Riyaz Ali

Riyaz Ali

Senior Director, Valve Instruments

Riyaz has extensive experience with Digital Valve Controllers with Emerson's Fisher brand of valves. These microprocessor-based DVCs are used for field devices mounted on Final Control Elements for Basic Process Control System and Final Element on Safety Instrumented Systems.

Posts by or with Riyaz Ali

Clarifying Rebuilds to Extend Valve Lifespans

Clarifying Rebuilds to Extend Valve Lifespans

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…

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Control Valves in Safety Instrumented Functions

Control Valves in Safety Instrumented Functions

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.

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Digital Valve Controller Travel Control with Pressure Fallback

Digital Valve Controller Travel Control with Pressure Fallback

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.

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Valve Travel Control-Pressure Fallback

Valve Travel Control-Pressure Fallback

A Digital Valve Controller, the DVC6200 (HART or Foundation Fieldbus) can detect position feedback problems and automatically revert to I/P [current to pressure] transducer mode to keep the valve operational. This avoids costly unplanned spurious trips, which are critical for plant operational performance.

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Extending Final Element Proof Testing Intervals

Extending Final Element Proof Testing Intervals

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).

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End of Life Expectancy for Final Control Elements in Safety and Control Systems

End of Life Expectancy for Final Control Elements in Safety and Control Systems

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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Approaches to Partial Stroke Testing Safety Valves

Approaches to Partial Stroke Testing Safety Valves

The safety valve within a safety instrumented function (SIF) must be tested regularly to help assure proper operation in the event of a safety demand. Operators usually perform an offline full stroke test during a scheduled shutdown because of the impact of this test...

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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.