In some process applications, it is important that the control valve be able to completely stop fluid flow…
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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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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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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 positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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(Will be addressed in future versions of this book)
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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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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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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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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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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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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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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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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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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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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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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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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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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