RE: Motor Operated Valve. The head of the operator is often shown as M inside a square. The limit switches ZSC/ZSO is acceptable under ISA. I have never seen ZSH/ZSL (high and low for a linear valve I suspect) in my industry. If the valve is used for on/off, it usually takes a XV or UV tag name. If the valve is used for regulatory control application, then they would take the normal PV, FV, TV type of designation. I have also seen HV for operator control only valves.
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