The flowing of the NO2 calibration gas shall be stopped

Calibration gas – propane; propane bypasses NMC

calibration gas — propane; propane bypasses NMC

calibration gas — methane; methane passes through NMC

Calibration gas means a purified gas mixture used to calibrate gas analysers.

Calibration gas – methane; methane passes through NMC.

It shall be immediately switched back to overflowing the NO2 calibration gas used to establish xNOxref.

Note: For the purpose of this Directive, accuracy is defined as the deviation of the analyser reading from the nominal calibration values using a calibration gas (= true value).

The real concentrations of a calibration gas shall be within ± 2 per cent of the nominal values.

This calibration gas shall be overflowed at the gas sampling system's probe or overflow fitting.

All concentrations of calibration gas shall be given on a volume basis (volume percent or volume ppm).

All concentrations of calibration gas shall be given on a volume basis (volume per cent or volume ppm).

The FID shall be spanned with CH4 span gas by bypassing the cutter.

The true concentrations of a calibration gas shall be within 2 per cent of the stated figures.

The analysers shall then be set to the calibration curves by means of span gases of nominal concentrations of 70 to 100 per cent of the range.