Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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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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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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 sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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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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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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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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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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