DEF: 10 FAQs Answered

By Published On: April 15, 2024Categories: Daily Market News & Insights

In the world of modern diesel engines, a significant component has emerged: Diesel Exhaust Fluid, or DEF. This fluid plays an important role in transforming engine operations by curbing harmful emissions. As diesel-powered vehicles and machinery continue to gain traction for their efficiency and power, understanding it becomes crucial for fleet owners and operators.

Diesel Exhaust Fluid is a solution primarily composed of urea and deionized water. It is a crucial element in the selective catalytic reduction (SCR) process, a technology that reduces nitrogen oxide (NOx) emissions from diesel engines. It is injected into the exhaust stream of diesel vehicles equipped with SCR systems, where it reacts with harmful nitrogen oxides and converts them into harmless nitrogen and water vapor. You can learn more about DEF here.

In today’s article, we’ll dive into ten common questions about DEF.

  1. How did introducing SCR engines change emissions control for heavy-duty diesel vehicles in the US?

The automotive industry has come a long way since the Clean Air Act was introduced in 1970. Though SCR engines had been used in other countries, they hit the US market by storm in 2011, revolutionizing emission controls for US heavy-duty diesel trucks, including buses, trucks, and (later) construction equipment. As a cost-effective and fuel-efficient solution, it became indispensable in helping fleet owners and operators comply with the EPA emissions standards, which demand reductions in particulate matter (PM) and nitrogen oxides (NOx).

  1. What maintenance is required for an SCR system?

Performing routine inspections and maintenance on the SCR system is crucial for preventing issues such as clogging and minimizing the risk of costly repairs. Adhering to the manufacturer’s recommended cleaning and inspection procedures is essential. Additionally, conducting regular checks for leaks in the SCR system and promptly addressing any identified leaks is imperative to prevent potential damage to the system. Learn more about SCR technology here.

  1. What happens if my vehicle runs out of DEF?

Running out of diesel exhaust fluid can lead to serious issues. If you find yourself in this situation, it’s crucial to refill your supply promptly. Running empty on DEF can result in noticeable signs such as a significant decrease in vehicle speed, potential damage to the header, and the risk of clogging or malfunction in the exhaust system.

  1. What happens to DEF if it’s exposed to high temperatures?

DEF’s shelf life may degrade at elevated temperatures. When kept at or above 120 degrees Fahrenheit, it gradually generates minor quantities of ammonia.  Stringent adherence to proper handling and storage practices within prescribed temperature ranges is pivotal for safeguarding quality. Don’t hesitate to ask your supplier for guidance on the proper storage and handling of DEF. Click here to learn how to maintain quality.

  1. Why is there a white, chalky residue around my container?

If the deionized water evaporates from the DEF solution, solid urea crystals will form, similar to what happens when salt water evaporates. Ensure your container caps are tightly sealed to minimize evaporation. Don’t forget to check regularly for leaks in your storage tanks.

  1. Is DEF a hazardous substance?

There’s a common misconception that mishandling it can lead to serious health problems. However, it is actually completely safe—it’s non-toxic, non-flammable, and non-hazardous. It’s perfectly safe for transport and poses no risk if it touches the skin.

  1. If I need to dispose of off-spec DEF, what is the best practice for doing so?

Although it is not a hazardous material, check with your local government, municipal, and environmental agencies on the proper disposal method. These entities will include (but are not limited to) your local water treatment facility and the Department of Health and Environmental Control. Also, check with your supplier for more instructions.

  1. How much DEF will my SCR vehicle consume?

Consumption typically correlates with diesel fuel usage, with rates ranging from 2% to 3%. Variations may arise based on engine specifications, with off-road vehicles potentially exhibiting higher consumption rates.

  1. How is DEF delivered and packaged?

DEF is available in various packaging formats, encompassing jugs, drums, totes, and bulk dispensing systems, catering to diverse fleet’s needs and goals. Using incorrect storage equipment can result in frequent run-outs and higher logistics costs. By right-sizing equipment, fleet owners can reduce DEF costs by 25% to 50%.

  1. Where can I get DEF?

Although DEF distribution in the US is an emerging industry, most major truck stops, gas stations, and auto/truck dealerships will carry the product in packaged form. Some of these establishments will also offer fill-up and top-off through dispensers. Users can also install bulk dispensing systems at their facilities. Learn how to manage your DEF program efficiently here!


Searching for a High-Quality DEF for your Fleet? Look no further!

Mansfield Energy understands the importance of protecting your fleet assets. Today’s high-tech diesel engines are expensive. Using poor quality, off-spec DEF can increase fuel consumption, equipment downtime, and maintenance expenses. Mansfield ensures customers always have a reliable supply of high-quality DEF that consistently meets ISO standards.

With our extensive network of distribution partners combined with our own dedicated assets, Mansfield offers unmatched logistics to ensure you always have the DEF you need. Contact us today!

This article is part of Daily Market News & Insights


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The information contained herein is derived from sources believed to be reliable; however, this information is not guaranteed as to its accuracy or completeness. Furthermore, no responsibility is assumed for use of this material and no express or implied warranties or guarantees are made. This material and any view or comment expressed herein are provided for informational purposes only and should not be construed in any way as an inducement or recommendation to buy or sell products, commodity futures or options contracts.

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