AdBlue

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AdBlue is the registered trademark for AUS32 (Aqueous Urea Solution 32.5%) and is used in a process called Selective Catalytic Reduction (SCR) to reduce emissions of oxides of nitrogen from the exhaust of diesel vehicles. As the name AUS32 would suggest, it is a 32.5% solution of high-purity urea in demineralised water that is clear, non-toxic and is safe to handle. However, it can be corrosive for some metals and must be stored and transported with the correct materials. The AdBlue trademark is currently held by the German Association of the Automobile Industry (VDA), who ensure quality standards are maintained in accordance with DIN 70070 specifications.^[1]

AdBlue is carried onboard SCR-equipped trucks and buses in specially designed tanks and is dosed into the SCR system at a rate equivalent to 3-5% of diesel consumption. This low dosing rate ensures long refill periods and minimises the tank’s impact on chassis space. On-highway SCR systems are currently in use throughout Europe, and in Japan and Singapore. The US EPA's 2010 legislation will limit NOx to levels that will require North American trucks to be equipped with SCR post-2010. The trademark - AdBlue - will not be used in the US market; the most likely name for AUS32 will be Diesel Emissions Fluid (DEF).

All European truck manufacturers currently offer SCR equipped models, and the future the Euro VI emission standard is set to reinforce the demand for this technology. SCR systems are sensitive to potential chemical impurities in the urea solution. Therefore, it is essential to maintain high standards of AdBlue quality and an ISO standard is being prepared to ensure this.

The use of SCR technology in Europe made it necessary to develop an AdBlue supply infrastructure. AdBlue is available in bulk or can be purchased by the litre at service stations.