DIN v. Yoke! Fight!

[The Chairman]

Yeah, it's apparent that even with a lot of abuse, yoke regs work just fine for most diving applications. They present no safety problems whatsoever.

I prefer DIN because it presents a bit less of an entanglement hazard. All O-rings will fail over time. The more you use or abuse them, the quicker they fail. I see very little difference between DIN and yoke, except that DIN are less common. Ergo, I carry a supply with me when I dive.

 

[Luis H]

When I started using DIN connections it was before it was even called DIN.

I have a carbon copy of a letter I sent to Scubapro in 1977 asking if they had an adapter for the MK-5 to use the 5/8” threaded European connection. Here in the US, they didn’t seem to have a clue of what I was talking about.

In any case I don’t use DIN much anymore.

DIN and yoke are both very reliable connections if used properly and there is no damage to the components.

In the long run (keep in mind I have regulators and valves that are over 40 and 50 years old) the yoke is a lot more durable.

If you use it a lot, DIN threads tend to wear a lot. DIN connections do not like sand, dust, and they are far better in fresh water. They can be used in most environments, but you need to take better care of a very clean connection. The threads tend to capture grit and dirt. Having a nylon bottle brush or a tooth brush to clean the female threads is a must if you want to avoid long term problems.

This brings me back to the use of DIN for rental tanks… very bad idea. I surely would not like to screw my nice well maintained regulator in a typical rental tank found in the Caribbean. The exception is of course a well maintained clean tank from a specialized tech shop.

It only takes one bad or dirty rental valve to do some damage to the threads in you regulator. Some undetected sand grit in the female threads will do a number when you turn on the air pressure. You will not even know anything happen until you go to take the regulator off.


The bottom line is that there is advantages and disadvantages to both. DIN is less likely to get entangled, but in general for the normal recreational diver the yoke connection is very robust and more tolerant to abuse.

 

[The Chairman]

When I started using DIN connections it was before it was even called DIN.

Deutsches Institut für Normung was established in 1917 and the valve specs were created by them. I remember them being called "yoke" back in 1969 and I remember a reference to "300 bar" regulators. I wonder if the Europeans first started calling them DIN valves and just when they were first developed.

 

[Diver0001]

DIN and yoke are both very reliable connections if used properly and there is no damage to the components.

I don't share this opinion. As divers we do a lot to limit the risks of all kinds of equipment failures for our safety and yet en masse people accept using a connection with a flat sitting that can -- and regularly does -- allow an exceedingly important o-ring to escape.... behind your head.... where you really can't do anything to fix it if it happens. I can't even remember the number of times I've seen O-rings escape from Yoke fittings but I *can* remember how many I've seen escape from a DIN fitting... ZERO. To me there's absolutely no question that a diver who takes safetly/risk management seriously wouldn't choose yoke over DIN. DIN fittings simply have none of the weaknesses of yoke and is a far FAR more secure fitting in terms of avoiding equipment problems.

R..

 

[The Chairman]

I don't share this opinion. As divers we do a lot to limit the risks of all kinds of equipment failures for our safety and yet en masse people accept using a connection with a flat sitting

Rob, that's simply not accurate. The o-ring on a yoke sits in a recess in the valve. The o-ring on a DIN sits in a recess in the regulator. Both sit in a recess and seal against a flat surface that should be in contact with with the raised portion of the recess and compressing the o-ring sufficiently to create a seal. All o-rings have to be supported in order to work. Leaving a DIN or a yoke reg loose can result in an extruded o-ring.

 

[boulderjohn]

I don't share this opinion. As divers we do a lot to limit the risks of all kinds of equipment failures for our safety and yet en masse people accept using a connection with a flat sitting that can -- and regularly does -- allow an exceedingly important o-ring to escape.... behind your head.... where you really can't do anything to fix it if it happens. I can't even remember the number of times I've seen O-rings escape from Yoke fittings but I *can* remember how many I've seen escape from a DIN fitting... ZERO. To me there's absolutely no question that a diver who takes safetly/risk management seriously wouldn't choose yoke over DIN. DIN fittings simply have none of the weaknesses of yoke and is a far FAR more secure fitting in terms of avoiding equipment problems.

R..

Rob, my experience has been quite different. In my dive travels I have seen probably 95% yoke being used. In my local OW instruction, my students and I have used yoke exclusively. In all my travels and instruction, I have only seen one regulator o-ring problem at depth, either in a pool or open water, and that one was with a DIN valve.

Now, since I mostly use DIN myself these days, I obviously prefer them and feel they are indeed more reliable. On the other hand, I don't see yoke failures much at all, so I would say they are pretty reliable.

 

[Diver0001]

ok. point taken, Pete. Nevertheless I'll stand by my observation that escaped o-rings are fact of life with yoke fittings. With a DIN fitting if it's too "loose" when you attach it then it will leak and you'll hear it immediately when you put the kit together. With a yoke fitting that is attached too "loose" it can "appear" to be correct when you charge the reg and the o-ring can escape (vigorously) at some unpredictable moment after that.

R..

