An important design parameter of a control valve is the position it will “fail” to if it loses…
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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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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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 machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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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 disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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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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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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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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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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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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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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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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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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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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There are multiple motives for compromising the security of an industrial control system, some of which…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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