ISA Takes on Asset Management

ISA108 Intelligent Device Management committee finishes first document, "Concepts and Terminology"

Ian Verhappen
CG1503 ISA

ISA Takes on Asset Management Asset management continues to be a critical but underused capability of modern control systems. Last year at this time, we talked about the different types of information available from modern microprocessor-based sensors. At that time I also mentioned the work being done by the ISA108 Intelligent Device Management committee. This committee is now close to completing its first document, ISA-dTR108.1-2015 "Part 1: Concepts and Terminology." The purpose of ISA108 is to define standard templates of best practices and work processes for the implementation and use of diagnostic and other information provided by intelligent field devices in the…

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Timeless Resources

Beginner's Guide to Differential Pressure Level Transmitters

By David W. Spitzer

The importance of level measurement cannot be overstated. Incorrect or inappropriate measurements can cause  levels in vessels to be excessively higher or lower than their measured values. Low levels can cause pumping problems and damage the pump, while high levels can cause vessels to overflow and potentially create safety and environmental problems. Vessels operating at incorrect intermediate levels can result in poor operating conditions and affect the accounting of material. Learn more.

Controllers: Direct vs. Reverse-Acting Control

By Bela Liptak

Valve failure position is determined by safety considerations. If, in case of failure, you want your column to go on full reflux, your selection where the reflux control valve is fail-open, and net overhead control valve is fail-close, is right. Assuming that the valve actuators are spring-operated pneumatic ones, and assuming that you define "failure" as the loss of air supply, the spring will act to open a fail-open (FO) valve and to close a fail-closed (FC) valve, regardless what the controller actions are. Read more.

Voices: Ask The Experts

Linear or Equal Percentage Valves: When Should I Use Which?

Since the goal is to control loop stability, the choice that gives you the best chance of that is the one to make.

By Bela Liptak

Question: Is there some general rule on when we should use =% (equal percentage) and when linear control valves? I know that the determining factor is the inherent flow characteristic, the flow vs. lift at constant pressure drop, or something like that. I do not know what this means, because…

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Control Talk Blog

Secondary Flow Loop and Valve Positioner Tips

A lot of time and money can be spent deciding which valves need positioners and which flows need measurement. We tend to look at short term costs such as hardware and not the cost of troubleshooting and the implications as to plant performance.

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