Preparation and characterization of NaAl(OH)₂CO₃ dry powder extinguishing agent with environmentally friendly and extinguishing efficiency

A novel type of ABC dry powder fire-extinguishing agent, alkaline sodium aluminum carbonate (NaAl(OH)₂CO₃) dry powder fire-extinguishing agent, which is phosphorus-free and halogen-free, was investigated. In Class A and B fire tests, NaAl(OH)₂CO₃ extinguishing agent (Na-DW) is able to extinguish Class A and B fires within 3.2 s and 0.34 s, respectively, and is 25.6% and 30.6% faster than common ABC extinguishing agent at 0.4 MPa, respectively. To explore its firefighting mechanism, the thermal decomposition of NaAl(OH)₂CO₃ was analyzed. The pyrolysis of NaAl(OH)₂CO₃ can be divided into two stages and stage 1 (E = 309.5 kJ mol⁻¹) can be characterized by the diffusion model g(α) = (1 − α)⁻³–1. Throughout the pyrolysis, the products CO₂ and H₂O in the gas phase are generated, which play a crucial role during fire extinguishing. In addition, consistent with common ABC extinguishing agents, the presence of NaAlO₂ and oxides of Al in the condensed phase in the char layer of Class A fires confirms that Na-DW can also form an insulating layer, which can act as a barrier to barrier flame retardant and firefighting.