Din or yoke?

[Bob DBF]

The yoke's design takes it up to 200 bar (3000 PSI). The DIN (Deutsche Industrie Norm) is designed to accept up to 300 bar (4500 PSI). There are a lot of tanks that have a service rating of 3500 PSI which in fact exceeds the yoke's design. Lots of people exceed the design with only a lot of prematurely failed o-rings to show for it. Me? I don't like to exceed design specs, so I dive a DIN.

I have a yoke reg designed for 4000# service made in the early '70's, may be more than one urban legend on the board.



Bob
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I may be old, but I’m not dead yet.

 

[The Chairman]

Could be... I would love to see a picture of that. Most that I have are marked 200 bar. I have heard of 240 bar yokes as well as 230 bar DIN... but I just haven't seen the former, though the converta-valves are all rated 230 bar for the DIN.

 

[DaleC]

Much ado about nothing.

As Luis said; both will do the job. A cave diver (a deep or penetrating wreck diver too) may prefer DIN because they are more prone to bang the valves on walls which might dislodge a Yoke. Losing the entire contents from a tank due to an uncorrectable leak caused by a bump may be a factor that sways a tech diver towards DIN. Most Rec divers do not have that problem and can always correct a leak by directly surfacing. For the rec world, constant use by multiple divers and variable attention/care would be the bigger issue. One the tech diver does not have. Here, Yoke is more forgiving.

As well, the problem with anecdotal evidence is that there are too many uncontrolled variables. Personally, after almost 1000 dives using Yoke connections I can report 0 tank O ring failures. Someone else says they see O ring failures on a weekly basis. What does it mean?

Below is a Yoke rated to 4000psi, a 40-50 year old yoke that still functions, the thumb screw from the 4000psi yoke (USD Conshelf Supreme), my everyday SP yoke, My everyday Zeagle DIN. Sorry for the mixed order, first time attempting direct upload from my PC.

I have not noticed a meaningful operational difference between any of them and am comfortable with all in a rec setting.

 

[scubafanatic]

I dive DIN regulators, travel all over the place for diving using their tanks, and rarely, very rarely do I ever have to use my DIN to yoke adapter. Not only do I avoid snags but I rarely have dive op monkeys screw around with my gear. They avoid anything they don't understand and I like that!

Like many urban legends, the one that you just can't find DIN around the world is quaint and it's probably put out there by someone who dives a yoke in order to justify their choice. The yoke's design takes it up to 200 bar (3000 PSI). The DIN (Deutsche Industrie Norm) is designed to accept up to 300 bar (4500 PSI). There are a lot of tanks that have a service rating of 3500 PSI which in fact exceeds the yoke's design. Lots of people exceed the design with only a lot of prematurely failed o-rings to show for it. Me? I don't like to exceed design specs, so I dive a DIN.

My Aqualung Titan LX regs have a 232 bar/3400 psi rating stamped on the 1st-stage yoke, so the 3000 psi 'limit' on yokes is another urban legend. I've never encountered a tank fill exceeding 3400 psi, even when diving with specialized 'boutique' HP steel tank ops in Cozumel. Sure, in a perfect world, DIN is superior, but the odds of a recreational diver, diving in the Western Hemisphere (or much of Asia as well) encountering a DIN tank are pretty low, so you better get used to yoke regs.

I do freshen up the yoke tank O-rings I use on rental tanks so at least I'm not diving 'tired' O-rings, so I'm not overly worried about not having DIN tanks available.

 

[viakovlev]

My understanding was that pressure rating is for the type of valve, rather than a specific make/model of a reg. As with other things, manufacturers may vary in their interpretation of ratings and safety margins. Can someone reference a government issued rating document of the valves?

