Although urea is a widely produced chemical compound used for years by the agriculture industry to infuse nitrogen into soil, the term "diesel exhaust fluid" (DEF), a specific composition of urea for application in transportation, only recently entered the lexicon of the U.S. fleet industry with the advent of a particular type of clean exhaust system called Selective Catalytic Reduction (SCR).

Diesel Exhaust Fluid will be required in any vehicle using diesel fuel manufactured in 2010 and beyond. Sale and distribution of DEF will continue to increase as more new vehicles are produced. Look to O'Day Equipment for retail and fleet sales options for DEF.

 What is DEF?

Diesel Exhaust Fluid (DEF) is one of the key elements involved in the SCR process.  It is a nontoxic solution of 67.5% water and 32.5% automotive grade urea. DEF helps to convert NOx into nitrogen gas and water vapor.  It is stable, non-flammable, odorless, and colorless.

What is Urea?

Urea is a compound of nitrogen that turns to ammonia when heated.  It is used in a variety of industries, including fertilizer in agriculture. Urea is naturally occurring, but is also commonly made from natural gas.

How is DEF quality defined and guaranteed?

DEF is defined by AUS32 specifications which meet or exceed the DIN 70070 August 2005 quality standard, the DIN V 70071 June 2005 analytical standard and the ISO 22141-1 2006 standard.  The American Petroleum Institute has developed a quality certification program that ensures North American supplies of DEF will meet these standards at the pump and across the nation, including standards of product manufacturing, handling, quality assurance, safety and environmental protection.

How does DEF work within an SCR system?

The goal of an SCR system is to reduce levels of NOx (nitrogen oxides emitted from the engine) that are harmful to our health and the environment.  SCR treats exhaust gas downstream of the engine. Small quantities of DEF are injected into the exhaust stream and when mixed with the NOx changes into a harmless nitrogen and water mixture.

Extensive testing has shown that SCR systems can exhibit a 4-6% fuel savings over standard engines and near zero emissions.

What are the shelf life and storage guidelines for DEF?

DEF should be kept in a clean environment and handled carefully to prevent contamination which could lead to damage of catalytic converters.  In order to maintain DEF product integrity, the SCR industry has adopted strict standards for DEF manufacturing, blending, storage, dispensing and testing. These standards are ISO 22241-1, ISO 22241-2, and ISO 22241-3.

The DEF solution is temperature sensitive, therefore when stored in extreme temperature environments, DEF must be housed in a climate controlled building. When stored between 12 and 90 degrees Fahrenheit, DEF shelf life is approximately 12 months. 

DEF can only be stored in stainless steel, coated carbon steel, or in a specific high density plastic container. Materials specifically not recommended include non-ferrous metals and alloys (copper, aluminum, magnesium, silver, zinc, lead), solders containing non-ferrous metals, and nickel-coated plastics and metals.

Why do I have to use an SCR system and DEF?

As part of the Clean Air Act of 1970, the Environmental Protection Agency (EPA) has mandated that all on-road diesel vehicles manufactured January 1, 2010 or later must be equipped with technology to reduce NOx emissions. All diesel vehicles from class I to class 8 are included in this requirement.