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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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 transformer is one of the most important components in all of AC circuitry. Principally used to…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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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 following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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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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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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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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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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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