Realisation and preliminary validation of a dilution device for the generation of CO2 gas mixtures

The present paper describes the activity carried out at Istituto Nazionale di Ricerca Metrologica (INRIM) within the EMPIR Joint Research Project 16ENV06 “Metrology for Stable Isotope Reference Standards - SIRS”, for the realisation of a dilution device for generating dynamic mixtures of CO2 at ambient mole fractions. The aim of the activity was to realise a system able to generate mixtures with isotopic composition and target uncertainties as the static gravimetric reference materials realised in the SIRS project. These dynamic reference materials can be used to validate the static reference materials and for stability and fractionation studies. The dilution system was realised and a preliminary validation was carried out, focusing on the performances of the mixing chamber, which represents the core of the system. The system was tested in terms of amount fraction, by using a Non-Dispersive Infrared analyser.