The IMGC/CENAM HG6 mercury manometer

The Centro Nacional de Metrología (CENAM, Mexico) has established a national primary standard for barometric pressure based on a mercury column and a laser interferometer, the first in this range in Latin America. The original design of the manobarometer, the HG5, was made at the Istituto di Metrologia 'Gustavo Colonnetti' (CNR-IMGC, Italy) and it served to develop this new version, the IMGC/CENAM-HG6 mercury manobarometer which was constructed and assembled at CENAM. The special features of this new version and its main design characteristics are presented here, together with the differences from its predecessor. To verify its performance, an internal comparison in absolute mode (gas, N2) was carried out with a primary pressure balance, a piston-cylinder assembly with 50 mm diameter having direct traceability to SI base units and measuring range to 2.5 kPa to 175 kPa. The results of the comparison are presented and discussed