Partnering Meeting EURAMET EMPIR Call 2018 - SI Broader Scope

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The Partnering Meeting for the Selected Reserch Topic "Metrology for ultra-trace water measurements in pure gases" will be held at INRIM on July 11th, 2018.

Humidity measurements are needed over a broad range of pressures and temperatures, and at water vapour amount fractions between parts per billion to unity. The manufacturing of ultra-high purity gases (i.e. impurities amount fractions below 10 ppb) where trace water is, in fact, the single largest matrix contaminant, is still lacking harmonised measurement standards.

Therefore proposals in response to this SRT should develop the metrological infrastructure to underpin the traceability of trace water measurements in terms of both the experimental framework and the relevant metrology practices.

Background to the Metrological Challenges


Bulk process gases need to be manufactured with ultra-high purity (UHP) grade (N6.0 or better) with total impurities below ppm amount fraction levels. However, in several applications, such as in the semiconductor industry, there is a demand for total impurities below 10 ppb, selectively below 1 ppb at the point of use.

The demand for UHP bulk gases (N2, H2, Ar, He, CO2) by the semiconductor industry presents great challenges to both the gas manufacturers and analytical instrument makers.

Water vapour is one of the most difficult impurities to eliminate because of its ubiquity and chemical properties.

Sensitive and traceable measurement techniques are required to detect water vapour amount fractions as low as few parts per billion, with an increasing pressure to reduce the detection level below ppb.

Similarly, instrument manufacturers need traceable references to support their product development down to a -100 °C frost point.

Last modified: 07/13/2018 - 12:31