A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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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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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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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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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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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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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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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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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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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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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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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 great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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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 addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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