A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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 pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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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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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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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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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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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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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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