Study on characteristics and combustion inhibition efficiency of compressed air foam under high temperature thermal radiation
Fang Chen, Jiulong Tao, Hanwen Gou, Heping Zhang, Xudong Cheng, Kun He
Abstract
Compressed air foam (CAF) is widely used in fire suppression due to its effective vapor-sealing and cooling capabilities. However, the influence of foam formulation and environmental factors on its thermal degradation behavior remains insufficiently characterized. This study systematically investigates the mass loss behavior and fuel evaporation suppression performance of CAF under varying expansion ratios, thermal radiation intensities, and foam thicknesses. Results show that under ambient conditions, drainage dominates the mass loss process. In contrast, thermal radiation significantly enhances evaporation, particularly at higher intensities, leading to increased total mass loss rates and shorter foam persistence times. Foam thickness plays a critical role in moderating drainage and evaporation: 100 mm foams exhibited faster drainage and a lower drainage mass proportion compared to 140 mm foams, which retained more mass through evaporation. Furthermore, expansion ratio notably influenced foam behavior—higher ratios reduced drainage but increased evaporation, resulting in a greater proportion of mass lost via evaporation. Overall, CAF with lower expansion ratios and greater initial thickness demonstrated superior thermal insulation and stability, effectively delaying evaporation and structural collapse, thereby improving fuel suppression performance. These findings provide valuable guidance for optimizing foam design and deployment strategies in high-risk fire scenarios.