Generally, depending upon the design of internal components of smart devices and their response to control change from the controller input signal, pneumatic parts like I/P (current-to-pressure transducer) and pneumatic relays are tailored to optimize control performance.
Emerson’s Riyaz Ali presented Digital Valve Controller Used with Final Control Elements Inching Towards Net Zero Emission at the 2024 Emerson Exchange conference in Düsseldorf, Germany. Here is his presentation abstract: Energy consumption is a big part of process...
I’ve often written about how digital valve controllers improve control valve performance and ongoing maintenance. But how about on-off valves? In this Valve World Americas featured story, How Digitized On-Off Valves Improve Operations, Emerson’s Riyaz Ali explains how...
For air-operated control valves, the pneumatic power at a constant supply pressure is proportional to the mass flow rate of instrument air. The pneumatic/eletro-pneumatic/microprocessor-based digital valve controller is used on most control valves operated in closed-loop control, where the input signal is continuously changing.
Riyaz Ali discussed with a major international oil company ways to eliminate supply line relief valves or needs for higher pressure-rated actuators should the air filter regulator (AFR) fail.
I received a question from an earlier post, End of Life Expectancy for Final Control Elements in Safety and Control Systems, by Emerson’s Riyaz Ali. The instrument & control engineer who came upon the blog post wrote…
When is it possible to use control valves like final elements for SIS [safety instrumented system] application? I am looking for other useful documents and technical requirements when it is possible to use only control valves as the final element instead of on/off valves and not in combination with it in the SIF [safety instrumented function] application.
The DVC6200 HW2 digital valve controller provides a unique feature to detect position feedback issues and automatically revert from travel control to pressure control (I/P transducer mode) to keep the valve operational. This can help avoid costly unplanned spurious trips that can affect plant operation.
Riyaz Ali provides clarity on when to assign the SIL suitability for valves used in different scenarios (process control vs. safety shutdown) and establish criteria to assign SIL applicability for the “Final Element”.
In a post, Valve Travel Control-Pressure Fallback, Emerson’s Riyaz Ali shared the process of how a control valve with a digital valve controller could fall back to standard pressure control upon an issue with the travel sensing mechanism.
I received a question from a very old post here on the blog, Credit for Partial Stroke Tests in Verification Process. The person was trying to get a better understanding about this chart showing how partial stroke tests (PSTs) can extend the intervals between full stroke tests for final elements in a safety instrumented function (SIF).
To summarize, mechanical equipment such as shutdown valves, control valves, actuators, and accessories such as positioners are designed keeping in mind a plant’s life of around 25 years. Though you may not find any written or stated document from any supplier or manufacturers since mechanical deterioration depends on many parameters like internal process-related conditions or external environmental conditions, operating media (air, hydraulic fluid, etc.), proper care exercised during application selection & sizing, and more.
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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.