoke reg is only rated for 3,000 psi service, so when going to DIN it sounds like one would need to go to a higher rating on the valve anyway if you had a 200 bar valve with the "yoke plug" in it. Am I understanding this correctly?

Christian

 

[rab]

The "two extra threads" keep a 200bar DIN reg from making a seal in a 300bar valve. In my DIN/K convertable valve on my PST E8-119, there's a little hole on the side of the valve so that if the DIN reg or the adapter plug isn't fully seated in the valve, the gas will "leak" out the hole.

-Rob

 

[CelticRavenVA]

Hmmm got ya.... perhaps I will just go AL80... Thanks for the info everyone!

 

[yknot]

I can think of two potential failures for yoke regs when used at very high pressure: 1) the o-ring blows out the side (they can actually squirt sideways, followed by a sudden and dramatic reduction in tank air pressure). This is why DIN valves are said to have a "captured" o-ring-it is trapped between the back face of the tank valve and the hidden face on your regulator's DIN threads. The o-ring cannot blow out, therefore higher pressures are attainable. 2) It is possible for the metal in the yoke itself to stretch open. Again, not as likely to shear the screw threads on a DIN valve so higher pressures allowable.
For a lot of regulators, there aren't any internal adjustment changes needed when changing between DIN and yoke. High pressure tanks will only contain DIN valves to prevent you from charging to 4500 PSI (300 bar) and then mounting a yoke valve.
As far as the new PST tanks, what is the service pressure? A quality reg with a yoke valve should be capable of handling 3400 PSI without too much concern but I have never seen anyone overfill a low pressure tank to 4500 and use a yoke valve. Ultimately, for the users of DIN/high pressure tanks, what are the advantages over low pressure, providing they are both steel tanks?

 

[rab]

As far as the new PST tanks, what is the service pressure? A quality reg with a yoke valve should be capable of handling 3400 PSI without too much concern but I have never seen anyone overfill a low pressure tank to 4500 and use a yoke valve. Ultimately, for the users of DIN/high pressure tanks, what are the advantages over low pressure, providing they are both steel tanks?

It's 3442psi@70*F for all E-series cylinders.

-Rob

 

[Mo2vation]

Hmmm got ya.... perhaps I will just go AL80... Thanks for the info everyone!

I was just thinking the same thing... too funny.

In simple terms - you'll love your HP100 cylinder. You won't get that wacky buoyancy swing that most Al80's deliver, you can likely lose some lead from the belt, and DIN really is a better connection.

Other considerations - can you get 3500 pound fills to take advantage of it? At shops, its a no brainer here, but only a couple of boats over here can deliver a fill up to even 3000, and only 1 or 2 go up to 3500. So most of the time, the true advantage (lots o' gas, little package) is lost.

I recommend filtering out all of the mechanical nonsense that, while being important, probably isn't important to you (or your question), get your regs converted to DIN and hunt down your PST HP100 or HP120.

Until we can bury you next time - take a snorkle!

ScubaBoard - where if information overkills, you're already dead.

K

 

[headhunter]

The E8 PST tanks are not HP tanks, so they can get away with using yokes.

I thought that the E8's were considered HP tanks.

So help me out here. The old 104s were replaced by the "higher" pressure E8 130s, but they are still actually a LP tank? Don't read that question as a "smart a$$" comment. I'm actually just an old guy trying to catch up with current technology.

Thanks.

Christian

 

[MechDiver]

I was just thinking the same thing... too funny.

In simple terms - you'll love your HP100 cylinder. You won't get that wacky swing that most Al80's deliver, and DIN really is a better connection.

I recommend filtering out all of the mechanical nonsense that, while being important, probably isn't important to you (or your question), get your regs converted to DIN and hunt down your PST HP100 or HP120.

Until we can bury you next time - take a snorkle!

K

Yea, try not to give anyone information to confuse them; and I would hardly consider it "nonsense". HP tanks still have as much, or more, swing than aluminium. They just don't go as positive.

 

[MechDiver]

I thought that the E8's were considered HP tanks.

So help me out here. The old 104s were replaced by the "higher" pressure E8 130s, but they are still actually a LP tank? Don't read that question as a "smart a$$" comment. I'm actually just an old guy trying to catch up with current technology.

Thanks.

Christian

There isn't really a LP tank anymore. The new tanks are just refered to as E8 Series due to the exception they were granted. You can't really call them HP, or they would have to have 7/8 thread and 300 bar valves. Excellent marketing on PST's part.
The E8 series dimensions are closer to the LP tanks they replaced, but lighter. The E8-130 weigh in very close to my LP-95s, but are longer like the LP-104s.

Totally confused? Me too. The HP tanks still have the same problems they had before.