Tag: instrumentation
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Fundamentals of Fiber Optics Sensing Technology
Fiber optics sensors basically consist of an optical source that is coupled to an optical transmission line that directs the radiation to a sensor head as illustrated below: The light is then returned after being modified in some way by the sensor interaction, via the optical fiber, in either a reflective or transmission mode, to…
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Wave Analyzers: Function, Types & Applications
The Function of a Wave Analyzer Generally, a periodic waveform can be represented as a sum of a dc component and a series of sinusoidal harmonics. The analysis of a waveform entails the determination of the values of amplitude, frequency and at times the phase angle of the harmonic components. A wave analyzer is an…
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Sheet Thickness Control System: Configuration & Operation
The Structure of Sheet Thickness Control System A typical process control system that may be used to control the thickness of sheet produced by rollers is illustrated in the diagram below: A block diagram of sheet thickness control system describing the above system is shown below: Operation of Sheet Thickness Control System The thickness of…
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Power Measurement in Fiber Optics, How it is Done
Optical Power The basic unit of measurement in fiber optics is the light power. Just like electric power, optic power is measured in watts. For light, the total energy Q is given by: Q = NQp Where Qp is the energy of a single photon and N is the number of photons, therefore: The Power…
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Impeller Flowmeters: Features, Installation Considerations & Uses
Impeller flowmeters at times referred to as paddlewheel meters are one of the frequently utilized flowmeters for industrial flow measurement applications. Impeller flowmeters are cost effective compared to turbine meters and can be used in applications that are challenging to handle with other types of flow metering instruments. They are related to turbine meters in…
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Absolute vs. Secondary Instruments
Measuring instruments may be classified as either absolute instruments or secondary instruments. Absolute Instruments This type of instruments gives the value of the measurand in terms of instrument constant and its deflection; this instrument type doesn’t require comparison with any other standard. For instance, the tangent galvanometer gives the value of the current to be…
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How to Measure Pressure using a U-tube Manometer
There are three categories of pressure measurement, namely absolute pressure, gauge pressure and differential pressure. The absolute pressure is the differences between the pressure at a particular point in a fluid and the absolute zero of pressure, that is, a complete vacuum. When the pressure measuring device measures the difference between the unknown pressure and…
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How to Size a Control Valve
Control valve sizing refers to the procedure determining the correct size of a valve body. A valve sizing equation for incompressible fluids is given by: Which is the same as: Where Cv is the valve flow coefficient/valve capacity P1 = Upstream fluid pressure P2 = Downstream fluid pressure ρ = Mass density of fluid Q…
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Process Control System Design for a Distillation Unit
The aim of a typical control system is to force a given set of process variables to act in some desired and prescribed way by either fulfilling some requirements of the time or frequency domain or achieving the best performances as expressed by an optimization index. The scope of the control tasks varies widely. The…
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Standard Process Signals for Industrial Instrumentation
Industrial measurement and control processes employ standard process signals that are used throughout all the industries. For instance, one of the most popular forms of signal transmission in modern industrial instrumentation systems is the 4-20 mA DC standard. The signal standards employed in industrial instrumentation are unique. Processes are referred to or measured as 0%…