Diesel engines, as we all know, contribute greatly to harmful pollutants in the environment. Diesel exhaust fluid (DEF), a substance found in diesel engines, is used to reduce the pollution.
Some people wonder if DEF liquid can catch fire at high temperatures, or when it is exposed to an ignition source. In other words, DEF fluid does not ignite under normal conditions. Because DEF fluid is mostly water-based, it is unlikely that it will catch fire. Let’s find out more. Is DEF Flammable? This article.
Contents
What is Def fluid made of?
Def fluid, a refined form of urea, is what it is. Urea is made up of ammonia and carbon dioxide. DEF is then extracted. It is simply a urea-water combination. Def fluid is composed of 32.5 percent urea, 67.5 percent deionized and 67.5 percent water.
The DEF is used in diesel engines as an additive to reduce the nitrogen oxide emissions. DEF chemically reacts to nitrogen oxide emissions to create nitrogen and water. Emissions can be reduced by as much as 90% by turning hazardous substances into non-hazardous.
Also, read: Is Brake Fluid Flammable?
What Happens If Def Gets Too Hot
The DEF fluid is kept in a separate container, and it is added to the container as necessary. Extreme temperatures can prevent DEF fluid’s efficient operation. Each 100 gallons it uses, the engine will consume 2 to 5 gallons DEF.
At high temperatures, Def fluids can quickly deteriorate and become unusable. Def Fluids should not be left in direct sunlight. They should be stored between 23-77 degrees Fahrenheit.
Between 1400-1600 F, the Def fluid and nitrogen dioxide gasses are combined. Although it won’t burn as strongly in direct sunlight or at very high temperatures, heat can reduce its efficiency and age. Fluids that are exposed to very low temperatures (12 F) can also freeze and cease functioning.
Can Def Fluid Set Fire to Its Promise?
DEF fluid does not ignite and will not cause fire. Because DEF fluid consists mainly of water, this is why it is so non-flammable. The majority of DEF fluid is water and evaporates when it is exposed to high heat.
DEF fluid is used to make diesel fuel. However, it isn’t combustible. DEF fluid will not catch fire if it is set on fire. You just need to keep the DEF liquid in a container that is not flammable. If the container is flammable, heat can be transferred to DEF fluid. This can lead to the DEF fluid expanding.
How Dangerous Is Def?
Def fluid is safe. It is not explosive nor flammable. DEF fluid consists mainly of water and a small amount of urea. There are situations in which DEF fluid could be hazardous.
- When exposed to sunlight or heat for a prolonged period, DEF fluid may expand. At high temperatures, the DEF fluid bottle may melt. Although it is uncommon, DEF fluid can explode if heated for an extended period.
- It can be vaporized at high temperatures, even though it will not catch fire. Because most of the DEF fluid’s volume is water, it can evaporate at temperatures higher than 86 degrees F. The DEF fluid should be kept in a cool, dry place.
- Contact with the DEF fluid on your skin can cause irritation. The DEF fluid can cause irritation and even infection to your eyes or skin if it comes into direct contact with them. When DEF fluid is in your skin, be sure to wash your hands well.
FAQ’s
Is Def Fluid Harmful to the Environment?
DEF is used in diesel engines to minimize emissions. It is safe for the environment. DEF fluid is non-toxic and has no negative environmental impact because it contains 67.5% water and 32.5% urea. However, you should not use it directly as an additive in diesel engines. It is kept in an external container and used as the exhaust gasses are released.
Will Diesel Run Without Def?
It is not suggested to drive a diesel vehicle if the DEF fluid level is low. The Environmental Protection Agency mandates that trucks and other diesel-engine vehicles use the DEF additive to reduce emissions.
When you run out of DEF fluid, you'll notice warning signs on the dashboard. If you drive without DEF fluid, your vehicle will slow and eventually stop. You may also hear grinding noises, and engine parts may wear out.
How Long Will Def Fluid Last?
The DEF fluid should be changed once a year. Normally, 2 to 5 gallons of DEF are required for every 100 gallons of fuel. So, you should refill the DEF fluid every third or fourth time you fill up with diesel. The shelf life of DEF fluid can range from 1–2 years, depending on the conditions under which it is stored. Heat and sunlight can shorten the life of DEF fluid.
Conclusion
DEF fluid is crucial for both the environment as well as the diesel engine. This fluid is used in diesel fuel additives, but is not flammable or toxic. This fluid is simply a mixture of water and urea which reduces the emissions when combined with nitrogen dioxide.
DEF fluid is completely safe to store, and it will not catch on fire when exposed high temperatures. Avoid storing it in direct sunlight or in hot environments as this could reduce its effectiveness and decrease its shelf life.

Hey, I’m Bryan and I have been working as a mechanic for the past 8 years. I want to help each one of you reach make wise decisions when it comes to choosing the right products for keeping your cars healthy.