Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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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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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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