Detonation Induced Flame Propagation Characteristics of Permitted Explosives under Different Methane–Air Mixture Environments

ABSTRACT Worldwide, the explosive detonation‐induced methane explosions in the underground coal mining industry are an issue of concern. Permitted explosives are specifically designed for ensuring safe blasting operations in flammable underground coal mine environments. However, inadequate explosive formulations may increase ignition susceptibility in flammable underground environments. Therefore, a comprehensive understanding of explosive detonation behaviour under varying methane–air mixtures in confined environments is essential for developing safer explosives to reduce accidents in underground coal mines. This article aimed to investigate the incendivity properties of the two different permitted explosive samples under 9% methane in the air atmosphere in a confined explosion gallery. In‐depth analysis was performed to map the detonation‐induced flame propagation behaviour of studied samples under various methane–air mixtures (0%, 7%, and 9% by volume) in a confined gallery using high‐speed imaging. Results indicated that the S‐2 sample was found unsuitable for use in underground coal mines in India as per the Directorate General of Mines Safety (DGMS) guidelines. Further, detonation‐induced flame propagation studies confirmed that flame intensity increased with an increase in methane concentration (0%, 7%, and 9% by volume) in air mixture under identical experimental conditions. Importantly, detonation wave propagation of the explosive was studied in unconfined conditions using high‐speed imaging. The study provides a unique example of quantitative evaluation of detonation‐induced flame propagation behaviour of the permitted explosive samples under various critical conditions.