Inertization parameters for alcohols and ketones with nitrogen and carbon dioxide

A flammable fuel/air mixture can be successfully prevented from entering the explosion range of concentration by the addition of an inert gas. This method of inertization is commonly used in industrial plants to keep processes safe. For this purpose, the oxygen concentration in the over-all mixture is often monitored, taking an appropriate safety margin into account. The mixture would not become flammable, independent of the amount of fuel added, while the oxygen content is below the so-called limiting oxygen concentration (LOC). The aim of this paper is to investigate the inertization-related characteristics of the two different inert gases nitrogen (N2) and carbon dioxide (CO2). The LOC of a series of alcohols and ketones was therefore measured. The experimental determination of the LOCs was carried out according to EN 1839 (2017) using the tube method at ambient initial pressure and suitable initial temperature to evaporate the liquid sample. Triangular diagrams, which represent the explosion ranges, were constructed from the results and additional inertization-related parameters derived: the minimum inert gas/air ratio (IAR) and the minimum inert gas/combustible gas ratio (ICR). It is well-known that carbon dioxide exhibits a stronger inerting effect than nitrogen. In agreement, the ratio LOC(CO2)/LOC(N2) was now determined to be a constant value of 1.33 ± 0.04 in the applied temperature range at ambient pressure. In inertization applications, this ratio in future helps to calculate LOC(CO2) from the much more often known LOC(N2).