Diesel Exhaust Fluid (DEF) is a solution of high purity urea and de-ionized water. It is the operating fluid required in
vehicles using Selective Catalytic Reduction (SCR) technology. Engineers developed the technology to meet the 2010
emission standards for reducing nitrogen oxide (NOx) exhaust emissions from diesel engines.
The fluid is contained in a designated DEF tank and it is sprayed into the exhaust system before the catalytic converter breaks down NOx into harmless nitrogen and water vapour.
DEF has a shelf life of 12 months if the required storage conditions are followed. However, DEF that has been stowed
for a longer period may be usable if analyzed to confirm that it still meets the DEF specification. Storage facilities can
be adapted to suit customer needs.