RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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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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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous 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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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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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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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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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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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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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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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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