To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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 simple control system drawn in block diagram form looks like this: Information from the measuring device…
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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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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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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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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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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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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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The final element of PID control is the “D” term, which stands for derivative. This is a calculus…
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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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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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(Will be addressed in future versions of this book)
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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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 vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for 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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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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There are multiple motives for compromising the security of an industrial control system, some of which…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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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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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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