Fire suppression performance of a new type of composite superfine dry powder

Summary To enhance the performance of existing dry powders and ensure process security, a new type of dry powder based on ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) was prepared. The prepared composite superfine dry powder was denoted as NH 4 H 2 PO 4 /zeolite composite in this paper. The effectiveness of commercial ABC dry powder, superfine dry powder, and the NH 4 H 2 PO 4 /zeolite composite in fire suppression were compared in a small-sized fire-extinguishing chamber. Laboratory-scale tests showed that the NH 4 H 2 PO 4 /zeolite composite had considerably superior fire-extinguishing efficiency to that of commercial ABC dry powder and superfine dry powder, along with shorter average extinguishing time and less average mass of powders consumed. In addition, the NH 4 H 2 PO 4 /zeolite composite also displayed much improved toxic gas suppression ability. The physical and chemical characteristics of commercial ABC dry powder, superfine dry powder, and the NH 4 H 2 PO 4 /zeolite composite were characterized using a range of techniques of laser particle size analysis, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Based on the analysis results, the improved fire suppression performance of the NH 4 H 2 PO 4 /zeolite composite can be ascribed to smaller particle size, larger surface area, and a special chemical decomposition process.