O ring visible between cylinder and valve.

[Agro]

I have checked that before. Tank is M25 same as valve.

You could have said befor.

By the way your o-ring 25x3.5 is wrong, must be 25x3.55. OK, I do not expect this to be any problem at all, 5/100 is very small difference and probably within tolerance. Nevertheless it is not according to the standards.

I hope it is 90 shore, not 70 shore.

 

[happy-diver]

Yeah those STEEL TANKS WITH A SQUARE SEAL can be quite problematic, think Mediterranean flat bread

STEEL TANKS WITHOUT THE SEALING TAPER


Not that Mediterranean flat bread is, but it is.