Z - Position, dimension
Reference for the ISA 5.1 first letter Z. Every plant with motor-operated valves carries Z tags by the dozens. Each ZSO, ZSC pair consumes two DI channels. One per switch state. A unit with 200 MOVs is 400 DI channels just for valve position feedback, an easy number to undercount at bid time. Which is exactly why the cabinet count comes in light when the panel builder starts wiring.
Read one of your own drawings.
Drop a P&ID, instrument index, or schedule. Tagsight reads it to the tag and opens a workspace you keep when you sign in.
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Also stands for.
- Open, closed status
Common second letters.
Transmitter, ZT. Position transmitter
Indicator, ZI. Position indicator
Switch, ZS. Position switch
Switch closed, ZSC. Valve confirmed shut
Switch open, ZSO. Valve confirmed open
Example tags.
Position switch closed, confirms valve 101 is fully shut
Position switch open, confirms valve 101 is fully open
Position transmitter, often on a control valve actuator reporting continuous position feedback to the BPCS
Typical placement.
On valves and motor-operated equipment where position feedback is required. ZSO, ZSC pairs on critical block valves. ZT on modulating control valves where the BPCS needs continuous position feedback.