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Calibration of Flow and Level Sensors

Calibration of Flow and Level Sensors . Presented to: Dr.Ing . Naveed Ramzan Presented by: Muhammad Adnan 07-Chem-72 . Outline. Definition Importance Historical background

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Calibration of Flow and Level Sensors

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  1. 12/15/2010

  2. Calibration of Flow and Level Sensors Presented to: Dr.Ing. NaveedRamzan Presented by: Muhammad Adnan 07-Chem-72  12/15/2010

  3. Outline • Definition • Importance • Historical background • General procedure • Standards used for calibration • Methods of Calibration • References 12/15/2010

  4. Definitions Of Calibration • Calibration of the measuring instrument is the process in which the readings obtained from the instrument are compared with the standard values in the laboratory at several points along the scale of the instrument. 12/15/2010

  5. Importance of Calibration • Instruments are calibrated to avoid wrong readings of highly critical parameters. • Allows for faster processes and of course with lesser errors and mistakes. • Operation under a standardized quality system like that of the ISO 9000. • Method aims to economize time, labor, and other resources in any production by means of accurate verification. 12/15/2010

  6. Importance Of Calibration. • Calibration is also extremely beneficial because it makes the construction of instruments possible that measure with sufficient precision to ensure correction. • Without instrument calibration, you cannot manufacture quality products that will satisfy the clients. 12/15/2010

  7. Historical Background • The term "calibration" probably was first associated with the precise division of linear distance and angles using a dividing engine and the measurement of gravitational mass using a weighing scale. • These two forms of measurement alone and their direct derivatives supported nearly all commerce and technology development from the earliest civilizations until about 1800AD. 12/15/2010

  8. General Procedure • Firstly, the readings obtained from the scale of the instrument are compared with the readings of the sub-standard and the calibration curve is formed from the obtained values. • In this procedure the instrument is fed with some known values (obtained from the sub-standard). • These are detected by the transducer parts of the instrument. The output obtained from the instrument is observed and compared against the original value of the substandard . • A single point calibration is good enough if the system has been proved to be linear, but if it is not, then readings will have to be taken at multiple points. 12/15/2010

  9. Calibration Graph 12/15/2010

  10. Standards For Flow Meter Calibration • Flow rate calibration depends on standards of volume (length) and time or mass and time. • Primary calibration, in general, is based on the establishment of steady flow through the flow meter to be calibrated and subsequent measurement of the volume or mass of the flowing fluid that passes through in an accurately time interval. • When primary calibration methods cannot be justified, comparison with a secondary standard flow meter connected in series with the meter to be calibrated may be sufficiently accurate. 12/15/2010

  11. Methods of flow meter calibration Calibration methods for the liquid flow meters In-situ methods • Insertion point velocity method • Dilution gauging Laboratory calibration method • Master meter method • Volumetric method • Gravimetric method • Pipe prover method 12/15/2010

  12. Flow meter calibration by weighing principle 12/15/2010

  13. Calibration methods for gas flow meters Laboratory calibration method • Soap film burette method • Water displacement method • Gravimetric method 12/15/2010

  14. Water-displacement method of calibration for gas flow meter 12/15/2010

  15. Calibration of level sensors Calibration procedure for Hydrostatic level sensor • In dip pipe applications, gas flows through a pipe that is submerged in the tank's liquid • A differential pressure transmitter measures the back pressure on the tube caused by an increase in the tank level • The high pressure port senses the pressure increase caused by the back pressure in the dip pipe • The low pressure port is vented to atmosphere. • To determine the height or level of a liquid the head pressure is measured and by knowing the specific gravity of the liquid the height can be calculated 12/15/2010

  16. References • S.K Singh;”Industrial Instrumentation and Control” McGraw Hill publishing company limited, New Delhi; page no (139-140) • Doblin, E. O.; “Measurement Systems: Application and Design”, 5th Ed., McGraw Hill, New York, 2003 • Alan S. Morris; “Principles of Measurement and Instrumentation”; second edition page no (70-71) • http://www.brighthub.com/engineering/mechanical/articles/50002.aspx#ixzz0SrRe3FTe (retrieved on 13-Dec-10) • “Flow Meters.” Laboratory handout (retrieved on 13-Dec-10) 12/15/2010

  17. Thank you

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