An important performance parameter for transmitter instruments is something often referred to as turndown or…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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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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There are multiple motives for compromising the security of an industrial control system, some of which…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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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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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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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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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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 key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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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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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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