An important design parameter of a control valve is the position it will “fail” to if it loses…
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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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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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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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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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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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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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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 very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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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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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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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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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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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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Abdelaziz, Ahmed (June 2014) Identified numerous typographical errors throughout the book, mostly repeated…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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(Will be addressed in future versions of this book)
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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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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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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 limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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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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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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