In summary, urea is the perfect reductant for use in DEF. Its high solubility and non-toxic nature allow for safe and efficient NOx reduction in diesel engine exhaust. Urea offers the ideal solution for making diesel engines cleaner and meeting emissions standards. Keep reading this blog post by Azure Chemical to learn more.
Contents
Urea Concentration in DEF
DEF comprises 32.5% high-purity urea and 67.5% deionized water. This urea concentration is critical to the proper functioning of the DEF system. Too much or too little urea can reduce the effectiveness of the DEF in reducing NOx emissions.
Extensive testing determined that the 32.5% urea concentration provides the ideal balance of urea to achieve effective NOx conversion while avoiding potential problems like deposit formation from too-high urea concentrations.
Lower urea concentrations below 32.5% will reduce the NOx conversion efficiency. Higher urea concentrations above 32.5% provide no additional NOx conversion benefit and can lead to urea crystal deposits forming in the exhaust system over time.
Maintaining the precise 32.5% urea concentration is essential for DEF to work as designed. Any deviation from this concentration due to improper mixing or dilution can impair the emissions reduction capability of the DEF system.
Proper handling and storage of DEF are important to maintaining the required urea concentration. Vehicles also have sensors to detect improper urea concentrations in the DEF tank and will activate a warning system if the concentration is too high or low. So, maintaining the correct 32.5% urea concentration is critical for effective NOx emissions reduction.
Quality Standards for DEF
To guarantee optimum performance and safety, Diesel Exhaust Fluid (DEF) is held to strict quality control requirements.
Some key quality standards for DEF include:
Concentration
DEF concentration must be 32.5% high-purity urea and 67.5% deionized water by weight. Even slight variations in concentration can negatively impact the DEF’s performance.
Purity
Impurities like calcium, magnesium, sodium, and potassium are limited to very low parts per million. Contaminants can corrode system components or clog injectors.
Storage
DEF must maintain purity for at least one year after production if stored properly between 12°F and 86°F. Storage tanks and dispensers at DEF filling stations must avoid conditions that could introduce impurities.
Handling
Standards dictate proper packaging, handling procedures, and materials compatibility to prevent DEF degradation during transport and storage.
By requiring DEF suppliers to meet precise quality benchmarks, the industry ensures the solutions will reliably provide the intended emissions reductions without harming vehicles or operators. Proper DEF quality gives fleet owners confidence in the performance and safety of their emissions control systems.
DEF Storage
To preserve quality and efficacy, diesel exhaust fluid (DEF) must be stored properly. DEF needs to be kept between 12°F and 86°F (-11°C and 30°C) in a cool, dry location.
Over time, exposure to strong sunshine and extreme temperatures can deteriorate urea.
DEF has a 12-month shelf life when stored correctly in sealed containers. The DEF should be used within a fair amount of time after opening. When not in use, any opening containers should be sealed to prevent evaporation and contamination.
DEF can break down after extended exposure to high temperatures exceeding 86°F, which lowers the concentration of urea. The expected reduction of NOx emissions by the DEF will not occur if the urea concentration falls below a specific threshold.
Storing DEF in areas with temperature fluctuations can also cause condensation inside the tank or container. The water can dilute the urea concentration, so finding an area with a stable, moderate temperature is best.
What is Urea in DEF? DEF should never be kept in a car with a temperature inside that is more than 140°F or in direct sunlight. The heat and UV exposure will quickly break down the urea.
Following the proper storage guidelines will maintain the quality and effectiveness of DEF over time. Proper storage helps avoid degraded DEF that no longer meets the required specifications.
Adding DEF
Diesel Exhaust Fluid (DEF) is added to a separate tank, not the fuel tank. The DEF tank is sized based on the vehicle’s expected driving range between refills.
Depending on driving habits and tank size, the DEF tank may need periodic refilling, similar to refueling the gas tank.
Filling the DEF tank appropriately is important, as this can damage sensors that detect DEF fluid levels. When refilling the DEF tank, it’s advisable to fill slowly and stop when it reaches its maximum fill line to avoid sensor damage. Most DEF fill necks have a narrow opening to prevent overfilling.
DEF evaporates when warm, so tanks may appear less full than expected right after driving. Allow time for the DEF tank to cool before refilling to ensure an accurate fluid level reading. Periodically check the DEF gauge and refill the tank to ensure a sufficient supply for the vehicle’s selective catalytic reduction system.
