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PRESSURE

PRESSURE. WMO TRAINING WORKSHOP ON METROLOGY FOR SOUTHWEST PACIFIC RA V ENGLISH SPEAKING COUNTRIES Melbourne, Australia, 21-25 November 2011. Plan of the discussion. I – CONCEPTS TERMS DEFINITION. II – PHYSICAL PRINCIPLE . III – DERIVED SYSTEM. IV – NMHSs and Pressure Measurement .

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PRESSURE

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  1. PRESSURE • WMO TRAINING WORKSHOP ON METROLOGY FOR SOUTHWEST PACIFIC RA V ENGLISH SPEAKING COUNTRIES • Melbourne, Australia, 21-25 November 2011

  2. Plan of the discussion I – CONCEPTS TERMS DEFINITION II – PHYSICAL PRINCIPLE III – DERIVED SYSTEM IV – NMHSs and Pressure Measurement V – BIBLIOGRAPHY VI – CONCLUSION

  3. Definitions • Atmosphere’s state parameter • Altimeter calibration for aviation • Input for numerical weather forecast model

  4. Definitions • Pressure is generally the result of molecules impacting on their surroundings

  5. HISTORY • 1648 : The french prodige Blaise Pascal (1623-1662) made a lot of experiments with some similar barometers at divers locations (Paris; Clermont-Ferrand). • 1644 : The Italian physician Evangelista Torricelli (1608-1647) built the first siphoon barometer Pascal (1623-1662)

  6. UNITS

  7. Range

  8. Measurement techniques

  9. Physical Principle Liquid column instruments

  10. Physical Principle Pressure balance and deight weight testers

  11. Derived System Mechanical deformation instruments

  12. Diaphragm

  13. Diaphragm Silicium diaphragm

  14. Capsule

  15. Capsule

  16. Bellows

  17. Bellows

  18. Bourdon Tube

  19. Bourdon Tube

  20. Mechanical deformation sensing • Mechanic display • Capacitive technics • Vibrating structures • Piezo-electric devices

  21. Mechanical deformation sensing • Mechanic display

  22. Mechanical deformation sensing • Capacitive technics

  23. Mechanical deformation sensing • Vibrating structures

  24. Mechanical deformation sensing • Piezo-electric devices

  25. CALIBRATION • operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication

  26. A national and primary standard Secondary Secondary Working Reference Reference Working Working Transfer Secondary Working General instrumentation (station barometer) NMHS & Pressure Measurement

  27. NMHS & Pressure Measurement • A suitable environment • An appropriate standard • A set of pressure connection • A method of generating and regulating the pressure • A system of recording measurements • A method for calculating results • A procedure • Trained staff

  28. NMHS & Pressure Measurement Calibration generator, principle NITROGEN BOTTLE CHAMBER Pump Pump OUT IN

  29. Met Office & Pressure Measurement Calibration generator Barometer without socket

  30. NMHS & Pressure Measurement Calibration generator Barometer with socket

  31. BIBLIOGRAPHY • Guide to the Measurement of Pressure and VacuumThe Institut of Measurement and Control87 Gower StreetLondon • WMO GUIDE TO METEOROLOGICAL INSTRUMENTS AND METHODS OF OBSERVATION WMO-No. 8 (Seventh edition) • Calibration Book Vaisalahttp://www.vaisala.com/en/services/technicalsupport/calibrationbook/Pages/default.aspx

  32. Conclusion • Pressure is the most important parameter in Meteorology and Aviation • Calibration is needed • For most contries, it is a turning point: mercury and electronic devices are present

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