A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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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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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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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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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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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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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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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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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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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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