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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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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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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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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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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 modern industry, the most popular form of field-level signal transmission for variable industrial…
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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 a manually-controlled process, a human operator directly actuates some form of final control element…
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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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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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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 transformer is one of the most important components in all of AC circuitry. Principally used to…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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(Will be addressed in future versions of this book)
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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