If you’re someone who uses a diesel vehicle, then at some point, you must’ve heard experts use DEF to reduce the emission of engine pollution. But wait, is Diesel Exhaust Fluid (DEF) flammable?
Well, no! DEF isn’t flammable, nor is it explosive. The DEF chemical composition has no such properties that can cause it to burn or explode. However, there are certain conditions where the container it’s being stored can result in a fire or cause an explosion.
Want to know how? Then binge on till the end of this blog!

Is There Any Possible Way for DEF to Start a Fire?
Well, no, not really! DEF (Diesel Exhaust Fluid) cannot catch fire on its own. The reason for such behavior is pretty straightforward. This fluid is not considered fuel and can stay unreactive at normal temperatures. Plus, if you consider keeping it near a fire, it won’t actually ignite or cause any fire hazard.
But here’s something you need to keep in mind! If you put DEF in a container, then there are chances for the additive to catch fire. This is because if you put DEF in certain flammable containers, the additive will start to expand, and this can cause a fire.
However, not the DEF will catch fire, but the container! So, it’s highly recommended that you choose the right container to store the additive to avoid such mishaps.
Is DEF Explosive? A Brief Overview
The answer is no! This is because the fluid has no flammable properties that can lead to a fire outbreak. So, there’s no chance of an explosion when dealing with DEF. Plus, the liquid is used in SCR (Selective Catalytic Reduction) system to ensure that your diesel engines don’t emit too much nitrogen oxide.

Even though DEF isn’t explosive, it still needs to be handled with caution, and you also need to store it correctly. This is because storing it in normal containers with certain heat sources can cause the container to explode, eventually leading to a fire.
Dos and Don’ts While Handling DEF
In this section, we’ve listed some of the possible dos and don’ts that you must always follow to ensure you’re handling the DEF safely. So, keep reading till the very end of the section.
Things You Need to Do:
- Ensure that the DEF is perfectly filled in the tank, and check that the outlet and nozzle are clearly marked. This will keep you secure from certain fire accidents.
- No matter how safe DEF might be, you must always put on protective gear like heat-resistant gloves, clothes, and eyewear. This is to keep you safe from sudden fire mishaps.
- Keeping your DEF equipment clean is one of the checklists that you need to fill since contamination of the equipment might result in certain mishaps and accidents.
- There can be times when your DEF container may get heated. In such cases, the best possible solution is to keep the container chilled with cold water.
- Although sealing might not always be needed when dealing with DEF, for proper safety, it’s recommended that you only use those DEF that are delivered to you with sealed packages.
Things You Shouldn’t Do:
- You should never fill DEF in a diesel tank as this can damage your engine and even lead to fire accidents. And the same goes for a diesel too. It’s not recommended that you put diesel in a DEF tank.
- If the DEF somehow gets into your eyes or spills on your skin, don’t just leave it like that. This can cause certain eye and skin irritation. Immediately rinse your face and skin with cold water.
- Never use DEF, especially when mixed with substances like diesel fuel or water. This can cause certain issues with your engine.
How to Extinguish DEF Container Fire?
Although DEF isn’t flammable or explosive, there are times when the container it’s being stored can backfire. This can possibly happen due to certain heat sources. So, here in this section, you’ll have a step-by-step guide to extinguishing DEF container fire.
Step-1: Whenever you see the DEF container caught fire, you first need to call your nearby fire service to handle the situation before it reaches out of hand. Even if the fire isn’t large enough, it’s recommended to take experts’ help, especially if you aren’t prepared for a sudden mishap.
Step-2: However, if you’re well equipped with the right fire extinguisher (Classes A, B, and C are the most suitable ones), then stand at a safe distance to start the extinguishing process.
Note: Make sure that you’re wearing the right fire gear, like fire-protective goggles, gloves, and clothes. It may appear not an essential step, but when things go south, this fire gear will come in handy.
Step-3: Once you’re in position, hold the fire extinguisher and spray directly at the DEF container’s base. This way, the fire won’t spread any further, and it’ll soon get extinguished.
Experts’ Tip: During your extinguishing process, remember not to inhale the fumes, as this can be detrimental to your health.
Is Lavender Oil More or Less Flammable Than Diesel Exhaust Fluid (DEF)?
Using lavender oil products is generally safe as they are not known to be highly flammable compared to commonly used fluids such as diesel exhaust fluid (DEF). DEF is a solution used in vehicular exhaust systems, making it a highly combustible substance. It is important to handle flammable materials with caution to avoid any accidents. With proper care and attention, lavender oil is a great alternative to potentially hazardous chemicals.
Frequently Asked Questions
1. Is the Blue DEF diesel exhaust fluid flammable?
Well, no! The Blue DEF is simply a colorless and non-flammable chemical that has no potential fire risks. But when it comes to contact with the skin, it needs to be rinsed immediately.
2. What’s the max temperature for the DEF liquid?
25 degrees Celcius is the max temperature for the DEF fluid. And it’s also recommended that you store it in a well-ventilated and cool area.
3. What happens when DEF gets exposed to sunlight?
Experts always recommend storing DEF out of direct sun exposure as it can degrade the DEF’s urea potency.
Bottom Line
After going through this article, you should clearly understand that DEF isn’t flammable or explosive.
However, under certain conditions, the container it’s stored in can get heated, which may cause the liquid to expand, leading to a fire in the container. So, make sure you read the dos and don’ts carefully while handling DEF to stay away from such mishaps.