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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 engined motor vehicles.

As the name AUS32 would suggest, it is a 32.5% solution of high-purity urea in demineralized 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 using 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 ISO 22241 specifications.

AdBlue is carried onboard SCR-equipped vehicles 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, in Japan, Australia, Hong Kong, Taiwan, Korea, New Zealand and Singapore. The ‎United States Environmental Protection Agency?'s (US EPA) 2010 legislation will limit NOx to levels that will require North American trucks to be equipped with SCR post-2010. The current generic name in North America for AUS32 is diesel exhaust fluid (DEF). Some trucking industry OEMs have already developed branded SCR solutions, such as Daimler's BlueTec.

All European truck manufacturers currently offer SCR equipped models, and the future Euro6 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 according to the ISO 22241 standard.

The use of SCR technology in Europe made it necessary to develop an AdBlue supply infrastructure. AdBlue is available from thousands of service stations. It can also be purchased in canisters of 5 or 10 litres at service stations. Larger quantities of AdBlue can be delivered in, for example, 208 litres (46 imp gal; 55 US gal) drums, 1,000 litres (220 imp gal; 260 US gal) Intermediate Bulk Containers (IBCs), and bulk.

AdBlue™ Pumping Equipment Specifications

AdBlue is very susceptible to contamination from both foreign matter and incorrect material selection. It is imperative that this is considered when deciding which dispensing solution is best for your application. 

Particulate ingress is an obvious problem for any transfer application but less evident problems are often overlooked.

One problem which continues to haunt pumps that are not specifically designed for handling AdBlue is that crystals can form and damage internal components. Due to the high crystalline content of the urea solution a chalky abrasive residue builds up when the DI water content evaporates or dries. This can occur anywhere where air can enter or get trapped in the system.

These crystals can cause uneven wear on motor shafts if left to build up on inner pump walls or pump impellors and may drag around the circumference of any seals causing further damage and deterioration of both components. Parts of broken impellor and seals can then pass through to the tank on the vehicle and melt onto the superheated head of the SCR.

The most common causes of premature SCR failure are typically either a result of the ingress of damaged pump parts or as a result of incorrect material selection. The main influence in this instance is where the de-ionised water element of the solution draws ions from materials it comes into contact with, this changes the chemi

cal composition of the AdBlue and causes salts to form which in turn clog the Ceramic head on the SCR. Inert materials should always be used to handle AdBlue.

Materials which are most likely to cause these problems are Zinc, Aluminium, Copper, Cast Iron and Brass. Plated and treated materials should also be avoided as the plating can wear away on contact/moving parts. Nickel plated aluminium regardless of being treated as either a electro-less or electrolytic process should be avoided at all times, this is regretfully a common error with existing systems.

Click the Adblue logo below for a selection of the available pumps for AdBlue transfer, you should never use diesel transfer pumps or fuel storage tanks for handling AdBlue.