Influence of Potassium Nitrate on the Combustion Rate of a Water-based Aerosol Fire Extinguishing Agent

A water-based aerosol fire extinguishing agent (WAE) is a safe and practical alternative to halons. It comprises an oxidizer, a fuel and a catalyst. The WAE combusts and generates large amounts of inert gases and vapor, which are released into the fire scenario, extinguishing the fire. KNO3 is used as an oxidizer to adjust the combustion rate and to ensure highly effective fire extinguishing ability and safe application of WAE. Generally, the combustion rate of WAE increases with an increase of KNO3%. However, within a specific range of KNO3%, the combustion rate decreases initially and then increases with an increase of KNO3%, called the ‘N’ effect in this study. The competition between these two effects leads to a decrease of the activation energy of the thermal decomposition of WAE as KNO3% increases along with an inhibiting effect of the liquid mixture that is generated during the combustion of the WAE. In addition, the relationship between the combustion rate and the fire extinguishing time is also discussed in this study.