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Joe Zajac
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Phone: (800) 658-7716

Diesel Exhaust Fluid

Diesel Urea

Chemicals Direct is a distributor of Diesel Urea.

Please contact our online sales manager, Joe Zajac,

What is DEF (Diesel Exhaust Fluid)?


Diesel Urea is comprised of 2 major components; urea and Deionized water (DI). Urea is an organic compound with the chemical formula (NH2)2CO.  Urea has common uses in fertilizer, agriculture, and the pharmaceutical industry. Urea is used at a 32.5 % mixture with 67.5% DI water in Diesel Urea in Selective Catalytic Reduction Systems (SCR). The fluid is in used to reduce the NOx pollutants, in exhaust gases from combustion from diesel, dual fuel, and lean-burn natural gas engines. In afore mentioned SCR systems; a water based urea solution is injected into the exhaust system. The ammonia produced by the hydrolysis of urea reacts with the NOx emissions and is converted into nitrogen and water within the catalytic converter.

Some quick facts regarding Diesel Urea

  • DEF is a stable fluid that will not separate, and is colorless
  • DEF is not flammable
  • DEF is not a pollutant
  • DEF is not listed by any U.S. or Canadian transit authority as a hazardous material
  • DEF is not impacted by freezing and subsequent defrosting. However it does freeze at 11°F. The heating and cooling system on board is used to thaw the fluid
  • DEF will degrade in direct sunlight
  • DEF may have a slight odor similar to ammonia
  • DEF weighs 9.10 lbs per gallon and is shipped Class 14  an “Environmentally friendly fluid”


Diesel Urea is recommended to be handled with care, with no contamination allowed. Diesel Urea does not pose any risk to humans, animals, the environment, or equipment. Product quality standards must be maintained throughout the supply chain. Distributors and users of the fluid must have dedicated transportation and storage (stainless steel and/or poly). The heating and cooling system on board is used to heat and cool the DEF tank until there is proper flow. The engine will operate up to 70 minutes in cold temperatures at what point DEF flow must be reached. Once the product is delivered to the user for use; dispensing the fluid properly is important. A closed sealed connector systems is always recommended. All pumps, valves, hoses, meters, and nozzles, must be dedicated for Diesel Urea and not shared with any other fluids.


To get the most out of product shelf life, the ideal storage temperature is between 20°F and 85°F. Expectations for shelf life are defined in ISO 22241-3 when stored properly. Diesel Urea  will degrade in time depending on temperature and exposure to sunlight. If the maximum temperature does not exceed approximately 75° F for an extended period of time the shelf life will be easily two years. Temporary exposure to high temperatures has little or no impact on DEF. Diesel Urea is stored at extremely cold temperatures (the fluid will freeze at 11°F), however the product is not impacted by freezing and subsequent defrosting of the fluid. *Easy tip: keep the fluid out of the direct sunlight, extremely hot, and extremely cold temperatures for a prolonged periods of time and you will be on your way. If the fluid is stored in extremely hot temperatures the fluid is not “bad” it will simply be consumed at a higher rate by the vehicle.

Shelf Life

Shelf Life is a function of Ambient Storage Temperature. Listed below is a chart outlining the guide for shelf life based on ISO 22241-3 specifications.

Temperature º F Temperature º C Minimum Shelf Life
< 50º F < 10º C 36 months
< 77º F < 25º C 18 months
< 86º F < 30º C 12 months
< 95º F < 35º C 6 months
< 95º F < 35º C Retest each lot

Usage & Fuel Economy

Diesel Urea will be consumed at a rate of 2-4% of diesel fuel. It is also true that Diesel Urea will contribute approximately 4% fuel economy savings to the average vehicle. SCR is designed to chemically reduce the NOx output of the exhaust gas after the diesel particulate filter. Because this is being completed after the combustion process, it allows the engine design to be modified for maximized fuel efficiency; lowering engine EGR rates, thus increasing the in cylinder oxygen content which can lower engine particulate matter output. Less particulate matter also reduces the amount of fuel used for soot regeneration cycles. Fleet owners can operate engines at higher efficiency and save money. See both of the examples below

+Joseph Zajac

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