---------- Post Merged at 07:43 PM ---------- Previous Post was at 07:39 PM ----------

Rob, my experience has been quite different. In my dive travels I have seen probably 95% yoke being used. In my local OW instruction, my students and I have used yoke exclusively. In all my travels and instruction, I have only seen one regulator o-ring problem at depth, either in a pool or open water, and that one was with a DIN valve.

Now, since I mostly use DIN myself these days, I obviously prefer them and feel they are indeed more reliable. On the other hand, I don't see yoke failures much at all, so I would say they are pretty reliable.

Well, John, I can only remember seeing a couple escape under water myself and only (knock on wood) in a pool so far, so I don't want to stress that aspect of it. The point i'm trying to make is that the fact that the yoke connection can *appear* to be ok when you put it together and that the o-ring can escape at some unpredictable moment after that is something that I find unnecessary and avoidable given the option.

R..

 

[Zung]

Statistics can be extremely misleading in this case.

It is true that I've seen quite a few issues with the yoke leaking when we were in the Maldives last Christmas, and that was from a German run dive op. No biggies, just small leaks at the surface, but that got me curious and I studied their procedure:

• Customer reports a leak
• DM digs inside a box full of (ugly-looking) yoke inserts
• DM replaces the customer's insert with the least-bad looking one
• DM puts the leaky insert back into the box!!!

 

[USdiver1]

Peeps, it's o-rings, wee pieces of rubber or silicone that we're debating as the major point of failure in both designs. O-rings are expendable, replaceable, damageable, what-ever-able you want to call them. If the first stage isn't properly placed on the valve and compressed gas is applied, it doesn't matter if it is a yoke or DIN fitting, the o-ring may fail; it's the part engineered to fail: easily replaceable by the user and just pennies for each unit. As we check out assembly (or should) at the surface by pressurizing the regulator almost all failures should occur topside. Both systems are susceptible to damaging their respective first stage o-rings through human error, and both are basically designed with projected failure hence the ease of replacement. As I said before, for OW diving in the western hemisphere and the Pacific, I'd go with yoke; eastern hemisphere as well as any overhead environment or technical diving DIN.

It's not so much an issue of which system is better as both have their faults, it is mostly an issue of equipment availability and ease of maintenance.

 

[Luis H]

ok. point taken, Pete. Nevertheless I'll stand by my observation that escaped o-rings are fact of life with yoke fittings. With a DIN fitting if it's too "loose" when you attach it then it will leak and you'll hear it immediately when you put the kit together. With a yoke fitting that is attached too "loose" it can "appear" to be correct when you charge the reg and the o-ring can escape (vigorously) at some unpredictable moment after that.


R..

I have witness a DIN connection have an O-ring let go a while after it was pressurized, just as you are describing that you have witness on yoke connections.

As I already mentioned, both connections can malfunction if they are not properly attached or the parts have been previously damaged.

I can’t comment on you personal experience with yoke connections, but where by any chance while using rental tanks? All rental tanks that I am familiar with are notorious for the abuse they receive. The valves surfaces many times are full of dings and imperfections, the O-rings look like have not been replaced in years, and corrosion is very normal. It is often surprising that they work at all, but most of the time they do. That being said I have never had a blown O-ring on any connection I have ever made in the past 40+ years (yoke or DIN, rental tank or personal)… now I just probably jinx myself…

A DIN valve would just not be able to take the kind of abuse that a yoke valve can. If you drop a tank on a DIN valve it will bend. You may still be able to screw in you regulator, but it will scratch the chrome on you regulator threads.

Every time I have witness a blown O-ring, yoke or DIN, it can be easily traced to operator error (normally beginner) or equipment damaged (bent yoke, damaged O-ring surface, etc).

Statistically makes a lot of sense that there will be more O-ring blown on yoke connections… they are by far the most common rental connection, they are probably the most common connection used by beginners, and at least in the US and Caribbean they are also by far the most common connection.

Deutsches Institut für Normung was established in 1917 and the valve specs were created by them. I remember them being called "yoke" back in 1969 and I remember a reference to "300 bar" regulators. I wonder if the Europeans first started calling them DIN valves and just when they were first developed.

I don’t know the history of when the connection was first named DIN, but I have several catalogs from the 60’s and 70’s for Poseidon and Drager and neither calls the connection or the adapters as DIN.

In the early 70’s I bought a set of Drager tanks from 1957 with DIN valves and a set of Poseidon tanks with similar valve. I bought them from a merchant marine sailor in Puerto Rico. The only regulator available in this side of the pond with the threaded connection was the Poseidon. Which happen to be my favorite regulator at the time.


Below are a couple of Poseidon catalog pages from the 60’s or 70’s. Notice that the term DIN is not used anywhere. It refer to the 5/8” threaded connection… yes, the connection is not metric.

Here are my old Poseidon tanks with DIN valves. If you notice the valve on the left was replaced. The threaded connection was damaged on the original valve.

Here are my Drager tanks. The valve on the left was also replaced. I also replaced the tank bands and manifold with Poseidon parts. The original manifold did not use an O-ring. It used phenolic gaskets on the male 5/8” threaded fittings (DIN).

This is a recent picture of me using my Poseidon tanks with a Phoenix Royal Aqua Master with DIN connection.

Sorry for the long post.