The parent engine shall meet the requirements of this Regulation on the appropriate reference fuels specified in Annex IX. Specific requirements shall apply to engines fuelled with natural gas/biomethane, including dual-fuel engines, as laid down in point 1.1.3.

1. (a)

   declare the fuels the engine family is capable to run on in point 3.2.2.2.1 of Part 1 of Appendix 4;

2. (b)

   demonstrate the capability of the parent engine to meet the requirements of this Regulation on the fuels declared;

3. (c)

   be liable to meet the requirements of in-service conformity specified in Annex II on the fuels declared including any blend between the declared fuels and the market fuels included in Directive 98/70/EC and the relevant CEN standards.

In the case of compressed natural gas/biomethane (CNG) there are generally two types of fuel, high calorific fuel (H-gas) and low calorific fuel (L-gas), but with a significant spread within both ranges; they differ significantly in their energy content expressed by the Wobbe Index and in their λ-shift factor (S_λ). Natural gases with a λ-shift factor between 0,89 and 1,08 (0,89 ≤ S_λ ≤ 1,08) are considered to belong to H-range, while natural gases with a λ-shift factor between 1,08 and 1,19 (1,08 ≤ S_λ ≤ 1,19) are considered to belong to L-range. The composition of the reference fuels reflects the extreme variations of S_λ.

The parent engine shall meet the requirements of this Regulation on the reference fuels G_R (fuel 1) and G₂₅ (fuel 2), as specified in Annex IX, without any manual readjustment to the engine fuelling system between the two tests (self-adaptation is required). One adaptation run over one WHTC hot cycle without measurement is permitted after the change of the fuel. After the adaptation run, the engine shall be cooled down in accordance with paragraph 7.6.1 of Annex 4 to UNECE Regulation No 49.

In the case of liquefied natural gas/biomethane (LNG) the parent engine shall meet the requirements of this Regulation on the reference fuels G_R (fuel 1) and G₂₀ (fuel 2), as specified in Annex IX, without any manual readjustment to the engine fuelling system between the two tests (self-adaptation is required). One adaptation run over one WHTC hot cycle without measurement is permitted after the change of the fuel. After the adaptation run, the engine shall be cooled down in accordance with paragraph 7.6.1 of Annex 4 to UN/ECE Regulation No 49.

At the manufacturer's request the engine may be tested on a third fuel (fuel 3) if the λ-shift factor (S_λ) lies between 0,89 (that is the lower range of G_R) and 1,19 (that is the upper range of G₂₅), for example when fuel 3 is a market fuel. The results of this test may be used as a basis for the evaluation of the conformity of the production.

In the case of an engine fuelled with CNG which is self-adaptive for the range of H-gases on the one hand and the range of L-gases on the other hand, and which switches between the H-range and the L-range by means of a switch, the parent engine shall be tested on the relevant reference fuel as specified in Annex IX for each range, at each position of the switch. The fuels are G_R (fuel 1) and G₂₃ (fuel 3) for the H-range of gases and G₂₅ (fuel 2) and G₂₃ (fuel 3) for the L-range of gases. The parent engine shall meet the requirements of this Regulation at both positions of the switch without any readjustment to the fuelling between the two tests at each position of the switch. One adaptation run over one WHTC hot cycle without measurement is permitted after the change of the fuel. After the adaptation run the engine shall be cooled down in accordance with paragraph 7.6.1 of Annex 4 to UNECE Regulation No 49.

At the manufacturer's request the engine may be tested on a third fuel instead of G₂₃ (fuel 3) if the λ-shift factor (S_λ) lies between 0,89 (that is the lower range of G_R) and 1,19 (that is the upper range of G₂₅), for example when fuel 3 is a market fuel. The results of this test may be used as a basis for the evaluation of the conformity of the production.

