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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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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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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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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 very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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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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There are many process control applications in the industry where it is desirable to have multiple control…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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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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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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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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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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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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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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