During the combustion of diesel fuel, nitrogen combines with oxygen to create nitric oxide, and ultimately nitrogen dioxide (NO2). These gases are referred to together as oxides of nitrogen (NOx).
NOx gases are irritants and can cause significant damage to the airways. NOx gases also contribute to smog and acid rain, which are also associated with adverse health effects.
Diesel Exhaust Fluid (DEF) is injected intro the exhaust stream of a diesel engine, to set off a chemical to reduce NOx gases. DEF contains urea, which decomposes to form Ammonia and carbon dioxide. Ammonia (NH3) is the component in the reduction of NOx gases, and it’s production depends on the amount of urea present in the DEF.
DEF is produced from a high purity solution of urea. The urea in DEF is of a high quality grade, and it is diluted with processed demineralized water – also of extreme high purity. Henceforth it is standardized as AUS 32 (aqueous urea solution) in ISO 22241, and given the name AdBlue®. The purity of DEF is very important, and the slightest of impurities can significantly damage the performance of the Selective Catalytic Reduction (SCR) of NOx.
Testing specification for AdBlue®
ACS conducts the full array of testing required for a diesel exhaust fluid certification, according to the ISO22241-2:2006 specifications. The following parameters can be assessed, and determined whether they sit in the acceptable limits.
- Urea (31.8-33.2 %w/w )
- Density @ 20oC (1.087-1.0930 g/ml)
- RI @ 20oC (1.3814-1.3843)
- Alkalinity as NH3 (<0.2 %w/w)
- Biuret (<0.3%w/w)
- Aldehyde (<5 mg/kg)
- Insoluble’s (<20 mg/kg)
- Phosphate (<0.5 mg/kg)
- Calcium (<0.5 mg/kg)
- Iron (<0.5 mg/kg)
- Copper (<0.2 mg/kg)
- Zinc (<0.2 mg/kg)
- Chromium (<0.2 mg/kg)
- Nickel (<0.2 mg/kg)
- Aluminium (<0.5 mg/kg)
- Magnesium (<0.5 mg/kg)
- Sodium (<0.5 mg/kg)
- Potassium (<0.5 mg/kg)
ACS provides testing to German Association of the Automotive Industry (VDA) certified manufacturers, according to the AdBlue® standard in Australia.
ACS can pre-screen urea pills to ensure that the end product (32.5% urea) will meet all the specifications listed in ISO 22241-1, reducing the risks associated with manufacturing out of specification product.
ACS have also developed an in house method for testing Triuret, utilizing LC-MS and FTIR, after having identified it as an impurity in inferior sources of Urea pills. High levels of Triuret in Urea prills can cause elevated levels of suspended solids which affects the filtration process during production.
ACS can also troubleshoot other Urea related issues such as Cyazine and any other sources of contamination.