Investigating the efficacy of expanded graphite/NaCl composite powder as an extinguishing agent for metal combustion suppression

Advancements in fire safety technology have led to the development of expanded graphite (EG)/NaCl composite powder, a dry powder fire extinguishing agent specifically for metal fires. This study used custom apparatus to examine the fire suppression properties of this composite powder in relation to its constituent elements, EG and NaCl. Compared to pure EG, this composite powder has a smaller particle size and better thermal stability. The flames of a sodium metal fire were effectively suppressed using only 8 g of the EG/NaCl composite powder. The powder suppressed the flames within 22 s. This performance surpassed that of the use of EG or NaCl alone. Moreover, after the fire was extinguished, the temperature decreased at a rate of 1.23 °C/s within the temperature range of 350–250 °C. This rate was 15.44% and 44.78% faster than those of EG and NaCl, respectively. The suppressive effects of the EG/NaCl composite powder are primarily attributed to heat absorption—which prevents contact between combustible metals and air—and the adsorption of depleting H∙ and OH∙ radicals. These results indicate that EG/NaCl composite powder has promising firefighting applications, particularly in fires involving the burning of metals.