RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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The efficient identification and correction of instrument calibration errors is an important function for…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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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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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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An important design parameter of a control valve is the position it will “fail” to if it loses…
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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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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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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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 machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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