---------- Post added April 16th, 2013 at 05:14 PM ----------

From Wiki:
There are three types of cylinder valve in general use for Scuba cylinders containing air:

• A-clamp or yoke - the connection on the regulator surrounds the valve pillar and presses the output O-ring of the pillar valve against the input seat of the regulator. The yoke is screwed down snug by hand (overtightening can make the yoke impossible to remove later without tools) and the seal is created by pressure when the valve is opened. This type is simple, cheap and very widely used worldwide. It has a maximum pressure rating of 232 bar and the weakest part of the seal, the O-ring, is not well protected from overpressurisation.
• 232 bar DIN (5-thread, G5/8) - the regulator screws into the cylinder valve trapping the O-ring securely. These are more reliable than A-clamps because the O-ring is well protected, but many countries do not use DIN fittings widely on compressors, or cylinders which have DIN fittings, so a European diver with a DIN system abroad in many places will need to take an adaptor.
• 300 bar DIN (7-thread, G5/8) - these are similar to 5-thread DIN fitting but are rated to 300 bar working pressures. The 300 bar pressures are common in European diving and in US cave diving, but their acceptance in U.S. sport diving has been hampered by the fact that United States Department of Transportation rules presently prohibit the transport of metal scuba cylinders on public roads with pressures above about 230 bar, even if the cylinders and air delivery systems have been rated for these pressures by the American agencies which oversee cylinder testing and equipment compatibility for SCUBA (Occupational Safety and Health Administration and Compressed Gas Association).

[h=6][edit]Pressure rating[/h]DIN valves are produced in 200 bar and 300 bar pressure ratings. The number of threads and the detail configuration of the connections is designed to prevent incompatible combinations of filler attachment or regulator attachment with the cylinder valve.
Yoke valves are rated between 200 and 240 bar, and there does not appear to be any mechanical design detail preventing connection between any yoke fittings, though some older yoke clamps will not fit over the popular 232/240 bar combination DIN/yoke cylinder valve as the yoke is too narrow.
Adaptors are available to allow connection of DIN regulators to yoke cylinder valves (A-clamp or yoke adaptor), and to connect yoke regulators to DIN cylinder valves. (plug adaptors and block adaptors) Plug adaptors are rated for 232/240 bar. Block adaptors are generally rated for 200 bar.

 

[Abdullah]

I have a yoke reg designed for 4000# service made in the early '70's, may be more than one urban legend on the board.


Bob
------------------------------------
I may be old, but I’m not dead yet.

I wouldn't think the yoke design would be any less secure at 4000psi than at 3000 psi. The yoke itself is a pretty sturdy chunk of metal. Have you had any trouble with the o-ring extruding at 4000 psi? Since the o-ring isn't trapped in this configuration, I think it could be extruded under high pressure conditions.

 

[flots am]

Which one and why? I have been looking for a new reg but seems like yoke is the more universal for the us and Caribbean.

If you're diving your own tanks, I'd go DIN. It's more compact, more secure and if it's on a stage bottle, you can't accidentally unscrew your reg underwater, thinking you're turning the tank on.

If you're using rentals, I'd go with yoke, since (almost?) all rental tanks in the US, Canada and the Caribbean are yoke.

flots.

 

[tphelps]

DIN hands down, much more reliable connection. Like everyone else is saying, you can get an adapter later.

 

[viakovlev]

I wouldn't think the yoke design would be any less secure at 4000psi than at 3000 psi. The yoke itself is a pretty sturdy chunk of metal. Have you had any trouble with the o-ring extruding at 4000 psi? Since the o-ring isn't trapped in this configuration, I think it could be extruded under high pressure conditions.

My understanding is that not the metal parts, but the o-ring is a limiting factor. It does not fully extrude in yoke, rather the pressure pushes it against the seat edges and makes nicks on the ring.

 

[The Chairman]

but the odds of a recreational diver, diving in the Western Hemisphere (or much of Asia as well) encountering a DIN tank are pretty low,

This just isn't true. I rarely need to use my DIN to yoke adapter and I've been all over. Why? Because there are lots of DIN valves out there. In fact there are a lot of dual DIN/yoke valves out there and that number is only increasing.