A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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A machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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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 November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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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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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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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 control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common…
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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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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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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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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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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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