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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

                                     DEF FAQ's

Q: Is DEF a hazardous material?
A: No, Diesel Exhaust Fluid is classified as a non-hazardous product.
Q: Should I be concerned about handling DEF?
A: No. DEF is a nontoxic, nonpolluting, non-hazardous and nonflammable solution. It is stable, colorless, and meets accepted international standards for purity and composition. DEF is safe to handle and store and poses no serious risk to humans, animals, equipment or the environment when handled properly.  
Q: What should I do if I spill DEF?
A: If DEF is spilled, contain the spilled liquid and absorb it with an inert, non-combustible absorbent material, such as sand. Shovel the material into a suitable container for disposal. Spills into a drain should be avoided. If spilled into a drain, flush thoroughly with water. For significant quantities, contact local authorities for proper disposal procedures. If DEF is spilled on your vehicle, rinse with water.
Q: What happens if I ingest or inhale DEF?
A: DEF should never be ingested. If it is ingested, do not induce vomiting. A physician should be consulted if you begin experience any symptoms. While pumping DEF will not cause significant exposure, inhalation may occur if exposed to DEF in a closed area and/or if DEF is misted into the air. Under normal conditions of use, harmful effects are not expected. If you inhale DEF, you should move to an area with fresh air and obtain medical attention if symptoms, such as irritation to nose and throat, develop or persist.
Q: Does DEF smell?
A: Due to its makeup, DEF may have a harmless ammonia smell.
Q: Is DEF corrosive?
A: DEF is corrosive to copper and brass as well as other materials. Only approved materials, such as high-density polyethylene (HDPE), will be used in the DEF tank, packaging and dispensing equipment.
Q: How much does DEF weigh?
A: DEF weighs approximately 9 pounds per gallon.
Q: What is the freeze point of DEF?
A: A 32.5% solution of DEF will begin to crystallize and freeze at 12 deg F (-11 deg C). At 32.5%, both the urea and water will freeze at the same rate, ensuring that as it thaws, the fluid does not become diluted, or over concentrated. The freezing and unthawing of DEF will not cause degradation of the product.
Q: Does DEF expand when frozen?
A: Yes, DEF expands by approximately 7% when frozen. DEF packaging and tanks are designed to allow for expansion. Caution needs to be taken at filling to allow for DEF expansion in case of freezing.
Q: How do I keep the DEF from freezing? What happens if the DEF freezes in the tank on the vehicle?
A: During vehicle operation, SCR systems are designed to provide heating for the DEF tank and supply lines. If DEF freezes when the vehicle is shut down, start up and normal operation of the vehicle will not be inhibited. The SCR heating system is designed to quickly return the DEF to liquid form and the operation of the vehicle will not be impacted. The freezing and thawing of DEF will not cause degradation of the product.
Q: Can an anti-gelling or freeze point improver be added to the DEF to prevent it from freezing?
A: No. Additives compromise the purity of the DEF solution. Any further blending or adjusting of the DEF mixture will damage its ability to perform correctly and may cause harm to the SCR system. Additives of any type are not approved for use in DEF today.
Q: Are there special storage requirements for DEF?
A: DEF should be stored in a cool, dry, well-ventilated area, out of direct sunlight. Ideal 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.
Q: What is the shelf life of DEF?
A: The shelf life of DEF depends on ambient storage temperature. DEF will degrade over time depending on temperature and exposure to sunlight. 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.
Q: What impact will exposure to high temperatures for an extended period of time have on DEF?
A: While DEF exposure to constant, high storage temperature may have some impact on shelf life, This should not concern operators. Extensive testing in very hot climates has been conducted confirming that DEF stored at a constant temperature of 95 deg F had a shelf life of over 6 months.