Selective Catalytic Reduction technology requires the use of Diesel Exhaust Fluid in order to meet the strict EPA and CEPA diesel emissions standards in place since January 2010.
Most diesel engine manufacturers have chosen SCR (Selective Catalytic Reduction) technology to achieve reduced NOx (oxides of nitrogen) levels and meet emissions standards.
SCR treats exhaust gas downstream of the engine. Metered amounts of DEF are injected into the exhaust from the engine, where it vapourizes and decomposes to form ammonia and carbon dioxide. The ammonia (NH3) together with the SCR catalyst, converts the NOx to nitrogen (N2) and water (H2O), both harmless, which are emitted through the exhaust reducing noxious emissions to almost zero.
SCR makes engines work more efficiently. NOx levels coming out of the engine are driven up which decreases the generation of particulate filter regeneration which burns extra fuel and allows the engine to run cooler.