#EMrexDD Minimising safety loop vulnerabilities in valve controllers

Emerson Process Management minimises safety loop vulnerabilities with the Fisher® FIELDVUE SIS Digital Valve Controller

50% of Safety System failures occur in the final control element. Typical valve failure modes during an emergency situation are: stuck open, not enough torque, too slow, high friction and broken shafts. Valve failure detection was limited because safety valves were normally operated with an on/off solenoid valve.

The Fisher® FIELDVUE SIS digital valve controllers with HART® protocol rely on their capability to uncover dangerous failures while the safety valve remains in operation, using Partial Stroke testing technology. Partial stroke testing confirms the valve will move when necessary and built-in pressure sensors continually monitor actuator pressure to eliminate spurious trip risks. The partial stroke test regime can be fully automated or can be managed using an (easy to use) local control panel with green, red, and yellow lights. A local control panel allows visualisation of Partial Stroke Test (PST) at the valve, or wired at a distance. If a solenoid valve is used, the FIELDVUE digital valve controller can also monitor the solenoid valve (SOV) health while in operation. In addition, the FIELDVUE SIS digital valve controller captures any safety trip in its non-volatile memory, much like an airplane ‘black box” recorder.

The latest evolution in the FIELDVUE platform, the DVC6200 SIS, is scheduled for later this summer. It will have the added capability of HART 7 communication and linkage-less, non-contacting travel feedback technology, in an explosion-proof housing. Integral travel feedback is also provided and is fully separated from the safety control signal.

About Eoin Ó Riain

Sé Read-out iris uaithoibríoch, ionstraim agus stiúradh na hÉireann agus an "Signpost" a áit ar an idirlín! Read-out is Ireland's journal of automation, instrumentation and control and the Instrumentation Signpost is it's web presence.
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