Effects of under-clothing airflow on thermal protective performance and thermal aging behaviors of flame-retardant fabric

Abstract

To investigate the effects of under-clothing airflows on the thermal protection performance (TPP) and thermal aging of flame-retardant fabrics, we constructed an under-clothing air-gap ventilation device based on the TPP tester. This device can generate different levels of airflow velocities such as 0.17, 1.0, and 2.0 m/s. The flame-retardant fabrics were exposed to a heat flux of 30 kW/m² to simulate an indoor fire scene_. The impacts of under-clothing airflows on the heat transfer behaviors of fabrics were analyzed with the temperature rise measured by thermocouples. The thermal aging behavior of the fabric was investigated based on the outer-shell morphology, mass loss, and residual tensile strength. The results of this study indicated that the under-clothing airflow enhanced the TPP of flame-retardant fabric and the best TPP was achieved under the airflow of 1.0 m/s. Under-clothing airflow increased the post-thermal-exposure mass loss of the fabric but did not further decrease the tensile strength. Higher severity thermal aging occurred for 2.0 m/s airflow than for 1.0 m/s airflow. The findings of this study are important for TPP prediction for firefighters' clothing and will help optimize firefighters' clothing design.