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Subject:  Reply to Kevin-Neil Klop/valves


Kevin wrote:

> Here's an assertion that I'm not too sure of.  Why are the thin threads 
>  of the DIN valve so much more secure than the threads on the yoke screw 
> and/or the brass form on the yoke itself?  Note that I dive with a DIN 
>  valve, I'm just not sure that it's all that much more secure than a 
> properly designed yoke.

>  Question:  What do they use on YOUR DIN valve to fill it?  On mine, they 
>  use a fill block and a (yep) yoke.

I believe the threads aren't the major concern...it's the o-ring.  In a
standard J or K valve, an A-yoke is used as the connector between the first
stage and the tank.  Here, the tank valve has the o-ring attached.  The tank
valve o-ring is very vulnerable to bursting if the first stage is jolted,
which may happen inside a wreck or cave.  What would happen in the case of a
strong knock on the first stage, is that the metal of the first stage would
press down on the bottom of the o-ring, causing the ring to pop, with
attendent loss of air.  With a DIN valve, the o-ring is on the first stage.
When the first stage is attached to the tank valve, the o-ring is recessed.
One would (practically) have to shear the valve off in order to loose air
from a DIN valve fitted tank.  In the case of a DIN valve, even a very
strong knock on the first stage will not budge the o-ring. (I was on a dive
where somebody actually DID crash so hard into the ceiling that they sheared
their first stage off a DIN valve.  Take that guy's scooter licence away,
already!)

Bernie Chowdhury
bernie@in*.ne*

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