Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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(Will be addressed in future versions of this book)
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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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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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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There are many process control applications in the industry where it is desirable to have multiple control…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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A machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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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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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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 next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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