SCR (Selective Catalytic Reduction) technology is used on Scania’s engines for EU Stage IV and US Tier 4f to reduce the NOX content in the exhaust gases.
A chemical process is started by injecting reductant, an urea and water mixture, into the exhaust gas stream. During injection the water evaporates and the urea breaks down to form ammonia. The ammonia then reacts with the nitrogen gases in the catalytic converter and forms harmless products such as nitrogen gas and water.
Through the use of SCR the exhaust gases are purged of poisonous levels of NOX in the best possible way. Scania is making use of a system that is carefully developed and tested in our own laboratory. The reductant tank is available in different sizes and is heated by the engine’s cooling system in order to avoid freezing of the urea solution; urea freezes at -11°C. The tank and a pump module are delivered as a unit which is fitted to brackets for an easy installation. The Scania system contains all mechanical and electrical parts needed except from the exhaust piping which is to be adapted according to the customers installation.