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.
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.
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.
In a Pumps&Systems article, Digitalization to Predict Reliability of Mechanical Valves, Emerson’s Riyaz Ali shares ways continuous monitoring technology can help.
The world of functional safety has its own tribal language and acronyms, e.g. safety instrumented systems (SISs), safety instrumented functions (SIFs), logic solvers, final elements (FEs), safety integrity level (SIL), probability of failure on demand (PFD), etc. In a...
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...
A safety instrumented function (SIF) within a safety instrumented system (SIS) consists of a sensor, logic solver, and final element. As part of the IEC 61511 global safety standard, these elements within the SIF must be tested during the operational phase of the...
Partial stroke test is one of the viable means to check mechanical integrity of Final Element of Safety Instrumented Function (SIF) loop. Generally, end users struggle on question of credit of PST for improvement in SIL (Safety Integrity Level). IEC 61508 and IEC...
Happy New Year everyone! I hope your holidays helped to recharge your batteries and get you off to a great start for 2018. I saw this exchange in my email over the holidays about the effects of using low-bleed relays with Fisher DVC6200 digital valve controllers for...
Some of the most consistently popular posts here on the blog involve compressor anti-surge control. It's a condition in centrifugal and axial compressors where a flow reversal condition can occur. Wikipedia defines centrifugal compressor surge as: …the point at which...
Let's continue our 5 Questions for an Emerson Expert podcast series with our guest, Riyaz Ali. You may recall Riyaz from numerous posts about digital valve controllers and final control elements in safety instrumented system applications. He has almost 40 years'...
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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.