A FIRST REVIEW OFCALIBRATION DEVICES ACCEPTABLE

FOR METROLOGY LABORATORY

Mr Drago GROSELJ Dr Jérôme DUVERNOY

Dr John GORMAN

www.arso.sigov.si www.meteo.fr

www.bom.gov.au

Drago.Groselj@gov.si Jerome.Duvernoy@meteo.fr

j.gorman@bom.gov.au

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Specialization

PRESSURE

TEMPERATURE

HUMIDITY

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PRESSURE

Primary Pressure Standard

M = Mass

P = Piston

C = Cylindre

Weight = Pressure

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PRESSURE

Primary Pressure Standards

Dead weight gauge

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PRESSURE

Advantages:

– Traceability to mass and length

– Long term stability

– Accuracy, reproducibility, reliability and stability

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PRESSURE

Disadvantages:

– Time consuming

– Measurements corrections (T, g, U…)

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PRESSURE

Secondary Pressure Standard

Quartz Barometer

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PRESSURE

Advantages:

– Faster and easier to use

– Easy to adapt to automatic operation

– Generally less expensive

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PRESSURE

Disadvantages:

– Not a basic measurement

– Higher measurement uncertainty

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PRESSURE

Travelling pressure standard

An example of electronic barometer

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PRESSURE

Calibration systems

example of a barometric chamber

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PRESSURE

Calibration systems

example of a pressure generator

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TEMPERATURE

EIT 90

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METEOROLOGY

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TEMPERATURE

EIT 90

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Gallium

Mercury

Water

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TEMPERATURE

Standard Platinum Resistance Thermometer (SPRT)

Example of an SPRT

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TEMPERATURE

Means of calibration

Stirring bath

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TEMPERATURE

Means of calibration

Climatic chamber

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HUMIDITY

Humidity Generators

Two Pressure Humidity Generator

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HUMIDITY

Humidity Generators

Split stream system

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HUMIDITY

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Climatic Chambers

Environmental Chamber

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HUMIDITY

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Climatic Chambers

Split stream chamber

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HUMIDITY

Salt Solutions Generator

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Salt/Temperature oC 5.0 10.0 15.0 20.0 25.0

Lithium chloride 11.3 11.3 11.3 11.3 11.3

Magnesium chloride 33.6 33.5 33.3 33.1 32.8

Potassium carbonate 43.1 43.1 43.1 43.2 43.2

Sodium bromide 63.5 62.2 60.7 59.1 57.6

Sodium chloride 75.7 75.7 75.6 75.7 75.3

Potassium chloride 87.7 86.8 85.9 85.1 84.3

Potassium sulphate 98.5 98.2 97.9 97.6 97.3

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HUMIDITY

Salt Solutions Generator

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The salt solution system at Meteo France

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HUMIDITY

Approximate Uncertainties

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HUMIDITY

Recommendations– The target uncertainty within a calibration laboratory = 2 % RH (0.3 oC dew point)

– Labs should have a humidity generator or chamber:

within the range 5 % RH at 15 oC to 90 % at 40 oC.

– The streams or parcels should be stable to within ± 0.2% RH per minute

– If the source of humidity is not a first principles device, then measurement of the humidity should be with a dew point hygrometer with an 95 % uncertainty of 0.2oC or better

– Calibration of field humidity probes should be done with a view to maintaining a low overall uncertainty. The whole of measurement cycle, including inspection frequency, must be considered and appropriate levels of calibration uncertainty applied

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CONCLUSION

Some possibilities in terms of calibration. This first review is not exhaustive Every other remaining devices, standard, generator not presented

here are still acceptable Metrology is the science of measurement Expression of the uncertainty

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THE END

THANKS FOR YOUR PATIENCE