Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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 Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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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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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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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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A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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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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A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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An important design parameter of a control valve is the position it will “fail” to if it loses…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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