Process control instruments | Data Logger | Level Indicators | Water Flow Meter | Digital Process In
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Posted On :
Sep-26-2011
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Article Word Count :
651
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Sensors to measure process conditions and valves to influence process operations are essential for all aspects of engineering practice. Engineers want to design and operate processes that remain in safe conditions, produce the desired amounts of high quality products and are profitable.
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Sensors to measure process conditions and valves to influence process operations are essential for all aspects of engineering practice. Engineers want to design and operate processes that remain in safe conditions, produce the desired amounts of high quality products and are profitable. Therefore, engineers must provide measuring devices for key variables and valves (or other devices, such as variable speed electric motors) to influence of “steer” the process. This site provides educational material on sensors and valves for use in the process industries.
While sensors and valves are important in all aspects of engineering, they assume greatest importance in the study of automatic control, which is termed process control when applied in the process industries. Process control Instruments deals with the regulation of processes by applying the feedback principle using various computing devices, principally digital computation. Process control requires sensors for measuring variables and valves for implementing decisions. Therefore, the presentation of this material is designed to complement other learning topics in process control.
Since successful process control requires appropriate instrumentation, engineers should understand the principles of common instruments introduced in this section. The descriptions in this section cover the basic principles and information on the performance for standard, commercially available instruments. Thus, selection and sizing of standard equipment is emphasized, not designing equipment “from scratch”.
Perhaps the best advice for engineering students is that “instruments are always incorrect”. This surprising statement is not intended to undermine reasonable confidence in applications of sensors and valves. However, new engineers sometimes tend to accept instruments as exactly correct without evaluating the likely errors associated with their use. Depending on the instrument, the process operating conditions and the application, the instrument errors can be small enough to be insignificant or can be large enough to seriously degrade control performance. The engineer must evaluate each application during the process design and select an appropriate instrument.
Temperature Measurement
Temperature control is important for separation and reaction processes, and temperature must be maintained within limits to ensure safe and reliable operation of process equipment. Temperature can be measured by many methods; several of the more common are described in this subsection. You should understand the strengths and limitations of each sensor, so that you can select the best sensor for each application.
In nearly all cases, the temperature sensor is protected from the process materials to prevent interference with proper sensing and to eliminate damage to the sensor. Thus, some physically strong, chemically resistant barrier exists between the process and sensor; often, this barrier is termed a sheath or thermowell, especially for thermocouple sensors. An additional advantage of such a barrier is the ability to remove, replace, and calibrate the sensor without disrupting the process operation.
Flow Measurement
Flow measurement is critical to determine the amount of material purchased and sold, and in these applications, very accurate flow measurement is required. In addition, flows throughout the process should the regulated near their desired values with small variability; in these applications, good reproducibility is usually sufficient. Flowing systems require energy, typically provided by pumps and compressors, to produce a pressure difference as the driving force, and flow sensors should introduce a small flow resistance, increasing the process energy consumption as little as possible. Most flow sensors require straight sections of piping before and after the sensor; this requirement places restrictions on acceptable process designs, which can be partially compensated by straightening vanes placed in the piping. The sensors discussed in this subsection are for clean fluids flowing in a pipe; special considerations are required for concentrated slurries, flow in an open conduit, and other process situations.
Types of Process Control Instruments
• Digit Process Indicator
• Data Logger
• Water Flow Meter And Totalisers
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Article Source :
http://www.articleseen.com/Article_Process control instruments | Data Logger | Level Indicators | Water Flow Meter | Digital Process In_85841.aspx
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Author Resource :
Process Control Instruments is a the right instrumentation can sharpen your competitive edge by measuring and controlling. Various Measuring Instruments like Calibrator, Calibration, Temperature Calibrator, Data logger, Level Indicator, Water Flow Meter, PH Indicator and Dry Block Calibrator.
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Keywords :
Process control instruments Manufacturers, Level Indicators, Water Flow Meter and Digital Process Indicator in India.,
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Business
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Customer Service
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