This topic contains 4 replies, has 3 voices, and was last updated by 
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I am working in a new 4 Drums Coker design and would like to know what’s best for operating Switch Valves, from DCS, the field or both. What is User operating experience/feedback if only DCS is being used? Thanks,
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Anonymousmy experience is only from the PLC in the field.
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AnonymousLot many activities in field are happening from the time the switch valve is ready to turn till the time the clean drum is brought in line. DCS can be just use for providing information on the status of the valve. Local PLC and the status panel is the key for operation.
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AnonymousAll movements are from the area, but the logic does not allow any valve is open, if not met the requirements (permissive), is preferable to perform this operation from the field, as the operator can be sure that all conditions Field have been met
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We just started up a new 4 drum coker. The switch valves are Velan valves that are actuated from the DCS. We had problems making them work because the valves rely on limit switches to determine the valve position. Because the valves can travel 360 deg the feed back through the MODBUS interface is not reliable. We doubled up the position switches and fixed the tolerances and they have been working pretty well. (For about 3 months). The valves are actuated by the operator in the control room. They are not typically monitored in the field while they are moving.
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