Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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 exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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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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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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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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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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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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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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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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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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