Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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(Will be addressed in future versions of this book)
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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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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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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