An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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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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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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 important rule to obey when using pneumatic instruments is to maintain clean and dry…
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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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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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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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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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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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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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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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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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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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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 design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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