What is this and does it matter if I cover it in insulation?

[Adsibob]

Making good progress insulating the copper pipes coming out of my UVC.

 There is a funny looking termination at the top of one pipe, that has a sort of valve/terminal on it that says it is rated for 10 bar. Looks like this (sorry, I should have photographed it before I insulated most of it). Can I completely cover it up?

[Conor]

That's an air valve. Keep it clear.

[MikeSharp01]

I think it should have a small plastic screw in the top hole (ours does) which allows you to bleed / shut it as required.