Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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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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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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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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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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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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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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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 key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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