A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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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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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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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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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Abdelaziz, Ahmed (June 2014) Identified numerous typographical errors throughout the book, mostly repeated…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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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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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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An important design parameter of a control valve is the position it will “fail” to if it loses…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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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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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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The final element of PID control is the “D” term, which stands for derivative. This is a calculus…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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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 sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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