SIAD SIT Centre 143 based in Italy, is the first and only SIT centre accredited Calibration Centre for the analytical calibration of gaseous mixtures.

SIAD Research centre 143, first received accreditation as a Calibration centre in December 2001, for gas mixture preparation by gravimetric method. Such certified mixtures are gas reference materials and traceability of the result of their preparation is directly linked to national mass standard and, for comparison, to national and international reference gas mixtures.

The centre, with a view of continuous improvement and market demand, decided to widen their range of their products. In May 2004, SIT approved the extension of the Accreditation for the Centre, for assessing technical competence to carry out calibrations in all the fields where a metrological traceability to national and international gas standards.

The Accreditation Table of the Centre Sit no. 143 – SIAD includes:
. Gas mixtures used in the analysis of air pollutants, which are mixtures with ppb of benzene (C6H6) and nitrogen oxide (NO);
. Gas mixtures with low concentrations of methane (CH4), propane (C3H8), carbon monoxide (CO);
. Gas mixtures used to analyze the emissions of the fireplaces, which are mixtures with sulphur dioxide (SO2) and nitrogen dioxide (NO2);
. Gas mixtures for the analyses in operating theatres, which are mixtures with nitrous oxide (N2O).

Since February 2005, SIAD SIT no. 143 is not only a calibration centre for gravimetrical preparation, but also for the analytical calibration of gaseous mixtures.