DEF Handling Precautions
When handling DEF, it’s important to take precautions to avoid exposure. If contact is made, DEF can irritate the skin, eyes, and respiratory system.
Here are some key precautions to take:
- Avoid skin or eye contact with DEF. If skin or eyes are exposed, rinse immediately with plenty of water. Seek medical attention if irritation persists.
- Avoid breathing DEF fumes. Use in well-ventilated areas.
- Rinse any spills thoroughly with water. If left, DEF residues can be corrosive and damage painted or metal surfaces.
- Store DEF tightly sealed in approved containers to prevent spills. Check regularly for leaks.
- Don’t mix DEF with any other chemicals. Incompatible substances may have dangerous reactions.
- Keep DEF away from extreme heat or cold. DEF freezes around 12°F (-11°C).
- Dispose of any waste DEF properly according to local environmental regulations.
By following basic precautions when handling DEF, exposure can be minimized. Rinse spills, wear protective equipment, and store DEF securely. Preventing contact with skin, eyes, or inhalation is key.
DEF Cost
While prices for DEF fluid vary by location, they typically range from $3 to $4 per gallon in the US. Two to three percent of the diesel fuel used is consumed as DEF.
The benefits of SCR and DEF systems for emissions reduction and fuel efficiency outweigh the costs associated with using DEF in diesel vehicles. DEF assists diesel vehicles in meeting strict emissions rules by lowering NOx emissions. DEF improves fuel economy by facilitating more thorough combustion, which makes the engine run more smoothly.
Most experts agree that the benefits of lower emissions and better fuel efficiency outweigh the relatively minor additional cost of purchasing and using DEF fluid. As more new diesel trucks and vehicles are equipped with DEF systems, the cost is likely to decrease over time while the positive impacts on air quality and fuel consumption continue.
Frequently Asked Questions
Here are some of the most requested answers to the specific questions:
What Is Urea in Diesel Exhaust Fluid (DEF)?
Urea in Diesel Exhaust Fluid, also known as DEF, is a non-hazardous solution comprised of 32.5% urea and 67.5% deionized water. Urea is a compound of nitrogen that turns into ammonia when heated. It’s used in DEF to help convert nitrogen oxide, a harmful pollutant, into harmless nitrogen and water.
What Is the Purpose of Urea in DEF?
What is urea in DEF? Urea is critical in the selective catalytic reduction (SCR) process used by diesel engines to reduce harmful nitrogen oxide emissions. When DEF is injected into the exhaust stream of a diesel vehicle, the urea breaks down into ammonia. The SCR process then converts nitrogen oxides, a harmful greenhouse gas, into nitrogen, water, and small amounts of carbon dioxide – all of which are harmless emissions.
How Often Do I Need to Refill DEF?
The frequency at which you need to refill DEF depends on your vehicle’s consumption rate, which can range from 2-3% of diesel fuel consumption. For a vehicle that achieves average fuel efficiency, the DEF tank will need refilling approximately every 5,000-7,000 miles.
Is Urea in DEF Harmful?
Urea in DEF is non-toxic, non-flammable, and non-hazardous. It poses no serious risks to humans or animals on exposure or ingestion. However, it’s always recommended to follow safety guidelines while handling DEF to avoid any discomfort or issues.
In Conclusion
Diesel exhaust fluid (DEF) has become integral to modern diesel engine emissions systems. As diesel engines continue to gain popularity, especially in heavy-duty applications like trucks and buses, DEF usage is expected to keep growing.
Most manufacturers of diesel engines for on-road use employ selective catalytic reduction (SCR) systems that rely on DEF injection. Stringent emissions regulations around the world are also driving increased adoption of SCR. While early SCR systems experienced some technical difficulties, advances in DEF injectors, dosing modules, and sensors have led to more reliable performance.
While DEF has proven to be an effective way to reduce NOx emissions, researchers continue exploring potential alternatives. Ammonia has been considered a replacement for DEF, but it presents safety risks. Hydrogen addition is another area being studied, but DEF still provides superior NOx conversion efficiency.
Given its proven track record and the emissions regulations requiring NOx reduction, DEF will likely continue to be the dominant emissions control agent used with diesel engines into the foreseeable future. The growth of diesel for commercial transportation, agriculture, and industrial applications ensures DEF’s widespread use will continue expanding globally, so act now! Schedule your DEF delivery from Azure Chemical now!
