Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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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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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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 advent of “smart” field instruments containing microprocessors has been a great advance for…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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