Optimization of Material Content on the Protective Performance of Fire Fighter's Clothing Using Box–Behnken Design

ABSTRACT Extreme fire‐protective clothing (FPC) designed for firefighters must simultaneously fulfil both comfort and fire protection requirements. The outermost layer of turnout suits plays a vital role in determining the protective performance of fire‐resistant fabrics. This study investigates the thermal protective performance of woven fabrics by varying radiative thermal intensity (20–40 kW/m 2 ), the air gap between the heating source and the fabric (0–12.5 mm), and para‐aramid content (0%–100%). A systematic analysis was conducted to examine the influence of para‐aramid content, air gap, and heat intensity on the protection time using the Box–Behnken experimental design. A quadratic model was developed and validated, demonstrating high accuracy, with an average relative error of 5.38% between the predicted and experimental values. ANOVA confirmed the model's significance, showing that all factors, their interactions, and the square of heat intensity significantly affected the protection time. Experimental results showed that protection time positively correlates with para‐aramid content and air gap but decreases with increasing heat intensity. Maximum protection exceeding 30 s was achieved using 100% para‐aramid composition, a 12.5 mm air gap, and a heat flux of 20 kW/m 2 . These findings offer a comprehensive framework for designing high‐performance thermal protective fabrics for extreme conditions.