From construction sites to power lines to aircraft, Aluminum is everywhere you can think of. For many years, people believed Aluminum to be combustible, thanks to its presence in numerous fire instances. So, is Aluminum flammable?
No, Aluminum isn’t flammable in standard environmental conditions. It doesn’t ignite or burn easily unless it’s in the form of a powder or very thin foil. However, if the temperature rises above 650°C or more, Aluminum might ignite and start melting.
Let’s dive into the details and find out which forms of Aluminum are flammable and what happens when you burn Aluminum.
Can Aluminum Burn in a Fire?
No, Aluminum is a fire-resistant metal, and it won’t burn in a fire unless the temperature rises over 650°C or 1200°F. By following the study results conducted by the Aluminum Association, the American Society for Testing and Materials (ASTM) has classified Aluminum as non-combustible.
The exact temperature at which Aluminum will ignite and burn depends on a number of factors, including the size and shape of the metal and the surrounding atmosphere.
Below are the most common forms of Aluminum and their flammability:
- Pure Aluminum Metal: As unmixed, Aluminum metal has a strong atomic structure; it doesn’t catch fire easily. It will only ignite if the temperature rises too high.
Due to its non-flammable nature, pure Aluminum has many practical applications, such as in building construction, aircraft manufacturing, and electric wiring.
- Aluminum Alloys: Similar to Aluminum metal, alloys of Aluminum are also non-flammable. Mostly, Aluminum-like solid metals are used to create these alloys, which prevent ignition in the presence of an open flame.
However, if any Aluminum composite includes highly flammable materials, it might burn depending on the environment.
- Powder Aluminum: Most metal powders burn, and so does Aluminum powder. When Aluminum is in powder form, it offers a larger surface area for airborne oxygen. As a result, the powder can easily catch fire if the circumstances are ideal for burning.
- Aluminum Foil: Generally speaking, Aluminum foils don’t catch fire up to 650°C. However, if the sheet is extremely thin, it might ignite at lower temperatures.
Why Is Aluminum Not Flammable?
Both the physical and chemical properties of Aluminum are its non-flammable nature. The strong atomic bond and chemical reactions with oxygen protect the Aluminum surface from burning. Here’s why Aluminum isn’t flammable-
Strong Molecular Bonds
When heat is applied to a material, the molecular bond between two atoms starts to become weak. As energy is passed to the atoms, they start vibrating, and the molecular bonds are further weakened. Eventually, the atoms separate from each other and react with the airborne oxygen when ignited. This is how a material burns.
Just like most metals, Aluminum is mostly available in its solid form. The molecular bonds of Aluminum atoms are so strong that even high can’t separate the atoms. Hence, Aluminum doesn’t easily catch fire when ignited.
Formation of Aluminum Oxide
Pure Aluminum is highly reactive with oxygen in the air. When ignited, it reacts and forms a very thin protective layer of Aluminum oxide on its surface. This oxide layer prevents further reaction with oxygen, which prevents the Aluminum from catching fire or burning.
As the Aluminum oxide layer is very stable, it can withstand high temperatures without decomposing, further protecting the Aluminum from combustion.
Small Surface Area
In general, the larger the surface area of a material, the faster it will combust. More oxygen molecules can react with the material at the same time if it has a large surface. On the other hand, when the surface area is smaller, the reaction between the material and oxygen will be slower and less intense.
As a result, a material with a small surface area is less likely to catch fire and burn compared to a material with a larger surface area. In the case of pure Aluminum, the protective oxide layer helps limit the Aluminium’s surface area that is available for combustion.
This way, ignition becomes more difficult due to the reduced number of oxygen molecules that can react with Aluminum. So, Aluminum becomes extremely difficult to burn.
Ignition and Melting Point of Aluminum
Although Aluminum is fire-resistant, it’s not completely fire-proof. It can ignite and melt at high temperatures. The approximate ignition point of Aluminum is 650° to 750°C (1200°F to 1380°F) depending on the Aluminum’s purity and amount of oxygen present in the air.
As for the melting point of Aluminum, at around 660.3°C or 1221°F temperature, Aluminum starts melting. Therefore, Aluminum is almost safe from potential fire incidents and widely used in many household and industrial applications.
Can Aluminum Be Explosive?
As mentioned, only Aluminum powder is a highly flammable form of Aluminum and it can be explosive under certain conditions. Aluminum powder is a finely divided form of metal with a very high surface area per unit mass.
This high surface area makes the powder highly reactive with oxygen, and it can lead to rapid combustion.
When the Aluminum powder is exposed to an ignition source, such as a spark or flame, the generated heat can cause the powder to burn very quickly. This rapid combustion produces a huge amount of flammable gas, which eventually leads to an explosion if it’s confined in a small closed area.
Frequently Asked Questions
1. Is it safe to burn Aluminum?
Although Aluminum won’t burn under normal circumstances, inhaling Aluminum dust is extremely harmful to your body. Avoid burning Aluminum powder or dust as it quickly catches fire and spreads in a large area.
2. What class of fire is Aluminum?
Aluminum powder fire is classified under class D. This class describes fires caused by combustible metal sources. Aluminum, magnesium, potassium, lithium, and titanium fires are class D fires.
3. How do you stop Aluminum fire?
First of all, never use water to burn an Aluminum fire. Use a class D fire extinguisher to put out the fire. Try to create a barrier between the fire and structures by digging a trench. Finally, use dry sand, limestone, talc, dry clay, or sodium chloride to control the fire.
Wrapping Up!
In this write-up, we’ve answered the commonly asked question, ‘is Aluminum flammable?’ No need to worry about that; Aluminum can be at your house as it won’t catch fire if ignited.
However, Aluminum powder is highly reactive and combustible. Therefore, you must handle it carefully and follow appropriate safety precautions while working with it.
