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What is DIN/Yoke......

Discussion in 'Tanks, Valves and Bands' started by TwoBitTxn, Jun 15, 2001.

  1. TwoBitTxn

    TwoBitTxn Instructor, Scuba

    # of Dives: 500 - 999
    Location: North Texas
    Yall keep talking about DIN offering a more secure fitting than yoke. I can understand how on a high pressure tank that would make a difference. I'm an ex EMT and that was where I thought I recognized the term DIN fitting, from dealing with O2 tanks. But why would you need the more secure fitting on a LP tank? I have never heard of a first stage comming off. Maybe I havn't read enough. Thanks yall...

  2. Lost Yooper

    Lost Yooper Loggerhead Turtle

    # of Dives: I'm a Fish!
    Location: Panama City Beach, FL
    It's not uncommon for yokes to become "dislodged" if you hit them while in an overhead environment. The result would be a catastrophic loss of gas. It's not much of an issue otherwise for LP tanks.
  3. scubabunny

    scubabunny Manta Ray

    Ok..now it makes more sense! We sell to alot of military divers (SEALS, and EOD) and they are the people interested in DIN valves and fittings. I thought it was just a "testosterone" thing to pump their tanks up to a higher pressure. But, now I guess its more because they are actually doing work down there, and not just looking at the pretty fishies! (Guess you can call diffusing bombs and saving the country work...right? *winks*)

    Thanks for all your help here!
  4. devjr

    devjr Manta Ray

    Reread my earlier posts. For tanks rated up to 3300 psi, the DIN is "optional". Above this pressure, industry practice requires DIN even though manufacturers know that the MODERN yoke screw attachment is safe up to 4000 psi. Use of DIN valves on low pressure tanks is becoming more wide spread due to myths, due to the unusually cautious attitudes of today's divers, but also due to standardization of the individual diver's kit.

    The DIN connection is actually an industrial connection of the type normally used for permanent(not temporary) installations. It's similar to the valve/tank screw in connection in this regard. It is more secure in a mechanical sense because of the long threaded insert. It is more secure at the O ring because of the closed design. However, a change to DIN fittings is not needed by the majority simply because the conditions for failure of their yoke screw connections are not present. Moreover, the DIN valve connections can trap water and grit making on board tank filling a bit of a chore, especially if the tank has no pressure to clear it. The exposed machine threads and nozzle are suspect. (Don't drop one of those things).

    The yoke valve is just so easy and reliable, it's hard to beat. When one of my ancient steel tanks failed hydro, PST replaced it gratis with a new 3500 psi fitted with DIN. This thing sat in my diving locker for a year. I bought a set of adapters, looked at all this junk, then at some point thought, "what am I trying to do, here?" I got off the duff and machined a new yoke screw valve to fit the hp tank neck. Later, I did a couple more. You see, with all my equipment, compressors, etc, all standardized to the older valve, I certainly didn't need yet another set of adapters to mess with. Everything worked fine, BTW.

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