Need yoke solution for Sherwood (7/8) tank

[tbone1004]

Just saying

most 300 bar din valves don't have indentations in the back to accept a yoke knob btw. If you absolutely must, then your only option is to get a VERY good machinist buddy and turn down a 200bar convertible valve from 3/4 to 7/8, but that is violating a whole lot of rules and realistically isn't safe because of yoke o-ring extrusion at high pressure. The 3500psi tanks are 300bar only for a reason...

 

[Bob DBF]

...and realistically isn't safe because of yoke o-ring extrusion at high pressure. The 3500psi tanks are 300bar only for a reason

Depends on how much over the service pressure of 3500# you are running the tank. I have a Faber MP 120 that has a 3180# service pressure and a + pressure of 3498# and have used fills over 3500# with my yoke reg. In addition, I have a 1980's vintage Sherwood reg that was specifically made for 4000# service which basicly was a beefed up yoke, it is however ironic that the valve yoke will not fit over the new design valves. I don't know the pressure limit for the practical use of a yoke valve might be, but I would bet it would be well over 4000#.


Bob

 

[Tracy]

most 300 bar din valves don't have indentations in the back to accept a yoke knob btw. If you absolutely must, then your only option is to get a VERY good machinist buddy and turn down a 200bar convertible valve from 3/4 to 7/8, but that is violating a whole lot of rules and realistically isn't safe because of yoke o-ring extrusion at high pressure. The 3500psi tanks are 300bar only for a reason...

Actually, most of the 7/8 neck, 300 bar valves I have seen, DO have the dimple in the back. And while it may be ill advised and you will most likely die. Cutting off two threads DOES work and it may have been done before. Just sayin

 

[stuartv]

I'm about to buy 2 older HP100 steel 7/8 thread for a great deal (just hydro), but my regulator (Aeris AT600) DIN converter is outrageous $120 on leisurepro (OCNDAK99) - more than I paid for first stage new on ebay! I need to see if I can find one cheaper, maybe another compatible brand as some are around $40. Having to carry a DIN to yoke on travel is an added hassle. Would love to have DIN200 on those tanks instead....

All my own tanks are those with the 300bar DIN valves. All my regs are DIN. I have the $20 DIN-to-yoke converter from DGX which I take on trips where I'll be renting tanks. I've never found it to be a hassle. The converter lives in a pocket in my reg bag, so I don't have to "think" about it to remember to take it. And I have only ever needed to use it maybe twice. Just about every operator I've dived with (in Mexico, Oahu, and Kona - so, admittedly, not that many) has been able to provide me tanks with convertible valves. I just needed to call in advance and let them know.

For a deal like that on tanks, I would buy a new DIN reg set and a DIN-to-yoke converter, swap over the octo, SPG, and inflator, and sell the old reg set.

Hog D3 Regulator Set - Dive Right in Scuba

 

[halocline]

...and realistically isn't safe because of yoke o-ring extrusion at high pressure. The 3500psi tanks are 300bar only for a reason...

That's not true at all. HP tanks (3442) use the 200 bar convertible valves and yoke regulators all the time. You think that extra 8 PSI is going to blow a yoke? Nonsense.

 

[Leadking]

Compressed Gas Association (CGA) rules dictated the outlets for SCUBA. I have been trying to explain all of this for over 10 years. The 3442 cylinder design came about as a result of CGA ruling that any recognized agency rules could be applied. An engineer at PST used a European agency standard, that when temperature compensated from C to F, allowed the maximum pressure for use of a 200 BAR connection to be 3442psi.

 

[tbone1004]

and many if not most of us use yoke fill whips to fill DIN tanks to close to 4000psi with no issue, but that doesn't mean that the CGA standards are written for a reason. Of course there are safety factors in there, but it's up to you on whether you want to push them. I have seen yoke o-rings extrude at 3500psi, I've seen them stay put up to 4200 psi, but that doesn't mean I'm going to let what was essentially an engineering loophole for marketing purposes risk an extruded valve because I'm too cheap to spend $50 on a DIN conversion or $100 on a new first stage.

 

[Killerflyingbugs]

DIN for the WIN!

 

[halocline]

and many if not most of us use yoke fill whips to fill DIN tanks to close to 4000psi with no issue, but that doesn't mean that the CGA standards are written for a reason. Of course there are safety factors in there, but it's up to you on whether you want to push them. I have seen yoke o-rings extrude at 3500psi, I've seen them stay put up to 4200 psi, but that doesn't mean I'm going to let what was essentially an engineering loophole for marketing purposes risk an extruded valve because I'm too cheap to spend $50 on a DIN conversion or $100 on a new first stage.

One more time. Every day, thousands of divers use yoke regs on 3442 PSI tanks successfully. This has been going on for decades, I guess, however long those tanks and convertible valves have been around. There is no practical difference between 3442 and 3500 PSI in terms of the stress on a yoke valve. You personally might not choose to use one, but to say "it isn't safe" is ridiculous. All the evidence is to the contrary.

It's one thing to voice an opinion or preference, its another to make some blanket statement about safety that is not based on any fact.

 

[tbone1004]

One more time. Every day, thousands of divers use yoke regs on 3442 PSI tanks successfully. This has been going on for decades, I guess, however long those tanks and convertible valves have been around. There is no practical difference between 3442 and 3500 PSI in terms of the stress on a yoke valve. You personally might not choose to use one, but to say "it isn't safe" is ridiculous. All the evidence is to the contrary.

It's one thing to voice an opinion or preference, its another to make some blanket statement about safety that is not based on any fact.

not decades, those tanks haven't existed for that long. Released in 2003 IIRC. Do not put words in my mouth though, I never once said "it isn't safe" hell I never once used the word safe. I used "safety" once in reference to a safety factor, but never once said safe so please do not put words in my mouth and accuse me of saying things that I haven't. I voiced my opinion, nothing more. My opinion is that you are toeing the line and the requirement from the DoT via the CGA is there for a reason. If you are comfortable violating that, then go for it. I do it all the time when I cave fill my 3AA tanks, but I won't do it with this when there is no reason for it other than being cheap.