This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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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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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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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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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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