Pan Renming

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.

Experimental research on the thermal decomposition of pentafluoroethane (HFC-125) extinguishing agent with n-heptane/air pool fire in confined space

To discuss the production law of hazardous gases (e.g. hydrogen fluoride) during the interaction between a pentafluoroethane extinguishing agent and an n-heptane flame, we designed a simulation of experimental total flooding conditions that is highly similar to the actual total flooding automatic extinguishing conditions. In this study, a qualitative and quantitative analysis on the thermolysis gaseous products was performed through GC-MS and ion chromatography (IC) by studying the thermal decomposition characteristics of the interaction between a pentafluoroethane extinguishing agent and an n-heptane flame in a 1 m3 fire-smothering room under different fire sizes and interaction times. Research results demonstrated that the thermolysis gaseous products of the pentafluoroethane extinguishing agent and n-heptane flame include hydrogen fluoride (HF) and other organic gases, such as CF3CHCF2 and CF3CH2CF3. The HF output was proportional to the fire size and interaction time. When the interaction time was controlled within 10 s, production of hazardous gases could be effectively reduced.