Abstract
We review the thermodynamics of combustion reactions involved in aluminum fires in the light of the spate of recent high-profile tower-block disasters, such as the Grenfell fire in London 2017, the Dubai fires between 2010 and 2016, and the fires and explosions that resulted in the 9/11 collapse of the World Trade Center twin towers in New York. These fires are class B, i.e., burning metallic materials, yet water was applied in all cases as an extinguisher. Here, we highlight the scientific thermochemical reasons why water should never be used on aluminum fires, not least because a mixture of aluminum and water is a highly exothermic fuel. When the plastic materials initially catch fire and burn with limited oxygen (O2 in air) to carbon (C), which is seen as an aerosol (black smoke) and black residue, the heat of the reaction melts the aluminum (Al) and increases its fluidity and volatility. Hence, this process also increases its reactivity, whence it rapidly reacts with the carbon product of polymer combustion to form aluminum carbide (Al4C3). The heat of formation of Al4Cl3 is so great that it becomes white-hot sparks that are similar to fireworks. At very high temperatures, both molten Al and Al4C3 aerosol react violently with water to give alumina fine dust aerosol (Al2O3) + hydrogen (H2) gas and methane (CH4) gas, respectively, with white smoke and residues. These highly inflammable gases, with low spontaneous combustion temperatures, instantaneously react with the oxygen in the air, accelerating the fire out of control. Adding water to an aluminum fire is similar to adding “rocket fuel” to the existing flames. A CO2–foam/powder extinguisher, as deployed in the aircraft industry against aluminum and plastic fires by smothering, is required to contain aluminum fires at an early stage. Automatic sprinkler extinguisher systems should not be installed in tower blocks that are at risk of aluminum fires.
Highlights
A well-known adage of the advice given in the event of a kitchen fire is, “Never put water on burning liquids!” There are several good reasons for this longstanding rule of engagement in the health and safety of professional fire-fighting literature
Automatic sprinkler extinguisher systems should not be installed in tower blocks that are at risk of aluminum fires
Fires are classified according to the rules for extinguishing them; inflammable liquids and molten plastics or metals are class B [1]
Summary
A well-known adage of the advice given in the event of a kitchen fire is, “Never put water on burning liquids!” There are several good reasons for this longstanding rule of engagement in the health and safety of professional fire-fighting literature. Moissan in 1893, in which the heating power of the electric arc was directly utilized, by extending the upper limit of working temperatures, fused aluminum takes up carbon readily with formation of the crystalline carbide AlC, and the oxides of many other metals furnish similar crystalline compounds when heated in the electric furnace with an excess of carbon The behavior of these substances with water furnishes the most convenient mode of classification. There has been a great deal of speculation as to why the fire spread so rapidly: the fire broke out on a warm night; windows were open with curtains blowing in the breeze, which would have contributed to the rapid spread of fire within the building; there were chimney ventilation effects from the cavities, etc Notwithstanding all of these observations, the basic reason that the fire spread out of control in just a few minutes is that water was sprayed upon a combination of burning molten plastic and aluminum. We review evidence that the 9/11 collapse of the World Trade Center twin towers may have been caused by similar reactions and cite other instances where the fires involved buildings that were known to have been refurbished with aluminum panels
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
