A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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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 previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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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In a manually-controlled process, a human operator directly actuates some form of final control element…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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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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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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