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The main mission of the world’s national metrology laboratories is to establish repeatable and comparable measurement standards across the globe. Measuring trace water vapor in gases is of particular interest because many industries, from industrial gas to semiconductor, depend on this critical measurement. In a recently published international comparison between eight leading national laboratories from Europe, Asia and South America, the labs tested their analytical capabilities in measuring ppm-levels of moisture in nitrogen. Different analytical methods were employed, but most labs relied on Tiger’s robust and easy to use Cavity Ring-Down Spectroscopy (CRDS) technology, with the Dutch VSL, the UK’s NPL, Brazil’s INMETRO, the Swiss METAS and China’s NMI all using various generations of Tiger Optics analyzers. This experiment highlights once again the important role that Tiger’s trace moisture analyzers have played for many years in the metrology community and how our instruments help to obtain an exact analysis with ease. As a company dedicated to precision measurement, we are proud to be able to support the world’s leading NMIs in their important mission.

All of the world’s leading metrology labs provide a primary reference for water vapor to be able to calibrate humidity sensors against a well-defined and stable standard. Most of these primary references are designed for moisture concentrations and pressures that are more typical for the lower atmosphere. The national metrology institute of Italy, INRiM, took a new approach to provide a primary reference for moisture concentrations that are lower than typical, as demonstrated in their recent publication in Measurement Science and Technology*. This new low frost-point generator is intended for the calibration of humidity sensors designed for conditions in the upper atmosphere, and covers the frost point range from -100°C to -20°C.

To evaluate their new standard, INRiM researchers relied on a pair of Tiger Optics CRDS trace moisture analyzers, one HALO RP analyzer for lower H2O concentrations and one Spark analyzer for the higher range. Both analyzers showed excellent agreement. All measurements are also consistent with the expected value within the reported measurement uncertainty, providing researchers an easy and reliable initial evaluation of their new generator.

*R. Cuccaro et al., Meas. Sci. Techn. 29, 054002 (2018), https://doi.org/10.1088/1361-6501/aaa785