Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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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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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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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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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous 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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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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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(Will be addressed in future versions of this book)
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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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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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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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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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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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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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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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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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(Will be addressed in future versions of this book)
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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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