Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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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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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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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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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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 hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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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 efficient identification and correction of instrument calibration errors is an important function for…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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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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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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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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