• DEF may have a slight odor similar to that of household ammonia.
• DEF is a high-purity urea solution complying with the Standards of ISO 22241.
• DEF is safe to handle.
• DEF weighs approximately 9.2 lbs. per gallon.
of diesel fuel consumed. It can be expected that 1 to 2
gallons of DEF fluid will be used for every 50 gallons of
diesel fuel. See the chart below.
The NOX reduction process starts with an engine burning clean Ultra Low Sulfur Diesel and producing exhaust that is already much cleaner due to leaner and more complete combustion.
Under the control of the vehicle’s onboard computer, precisely metered spray patterns of DEF are injected into the exhaust stream ahead of the SCR converter allowing the exhaust gases and atomized mist of DEF to enter the converter simultaneously. Together with the catalyst inside the converter, the mixture undergoes a chemical reaction that converts the nitrogen oxides to elemental nitrogen (N2)
and water (H2O).
Exhaust gases are monitored via a sensor as they leave the SCR catalyst. Feedback is supplied to the main computer that adjusts the DEF flow to keep NOX levels within acceptable parameters.
without DEF. In response, manufacturers have equippedboth on-road and off-road SCR units with multiple step
driver notification systems. Before the DEF tank runs empty the operator is given a series of alerts on their dashboard
display. The dashboard DEF indicator will include the following symbol:
maximum of 12 months. Shelf life deteriorates to 6 months
when temperatures are held at a constant 95°F or higher