A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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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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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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 hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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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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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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