Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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 efficient identification and correction of instrument calibration errors is an important function for…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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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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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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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 unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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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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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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