Basics of pH Measurement in Industrial Control

Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…

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Pilot Valves and Pneumatic Amplifying Relays

Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…

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Displacement and Displacer Level Instrumentation

Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…

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Tuning PID Controllers

Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…

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Concepts and Laws of Probability

While the term “probability” may evoke images of imprecision, probability is in fact an exact…

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Analog Electronic PID Controllers

Although analog electronic process controllers are considered a newer technology than pneumatic process…

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Process Flow Diagrams

To show a practical process example, let’s examine three diagrams for a compressor control system,…

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Electrical Resistance and Ohm’s Law

To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…

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Valve Positioners

The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…

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Dampers and Louvres

A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…

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On/off Control (Bang-bang Control)

Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…

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Force-balance Pressure Transmitters

An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…

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Basics of Electrical Current

Current is the name we give to the motion of electric charges from a point of high potential to a point of low…

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Metric Prefixes and Prefix Scale

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Motives for Compromising the Security of an Industrial Control System

There are multiple motives for compromising the security of an industrial control system, some of which…

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Loop Diagrams (Loop Sheets)

Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…

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Design-based Fortifications

A design-based fortification is one rooted in technical details of system architecture and functionality. Some…

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Pipe and Pipe Fittings

Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…

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Proportional-only Offset

A fundamental limitation of proportional control has to do with its response to changes in setpoint and…

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National Institute of Standards and Technology (NIST) Traceability

As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…

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