A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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 final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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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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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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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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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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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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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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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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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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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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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 pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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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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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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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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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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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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The key to understanding how three-phase electric motors work is to have an accurate mental picture of 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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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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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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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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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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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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