Study on Fire Extinguishing Performance of Superfine Powder Fire Extinguishing Agent in a Cup Burner

A modified cup-burner apparatus with a vibrating-spiral micro feeder was developed for testing the extinguishing performance of superfine powder fire extinguishing agent (SPEA). The suspension velocity of SPEA particles was calculated using the suspension-grade-model (SGD). The formation mechanism of SPEA-based aerosols was investigated theoretically, and the minimum air velocity for the SPEA particles was about 0.05m/s. Experiments were conducted on both ethanol and heptane fuels burning flames using NH4H2PO4-based SPEA with air flow rate of 60 L/min. The results show that the minimum extinguishing concentrations (MEC) of NH4H2PO4-based SPEA for ethanol and heptane fuel are 79.8g/m(3) and 98.8g/m(3), respectively. It is demonstrated that the NH4H2PO4-based SPEA is a highly efficient fire-extinguishing agent, which is an average of 2 similar to 3 times more effective than CF3Br, and an average of 5 similar to 8 times more effective than HFC-227ea.. This research is helpful for the engineering design of superfine powder fire extinguishing equipment, as well as has vital significance to the fire protection.