Safeguarding the operation of process control valves

31 March 2011

A high-integrity pressure regulator, designed for use with pneumatic control systems used for valve actuation in the oil, gas and other processing industries, has been introduced by Midland-ACS.

The OPD Stemsaver is said to guard against failure of the filter-regulator that controls compressed air system pressure, by providing dual-redundant over-pressure protection, ensuring that any downstream actuators cannot be accidentally exposed to over-pressure. The provides plant and automation engineers with a safeguard against a failure mechanism that could lead to process shutdown or injury.

In hazardous areas, actuated valves are often elements of a plant's emergency procedures, such as the safety instrumented system (SIS) that controls emergency shut down (ESD). Depending on the emergency and type of process, valves may be automatically closed – to stop media feeding a fire for example – parts of the plant may be isolated, or media might be vented to atmosphere, via an emergency system vent (ESV).

OPD Stemsaver was developed following a request from an engineering, procurement and construction firm working for a North Sea oil producer. A failed filter-regulator had led to the cover of a pneumatic actuator being blown off, leading to costly downtime of operations.

As standard, OPD Stemsaver can be set to regulate pressure in the 4-8 Bar range. The device is supplied as a single compact unit, fabricated in 316 stainless steel to meet the anti-corrosion requirements of environments such as offshore platforms, and process plants handling harsh media. In use, the secondary regulator is set to operate at a slightly higher pressure than the primary regulator. If the secondary regulator is activated, a reset button also automatically pops up. This can be linked to a proximity switch, to provide feedback to the plant's DCS.

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