A primary facility for the dynamic preparation of nitrogen dioxide gas standards has been established at the BIPM. The BIPM NO2 facility is used to dynamically generate gravimetric mixtures of NO2/air or nitrogen in the range (1 to 15) µmol/mol, and for the coordination of CCQM-K74, an international comparison of NO2 in nitrogen standards.
The facility is based on the constant permeation of NO2 through a fluoropolymer membrane (permeation tube). The mass of the permeation tube is constantly monitored by a magnetic suspension balance. A multiple gas cylinder sampling module has been constructed with a capacity of up to 15 cylinders. This system will allow the comparison of NO2/air mixtures in high-pressure cylinders with primary mixtures generated dynamically.
The BIPM facility is the basis of the reference value for CCQM-K74.
BIPM facility for dynamic generation of NO2 in nitrogen mixtures
in the range 1 µmol/mol to 15 µmol/mol.