Physics of Combustion: Scientific Inquiry into Grenfell Fire Root-Cause Mechanisms

Abstract

Grenfell Tower in London* was destroyed in the early hours of 14 th June 2017 by a conflagration that started as a small domestic fire in a refrigerator in the kitchen of an apartment. Seventy-two people died. Questions, why and how this tragedy happened, with a well-developed London fire-fighting infrastructure, prompted the UK government to launch a public inquiry. A Judge with a team of lawyers was commissioned to establish the reason why a domestic apartment fire, flickering from a 4 th floor kitchen window, began to spread rapidly less than two-minutes after first fire engines arrived, to an inferno reaching the top floor in 20 minutes. The inquiry collected 1100 statements and took 7 years to complete. Interim and final inquiry reports, resting on expert-witness testimony, found that the rapid spread of the fire was “caused by the polymer insulation in the aluminium cladding”. An extensive public final report concludes with a nebulous distribution of culpability amongst a plethora of manufacturers and suppliers of the aluminium cladding, and various national and local unnamed government officials. Here, we address the research problem of identifying the underlying combustion physics factors that can explain all the experimental observations as they unfolded in a scientific timeline. We apply the scientific method using the laws of thermodynamics and known chemical kinetic combustion mechanisms that contradict the “expert witness” evidence. Our principal findings are that the prima facie scientific evidence for the rapidity of conflagration was a fierce reaction to the first application of water to extinguish an aluminium fire. As the number of fire engines pumping water escalated around the towerblock, so did the fire. Water is the catalyst for both the initiation and propagation of highly exothermic oxidation reactions of aluminium. It reacts ferociously with molten aluminium and can be explosive. The implications are that, to avoid future catastrophes, water must not be used as a would-be extinguisher on Al-clad building fires. Such fires are readily suffocated at early stages with CO 2 -foam or powder extinguishers. Our scientific inquiry complements the UK Public Inquiry final report by analyzing and revealing the root cause of the disaster.