How does the valve position of the on-site control valve change in the event of a DCS crash?
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How does the valve position of the on-site control valve change in the event of a DCS crash?
It depends; if it’s just a fault in the control station, the valve position on site remains unchanged； If it is a controller failure, the on-site valve position will move.
Let’s analyze it this way. Control valves receive either pulse signals or continuous signals, while control valves generally accept continuous analog signals; there are also terms such as FO and FC, which refer to opening or closing in the event of a loss of air supply or power. And the cut-off valve receives digital signals; it also has FO and FC, right? Personal opinion
If the host computer crashes, it prevents the operator from performing any actions, but the controller continues to carry out the commands it received earlier; therefore, the valve position should remain unchanged
If it is only a problem with the DCS system, the valve position should remain unchanged. But if there is a problem with the entire power supply or gas supply, then it depends on the design of each valve you have. Control valves generally have emergency opening, emergency closing, and emergency holding functions. Each valve is different. Be familiar with the accident conditions of each valve.