Page 638 - The Central Motor Vehicles Rules, 1989

610 THE CENTRAL MOTOR VEHICLE RULES, 1989 ANNEXURE IV-L

ANNEXURE IV-L
[Refer Rule 115(15)] ANNEXURE IV-L
SPECIFICATION OF REFERENCE FUEL FOR CNG
CNG reference fuel for category M and category N vehicles
not exceeding 3,500 kgs GVW and Two and Three-wheelers

Characteristic Units Basis Limits Test method
Minimum Maximum

Reference fuel G20
Composition :

Methane % mole 100 99 100 ISO 6974
Balance (1) % mole — — 1 ISO 6974
N2 % mole ISO 6974
3 (2)
Sulphur content mg/m — — 10 ISO 6326-5
Wobbe Index (net) MJ/m 3 (3) 48.2 47.2 49.2

Reference fuel G25
Composition :
Methane % mole 86 84 88 ISO 6974
Balance (1) % mole — — 1 ISO 6974
N2 % mole 14 12 16 ISO 6974
3 (2)
Sulphur content mg/m — — 10 ISO 6326-5
3 (3)
Wobbe Index (net) MG/m 39.4 38.2 40.6
(1) Inerts (different from N2) + C2 + C2+.
(2) Value to be determined at 293, 2 K (20˚C) and 101.3 kPa.
(3) Value to be determined at 273, 2 K (0˚C) and 101.3 kPa

The above type of vehicles should be tested with both types of Reference Fuels.
CNG Reference Fuel for Vehicles above 3,500 kgs GVW
Characteristic Units Basis Limits Test method

Minimum Maximum
Reference fuel GR
Composition :
Methane 87 84 89
Ethane 13 11 15
Balance (1) % - mole — — 1 ISO 6974
3 (2)
Sulphur content mg/m — — 10 ISO 6326-5