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CAREFUL! Isn't the M25 (i.e., Metric 25 x 0.75) thread different from the 3/4" NPSM thread we see here in the USA on LP cylinders?
rx7diver
This would be the first time I have ever seen a Y-Valve.
View attachment 678114 View attachment 678116 View attachment 678118
@Ulfhedinn ,
First pic is a relatively recent pic (12/27/2020) showing one of my Y-valves mounted on a LP OMS/Faber 121/125. (Pic shows a broken valve knob.)
Second and third pics are old pics (08/29/2010) showing my other Y-valve mounted on an old-school PST 72, with two Scubapro Mk 10 Plus 1st stages attached. This configuration is one of my favorites for the type of diving I typically do these days. Note: Primary 2nd stage is a Scubapro D400, and backup is a Scubapro G250.
rx7diver
Here are the type that I use and I run them in DIN
On a side note, the metric sized valves won't even make it to one fill. We had one on a cylinder that made it about half way to full before the valve was launched up through the ceiling tiles of the dive shop. I still have two Beuchat Y valves that are metric but I just hang on to them for parts if needed.