Measurement of humidity (water vapour) in gases spans more than nine orders of magnitude, addressing diverse scientific and industrial applications. Humidity needs to be known in various matrices, from process gas mixtures to UHP gases where, in fact, water is the single largest matrix contaminant. While mid-to-high range have been investigated and standards do exist, there is still a lack measurement traceability to underpin trace water measurements.
Water vapour is a critical contaminant in vacuum systems and UHP gases. According to the International Technology Roadmap for Devices and Systems (formerly ITRS), water vapour measurement techniques need to measure amount fractions as low as few parts per billion at the point of use. From 2015 to 2020 these requirements have tightened for some gases (nitrogen, argon) by more than 5-fold. This presents great challenges to both gas producers and analytical instrument makers.
In trace water measurement in gases, several effects have a significant impact on the measurement accuracy and need to be thoroughly investigated to underpin measurement traceability of new/improved products, thus facilitating their acceptance by the industry.
- Improved, metrologically-sound, methods and techniques for trace water measurements;
- Development of primary standards for trace water in selected gas matrices;
- Improvement of thermophysical data knowledge of non-ideal humid gas mixtures;
- Demonstration of improved methods for trace water measurement in industrially relevant facilities (test beds).
- Impact on industrial and other user communities: the analysis of water vapour impurity is important in a number of speciality gas applications;
- Impact on the metrology and scientific communities: the project will provide a point of contact for European NMIs bringing strong co-operation for the humidity field and other RMOs to provide channels for global dissemination;
- Impact on relevant standards: the project outputs regarding traceable calibrations available for instruments measuring water vapour in the trace range;
- Longer-term economic, social and environmental impacts: Improved, traceable, trace water measurement techniques in pure gases are likely to affect the global industrial gases market, an important industrial sector, and a very large number of their customers globally.