Voices: Lipták

Controller Action and Positioner Rules

Two of Our Readers Ask Our Experts to Clarify Their Views on Controllers and Positioner Rules

By Bela Liptak

*Q:* I am an instrumentation engineer working for a EPC company in Dubai, UAE. I follow your articles closely. I have a query about one of your replies to the query on the subject of direct and reverse controller action. My understanding is that the controller action should be decided based on the control valve failure position, plus the process requirements, while the control valve failure action position is decided independently, considering only the safety requirements. I am still skeptical about the controller action. Can you please review my paper and help me? I tried to get this concept from books and the Internet, but nowhere is it complete.

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