One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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(Will be addressed in future versions of this book)
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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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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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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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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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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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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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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