Avoiding Unplanned Downtime with Smart Pneumatic and Hydraulic Valve Monitoring

A Forbes article, Unplanned Downtime Costs More Than You Think, cites this statistic:

An overwhelming 82% of companies have experienced at least one unplanned downtime incident over the past three years. Most have suffered two or more.

In an Industrialvalves.de article, Outperforming traditional Valve design meets smart monitoring system for pneumatic and hydraulic valve actuators, Emerson’s Knut Riegel shares ways to avoid unplanned downtime caused by valves equipped with fluid-powered actuators.

Knut opens the article by highlighting the use of these valves in safety instrumented system (SIS) applications. He describes the concept of a safety integrity level (SIL) and how this analysis is done in accordance with the IEC 61511 and IEC 61508 global safety standards.

IMVS-mounted scotch-yoke actuatorElectric valve actuators can be effectively used in SIS applications.

Electric valve actuators offer many advantages—such as enabling preventive maintenance, partial stroke tests, timestamped event logs, and communications via standard protocols— and have been successfully implemented in a range of applications and industries. Thus, many greenfield projects are equipped directly with electrics, such as Emerson’s Bettis XTE3000, rather than conventional air-powered actuators with a control unit.

Knut explains how electric valve actuators are incorporated.

Pneumatic low-pressure actuators and especially hydraulic high-pressure solutions are often used as emergency shutdown (ESD) devices designed to stop the flow of a hazardous fluid upon detecting a dangerous event. These devices are usually used to control the functions of a control unit using additional smart valve positioners and analog limit switch boxes, with a smart electric valve actuator added to gain benefits from it.

Testing the performance of valves used in safety instrumented functions must be done periodically.

ESD [emergency shutdown] functionality is usually only tested during planned maintenance events (STOs) by a full stroking test (FST), in which the valve is completely opened or closed. This is because the system cannot be tested during operation, as it would disrupt the process and prevent the maximum production capacity from being reached. The ESD mode typically switches the solenoid valve off from the power source, and the valve moves into its emergency position. However, this would mean a disruption of the process.

Testing intervals to perform full stroke tests can be extended by performing partial stroke testing (PST). Knut described Emerson’s Smart Integrated Monitoring of Valve Systems (IMVS), the Biffi IMVS2, for fluid-powered (pneumatic and hydraulic) valve actuators as:

…an intelligent partial lifting device particularly suitable for preventive diagnostics in valve solutions that use compressed air or mineral oil as a working medium.

He details how the IMVS works.

The sensor-integrated, electromechanical IMVS is operated on single (spring close/open) or double-acting pneumatics, as well as hydraulic actuators, mounted analogously to a limit switch box, and controlled by a separate single or redundant solenoid valve. Diagnostics, operational insights, and safety functions are thus guaranteed. The SOVs (solenoid valves) used are explicitly tested for each partial stroke test, as they are switched voltage-free at the same time at the start of the test. Still, it is also possible to test the functionality of each SOV separately without a partial stroke test.

During the partial or full stroke test, the integrated IMVS controls the SOV, which is used to control the actuator as a combination of valve and actuator. This ensures that the actual dynamics of the automated valve package are detected, and that the solenoid valve is fundamentally checked in parallel. The partial stroke describes a movement at an angle of 10 to 15 degrees (with a 90°-fitting) to avoid possible effects on the process. The Partial Stroke Test (PST) angle is settable in the intuitive device menu.

Read the article for more on how this IMVS solution is fitted onto premium process valves, such as a Vanessa Series 30,000 triple-offset valve, to help you avoid unplanned downtime through predictive analysis.

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