When you hear helium, most people think about balloons. And that is probably one of the most common uses for this compressed gas, though it’s not the only use. You may be wondering if a helium balloon is safe, especially if you may have it at a birthday party. There are even some claims that helium balloons can catch on fire or explode, is this true?
Helium is not a flammable or explosive gas. Helium is an inert gas, which means that it is very stable and not very reactive. A balloon filled with helium will not explode.
Now, you may be saying, “that’s not true, I have seen a video of balloons catching fire.” I have seen those videos as well and it’s not what it seems… Let’s take a look.
Also read: What Makes Something Flammable?
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Is Helium Flammable or Non-Flammable?
As we mentioned above, helium gas is not flammable. It is not explosive either. You can heat it up or cool it until it turns to a liquid (at below absolute zero) and it still won’t catch fire.
It is so stable that liquid helium is used, as a cooling agent, even around rocket engines.
It is also used for manufacturing electronics, to cool MRI machines, in car airbags, and for welding.
It is less dense than the air around us and that is why it wants to rise. Use a helium tank to fill the balloon (or even a blimp) and the latex balloon will rise.
So, what about the exploding balloons?
There are quite a few videos like this…
Many even say they are helium balloons.
This is false.
A helium-filled balloon will not explode. So what balloon gas was used? The balloons in that video are filled with hydrogen gas.
Also read: Is Bleach Flammable or Explosive?
Can Hydrogen Balloons Catch Fire?
They certainly can…
Hydrogen gas, like helium, is lighter than air and will rise. In fact, it is even lighter than helium. However, it is much more reactive than helium and is a very flammable gas.
Hydrogen was even used to fill blimps and other airships, until the Hindenburg disaster in 1937, where a blimp filled with hydrogen burst into flames and killed 35 people. They aren’t exactly sure what sparked the fire, but it is quite clear that the hydrogen gas is what caused the fireball.
After this kind of thing happening, why would they put hydrogen, or other flammable materials, in a balloon, especially at a birthday party with kids?
- Hydrogen is generally less expensive than helium.
- Helium supply is getting low. (There is a helium shortage)
- Hydrogen is easier to find than helium in some parts of the world.
These may not be good enough reasons to justify the dangers, but balloons are still filled with hydrogen in some areas. This is especially dangerous if people aren’t aware of what is in the balloons they have.
Here is a demo of the difference in the flammability of helium vs. hydrogen:
There are other instances of balloons catching fire without hydrogen.
I have heard of balloons being filled with acetylene gas as well.
Acetylene is another dangerous choice for balloons. It is used as a fuel for welding, because of its flammability.
Is Helium Explosive?
For a substance to be explosive, it has to be reactive and contain a large amount of potential energy (energy not yet released). It has to react so quickly that it causes a sudden expansion and produces pressure and sometimes light and heat.
This usually means the substance must be flammable, as flammable materials contain potential energy that is released when ignited. (there are some other types of explosions based on pressure or nuclear energy).
Since helium is non-flammable, it is generally not explosive.
(If a helium tank stored at a high pressure was ruptured, it could cause an explosion, but this is due to the pressure and not the reactivity of the gas. It would be the safe with any compressed gas.)
Where Does Helium Come From?
Helium is the second most abundant element in the universe, but there is a limited amount on earth. It is used for many important things besides just party balloons and our supply is running low.
Helium is created under the earth’s surface from naturally-occurring, decaying radioactive materials. They give off helium, most of which rises into the atmosphere and is gone forever. Some of the helium does get trapped in natural gas deposits. It then has to be removed from the other gas to be useful. This is a tricky and expensive operation.
It is important to know what gas you are using. As we saw here, even though they can all make a balloon float, there is a big difference between helium, hydrogen, or even acetylene. As the helium supply continues to go down, it may even become more common to see other gases used, but that can have consequences. If possible, stick to helium, as it is not flammable.