Hollon Oil Company

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Diesel Exhaust Fluid (DEF)

DEF Home | What is DEF? | DEF Usage | What is SCR? | DEF FAQ's | DEF Equipment | DEF Truck Stop Prices

                                     What is DEF?

Q: What is DEF?
A: DEF or Diesel Exhaust Fluid is a high purity automotive grade solution containing 32.5% urea and 67.5% de-ionized water used in the Selective Catalytic Reduction (SCR) control systems on most new 2010 model diesel vehicles.
Q: What is Urea?
A: Automotive grade urea is the active ingredient of Diesel Exhaust Fluid. Urea is created from synthetic ammonia and carbon dioxide.  Automotive grade urea is a non-hazardous and nontoxic nitrogen-based compound.
Q: What is DEF used for?
A: Diesel engines are required to meet stringent emissions requirements in 2010. Many diesel engine manufacturers have chosen a technology called Selective Catalytic Reduction (SCR) to meet these requirements. When added to the exhaust gases Diesel Exhaust Fluid reduces the NOx to the EPA required levels. If you purchase a car, truck, tractor or any diesel powered product with SCR technology it will require Diesel Exhaust Fluid.
Q: Is DEF added to the diesel fuel tank?
A: No, DEF should not be added to the fuel tank. Vehicles manufactured with SCR technology are designed with a separate urea tank to hold Diesel Exhaust Fluid. The fluid is then sprayed into the exhaust system.
Q: What measures have been put in place to prevent diesel from being pumped into the DEF tank?
A: The standard nozzle diameter for dispensing DEF has been designed at 19mm versus the standard diesel fuel nozzle diameter, which is 22mm. In addition, the tank cap for the DEF tank will be blue to further differentiation from the diesel tank.
Q: What happens if a non-DEF substance is accidentally entered into the DEF tank?
A: The SCR system will recognize solutions other than DEF, and the DEF indicator light will appear notifying the driver. Depending on the level of contamination in the tank, the vehicle may require servicing.
Q: What happens if the vehicle runs out of DEF?
A: Vehicles using DEF will have indicators on the dash that will alert the driver of the DEF quantity on board. A gauge similar to a fuel gauge will indicate the DEF level. There will be a DEF low level warning lamp illuminated when DEF is low. If a vehicle is operated to the degree of running out of DEF, vehicle power will be reduced enough to encourage the operator to refill the DEF tank. Once the tank has been refilled the engine will resume normal power levels.
Q: How is the quality of DEF insured?
A: A key factor to insuring DEF quality is only purchasing American Petroleum Institute (API) certified DEF. The API symbol on packaging guarantees the product meets the required International Organization for Standardization ISO 22241-1 and AUS 32 specifications. These standards will ensure the proper purity and concentration (32.5%) of urea. 

Another key factor to insuring DEF quality is the proper handling and delivering procedures of the product. DEF should only be purchased from companies such as Hollon Oil Company that can provide proof that they follow these procedures.

Q: How often will refueling of DEF be required?
A: The average consumption rate of DEF is between 2-3% of the diesel fuel consumption. For example, for every 100 gallons of diesel fuel consumed, between 2 and 3 gallons of Diesel Exhaust Fluid will be automatically injected into the exhaust system. A typical diesel truck should go about 300 miles on one gallon of Diesel Exhaust Fluid. The refueling interval will depend on the size of tank you have.
Q: How will DEF be stored and dispensed?
A: DEF is stored in dedicated containers and dispensed through dedicated dispensing units. 
Q: How do I obtain DEF?
A: Hollon Oil Company can provide you with Diesel Exhaust Fluid in a variety of package and dispensing solutions that meet your needs.