Differences between PVZV and PVV Differences between PVZV and PVV nasim123 (Mechanical) (OP) 3 Nov 16 06:49 Dears Can you pls explain the differences between PVZV and PVV? Thanks RE: Differences between PVZV and PVV met11 (Chemical) 3 Nov 16 14:28 One has a Z, the other does not. We need more context RE: Differences between PVZV and PVV RaRo (Chemical) 15 Nov 16 12:15 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.