As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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(Will be addressed in future versions of this book)
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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(Will be addressed in future versions of this book)
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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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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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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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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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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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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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