SCR Technology

What is SCR?

Selective Catalytic Reduction (SCR) is an innovative technology which leading North American manufacturers of diesel vehicles have jointly adopted after comparing and testing a variety of available technologies aimed at reducing NOx emission levels to the required limits. SCR is the only technology that produces the reduction of exhaust emissions required by legislation while allowing optimum engine operation in terms of performance and fuel consumption.

How does SCR work?

SCR technology reduces emissions of NOx gases that are produced inside the engine during combustion. This process requires the correct injected volume of DEF; a non-toxic, high quality, urea solution. DEF is sprayed into the hot exhaust gas stream just prior to the SCR unit and is then hydrolyzed to ammonia (NH3). Once inside the SCR unit, it assists in the breakdown of NOx to harmless Nitrogen gas (N2) and water (H20).

DEF Handling

DEF is safe to handle and use; it is not explosive, flammable, toxic, or subject to any hazardous product regulations.

DEF Storage

Solutions can be tailored to suit customer needs allowing for the usual precautions to prevent spillage into nearby drains. DEF has a shelf life of 18 months if the stipulated storage conditions are observed. However, DEF that has been stored for longer than 18 months may still be perfectly usable and simply needs to be analyzed to check that it still conforms to the DEF specification. (Storage temperatures between 25°F – 80°F are recommended.)


Product traceability ensures that there is no risk of contamination. Our strict quality and chain of custody procedures assures that the Colonial™ Diesel Exhaust Fluid (DEF) product maintains its integrity, as all ISO 22241 specifications are adhered to throughout the production and shipping process. Each batch is verified so you can rest assured that your vehicle’s SCR system will not be damaged by poor or inconsistent product quality.



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