ISO 17034 and ISO 17025 Natural gas and LNG mixture ranges and uncertainties

This table was reviewed on 19 March 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 (CRM)

Component	Range (amount fraction % mol/mol)
nitrogen	0.1 to 22
carbon dioxide	0.05 to 15
methane	34 to 100
ethane	0.1 to 35
propane	0.05 to 15
iso-butane	0.01 to 2
n-butane	0.01 to 2
neo-pentane	0.002 to 0.35
iso-pentane	0.005 to 0.35
n-pentane	0.005 to 0.35
n-hexane	0.005 to 0.35
2-methylpentane	0.001 to 0.35
3-methylpentane	0.001 to 0.35
2,2-dimethylbutane	0.001 to 0.35
benzene	0.001 to 0.2
cyclohexane	0.001 to 0.2
n-heptane	0.001 to 0.2
toluene	0.001 to 0.1
methylcyclohexane	0.001 to 0.1
n-octane	0.0005 to 0.05
n-nonane	0.0001 to 0.02
n-decane	0.0001 to 0.005
helium	0.005 to 0.2
hydrogen	0.005 to 20
oxygen	0.05 to 22.5*

*The upper limit for oxygen may be limited due to restrictions in place required for the safe manufacture of such mixtures.

Primary Reference Gas Mixtures (PRGM)

Component	Range (amount fraction % mol/mol)
nitrogen	0.02 to 25
carbon dioxide	0.05 to 25
methane	34 to 100
ethane	0.1 to 35
propane	0.05 to 20
iso-butane	0.01 to 2
n-butane	0.01 to 2
neo-pentane	0.001 to 0.5
iso-pentane	0.002 to 0.6
n-pentane	0.002 to 0.6
n-hexane	0.001 to 0.5
2-methylpentane	0.001 to 0.35
3-methylpentane	0.001 to 0.35
2,2-dimethylbutane	0.001 to 0.35
benzene	0.001 to 0.2
cyclohexane	0.001 to 0.2
n-heptane	0.001 to 0.2
toluene	0.001 to 0.1
methylcyclohexane	0.001 to 0.1
n-octane	0.0005 to 0.05
n-nonane	0.0001 to 0.02
n-decane	0.0001 to 0.005
helium	0.005 to 0.2
hydrogen	0.005 to 0.2

Not sure what the difference is between PRGMs and CRMs?

Find out more about our calibration gases here.