24th ABCM International Congress of Mechanical Engineering December 3-8, 2017, Curitiba, PR, Brazil COBEM-2017-2788 EFFECTS OF INERTIZATION PROCESS IN CONFINED SPACES WITH APLLICATION IN THE AERONAUTICAL INDUSTRY Edwin Santiago Rios Escalante Christian Jeremi Rodriguez Coronado São Paulo State University (Unesp), Engineering School, Campus of Guaratinguetá. Av. Ariberto P. da Cunha 333, Guaratinguetá, SP CEP 12510410, Brazil. Federal University Itajubá (Unifei), Mechanical Engineering Institute. Av. BPS 1303, Itajubá, MG CEP 37500903, Brazil. esre_2808@hotmail.com christian@unifei.edu.br Eliana Vieira Canettieri São Paulo State University (Unesp), Engineering School, Campus of Guaratinguetá.. Av. Ariberto P. da Cunha 333, Guaratinguetá, SP CEP 12510410, Brazil evcanettieri@feg.unesp.br João Andrade de Carvalho Junior São Paulo State University (Unesp), Engineering School, Campus of Guaratinguetá. Av. Ariberto P. da Cunha 333, Guaratinguetá, SP CEP 12510410, Brazil joao@feg.unesp.br Abstract. A long time ago, you have heard about accidents by gas explosion, and the destruction that they can cause. To be able to avoid it requires the understanding of what a gas explosion is and what can reduced the frequency and consequences of these events. The upper and the lower flammability limits (UFL and LFL, respectively) are the maximum and the minimum concentration of the fuel in the air, respectively, in which a flame propagate, they are considered key tools in the prediction of fire, evaluating the possibility of explosion and design of protection systems. There is an interest in finding the flammability limits of ethanol mixed with an inert gas at reduced pressure as a safety measure for the future used of this biofuel in aeronautical applications, taking into account the typical altitude of a commercial airplane (<40 000 ft.). In this work the flammability of hydrated ethanol (5,18%vol. Water) was evaluated experimentally and the nitrogen was used as inert gas. The experimental bench was build according with the norm ASTM E-681. The ethanol was inject using a precision syringe with 1 ml of volume, nitrogen and air was injected using partial pressure law of Dalton. The method for measure the flammability was by visual observation of flame propagation. The results plotted as a function of the additions of nitrogen shows that when the initial pressure decreases, the UFL decreases and both the LFL and the limit oxygen concentration (LOC) increases. In addition, the variation of UFL is more noticeable than the LFL when the percentage of nitrogen increase in the ethanol/air mixture. Keywords: Flammability limits, Inert gas, Nitrogen, Hydrated ethanol, Visual criteria, Experimental measure 1. INTRODUCTION The confined spaces are characterized by enclosures with enter and exit limited, natural ventilation unfavorable, and in the most cases with lack oxygen (< 20.8% ), presence of toxic contaminants or flammable substances, that were not designed for the permanent occupation of workers, as is the case of the airplane fuel tank. According to their characteristics, they are divided into; open (tunnels, sewage) or closed (tanks, silos, wells). Potential hazards in confined spaces called “class A” correspond to those where there is a great danger to life. Generally hazards atmospherics, such as flammable or toxic gases, deficiency or oxygen enrichment (Dag Bjerket et al., 1995). Therefore, know the risks that involve the gaseous and liquid fuel mixture explosion with air is very important to guarantee the industry and domestic security as well as in the aeronautical sector (Coronado et al., 2014). Flammable substances, which characterized by having an exothermic reactions in the presence of air when are exposed to an ignition source are very important so far. Various hydrocarbons are extremely volatile under normally operated condition. To prevent explosions in the workplace it is necessary to know in what range of concentrations and conditions the handling of these materials are capable of forming flammable atmospheres (Zhao, 2008). Electronic copy available at: https://ssrn.com/abstract=3894642