Question:

What is Diesel Exhaust Fluid?

Answer:

DEF (Diesel Exhaust Fluid) is an organic, non-toxic compound made of 32.5% urea and 67.5% de-ionized water that, when carefully added to diesel exhaust, helps neutralize NOx emissions. It is carefully regulated by the American Petroleum Institute. DEF will be available through most dealers, distributors and major truck stops. It will be packed many ways including: 2.5-gallon jugs, 275-gallon IBC, and bulk storage at truck stops and fleet locations.

2.5 gallons of DEF will yield over 800 miles of travel. You can drive from L.A. to Boston and back on less than a single 23-gallon tank of it (estimated usage rate is approximately 2% per gallon of fuel).

Estimated cost is about $2.75 per gallon when pumped in bulk at truck stops or other retailers.

Under temperatures below 12 degrees Fahrenheit, DEF will freeze, and trucks will be immediately operational throughout the DEF tank thawing process. DEF storage units should be kept above ground and within an enclosure with a small heater. There is no concern regarding thermal stress with the plastic DEF tank. Tanks have been extensively tested in a variety of extreme climates. DEF, when heated and maintained at a temperature above 120 degrees Fahrenheit, will very slowly start to form small amounts of ammonia. It would take over two years at this constant temperature to convert DEF into levels of household ammonia.

If you’re running low on DEF visual indicators in the cab — like fuel gauges—will provide an advanced low-level warning. If a driver runs out of DEF, the vehicle can continue to be driven with no derates until:

1. Diesel refueling occurs with no increase in DEF level (refuels without filling DEF tank)
2. Vehicle is stationary for more than one hour
3. Vehicle has been shutdown or restarted

Roadside assistance personnel will carry DEF.