Division 6.1.2 The following pure gases shall be available, if necessary, for calibration and operation:

F1Nitrogen:

Purity: ≤ 1 ppm C₁, ≤ 1 ppm CO, ≤ 400 ppm CO₂, ≤ 0,1 ppm NO, ≤ 0,1 ppm N₂O, ≤ 0,1 ppm NH₃;

Synthetic air:

Purity: ≤ 1 ppm C₁, ≤ 1 ppm CO, ≤ 400 ppm CO₂, ≤ 0,1 ppm NO, ≤ 0,1 ppm NO₂; oxygen content between 18 and 21 per cent volume;

Oxygen:

Purity: > 99,5 per cent vol. O₂;

Hydrogen (and mixture containing helium or nitrogen):

Purity: ≤ 1 ppm C1, ≤ 400 ppm CO₂; hydrogen content between 39 and 41 per cent volume;

Carbon monoxide:

Minimum purity 99,5 per cent;

Propane:

Minimum purity 99,5 per cent.