At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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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 valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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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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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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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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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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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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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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In our first signal characterization example, we tackle the problem of measuring fluid flow through a pipe. To…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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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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Learn about Modbus function codes, the structure of Modbus message packets, and the various types of channels used to transmit Modbus telegrams between controllers.
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