Helium is a colourless, odourless gas that is less dense than air. It is used in a variety of applications, including filling party balloons and making voices sound high pitched.
Helium is not flammable. Helium is an inert gas that is safe to use. It is non-flammable and does not react with other elements or compounds.
Liquid Helium is used by NASA for this same reason – because it is inert and won’t burn (or explode).
NASA uses liquid helium as a coolant for its space probes. If helium were to be hazardous it would hardly make sense that NASA would use this gas to preserve the lives of its astronauts.
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There are multiple reasons why helium can be used safely, some of which include:
- Helium has low reactivity with atmospheric gases
- The rate of combustion is extremely slow
- There is little heat release and the temperature may even decrease with burning helium
Helium will not burn – it supports the burning process very poorly. The rate at which a substance burn is termed its “combustion velocity”. If the velocity of burning exceeds 1 cm/sec, self-sustained burning will occur. This means that if you apply a flame to the material, it will burn at its own rate without any external source of ignition
The combustion velocity of helium is less than 0.001 cm/sec. Combustion requires three elements
- heat (energy),
- oxygen, and
- fuel material.
Without one or more of these elements, combustion will not occur. One of the elements needs to be present in at least trace amounts to begin the combustion process.
Is helium a fire hazard?
While helium may be known for its fun, light hearted party uses, some people are concerned that it could be a fire hazard.
No, helium is not a fire hazard because it is an inert gas, meaning it doesn’t react with other elements or compounds. It has a very high ignition temperature which means the heat required to start combustion is really high too.
This means if you are using helium party balloons, there is no risk of them accidentally catching on fire.
Of course, you should still keep them away from open flames and hot surfaces.
The combustion velocity for helium is less than 0.001 cm/sec and therefore self-sustained burning in the presence of a naked flame will not occur in most circumstances.
Can helium gas tanks explode?
There is no risk of helium gas tanks exploding. This is because helium cylinders are supplied with an approved burst disc. This is to ensure that if a fire occurs, the helium gas cylinder will release gas in a controlled manner and will not explode.
So helium gas cylinders can be used and stored at home. The only thing you need to do is ensure your cylinder is stored properly and never tampered with.
So no, helium is not flammable, but it is also not explosive
Helium (He) has a very low combustion velocity, an autoignition temperature of above 1000°C (in fact the fourth highest among all elements), and requires an oxidizer (oxygen). When burned in air, the dominant reaction is the formation of elemental nitrogen (N2).
Thus, helium does not support combustion.
There are few materials that can burn in the air when pure, but when compounds are present the rate of burning increases significantly. Thus, if an oxidizer is present in sufficient concentrations with a fuel material to provide the required heat for ignition, it would be possible for an explosion to occur in the presence of helium. For example detonation of trinitrotoluene (TNT) could ignite helium in this manner.
However, helium is used as a protective shielding gas when welding because it dilutes around half its volume to avoid spontaneous detonations (sensitivity).
It should be clear that even though helium is non-flammable, there can still be instances where it could pose other hazards such as spontaneous explosion.
Is helium as flammable as hydrogen?
Hydrogen and helium may have similar names, but that doesn’t mean they are equally flammable.
As helium and hydrogen are both colourless, odourless gases, it can be difficult to tell them apart. However, there are some key differences between these two elements that all should know.
Helium has an outer shell that does not combine with other elements and it is not flammable. On the other hand, the outer shell of Hydrogen has only one electron, so it tends to share another electron with an oxidizer such as Oxygen.
This key difference is what makes hydrogen much more flammable than helium.
Hence, helium is not explosive at all because it won’t react with other elements to create a fire. Second of all, its autoignition temperature is way higher than flame ignition. With this in mind, helium is actually less flammable than hydrogen.
Helium is not flammable
It is inert, meaning it will not react or catch fire in normal conditions. Even when mixed with an oxidizer, helium is still non-flammable because its autoignition temperature is way higher than flame ignition. Thus, there are no drawbacks to using helium in balloons for parties and events.
However, the lack of understanding about what can actually burn may lead some people to avoid mixing helium with any substances at all in the safety measures they take while storing their helium tanks.