Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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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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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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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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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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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 term “grid” refers to the conductors and equipment interconnecting power sources to power…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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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 Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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