Directive 2005/55/EC of the European Parliament and of the Council of 28 September 2005 on the approximation of the laws of the Member States relating to the measures to be taken against the emission of gaseous and particulate pollutants from compression-ignition engines for use in vehicles, and the emission of gaseous pollutants from positive-ignition engines fuelled with natural gas or liquefied petroleum gas for use in vehicles (Text with EEA relevance) (repealed) (c. 55)

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ANNEX IVTECHNICAL CHARACTERISTICS OF REFERENCE FUEL PRESCRIBED FOR APPROVAL TESTS AND TO VERIFY CONFORMITY OF PRODUCTION

2.NATURAL GAS (NG)

European market fuels are available in two ranges:

the H range, whose extreme reference fuels are G_R and G₂₃;
the L range, whose extreme reference fuels are G₂₃ and G₂₅.

The characteristics of G_R, G₂₃ and G₂₅ reference fuels are summarised below:

Reference fuel G_R

Characteristics	Units	Basis	Limits		Test method
^a Inerts +C₂₊
^b Value to be determined at standard conditions (293, 2 K (20 °C) and 101, 3 kPa).
Characteristics	Units	Basis	Minimum	Maximum	Test method
Composition:
Methane		87	84	89
Ethane		13	11	15
Balance^a	%-mole	—	—	1	ISO 6974
Sulphur content	mg/m³ ^b	—	—	10	ISO 6326-5

Reference fuel G₂₃

Characteristics	Units	Basis	Limits		Test method
^a Inerts (different from N₂) +C₂₊ +C_2+.
^b Value to be determined at standard conditions (293,2 K (20 °C) and 101,3 kPa).
Characteristics	Units	Basis	Minimum	Maximum	Test method
Composition:
Methane		92,5	91,5	93,5
Balance^a	%-mole	—	—	1	ISO 6974
N₂		7,5	6,5	8,5
Sulphur content	mg/m³ ^b	—	—	10	ISO 6326-5

Reference fuel G₂₅

Characteristics	Units	Basis	Limits		Test method
^a Inerts (different from N₂) +C₂₊ +C_2+.
^b Value to be determined at standard conditions (293,2 K (20 °C) and 101,3 kPa).
Characteristics	Units	Basis	Minimum	Maximum	Test method
Composition:
Methane		86	84	88
Balance^a	%-mole	—	—	1	ISO 6974
N₂		14	12	16
Sulphur content	mg/m³ ^b	—	—	10	ISO 6326-5