5.4.1 Each normally used operating range shall
be calibrated. Analysers shall be calibrated not more than 3 months
before being used for testing or whenever a system repair or change
is made that can influence calibration, or as per provided for by
1.3.2.2.
5.4.2 Using purified synthetic air (or nitrogen) the CO,
CO2, NOx and O2 analysers shall be set at zero. The
(H)FID analyser shall be set to zero using purified synthetic air.
5.4.3 The appropriate calibration gases shall
be introduced to the analysers, the values recorded, and the calibration
curve established accordingly.