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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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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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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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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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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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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 purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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 variety of problem-solving techniques have been presented for students over the years which are all helpful…
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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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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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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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