To show a practical process example, let’s examine three diagrams for a compressor control system,…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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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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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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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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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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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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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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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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In a manually-controlled process, a human operator directly actuates some form of final control element…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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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 basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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 fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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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