Hatul
Contributor
The DIN fitting is hailed as the better of the two. Are there any documented instances where the O ring or the Yoke fitting failed under water?
Adam
Adam
DIN vs Yoke
- Thread starter Hatul
- Start date
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Go sit in a dive shop for a day while they are filling tanks. You're bound to see several yoke o-rings blow.
OP
Hatul
Contributor
The main hazard UW with the yoke is hitting it on something - which is why DIN is used in Cave and Wreck penetration
If you do, get another shop that knows how to fill tanks.
It is a little known and/or widely ignored fact that a yoke connection is also a metal to metal contact fitting - just like a DIN valve. So unless;
1. The conenction is loose,
2. The mating surfaces are worn,
3. or the service pressure of the yoke is exceeded causing it to stretch,
You are not going to have an issue with o-ring extrusion with a yoke valve.
#1 is also an issue with DIN fittings, the difference being the o-ring is mounted on the reg and will not get blown off the tank valve.
DIN connections are less likely to get knocked loose if you hit something in an overhead environment. They area also "stronger" and are rated for higher presure (although a heavy duty yoke will work fine at up to 3000 psi and using them on 3442 psi tanks is common). They are also more streamlined as their is no knob sticking out the back of the tank valve. The downside is that a DIN valve will trap more water and unless care is taken to ensure any water is blown out before filling, it greatly increases the potential to get water in the tank.
Damage wise, if a yoke valved tank falls over there is greater potential to damage the face of the valve where the o-ring is contained. At the other extreme, a 7 thread 300 Bar DIN valve is quite long and it you drop a 300 bar DIN valved tank on the valve it is likely to get bent and the round DIN connection will no longer screw in the resulting oval hole. In that regard the shorter 5 thread 200 bar DIN valve is probably the most damage resistant.
DIN valves are the norm in techncial diving, but they are not yet found everywhere so for a diver making tropical dive trips yoke valves are likely to be encountered. You can add a yoke to DIN converter, but it adds 3/4" to 1" to the lenght of the connection and makes it more prone to hitting you in the head.
So in short, if you are doing techncial diving, you need DIN valves. If however you are strictly a recreational diver, they are not needed and there is nothing wrong with using yoke valves. Anyone who says different needs to explain the yoke valve's 50 year record of safe service.
In my 25 years of diving, and something around 2000 dives, I have encountered several divers who have had blown o-rings when the diver sat up his or her gear and fails to align it or tighten it, but I never seen one extrude under water beyond. Yoke screws are very hard to unscrew under pressure and it won't happen by accident. If a yoke connection is going to fail due to improper assembly, it will fail immediately.
Thank you, I am well aware of these facts, however I can say that I worked for Dive Rite Express/Fill Express for almost 2 years, and I assure you it was a regular occurance.
Now this might be that in the real world divers are careless with their gear, and it gets abused, but I guarantee you, it wasn't the fault of the fill operators there.
Now this might be that in the real world divers are careless with their gear, and it gets abused, but I guarantee you, it wasn't the fault of the fill operators there.
rstofer
Contributor
Yes... My 100th dive was a moonless night dive in high current. The yoke o-ring blew at about 60'. There was no problem breathing off the regulator but the noise was horrendous! The swim back to the boat was really ugly.
To this day I don't know if I made a mistake in mounting the first stage or if it was just random perversity. I have always assumed it was my fault.
I have a picture that was taken to memorialize the event.
Richard
OP
Hatul
Contributor
Valves are like bedroom linen, there is WHITE, and there is is VULGAR.
Yokes are Vulgar.
Yokes are Vulgar.
Yes - for the same reasons. I had an O2 reg come partially unscrewed on a dive. The reg depressurized during the dive and apparently got bumped or scraped against something to the extent that it unscrewed 1/2 turn or so. The result was lots of bubbles when I went to make the gas switch.
The advantage of a DIN valve in this situation is that the o-ring is not lost and you can just turn the valve off, tighten the connection and turn it back on (although the odds are good the reg is at least partially flooded and should be re-cleaned or at least inspected for moisture.)
On the other hand, prior to switching to DIN (I have been doing deco dives since 1987)
I never had a yoke valve loosen underwater. So again, there are pros and cons. DIn valves are great but they are not the perfect solution.
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