An experimental investigation of improvised incendiary devices used in urban riots: The “Molotov cocktail” Dionysios I. Kolaitis ,1,2 1 Greek Firefighting Academy, Matsa 32, Kifisia 145 64, Greece. 2 Laboratory of Heterogeneous Mixtures & Combustion Systems, School of Mechanical Engineering, National Technical University of Athens, Greece. Abstract Motivated by the extensive use of the Molotov cocktail in recent urban riots in Greece, an experimental investigation of the fire behaviour of the Molotov cocktail and the effectiveness of relevant suppression techniques is performed. During the first testing phase, a series of glass bottle impact tests were performed, aiming to investigate the geometrical characteristics of the liquid pool created by the glass impact. A variety of throwing distances and target surface orientations (e.g. vertical, horizontal) were examined. The second testing phase focused on fire suppression. A variety of liquid fuel mixtures, typically used in Molotov cocktails, were ignited, aiming to comparatively assess the effectiveness of relevant fire suppression agents, i.e. carbon dioxide and dry powder.  Corresponding author: dkol@central.ntua.gr Proceedings of the 2 nd IAFSS European Symposium of Fire Safety Science Introduction Improvised incendiary devices, such as the “Molotov cocktail”, are widely used by various riot groups operating in urban environments. Motivated by the extensive use of the Molotov cocktail in recent urban riots in Greece, which have occasionally lead to the loss of human life, the Greek Firefighting Academy has initiated a research programme, aimed at investigating the fire behaviour of the Molotov cocktail, as well as to establish effective suppression techniques. In this context, some preliminary experimental results are presented in this study. In the first testing phase, a series of glass bottle impact tests were performed, aiming to investigate the geometrical characteristics of the liquid stain formed after the impact. A variety of throwing distances and target surface orientations (e.g. vertical, horizontal) were examined using typical glass bottles containing a non-flammable liquid. The shape of the post-impact liquid stain was recorded using optical cameras; the obtained measurements were used to determine “average” liquid stain dimensions, as well as “worst- case” values. The next testing phase focused on fire suppression. In this context, a variety of typical Molotov cocktail liquid fuel mixtures were ignited, with the aim of comparatively assessing the effectiveness of relevant fire suppression agents (e.g. carbon dioxide, dry powder). A metal pan was used to contain the liquid, as a means of simulating the post-impact pool fire; its size was determined based on information obtained in the glass bottle impact tests. Identical pool fires were used to evaluate the suppression efficiency of the two different agents. The “Molotov” Cocktail A Molotov cocktail consists of a breakable glass bottle that contains a flammable liquid mixture; an ignition source, usually in the form of a liquid soaked cloth (wick), is used to cover the bottle opening. The ignition source is lit and the bottle is immediately thrown on the target surface (Figure 1); upon impact, the glass breaks and spills its contents on the surface, thus resulting in the formation of a liquid pool that is instantly ignited by the ignition source. Figure 1: Photograph of a protester prepared to throw a Molotov cocktail (Greece, 2012). The Molotov cocktail has been originally developed to be used in war, mainly as a weapon against tanks [1]. The first documented use of such an improvised incendiary device occurred in the Spanish Civil War (1936-1939); it was given its name (Molotov cocktail) by the Finnish army that has used it extensively against the Soviet tanks during the Winter War (1939-1940) [2]. Due to the low cost and wide availability of the required raw materials, Molotov cocktails are frequently used today by protesters and riot groups in urban guerrilla warfare operations and incidents between demonstrators and law enforcement bodies [3-6]. In Greece, use of the Molotov cocktail by protesters and anti-authoritarian groups is extensive. In 2010, Molotov cocktails thrown at a bank, located in Athens, resulted in the death of 3 bank employees.