A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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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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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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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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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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 unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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 wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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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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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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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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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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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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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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