When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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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 fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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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 power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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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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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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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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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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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 electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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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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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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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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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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