How many psi for a yoke valve?

[fisherdvm]

If you got HP tanks rated for 3400 psi, and have yoke/din valves on it. How much pressure can one put into the tank (legally) if the yoke adapter is screwed in? I was told by one instructor that you can not put in more than 3200 psi on a yoke valve, as some older yoke type regulator can not handle higher pressure.

But, will most modern first stages (1985 and forward), like my sherwoods, handle 3400 psi? Apparently some LDS think it is ok?

If you put din adapter on these regs, can they handle the higher pressure? It is probably first stage dependant, and have little to do with yoke vs din, right?

 

[spectrum]

By the book HP begins at 3500 so yoke is by the book to 3499. Hence the current 3442 PSI DIN/ Yoke pseudo high pressure cylinders. They skirt right under yoke cutoff.

Most modern stuff is good to that range. I cannot speak to yours specifically. I'm not sure that 1985 counts as modern.

Again not specific to yours the limit could be the yoke of the actual first stage depending. Visibly detectable deflection in vintage yokes on modern high pressures has been observed. This can set you up for o-ring extrusion/failure.

I have no idea where your instructor got the 3200 figure.

Pete

 

[seaducer]

The other night I brought my GF to a pool session, we grabbed a couple tanks from the shop that was having the class, my tank read 3300 PSI, and hers was still reading 3500 after 20 minutes of playing around.:11: Both were AL80's with straight up yoke valves.

I do not believe that is legal, but I will tell you that my reg (10 year old Dacor Quantum) and whatever shop reg Kelly had, plus the valves held the pressure ok. I wouldn't make a practice of that with that gear though...

 

[mike_s]

THERMO and San-O-Sub DIN/Yoke valves are 3442psi rated.

However there are some 3000psi only k valves also. It all just depends on the valve.



As for what a yoke 1st stage will support, it all depends on the regulator. I've got a YOKE 1st stage that has 4000psi rated stamped on the yoke. So not all yokes are rated only for 3000psi.

 

[DA Aquamaster]

That instructor is wrong but well intended.

The convertible yoke/DIN valves are normally used for tansk with a service pressure of 3442 psi - per the current convention - and can be used with either DIN or yoke connection at that pressure.

That, said, not all yokes or regs are created equal. Really old thin yokes found on regs in the 50's 60's and early 70's were often only intended for 2250 psi and are stamped as such. Some slightly thicker yokes were stamped 3000 psi but have a tendency to stretch and this can cause the o-ring to extrude.

Generally speaking if the yoke has a large 9/16" yoke screw in it, it will be a heavy yoke that is intended fr 3300 psi service and will have enough margin of strenght to handle pressures up to 4000 psi and some Sherwood and other brand yokes are even stamped 4000 psi. So 3442 psi/3500 psi is no big thing. Mares is currently using a very light looking yoke, but I am not sure what pressure it is rated to. It is "modern" and should be designed for 3300-3442 psi but I'm not sure.

What complicated matters though is that Genesis/Sherwood produced 3500 psi "high Pressure" tanks that used a smaller valve thread and a DIN connection. This has led to the belief that 3500 psi is really extreme pressure and a 3000/3300 psi yoke is going to explode at 3442/3500 psi. That is not the case and the 3442/3500 difference is pretty arbitrary.

Regulators are also a variable. In the old days the europeans had 200 and 300 bar DIN connections on regs with the idea of protecting the low pressure regs from 300 bar pressures that would damage them as the 200 bar reg connection is too short to seal in a 300 bar valve. In practice though most regs sold today are fine at pressures to 3500 psi and 200 bar connections have all but dissapeared. 232 bar valves however are now veryt common and have the convertible K insert to accommodate either yoke, 200 bar DIN or 300 bar DIN regs.

Some designs may be more prone to some long term problems (such as the Scubapro Mk 10 that, if excessive wear has occured, may develop excessive clearance between the piston stem and regulator body causing the high pressure o-ring to be prone to getting pinched with small pieces gettign smipped off at pressures over 3300-3500 psi) but many are designed for 300 bar pressures (4350 psi). So it's a good idea to check the owners manual or check with the manufacturer and also to ensure your reg is in good condition.

So in short, with the DIN insert you can legally fill it to the full 3442 psi and in practice the shop will probably go to 3500-3600 during the fill to give you 3442 ish pressure once the tank cools. No explosions will result once the magic 3442 psi is exceeded. But you may not want to connect it to a reg with a lightly constructed yoke as that is generally an indicator that the reg is not designed or configured for high pressures (and here I mean anything over 2500 psi, not anything over 3200 psi. I suspect the instructor got 32oo psi from the normal practrice of overfilling a 3000 psi tank by a coupel hundred psi to ensure a solid 3000 psi fill once the tank cools.

 

[matjo1]

If you got HP tanks rated for 3400 psi, and have yoke/din valves on it. How much pressure can one put into the tank (legally) if the yoke adapter is screwed in? I was told by one instructor that you can not put in more than 3200 psi on a yoke valve, as some older yoke type regulator can not handle higher pressure.

But, will most modern first stages (1985 and forward), like my Sherwood's, handle 3400 psi? Apparently some LDS think it is ok?

If you put din adapter on these regs, can they handle the higher pressure? It is probably first stage Dependant, and have little to do with yoke vs din, right?

What's the question? Is your worry the yoke or your first stage? You are right in the last part of your post by saying that the limit of the first stage has nothing to do with DIN or yoke. Yokes have pressure limits (so do DIN for that matter) and 1st stages have pressure limits. Most yokes have their limit stamped right on them (usually expressed in bars) and your regulator's limits should be easy to determine with a little research. (mainly the owner's manual!)

 

[fisherdvm]

I looked it up. It is rated for 232 bar, which is about 3400 psi. I guess that would be fine for the 3400 HP tanks.

 

[Nemrod]

Most of my newer equipment shows 232 BAR or 3300 psi stamped on the yoke. Since those two numbers are not exactly equal I suspect that your good to 3400 psi. I have used yokes on tanks to 3,500. I have also used the heavy yoke version of the Aqua Master to 3,400 psi. It is true than many regulators even fromas recently as the late 80s have lighter yokes that may stretch, usually within the elastic range so there is no permenant deformation but nonetheless allow the O-ring to extrude.N