Understanding DEF

Diesel Exhaust Fluid (DEF) is the USA’s operating fluid for Selective Catalytic Reduction (SCR).  It is a non-toxic solution that turns harmful nitrogen oxide (NOx) emissions from diesel-powered engines into harmless water vapor and nitrogen.

The market for DEF was created due to the new emission requirements set forth by the EPA to meet the most recent Clean Air Act specifications.  The progressive reduction in diesel emissions has driven tremendous changes in engine requirements over the past 15 years.  These efforts have been focused on reducing particulates, sulfur, and NOx emissions.  DEF is focused on meeting the 2010 requirement for NOx emissions reductions.

The specific approach used to reduce NOx emissions requiring DEF is referred to as SCR, or selective catalytic reduction.  SCR uses DEF and the SCR catalytic converter to significantly reduce nitrogen oxide (NOx) emissions in diesel engines.  SCR has been selected by all major engine manufacturers as their method to meet the 2010 specification.

Engine manufacturers chose SCR over competing technologies due to the fuel economy benefits of SCR as compared to other options.  SCR is expected to improve overall fuel economy by approximately 5%.

DEF Short Life & Storage

  • If Diesel Exhaust Fluid is kept to temperatures between 10 and 90 degrees Fahrenheit, it will last a minimum of 1 year without problems.
  • Big bulk dispensers (1,000 gallons) have internal climate control systems.
  • In cold temperature regions it is recommended to store Diesel Exhaust Fluid in a storage unit. In warm temperature regions it is recommended to store Diesel Exhaust Fluid in a shaded area.
  • New climate control systems specifically for Diesel Exhaust Fluid are being developed.