Is Brake Fluid Flammable? (Answered)

Brake fluid is an essential element of a vehicle’s clutch and brake system. It plays a significant role in ensuring power transmission in a car. It features a viscosity and high boiling point that contributes to its high-performance level as a hydraulic fluid. But is brake fluid flammable?

Yes, brake fluid is flammable! This is because it is derived from an ethyl-glycol chemical.

It is flammable, and you should also be very mindful of how you handle it, especially when there is an open fire source or heated substance. Brake fluid is toxic too and can rust your paint.

Is Brake Fluid Flammable?

If you are an experienced driver or mechanic, you will know that the engine bay features many dangerous and highly flammable fluids in its tight space.

Since the engine operates at a high temperature, the parts around it require high tolerating abilities to enable it to keep the engine oil, fuel and fluids separated.

Due to the above factor, it becomes crucial to know which flammable fluids and those that are not. However, brake fluid is a flammable liquid but not capable of causing an explosion in a general sense. In other words, it may not ignite a fire but can flame up an already existing fire.

Brake fluids are flammable because they are made of polyalkylene glycols, which can ignite spontaneously on a surface heated to 390 or 400 degrees Celsius.

Therefore, when accidents occur, a modern brake fluid that spills on an exhaust system at or above 400 degrees Celsius will light up spontaneously.

In addition, the fireball that burns from the resulting ignition is enough to distribute to other plastics like cable covers, air filters, etc., except it is put off as quickly as possible.

How Is It Possible for a Brake Fluid to Catch on Fire?

As we earlier discussed, brake fluid is a flammable substance but not volatile as the likes of gasoline and others.

It is usually poured within the sealed brake mechanism, covered and secured from an external source of heat; therefore, the brake calipers are its only source of heat due to the friction between the pads and the brake disc.

So, the only guarantee that brake fluid will catch on fire is when you expose it to excess heat, not only a direct flame.

And there is no way it will occur except if something else around or inside the engine bay catches on fire and burn with enormous power. 

Even at that, such an amount of heat mainly results in the brake system leak, which will cause the brake fluid to leak out and spill over before it can lead to an explosion. But whatever be the cause, we would advise you to be careful to avoid any form of disaster.

What Is Brake Fluid Made Of?

You can only determine what brake fluid is made of via its DOT standard. DOT 2 fluid is composed of castor oil or alcohol, and while those elements are incredibly flammable, DOT 2 has long been outdated. The DOT 4, DOT 4+, and DOT 5.1 brake fluids utilize any one glycol ether or borate ester. 

DOT 3 composition includes just the glycol ether. They are all added to the 5-30% polyethylene glycol lubricants and 5% additives. Unfortunately, all three elements are incredibly flammable, thus making the mixture pretty risky and a fire hazard.

As far as the DOT 5 brake fluid is concerned, it is entirely different from others because it is composed of silicone instead of glycol.

Flammability-wise, it is the safest because it is highly resistant to heat. However, that doesn’t prevent it from catching on fire, especially if you heat it to a certain degree.

Frequently Asked Questions

Is Brake Fluid Highly Flammable?

Brake fluid might be flammable but not highly flammable. Unlike gasoline, it cannot be ignited by just a single spark and needs a certain degree of heat before it can start to burn, and even if it ignites, it doesn’t produce a ferocious flame.

Is DOT 3 Brake Fluid Flammable?

Since the DOT 3 brake fluid is primarily made of glycol ether, considered a moderately flammable chemical, you can see it as volatile but not highly flammable or easily catch on fire.

What should be my immediate remedy to spilt brake fluid?

Brake fluid is a very toxic substance; therefore, you must take as much as possible. You can use paper towels to contain enough fluid as possible before washing the spot with water.

What car fluids are flammable?

Generally, every car fluid is flammable, with fuel being the most explosive. The engine and transmission fluid can efficiently combust, but the same goes for the coolant, power steering fluid, and brake fluid. Most times, the window washer fluid can be flammable in as much as it has the ideal formula. But in general, it’s precisely the safest liquid within the engine bay.

Can Brake Fluid start a fire?

Brake fluid can hardly start a fire since the system lacks any heated substance to make it ignite, even though leakage occurs in it.

Does Brake Fluid evaporate?

Like all liquid, brake fluid tends to evaporate, even though its primary function is to resist heat and not evaporate since that will affect the effectiveness of the brake component. The dry boiling point of brake fluid is approximately 230 degrees Celsius. That is significantly higher than the boiling point of water.

Is DOT 4 Brake Fluid Flammable?

Since DOT 4 brake fluid is made of polyglycol ether, it can burn if exposed to high temperatures. Its flashpoint lies within 210 to 375 degrees Fahrenheit. In other words, it is more volatile than those fluids made of silicon. If you expose the DOT 4 to temperatures of 540 to 675 degrees Fahrenheit, it can cause fire on its own.

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