Is Diesel Exhaust Fluid Flammable

Is Diesel Exhaust Fluid Flammable?

When it comes to diesel exhaust fluid, commonly known as DEF, one question that often arises is whether it is flammable or not. In this article, we will explore the flammability of DEF and provide a clear answer to this frequently asked question.

In simple terms, no, diesel exhaust fluid is not flammable. DEF is a non-hazardous, non-flammable fluid that consists of a mixture of urea and deionized water. It is used in modern diesel engines with selective catalytic reduction (SCR) technology to reduce harmful nitrogen oxide (NOx) emissions.

The combination of urea and deionized water creates a liquid solution that is designed to be sprayed into the exhaust stream of diesel engines. This solution breaks down harmful nitrogen oxide emissions into harmless nitrogen and water vapor, significantly reducing air pollution. The injection of DEF into the exhaust system is a crucial part of the SCR process to meet strict emission standards.

One of the reasons why DEF is not flammable is its composition. Urea is a non-flammable substance commonly found in fertilizers, and deionized water does not have flammable properties either. The precise mixture of urea and deionized water in DEF ensures that it remains safe and non-flammable in any situation.

Is Diesel Exhaust Fluid Flammable


Is Diesel Exhaust Fluid Flammable


Flammability Testing of Diesel Exhaust Fluid

To demonstrate the non-flammability of DEF, let’s delve into some flammability testing results conducted on this fluid. DEF has been extensively tested according to various flammability standards, including ASTM (American Society for Testing and Materials) tests.

During these tests, DEF was exposed to open flame or high temperatures, which are typical scenarios where flammable substances would ignite or catch fire. The results consistently showed that DEF does not catch fire, even when exposed to direct flames or extreme heat.

Additionally, DEF has a high flash point, which means that it requires a significantly higher temperature to produce flammable vapors compared to other substances. This further emphasizes its non-flammable nature and reinforces its safety for handling and storage.

Safe Handling and Storage of Diesel Exhaust Fluid

Due to its non-flammable properties, DEF does not require any special safety precautions during handling or storage. However, it is always a good practice to follow a few basic guidelines to ensure the quality and effectiveness of DEF:

  • Store DEF in a cool, dry place, away from direct sunlight or extreme temperatures.
  • Use closed containers designed specifically for DEF to prevent contamination and maintain its purity.
  • Avoid contact with petroleum-based products, as they can damage the composition of DEF.
  • Handle DEF with care to prevent spills, and clean any spills immediately with water.

By following these simple guidelines, you can ensure the proper handling and storage of DEF and maintain its quality for optimal performance in your diesel engine.

Frequently Asked Questions On Is Diesel Exhaust Fluid Flammable

Is Diesel Exhaust Fluid Flammable?

Diesel Exhaust Fluid (DEF) is non-flammable and has a high flash point, making it safe to handle and transport.

Can Diesel Exhaust Fluid Ignite?

No, Diesel Exhaust Fluid does not ignite. It is designed to break down harmful emissions without posing any flammability risks.

What Happens If Diesel Exhaust Fluid Catches Fire?

In the rare event of a fire involving DEF, it would not burn or contribute to the flames. It simply evaporates, leaving behind water vapor.

Is It Dangerous To Store Diesel Exhaust Fluid?

No, storing DEF is safe as long as it is done properly. It should be stored in a cool, dry place away from direct sunlight or extreme temperatures.


In conclusion, diesel exhaust fluid is a non-flammable substance that plays a crucial role in reducing harmful emissions from diesel engines. Its composition, flammability testing results, and safe handling guidelines all confirm the non-flammability of DEF.

So, for anyone concerned about the flammability of diesel exhaust fluid, rest assured that it is a safe and non-flammable solution that helps protect the environment and comply with emission regulations.

Updated: February 13, 2024 — 2:53 am