An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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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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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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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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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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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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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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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 completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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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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In a manually-controlled process, a human operator directly actuates some form of final control element…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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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 damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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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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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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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 fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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