Zero adjustment is not required. In principle, the zero point of a vortex flowmeter is the state in which no Karman vortex is generated by the vortex shedder bar (i.e., the piezoelectric sensor does not detect the vortex frequency).
The Vortex Flowmeter VY series supports condition-based maintenance, rather than time-based maintenance based on operating hours, through enhanced self-diagnostic functions.