Plants tend to run longer in between turnarounds, or the period of time in which a plant is shut down for maintenance. These turnaround time intervals can be three, four, five, or even longer depending on the process and the industry. Emerson's Riyaz Ali, whom you may...
Riyaz Ali
Testing the Safety Valve in a Safety Instrumented Function
Safety instrumented functions (SIFs), also known as safety loops, are comprised of a sensor to sense the process condition, a logic solver to decide the safety action to take, and a final element to perform the action. Emerson's Riyaz Ali and I & C Specialist's C...
Failure Modes of Positioners in Safety Applications
A few weeks ago, I highlighted a thread from the ISA Safety email list on partial stroke testing using control valve positioners. A few weeks later, this thread is still going strong. Emerson's Riyaz Ali sent me some of the recent exchanges. A concern was expressed...
Addressing Safety Valve Opening Times with Partial Stroke Tests
A question came into the ISA's Safety email list concerning the use of valve positioners in partial stroke tests for valves used in safety shutdown applications. The person asking the question wrote: I was informed that PST using positioner such as the Fisher/Emerson...
Diagnosing Valve Performance Issues
My good friend Riyaz Ali, whom you may recall from earlier process safety and digital valve controller-related posts, was kind enough to send me an article he's recently written. The subject is performance diagnostics for control valves. Since control valves are in...
Final Control Element Partial Stroke Testing
Emerson's Riyaz Ali, whom you may recall from earlier posts, wrote an Inside Functional Safety article recently titled, Digital Technology: A remedy for sick shutdown valves in Safety Instrumented System (SIS) applications. The paper is available for purchase from...
Positioners and Partial Stroke Tests in Safety Applications
InTech magazine has a web exclusive on the importance of safety valves in a safety instrumented system. The article, Valve failure: Not an Option, describes methods of implementing partial stroke testing (PST) to reduce the probability of failure upon demand, average...
Solutions for SIS and Foundation Fieldbus
I'm lucky enough to receive a copy of Andrew Bond's Industrial Automation Insider newsletter each month through an Emerson subscription agreement. Andrew covers the happenings among the automation suppliers and standards bodies. You can also find some of Andrew's...
Questions about DVC 6000 SIS and Solenoids
I received an email last week with some questions to an earlier post, Checking Your Safety Solenoid Valves. While protecting the emailer's anonymity, I thought I'd share the questions and answers provided by Emerson's Riyaz Ali with you. The first question was about...
Safety Shutdown Valves with Quick Exhaust and Partial Stroke Testing
I received an email with a great question to an earlier post, Improving Local Control around Safety Shutdown Valves. The question was:Can you provide more information on your Local Control panel with Safety Shutdown Valve that haves a quick exhaust systems; can the...
Digital Valve Controllers in Safety Applications Get Smarter
In the world of process safety, technology continues to advance to assist process manufacturers in their IEC 61511 safety compliance efforts. I saw a recent press release on enhancements to the Fisher DVC6000 digital valve controller. The news was:...enhancements...
Vessel Level Control Can Reduce Process Variability
Like capacitors do for electrical circuits, vessel levels provide capacity that can absorb variability within the process. In many cases, a properly tuned level controller can make the variability of the vessel outflow can be much less than the variability vessel...
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