Hi greener, thanks for it.
After doing a phisycal search here in my location with the cylinder vendors , I noticed that each country has it's own standard
Here we use 1/2" BSP male for Oxigen,
5/8" Bsp female for nitrogen
3/4" Bsp female for acetylene
and 3/4" Bsp femele left thread for Hydrogen.
If needed I have the drawings .
Pardal