Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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Abdelaziz, Ahmed (June 2014) Identified numerous typographical errors throughout the book, mostly repeated…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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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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