ISO 17034 and ISO 17025 Continuous Emissions Monitoring (CEM) gas mixture ranges and uncertainties

This table was reviewed on 30 April 2025 and refers to the ISO 17034 scope (Issue No. 006) and ISO 17025 scope (Issue No. 059) for EffecTech. For details of the Expanded Measurement Uncertainty (k = 2) for each component, please check the most recent version of the ISO 17025 scope.

Certified Reference Materials (CRMs)

Component	Amount fraction (µmol/mol or %mol/mol)
oxygen in nitrogen	10 ppm to 22.5 %*
carbon monoxide in nitrogen or synthetic air	10 ppm to 1000 ppm
nitric oxide in nitrogen	10 ppm to 600 ppm
nitrogen dioxide in synthetic air	5 ppm to 500 ppm
sulphur dioxide in nitrogen or synthetic air	10 ppm to 1000 ppm
methane in nitrogen	0.1 % to 5 %
methane in synthetic air	0.1 % to 2.5 %
propane in nitrogen or synthetic air	3 ppm to 100 ppm
carbon dioxide in nitrogen or synthetic air	0.1 % to 15 %
	*Please check the ISO 17025 scope for the uncertainties for your required range as there are two Technical Methods available

Calibrated Gas Mixtures (CGM) – Tertiary CEMs

Component	Amount fraction (mol/mol)
nitric oxide	10 ppm to 600 ppm
nitrogen dioxide in nitrogen	5 ppm to 500 ppm

Primary Reference Gas Mixtures (PRGM)

Component	Amount fraction (mol/mol)
carbon monoxide in nitrogen	10 ppm to 1000 ppm
carbon dioxide in nitrogen	0.1 % to 15 %
oxygen in nitrogen	10 ppm to 22.5 %
nitric oxide in nitrogen	10 ppm to 600 ppm
nitrogen dioxide in synthetic air	5 ppm to 500 ppm
sulphur dioxide in nitrogen	10 ppm to 1000 ppm
methane in nitrogen	0.1 % to 5 %
methane in synthetic air	0.1 % to 2.5 %
propane in nitrogen	1 ppm to 2 %
propane in synthetic air	1 ppm to 1.1 %