Is Antifreeze Flammable? What You Need to Know

Do you live somewhere cold and drive a car? If so, then surely you've come across antifreeze. Antifreeze is the colored liquid we dump into our vehicles to help regulate the engine in freezing temperatures. 

Given that circumstance, does it even make sense to ask the question - is antifreeze flammable? You may be surprised at the answer, so let's dig deeper into what antifreeze is, what it does, and how to manage it safely.

So, is antifreeze flammable? Yes, antifreeze is flammable and has been categorized as a flammable liquid by the National Fire Protection Association (NFPA).

Is Antifreeze Flammable

What Is Antifreeze?

Antifreeze is an ingredient that can be added to any water-based liquid to lower its freezing point. This means if water freezes at 32°F, antifreeze can reduce that to 10°F to 15°F, depending on the concentration and circumstances. 

Because of this, antifreeze can help the operation of machinery and engines in cold weather by allowing fluids not to freeze up.

Since water is cheap and found almost everywhere, it was initially used as a coolant for internal combustion engines to remove heat waste. However, water's limitations (limited temperature range before freezing or boiling) made it less ideal in more extreme climates. 

This is where antifreeze comes in. When you add antifreeze to water, it expands, and its ability to function beyond the typical temperature range improves - both freezing and boiling.

Antifreeze is typically comprised of mostly ethylene glycol or propylene glycol. However, it contains other additives such as silicates, nitrates, azoles, or borates. These additives help prevent oxidation which causes corrosion. With that said, all these additives still make up less than 10% of the antifreeze solution.

You will also hear many people use antifreeze and coolant interchangeably. But they are different. Coolant is a mixture of antifreeze with water, typically in a 50/50 ratio, but that can vary. 

This is important to understand because some types of automotive antifreeze are already mixed with water; therefore, before you put it in your car engine, it's essential to read the label and understand if you need to include any water.

What Is Antifreeze Used For?

Antifreeze is usually mixed with water in equal parts, depending on the engine and your car, creating engine coolant. Either ethylene glycol or propylene glycol is typically the main ingredient of antifreeze. 

The glycol becomes a base to form a liquid pumped through the car engine block or other heavy machinery. This allows the water-based fluid not to freeze and perform perfectly fine, even in extreme temperatures. 

Antifreeze and coolant have additional uses, such as in solar water heaters, HVAC chillers, fire abatement systems, and other places. Anywhere there is a need for fluids to regulate temperatures and transfer heat. 

In addition, ethylene glycol, in particular, has a lower viscosity, so it’s helpful when pumping requirements exist.

Depending on the quality, antifreeze and coolant can also help prevent corrosion and cavitation due to the additives in the solutions. 

In the early days, most coolants used methanol; however, more recently, other elements such as propylene glycol, methyl ether, or glycerol have become the main additives in antifreeze.

Is Antifreeze Flammable?

As we've discussed, antifreeze is flammable, whether it contains ethylene glycol or propylene glycol. Through time, antifreeze has been one of the main contributors to a vehicle's fire hazard risk, so you should use it safely to avoid an engine fire. You don't want other vehicle fluids like brake fluid, transmission fluid, or motor oil to start burning as well.

Antifreeze typically has a flash point of approximately 232°F and an auto-ignition temperature between 950°F and 1,245°F, depending on concentrations and surroundings. 

However, according to tests conducted by JCM Machine & Coatings, temperatures from 650°F to 750°F can be enough to start auto-ignition. What is more dangerous is that no spark is needed so that ignition can be spontaneous and immediate. 

In addition, CAMEO Chemicals, a database of hazardous chemical information used by emergency planners and responders, and created by the National Oceanic and Atmospheric Administration (NOAA), classifies antifreeze as a flammable liquid

We've discussed the flammability of antifreeze; what about the flammability of coolant? Is coolant flammable? While you may think that since coolant has a 50/50 concentration of water and antifreeze, it may not be flammable. However, coolant is still flammable.

This is because ethylene glycol and propylene glycol tend to evaporate quickly, leaving the coolant to condense again nearby or even ignite as a vapor.

Is Coolant Flammable

Can Antifreeze Catch Fire?

As we’ve seen, antifreeze does have the capability of being flammable. As far as the solution being able to catch fire, the answer is still a yes. Antifreeze quickly catches fire and has an auto-ignition temperature of around 650°F to 750°F.

In closed cup tests, antifreeze has a flash point of around 232°F, which means that antifreeze cannot easily catch fire in ordinary usage at reasonable temperatures. However, it should be used safely and treated with caution because the solution is flammable. 

When using antifreeze, ensure you’re not around a naked flame or high temperature. To prevent an explosion, you should also avoid electrical sparks or places with exposed electrical wiring.

Is Water-Based Antifreeze Flammable?

When discussing antifreeze and its variations, another question that comes up is whether or not water-based antifreeze is flammable. Unfortunately, this situation is more complicated.

It's rare for a water-based antifreeze to catch on fire or become flammable. Water-based antifreeze is typically not involved in fires because the high element of water can extinguish the fire.

With that said, water-based antifreeze is not practical because once the water evaporates, it will leave the glycol behind to continue the combustion.

Safety Measures For Antifreeze

Since we’ve determined that antifreeze is flammable, it should always be kept in storage that is out of reach of children and pets. Ingesting antifreeze can lead to liver failure and even death. It should be stored in a cool and dry place, away from any sparks or sources of fire that can trigger the solution to burn.

Another critical factor is to always keep the label on. This will help anyone identify the antifreeze and treat it carefully. Finally, always use gloves and never allow the antifreeze to contact your skin. In case it does, immediately wash with soap and water. 

Perhaps most importantly, you should always keep antifreeze away from a fire or naked flame. That will only trigger the solution's ignition and lead to a fire.

In addition, antifreeze solutions are toxic and environmentally harmful, so you should properly dispose of any waste at your local hazardous waste facility.

Is Antifreeze Flammable 1

Why Is Antifreeze Used In Sprinkler Systems If It's Flammable?

Even though antifreeze is flammable, it's a key ingredient in modern sprinkler systems. So how exactly is antifreeze used, and why?

One of the primary reasons why antifreeze is used in a fire sprinkler system is to prevent freezing temperatures from damaging the system. Unfortunately, freezing can block sprinkler-system pipes, leading to costly repairs. 

Another way antifreeze helps to protect sprinklers is by preventing moisture-related corrosion. Unfortunately, such corrosion often causes pinhole leaks, leading to more problems within a system.

Although it may sound counterintuitive at first glance, many experts agree that antifreeze can provide reliable protection when appropriately used in a residential or commercial fire protection system – so long as caution and common sense are employed throughout!

Final Thoughts 

So, is antifreeze flammable? Most definitely.  And it is an essential component of a car's cooling system, but unfortunately, it can also be dangerous if mishandled. 

It is highly recommended to take all necessary safety precautions when storing and handling antifreeze since its fumes can be toxic and flammable. 

As with any other chemical product, ensure you read the instructions on the container before using it and keep it away from children or pets.

By being informed about the potential risks associated with antifreeze, you can ensure a much safer environment for your vehicle and your family. 

Knowing is half the battle—now you know!