Is Brake Fluid Flammable?

Does brake fluid burn or not? Does DOT classification matter? Here's a super simple guide, which includes the flashpoint of brake fluid.

Any vehicle fire is a driver’s worst nightmare.

Knowing what might lead to a fire in your car is essential. Maybe you’re coming to top up the brake fluid? Perhaps you’ve been involved in an accident? Or maybe you want to know what to do if it ever happens?

Whatever your situation, “Is brake fluid flammable?” is a reasonable question.

This guide will explain why brake fluid can catch fire but poses a low risk in most situations.

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Properties Of Brake Fluid

car brake fluid

Brake fluid is one of a car’s most vital fluids. Slowing down is, of course, essential. When we brake, we prevent collisions and otherwise fatal accidents.

It makes sense to take a closer look at this unique liquid.

  1. Brake fluid must withstand extreme temperature changes.
  2. Good brake fluid maintains a constant viscosity in all circumstances.
  3. Brake fluid must also not corrode other parts of the brake system like any metal or valves.
  4. You may have noticed how it takes longer to slow down when braking an old car compared to a new one. This issue, in part, concerns the level of brake fluid compression.
  5. The higher the brake fluid’s boiling point, the better. This keeps water vapors out of the system and means the brakes work correctly.
  6. Nowadays, a braking system is full of modern technology that improves road safety. All new cars come with ABS and ESP as standard.

These are the primary functions and most important aspects of brake fluid. They mean it must be a specific, carefully-engineered chemical formula.

The chemicals used in all brake fluids (DOT 3 and DOT 4 being the most common on passenger vehicles) mean that this formula can – unavoidably – ignite.

So, Does Brake Fluid Burn?

Brake Fluid Change Cost

With the knowledge we’ve gathered on these special fluids, is brake fluid flammable?

study by the Transportation research board demonstrated that brake fluid is inflammable. The tests in this study revealed that brake fluid ignited above 734 – 752 degrees Fahrenheit (390 – 400 degrees Celsius).

Inflammable” doesn’t mean brake fluid can’t catch fire. It actually means it can ignite without an ignition source. This means you should treat it with even more care than flammable liquids.

The flashpoint of a liquid is the temperature at which the vapors could ignite and sustain a fire. The flashpoint of brake fluid depends on its precise chemical makeup. The University of Washington lists the flashpoint of brake fluid as between 210 – 375 degrees Fahrenheit.

Brake fluid doesn’t burn so intensely as other liquids in your car (gasoline, for example). Nevertheless, it’s obviously a major risk to your safety.

A fire could start if you’re involved in a crash, and brake fluid spills out onto the hot exhaust system. This fire could spread to other car areas, which is a severe danger.

In minor crashes, this is very unlikely. It usually takes a significant, high-impact collision to crack the braking system open to this extent.

You should also be careful when topping up your brake fluid. Don’t spill it onto a hot exhaust!

Should I Be Worried About Brake Fluid Igniting?

Cooling

Brake fluid can catch fire, but the risk to you is very low. You still need the brakes, right? Don’t worry about it too much.

When topping up your brake fluid, it’s worth ensuring your car is cool. Give the vehicle time to cool down if you’ve just driven (especially at high loads). Wait at least half an hour.

This means you won’t drip brake fluid onto the exhaust manifold, which can reach temperatures high enough to ignite it.

Maintaining your braking system is more important than worrying about unlikely fires. In the improbable situation that your car does set itself alight, safely get out and wait for the emergency services.

Let’s assume your car hasn’t yet caught fire. In the meantime, remember to:

  • Keep your brake fluid topped up
  • Check your discs and pads
  • Have the brakes bled every year or two
  • Go straight to a mechanic if you notice any strange symptoms

International standards set rigid guidelines for brake fluid manufacturers to follow. This means your brake fluid is safe in the vast majority of scenarios on the road.

The best you can do when driving is to keep your eyes on the road and avoid a big crash in the first place. Maintaining your brake fluid with regular services also means the lines are far less likely to corrode or leak.

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Benjamin Kitchen

Ben is an automotive author from England. With experience in a fast-fit garage, he's an IMI-qualified light vehicle technician. He aims to help drivers worldwide with common automotive problems. You’ll often find him working with his 1.2 Vauxhall Corsa – it may have a tiny engine, but in eight years it's never once let him down!

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