Diesel Exhaust Fluid

Commercially, diesel exhaust fluid is standardized and supplied mainly as a 32.5% high-purity urea solution in deionized water, often referred to as AUS 32. This precise composition ensures optimal SCR performance and consistent ammonia release during exhaust treatment. DEF is widely used in passenger diesel vehicles, heavy-duty trucks, buses, construction machinery, agricultural equipment, marine engines, and stationary diesel generators equipped with SCR systems. Key components include automotive-grade urea and ultra-pure deionized water, free from minerals, metals, and contaminants that could damage catalysts. Technical characteristics such as urea concentration accuracy, purity level, freezing point (approximately -11 °C), and thermal stability are critical to ensure reliable dosing and emission control performance.