D6 oil is a term commonly used in the oil trading and refining industry to refer to a specific grade of residual fuel oil , often categorized as a heavy fuel oil (HFO). It is part of the broader classification system for petroleum products, where different grades of oil are labeled with codes like D2, D6, etc., depending on their refining process, composition, and intended use.
Sulfur Content :
The sulfur content in EN590 diesel is limited to 10 mg/kg (ppm) or less. This ultra-low sulfur diesel (ULSD) is essential for reducing harmful emissions and ensuring the proper functioning of emission control devices such as catalytic converters and particulate filters.
Cetane Number :
The cetane number, which measures the ignition quality of diesel fuel, must be at least 51 . A higher cetane number improves combustion efficiency, reduces engine noise, and enhances cold-start performance.
Density :
The density of EN590 diesel is specified to be between 820 kg/m³ and 845 kg/m³ at 15°C. This ensures consistent fuel flow and injection performance.
Cold Weather Performance :
EN590 includes specifications for cold weather performance, measured by the Cloud Point and Cold Filter Plugging Point (CFPP) . These parameters ensure that the fuel remains fluid and can be pumped at low temperatures, preventing issues like fuel gelling in winter conditions.
Cloud Point : The temperature at which wax crystals begin to form in the fuel.
CFPP : The lowest temperature at which the fuel can still pass through a filter.
Lubricity :
Diesel fuel must have adequate lubricity to prevent excessive wear on fuel injection components. EN590 specifies a maximum wear scar diameter of 460 microns in the High-Frequency Reciprocating Rig (HFRR) test.
FAME (Biodiesel) Content :
EN590 allows for the inclusion of up to 7% Fatty Acid Methyl Esters (FAME) , which are bio-components derived from renewable sources. This helps reduce the carbon footprint of diesel fuel while maintaining compatibility with existing engines.
Viscosity :
The kinematic viscosity of EN590 diesel is specified to be between 2.0 mm²/s and 4.5 mm²/s at 40°C. Proper viscosity ensures efficient fuel atomization and combustion.
Flash Point :
The minimum flash point for EN590 diesel is 55°C , ensuring safe handling and storage.
Polycyclic Aromatic Hydrocarbons (PAHs) :
The content of PAHs is limited to 8% by mass . PAHs are harmful compounds that can contribute to particulate emissions, so limiting them helps reduce environmental impact.
Reduced Emissions : The low sulfur content and high cetane number help reduce harmful emissions, including nitrogen oxides (NOx), particulate matter (PM), and carbon monoxide (CO).
Compatibility with Emission Control Systems : Modern diesel engines are equipped with advanced emission control technologies like DPFs and SCR systems, which require ultra-low sulfur diesel to function effectively.
While EN590 is primarily used in Europe, similar standards exist in other regions:
ASTM D975 in the United States
JIS K2204 in Japan
These standards may have slightly different specifications, but they all aim to ensure clean, efficient, and reliable diesel fuel for modern engines.