Differences between PVZV and PVV

[nasim123]

Dears

Can you pls explain the differences between PVZV and PVV?

Thanks

 

[met11]

One has a Z, the other does not. We need more context

 

[RaRo]

Using my local nomenclature, the Z would indicate a critical and piloted safety function of the valve. So a motorized PVV with a safety role.
Which would make it a pressure control valve and not a (purely mechanical) pvv.
However there are as many nomenclatures as they are sites.
It may just show a limit switch in our case, or that it is painted in blue with yellow polka dots for all we know.