I want to use metal compression fittings rather than the standard push-fit MDPE couplings on 20mm (I/D) blue MDPE pipe.

Can I use what is described as standard 22mm compression fittings where 22mm presumably is the O/D?

Incidentally, I have a brass stopcock for use with 20mm ploy pipe and it has 20 cast into the side of it -suggesting that 20mm MDPE might require a special type of compression fitting.

Can someone help clarify please?