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...
With the emphasis on improving energy efficiency and reducing greenhouse gas emissions, process manufacturers have turned to pneumatic low-bleed and zero-bleed valve positioners. Emerson's Riyaz Ali copied me on an email about a recent article that mentioned a...
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'...
For process manufacturers and producers with safety shutdown applications, local control panels are often installed to provide visibility and control actions to operators locally out in the process area. Actions can be taken at these panels to initiate an emergency...
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