Abstract: In this paper, the combustion characteristics of magnesium chip stack in two forms (horizontal and conical) were tested, revealing that the combustion flame height of magnesium chip stack is low, the temperature is high, and the continuous internal oxidizing combustion leads to the "double peak" characteristics of temperature. To address the issue that traditional metal fire extinguishing agents struggle to adhere to the surface of magnesium chip stack, resulting in poor air insulation effect, a new dry powder fire extinguishing agent (NaCl/LMG) with low melting point glass powder and sodium chloride dry powder as the main raw materials was formulated. Fire extinguishing tests of conical stack of magnesium chips were carried out. The test results show that both the traditional NaCl dry powder and the new NaCl/LMG can extinguish the surface combustion of the conical stack. However, the NaCl dry powder fails to effectively inhibit the internal oxidation, while the NaCl/LMG can form a hard cover layer that effectively isolates air and inhibits the oxidation of the internal magnesium chips. During the fire extinguishing process by NaCl/LMG, the surface temperature of the stack decreased at a rate approximately 4.64 times that of the NaCl dry powder. Additionally, NaCl/LMG dry powder reduced the internal temperature of the stack to 200 ℃ in 1 200 s, achieving effective fire extinguishing. The fire extinguishing time and the extinguishing agent consumption of NaCl/LMG dry powder were reduced by 50% and 53% compared with NaCl dry powder, respectively.

Key words: magnesium chip stack, metal fire, dry powder extinguishing agent, low melting point glass powder