$r=\frac{\mathrm{emission\; result\; on\; reference\; fuel\; 2}}{\mathrm{emission\; result\; on\; reference\; fuel\; 1}}$

or,

$r_a=\frac{\mathrm{emission\; result\; on\; reference\; fuel\; 2}}{\mathrm{emission\; result\; on\; reference\; fuel\; 3}}$

and,

$r_b=\frac{\mathrm{emission\; result\; on\; reference\; fuel\; 2}}{\mathrm{emission\; result\; on\; reference\; fuel\; 3}}$

In the case of LPG there are variations in C₃/C₄ composition. These variations are reflected in the reference fuels. The parent engine shall meet the emission requirements on the reference fuels A and B as specified in Annex IX without any readjustment to the fuelling between the two tests. One adaptation run over one WHTC hot cycle without measurement is permitted after the change of the fuel. After the adaptation run the engine shall be cooled down in accordance with paragraph 7.6.1 of Annex 4 to UNECE Regulation No 49.

The parent engine shall be tested on the relevant reference fuel, as specified in Annex IX, for the relevant range. The fuels are G_R (fuel 1) and G₂₃ (fuel 3) for the H-range of gases and G₂₅ (fuel 2) and G₂₃ (fuel 3) for the L-range of gases. The parent engine shall meet the requirements of this Regulation without any readjustment to the fuelling between the two tests. One adaptation run over one WHTC hot cycle without measurement is permitted after the change of the fuel. After the adaptation run the engine shall be cooled down in accordance with paragraph 7.6.1 of Annex 4 to UNECE Regulation No 49.

At the manufacturer's request the engine may be tested on a third fuel instead of G₂₃ (fuel 3) if the λ-shift factor (S_λ) lies between 0,89 (that is the lower range of G_R) and 1,19 (that is the upper range of G₂₅), for example when fuel 3 is a market fuel. The results of this test may be used as a basis for the evaluation of the conformity of the production.

r=emission result on reference fuel 2emission result on reference fuel 1

, or

ra=emission result on reference fuel 2emission result on reference fuel 3

, and

rb=emission result on reference fuel 1emission result on reference fuel 3

On delivery to the customer the engine shall bear a label as specified in Section 3.3 stating for which range of gases the engine is approved.

The parent engine shall meet the emission requirements on the reference fuels G_R and G₂₅ in the case of CNG, on the reference fuels G_R and G₂₀ in the case of LNG, or on the reference fuels A and B in the case of LPG, as specified in Annex IX. Fine-tuning of the fuelling system is allowed between the tests. This fine-tuning will consist of a recalibration of the fuelling database, without any alteration to either the basic control strategy or the basic structure of the database. If necessary, the exchange of parts that are directly related to the amount of fuel flow such as injector nozzles is allowed.

In the case of CNG, at the manufacturer’s request the engine may be tested on the reference fuels G_R and G₂₃, or on the reference fuels G₂₅ and G₂₃, in which case the type-approval is only valid for the H-range or the L-range of gases respectively.

On delivery to the customer the engine shall bear a label as specified in point 3.3 stating for which fuel-range composition the engine has been calibrated.

A fuel specific type-approval may be granted for LNG fuelled engines, including dual-fuel engines, labelled with an approval mark containing the letters ‘LNG₂₀’ in accordance with point 3.1 of this Annex.

The manufacturer can only apply for a fuel specific type-approval in the case of the engine being calibrated for a specific LNG gas composition resulting in a λ-shift factor not differing by more than 3 per cent from the λ-shift factor of the G₂₀ fuel specified in Annex IX, and the ethane content of which does not exceed 1.5 per cent.

In the case of a dual-fuel engine family where the engines are calibrated for a specific LNG gas composition resulting in a λ-shift factor not differing by more than 3 per cent from the λ-shift factor of the G₂₀ fuel specified in Annex IX, and the ethane content of which does not exceed 1.5 per cent, the parent engine shall only be tested on the G₂₀ reference gas fuel, as specified in Annex IX.