A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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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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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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In modern industry, the most popular form of field-level signal transmission for variable industrial…
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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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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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 some process applications, it is important that the control valve be able to completely stop fluid flow…
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(Will be addressed in future versions of this book)
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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 laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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