Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Abdelaziz, Ahmed (June 2014) Identified numerous typographical errors throughout the book, mostly repeated…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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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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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 power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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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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An important design parameter of a control valve is the position it will “fail” to if it loses…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on 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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of 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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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The efficient identification and correction of instrument calibration errors is an important function for…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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In a manually-controlled process, a human operator directly actuates some form of final control element…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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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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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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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 bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into 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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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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