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March 20, 2019   |   Transport Topics


Opinion: Ensuring Quality of Diesel Exhaust Fluid Can Help Keep Trucks Running Smoothly

By Jeffrey Harmening, Team Lead, Diesel Exhaust Fluid, American Petroleum Institute

Fleet managers and truck drivers both need to understand that the quality of the diesel exhaust fluid (DEF) going into their vehicles is as important as the quality of the engine oils or fuels used in their vehicles.


Fleet managers responsible for procuring DEF should confirm that their suppliers are providing DEF that meets this ISO quality standard. One way to do this is to ensure that their supplier is providing a Certificate of Analysis with every shipment that addresses all of the quality characteristics that the specification requires.

DEF is composed of 32.5% technically pure urea in pure water. Each of these components is critical to the manufacture of DEF that meets the quality standard. Use of substandard urea (such as agricultural-grade urea commonly used as fertilizer) or use of water derived directly from the public water system without proper treatment can introduce contaminants and metals that are not only detrimental to the life of the selective catalytic reduction (SCR) system but can also affect the SCR system’s ability to reduce harmful NOx emissions.


Ultimately, ensuring the quality of DEF can keep a truck running smoothly, and the proper handling and storage of DEF is vital. Fleet managers and truck drivers should ensure they are using quality DEF to meet the high standards that are required by today’s engine and vehicle manufacturers.

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