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Diesel Exhuast Fluid (DEF)

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What is D.E.F.?
Diesel exhaust fluid remains quite a mystery to most of the population of diesel engine users in the U.S.  today.  This will hopefully clear up what DEF is , why it is so rapidly expanding to diesel engines and what that means to your operation.

Diesel Exhaust Fluid (DEF), also referred to as AdBlue and standardized as ISO 22241[1], is an aqueous urea solution made with 32.5% high-purity urea and 67.5% deionized water. DEF is used as a consumable in selective catalytic reduction in order to lower NOx concentration in the diesel exhaust emissions from diesel engines. 

Below is a simple sketch of how it works:

Diesel engines can be run with a lean burn air-to-fuel ratio to ensure the full combustion of soot and to prevent the exhaust of unburnt fuel. The excess oxygen leads to the generation of nitrogen oxides (NOx), which are harmful pollutants. Selective catalytic reduction is used to reduce the amount of NOx released into the atmosphere. Diesel exhaust fluid (from a separate DEF tank) is injected into the exhaust pipeline, the aqueous urea vaporizes and decomposes to form ammonia and carbon dioxide. Within the SCR catalyst, the NOx are catalytically reduced by the ammonia (NH3) into water (H2O) and nitrogen (N2), which are both harmless. They are then released through the exhaust.

What quantities of DEF does Cooperative Elevator Co. provide?



Storage Requirements
DEF dependent diesel systems are sensitive to potential chemical impurities in the urea solution; therefore, the solvent is deionized water. The urea solution is clear, non-toxic and safe to handle. However, it can corrode some metals so it must be stored and transported carefully.

DEF should be stored in a cool, dry, well-ventilated area, out of direct sunlight. While the optimum storage temperature is up to 77 deg F (25 deg C), temporary exposure to higher temperatures has little to no impact on the quality of DEF.

Does DEF have a shelf life?
The shelf life of DEF is a function of ambient storage temperature. DEF will degrade over time depending on temperature and exposure to sun light. Expectations for shelf life as defined by ISO Spec 22241-3 are the minimum expectations for shelf life when stored at constant temperatures. If stored between 10 and 90 deg F, shelf life will easily be one year. If the maximum temperature does not exceed approximately 75 deg F for an extended period of time, the shelf life will be two years.

Can I make my own DEF?
DEF has strict requirements for maintaining concentration and purity of ingredients that is critical to the proper functioning and longevity of the SCR system. OEMs require that DEF used with their SCR systems meet all ISO22241 specifications as well as API certification requirements. It is recommended that end users purchase certified DEF and avoid blending it themselves. For more information about the quality standards, refer to ISO22241 which details specifications for DEF quality, handling, testing, transportation storage and refilling. Cooperative Elevator Co. goes the extra mile to ensure that our product comes from the supplier in locked containers to ensure quality standards are met.

How much DEF will by equipment burn?
This can vary depending on your equipment.  Always check your operator’s manual to know for certain.  DEF is stored in a tank on board the vehicle and injected into the exhaust stream by a metering system. The injection rate depends on the specific after-treatment system, but is typically 2-6% of diesel consumption volume. This low dosing rate ensures long fluid refill intervals and minimizes the tank's size. An electronic control unit adjusts the addition of fluid in accordance with such parameters as engine operating temperature and speed.

DEF consumption will be between 2% and 6% of the diesel fuel consumed. Another way to consider it is that DEF will be consumed on a 50 to 1 ratio with diesel. (For every 50 gallons of diesel fuel burned, you will use 1 gallon of DEF). If you know the average fuel consumption of a vehicle, you can easily calculate the amount of DEF that will be used.

Annual miles for average truck = 50,000 miles
MPG for average truck = 8 mpg
50,000 miles / 8 mpg = 6,250 gallons diesel fuel per year
DEF usage @ 2% of fuel consumption = 125 gallons of DEF / year
125 gallons / 10 gallon tank (average size) = 13 DEF fill-ups / year

We hope that you have found this useful and informative.  Cooperative Elevator Co. can supply all of your Diesel Exhaust Fluid needs all year long.  Please stop by any of our convenient locations or contact your Energy Sales Specialist, Joey Adams, at 989-963-9140.

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