Diesel Exhaust Fluid

DEF, an acronym for Diesel Exhaust Fluid, is the trucking industry’s response to U.S. Environmental Protection Agency standards requiring all medium and heavy-duty diesel vehicles to significantly reduce engine emissions, particularly nitrous oxide as well as particulate matter.

DEF is a clear, colorless, non-hazardous liquid looking exactly like water but that has a slight odor of ammonia. It is composed of urea and deionized water. The urea component is an organic compound made up of nitrogen, hydrogen, carbon, and oxygen.  Diesel Exhaust Fluid (DEF) chemically reduces nitrogen oxides (NOx) emissions from diesel-powered vehicles. Diesel Exhaust Fluid is NOT to be added to the diesel fuel, it should be dispensed in a separate DEF tank used in diesel vehicles which are equipped with a selective catalytic reduction (SCR) that lowers the concentration of nitrogen oxides (NOx) in the diesel exhaust emissions from a diesel engine.


How DEF Works

DEF is not a fuel additive and has no influence on the tuning and efficiency of diesel engines. The way it works is that the fluid, an organic compound comprising urea and deionized water, is mixed with the hot gases that follow diesel combustion, breaking DEF down into ammonia and carbon dioxide. These two gases meet with the diesel exhaust and chemically bond with the nitrogen oxides, thus resulting in nitrogen and water exiting the tailpipe. The result is a much cleaner diesel exhaust.


Who Regulates DEF

The production, handling and transportation of DEF are governed by the Environmental Protection Agency through its ISO 22241 standard. The urea concentration of DEF must by 32.5 percent by weight, which was mandated because that concentration has the lowest freezing temperature of 12° Degrees Fahrenheit.  Diesel Exhaust Fluid is classed as non-hazardous and is certified as a Diesel Exhaust Fluid by the American Petroleum Institute.


It is recommended to store DEF between 23°F to 86°F (-5°C to 30°C).  Freezing point 12°F. 

Keep lid tightly closed when not in use. Do not add any other substances. Avoid direct sunlight.



Diesel Exhaust Fluid (DEF) is Brokered / Distributed by:

KM Solutions

Products are certified as a Diesel Exhaust Fluid by American Petroleum Institute