In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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There are multiple motives for compromising the security of an industrial control system, some of which…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets 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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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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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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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 I began teaching full-time in 1998, most of what I thought I understood about good teaching was actually…
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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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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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Learn about Modbus function codes, the structure of Modbus message packets, and the various types of channels used to transmit Modbus telegrams between controllers.
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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