How to Get the Best Performance from Your Control System

Make sure your control system achieves the potential possible with today's instrumentation.

Greg McMillan and Stan Weiner
CG1503 ControlTalk

Practical Installation Best Practices Stan: We continue our conversation started last month with Tim Green, operations manager, field services at Maverick Technologies, on how to make sure a control system will meet the performance capability possible with today's instrumentation. Greg: What guidance can you offer based on your field experience and that of your key field people? Tim: There are many considerations, but here are the foremost installation best practices. The list is a collaborative effort that involved the Maverick construction managers and commissioning managers: Install steam and liquid transmitters below the process tap, and air and gas transmitters…

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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.

Control Talk Blog

Most Recent

  • Reader Feedback: Three Reasons Big Data Is a Big Deal

    By Bernie Anger

    I read with interest your control report on page 78 of the January issue, and I’d like to offer a couple of add-on points. While it is true that big data is just data, the “big deal, which I’d translate into improved profitability for customers comes when you aggregate and analyze all those…

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  • Online Resources: Loop Control Systems

    This System Is Closed This is a basic tutorial on closed-loop control systems. It covers the basic definitions and descriptions of how closed-loop systems work, a discussion of closed-loop summing points and how to use them, transfer functions, multi-loop closed-loop systems and closed-loop motor…

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  • ISA Takes on Asset Management

    By Ian Verhappen

    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…

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

    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…

    Full Story
  • Béla Lipták Looks Back at a Half-Century of Process Automation

    By Bela Liptak

    When I started to work as a process control engineer in the late 1950s, the toilet float and the thermostat were considered to be automation. At that time, the main job of the instrument department in a plant was to clean plugged pressure taps and stuck control valves, while our control panels were…

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  • Can Improved Physical Layer Diagnostics Save Christmas Dinner?

    By John Rezabek

    Physical Layer Diagnostic Improvements Why is it, after weeks of seemingly trouble-free plant operation, the phone rings on the holiday weekend when the goose is in the oven and the table is set for dinner? Fortunately for me, the crew on shift was prepared to muddle through until normal business…

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