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On Fri, 22 Sep 1995, Kevin-Neil Klop wrote: > >Since the treads of a Din valve provide greater contact area this makes for > >a stronger connection. Plus the captured O-Ring is designed to prevent > >o-ring blow outs more so than a yoke valve. >etc. > Are you sure there is more contact area for the DIN? Are you sure that > the threads are the same strength? Is a hollowed tube stronger than a > machined, solid metal, screw? > > The captured O-Ring thing also bothers me since (I think it was) Bill > Gavin or George talked about this. When connected to a tank valve, are > you saying that the O-Ring in a yoke is NOT captured? What keeps it from > expanding and breaking, then? Neoprene does NOT deal well with 3000PSI > (or higher) against it unless it's backed by something a bit stronger. > What most people are overlooking is that the strength rating on the traditional yoke is not just for the strength of the screw but also for the strenght of the open portion of the yoke that reaches around the tank valve. There is 3000psi of tension placed on this material. As for the contact area, take one of your yoke screws out and count the number of threads that will actually be making contact with the female portion of the yoke, go to a hardware store and find out the pitch of the aforementioned threads, and then count the threads on a DIN 300 fitting and check the thread pitch on them also. I think that you will find a greater amount of contact are on the DIN 300 fitting. On a DIN 200 fitting I'm not so sure. On the yoke you have two areas of concern for strength. The threads and the "Y" portion of the yoke. On a DIN fitting you only have the strength of the threads to worry about, in comparison. Incidentally, I have seen some newer yokes on fill stations that claim to be rated at 4000psi, (they are stamped that rating in the yoke). I would still question using a yoke and a block to fill a DIN 300 female fitting on a tank.
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