Diesel Exhaust Fluid, more commonly known as DEF, is an emissions control liquid, injected in the exhaust stream of modern diesel engines. DEF is a non-hazardous solution composed of 32.5% automotive-grade urea in 67.5% de-iodized water. It is a clear and colorless fluid that looks exactly like water, but has a slight smell of ammonia. When handled properly, DEF is non-toxic and non-flammable. It will not harm people, animals, equipment, or the environment. By using Selective Catalytic Reduction (SCR) technology, DEF helps remove harmful NOx emissions generated by diesel engines.

How Selective Catalytic Reduction (SCR) Works

The primary function of SCR technology is to use ammonia to break down dangerous NOx emissions into nitrogen and water. For automotive purposes, the selective catalytic reduction is activated when the urea solution, DEF, is constantly sprayed into the exhaust steam. With a special catalyst present, the NOx emissions are converted into harmless nitrogen and water vapor. This technology is a popular choice among truck and engine manufacturers as a way to meet emissions standards which now apply to all light, medium and heavy duty diesel engines in the United States. Diesel engines with SCR use DEF at a rate of about five percent of the amount of diesel consumed.

EPA’s Stringent Emission Standards Calls for more DEF Products

To ensure acceptable air quality, the EPA has set extensive emissions standards. As NOx and particulate matter (PM) are associated with a number of health problems, the EPA has estimated that the emission standards will prevent more than 8,300 premature deaths. Since the advent of SCR technology in 2004, there have been more engines introduced utilizing the system as an “after treatment”. Evidently, the call for a healthier environment, cleaner air, and fuel efficient engines is making DEF products more popular in the market.