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

Abstract

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.