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Posts Tagged ‘digital valve controller’

Avoid Operational Issues with Proper Control Valve Selection

Posted in Final Control Element on Wednesday, April 10th, 2019. No comments yet
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Because they directly touch the process flow, control valves play a significant role in the stability, robustness and variability in the process. One bad-acting control valve can create large problems for safe and reliable operations. At last week’s AIChE Spring Meeting, Emerson’s James Beall presented Specifying Control Valve Performance to Achieve Desired Process Performance. In […]

Simplifying Safety Valve Proof Testing

Posted in Safety on Wednesday, December 19th, 2018. No comments yet
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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 safety lifecycle. Of the 3 elements, the final control element, typically a […]

Partial Stroke Test for Final Elements—Diagnostic Coverage Factors

Posted in Final Control Element, Safety on Thursday, December 13th, 2018. No comments yet
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Author: Riyaz Ali 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 61511 define diagnostic coverage factors (DCF), but do not […]

Low-Bleed or Standard Relays for Control Valves?

Posted in Controllers & Positioners, Final Control Element on Tuesday, January 2nd, 2018. No comments yet
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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 control applications as compared to standard relays. This […]

5 Questions for Digital Valve Controller and Safety Expert Riyaz Ali

Posted in Controllers & Positioners, Safety on Wednesday, May 3rd, 2017. No comments yet
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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’ experience in process control instrumentation and holds numerous patents related to use of digital […]