This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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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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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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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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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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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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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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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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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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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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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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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