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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging 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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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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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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 transformer is one of the most important components in all of AC circuitry. Principally used to…
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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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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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 Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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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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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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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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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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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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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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 following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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