The national temperature standard ETN 02-12 in the context of the SI redefinition

Abstract

This paper analyzes the impact of the 2019 redefinition of the International System of Units (SI) on the national temperature standard ETN 02-12 realized at the National Institute of Metrology of the Republic of Moldova. After outlining the historical role of the International Temperature Scale of 1990 (ITS-90) and the shift to a constant-based definition of the kelvin via the Boltzmann constant, we discuss the consequences for the practical realization, traceability, and measurement uncertainty of ETN 02-12. We show that, although the formal definition has changed, the operational procedures of ETN 02-12 in the range -40 °C to 961 °C remain largely unaffected; the additional uncertainty propagated from the fixed value of the Boltzmann constant to the triple point of water is negligible in practice. In the longer term, the constant-based SI enables advances in primary thermometry and supports future quantum-based realizations.