The employer shall ensure, by carrying out an analysis or having an analysis carried out, and before their use, that :
1° that breathing gases supplied by compressors comply with the occupational exposure limit values laid down in this sub-section;
2° that the oxygen content of mixtures other than air complies with the occupational exposure limit values laid down in this sub-section;
3° where binary or ternary mixtures are used, that the nitrogen and, where appropriate, helium content complies.