Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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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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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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In our first signal characterization example, we tackle the problem of measuring fluid flow through a pipe. To…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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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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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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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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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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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 two “process variables” we rely on most heavily in the field of electrical measurement and…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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Lipták, Béla G. et al., Instrument Engineers’ Handbook – Process Measurement and Analysis Volume I,…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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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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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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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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There are many process control applications in the industry where it is desirable to have multiple control…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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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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