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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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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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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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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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(Will be addressed in future versions of this book)
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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 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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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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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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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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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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To summarize some of the key points and concepts for teaching: Do not waste class time transmitting facts to…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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This section shows some of the many instrument symbols found in different types of technical diagrams used 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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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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