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Midland-ACS has launched the OPD Stemsaver, a high-integrity pressure regulator for pneumatic control systems used for valve actuation in the oil, gas and other processing industries.

The device guards against any failure of the filter-regulator that controls compressed-air system pressure by providing dual-redundant over-pressure protection.

It ensures that any downstream actuators for controlling process valves cannot be accidentally exposed to dangerous over-pressures that could be high enough to shear a valve stem or cause other damage.

The device provides plant and automation engineers with a high-integrity safeguard against a failure mechanism that could lead to costly process shutdown or injury.

Pneumatic actuation is widely used in process automation systems for controlling and sequencing valves.

Automated control valves are particularly common in hazardous areas, such as offshore platforms and refineries.

In hazardous areas, actuated valves are often elements of a plant’s emergency procedures, such as the safety instrumented system (SIS) that controls emergency shutdown (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).

Pneumatic actuation systems typically use a single filter-regulator component, and the failure of this component can expose downstream devices to pressures as high as two or more times the norm.

This can be enough to cause significant damage, even providing an actuator with enough torque to shear a valve stem.

Midland-ACS developed OPD Stemsaver following a request from an engineering, procurement and construction (EPC) company 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.

The company’s OPD Stemsaver design avoids this possibility by providing a dual-redundant pressure regulation facility with one diaphragm regulator, coupled to a spring-tensioned poppet valve.

The use of these two different regulation mechanisms provides additional reliability.

As standard, OPD Stemsaver can be set to regulate pressure in the 4-8 bar (58-116lb/in2) 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 distributed control system (DCS).

OPD Stemsaver is available from Midland-ACS as an individual component.

It is also compatible with the company’s modular pneumatic control manifold – Impact.

This is a universally compatible interface block that mounts directly onto valve actuators and accepts a range of field-proven pneumatic components.

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