A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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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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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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The efficient identification and correction of instrument calibration errors is an important function for…
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A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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(Will be addressed in future versions of this book)
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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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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