Assessment of sustainable compositions to reduce emissions and sound pressure level of flash powder

Abstract

Flash powder, an explosive compound widely used in flash bangers and pyrotechnic shells, among others, has emerged as a critical point in discussions about the negative effects of its use. Currently, fireworks present significant challenges due to their adverse impacts on the environment and the generation of acoustic disturbances in residential and urban areas due, among other compounds, to flash powder. This powder, mainly composed of potassium perchlorate and metallic compounds such as aluminium or magnesium, is crucial to achieve the opening and bursting of pyrotechnic devices. Therefore, it is necessary to develop alternatives that solve the flash powder associated problems to give a sustainable future to the pyrotechnic sector. This study proposes compositions that could be possible alternatives to reduce emissions and sound pressure levels, whit the intention of ensuring suitable performance for these pyrotechnic articles. F2 category flash bangers from different manufacturers were collected. The operation of these bangers was compared in different tests, by adding inert materials such as sodium bicarbonate (NaHCO₃) and recycled glass, at 10 % and 20 % (w/w), and by replacing the flash powder with nitrocellulose ([C₆H₇(NO₂)₃O₅]n), with a nitrogen percentage of less than 12.6 %, as stated in the European pyrotechnics regulation. The samples were subjected to sound pressure level measurements according to EN 15947-4:2022 standard, but also CO and CO₂ emissions were evaluated. It was observed that the compositions studied could lead to a significant reduction in both pollutant emissions and the noise level generated by the pyrotechnic articles. After studying the explosion pressure generated for their substitution in pyrotechnic shells, it is concluded that the addition of inert compounds can be a real alternative. However, the nitrocellulose does not achieve a correct operation as a substitute for flash powder, and nitrocellulose with a higher nitrogen content must be studied.

Keywords: Acoustic pollution; Emissions; Explosion pressure; Flash powder; Sound pressure level.