Water-diesel emulsions which comply with the following specification were eligible for a reduced excise duty rate in Italy, effective 200.10.1 through 2005.12.31. The emulsions were allowed for use in medium- and heavy-duty vehicles, and were available only at commercial sites not open to general public.

Table 1
Water-Diesel Fuel Emulsion Specification (April 2001)
Fuel Property Unit Limit Test
Min Max
Appearance   Milky Visual
Density @15°C kg/m3 835 870 ISO 3675, ISO 12185
Water content % m/m 12.0 15.0 ISO 8534
Stability, by centrifuge (4200 rcf, 5 min)*  
- phase separation % v/v - 9.0 UNICHIM 1548
- free water   Pass  
Viscosity @40°C mm2/s 2.0 7.0 ISO 3104
Sulfur % m/m - 0.031 ISO 14596, EN 24260
Sulfated ash % m/m - 0.01 ISO 3987
Total contaminants mg/kg - 24 EN 12662
Copper corrosion, 3h @50°C   Class 1   ISO 2160
Flash Point °C 55 - ISO 2592, EN 22719
Total nitrate content† mg/kg 750 - ISO 13759
Lubricity (corrected wear scar diameter, wsd 1.4 @60°C) µm - 460 ISO 12156-1
CFPP‡ °C - W: -10
S: 0
EN 116
* Sample must be taken immediately upon delivery
† Expressed as 2-ethyl-hexyl-nitrate (EHN)
‡ Antifreeze additives are allowed for winter grade, provided the total water content is unchanged

Furthermore, the following requirements apply:

  • The emulsion must be used within 4 months from delivery
  • Mixing of emulsions produced with different technologies, or mixing of emulsions with diesel fuel in depots, is not allowed
  • Diesel fuel used for emulsions must conform to UNI EN 590:2000
  • For the preparation of emulsion de-ionized water must be used with maximum conductivity of 30 µS/cm
  • Emulsifiers and additives must not contain compounds of fluorine, chlorine, or heavy metals