Diesel Exhaust Fluid (AUS 32 / AdBlue-type) 32.5% Urea Solution

AUS 32 to ISO 22241 | 32.5% urea in deionised water for SCR fleets, distributors and blenders

Diesel exhaust fluid is the reducing agent that selective catalytic reduction (SCR) systems inject into diesel exhaust to convert NOx to nitrogen and water; the standard names it AUS 32 (aqueous urea solution 32%) and the AdBlue name is a VDA trademark used under licence. The product is 32.5% urea in 67.5% deionised water, and the specification is ISO 22241-1: urea 31.8–33.2% (m/m), density 1.0870–1.0930 g/cm³ at 20 °C, refractive index 1.3814–1.3843, alkalinity as NH₃ ≤ 0.2%, biuret ≤ 0.3%, aldehydes ≤ 5 mg/kg, insoluble matter ≤ 20 mg/kg, phosphate ≤ 0.5 mg/kg, calcium, iron, magnesium, sodium, potassium and aluminium each ≤ 0.5 mg/kg, and copper, zinc, chromium and nickel each ≤ 0.2 mg/kg, tested by the annex methods of ISO 22241-2. The metals and phosphate limits are the reason the feedstock must be uncoated technical-grade urea and the water must be deionised: a coated agricultural prill or tap water fails the certificate and fouls the dosing injector and the catalyst. Dosing runs at typically 2–6% of diesel consumption by volume, which sets the buyer's storage and tank sizing.

Handling is part of the specification. The fluid freezes at −11 °C and can be thawed and used without loss of quality, and it begins to decompose at about 60 °C, so shelf life is set by storage temperature: about 3 years below 10 °C, 18 months below 25 °C, 12 months below 30 °C and under 6 months at 35 °C, with the filling date on every container. Containers are high-density polyethylene or stainless steel; repurposed fuel drums contaminate the product with oils, grease and dirt. CBIL brokers DEF from ISO 22241 producers, with the certificate of analysis for each batch, the filling date and the container specification on the documents, in 1,000 L IBCs, 210 L drums, 10 and 20 L cans, and bulk by road tanker or ISO tank; where a distributor blends in-market, the desk supplies the technical-grade urea (see the prilled urea page) with the feedstock certificate the blender needs to meet the standard. Buyers are fleet operators and truck stops, fuel distributors and lubricant blenders adding a DEF line, and OEM dealer networks. Prices are negotiated per lot on pack and delivery point.

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Excluded origins are not offered, including product re-exported, blended or re-processed through a third country. Every lot moves with a certificate of origin naming the producing plant, mine or grower country, and nothing is quoted before the seller and loading point are known.