EN590 describes the physical properties that all automotive diesel fuel must meet if it is to be sold in the UK, the rest of the European Union, Croatia, Iceland, Norway and Switzerland.
EN590 was introduced to coincide with the development of new emissions standards across the European Union.
Although EN590 covers numerous fuel characteristics, water content is the most relevant contaminant for fuel maintenance. To comply with EN590, fuel can contain no more than 200mg of water per kg of fuel.
This is an extremely demanding standard. 200mg of water per kg of fuel represents just 0.02% water contamination. Because modern biodiesel blends absorb water naturally (i.e. they are hygroscopic) it is practically impossible to adhere to the standard without regular testing and the use of a water extraction process such as a polishing system or regular tank cleaning.
As the table below shows, EN590’s requirements include the blending of up to 7% Fatty Acid Methyl Ester (FAME) biodiesel with conventional petrochemical diesel.
| Property | Unit | Lower limit | Upper limit |
| Cetane number | 51.0 | ||
| Sulphur content | mg/kg | 10.0 | |
| Flash point | oC | Above 55 | |
| Carbon residue | %m/m | 0.30 | |
| Ash content | %m/m | 0.01 | |
| Water content | mg/kg | 200 | |
| Total contamination | mg/kg | 24 | |
| Fatty Acid Methyl Ether (FAME) (biodiesel) content | % v/v | 7 |
EN590 was introduced to coincide with the development of new emissions standards across the European Union. The overall goal has been to reduce the sulphur content of diesel fuel. Sulphur had been used as a lubricant in the fuel. Its role is taken by special additives in ULSD.
Since 2007, diesel that conforms to EN590 has been referred to as Ultra Low Sulphur Diesel (ULSD) in the European Union. The phrase “Ultra Low Sulphur Diesel” is governed by different standards in other parts of the world.
Unlike the EU directives, EN590 is not available free-of-charge. It has to be purchased from the British Standards Institute’s online shop. For this reason, it cannot be made available for download from IPU’s web site. The full text of the standard can be purchased from the BSI shop.