As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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When I began teaching full-time in 1998, most of what I thought I understood about good teaching was actually…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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When I began teaching full-time in 1998, most of what I thought I understood about good teaching was actually…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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In our first signal characterization example, we tackle the problem of measuring fluid flow through a pipe. To…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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(Will be addressed in future versions of this book)
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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