Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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 chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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(Will be addressed in future versions of this book)
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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