The effects of moisture on the thermal protective performance of firefighter protective clothing under medium intensity radiant exposure

Abstract

Current firefighter protective clothing is composed of multilayer fabric systems. The outer shell fabrics inevitably become wet in the process of firefighters performing their duties, and sweat may also increase moisture in the inner layers of protective clothing. In this study, two kinds of outer shell fabrics (aramid IIIA fabric and aramid 1313 and flame-retardant viscose-blended fabric) and two kinds of thermal liner fabrics with different thicknesses were selected. Three wetness conditions were simulated for the outer shell fabric, thermal liner fabric and both fabrics together. A modified thermal protective performance (TPP) tester was applied to assess TPP provided by these wetted fabrics; in addition, second-degree skin burn time was predicted and absorbed energy indexes were calculated. The regression method was employed to create fitting curves for absorbed energy and second-degree burn time in different configurations and the Pearson correlation was established to analyze their relationship, in which the lowest R2 value could reach 0.9122 and p-values were all much less than 0.05. Performance results for both wet conditions indicated that outer shell moisture and a thicker thermal liner have a positive and increased negative effect, respectively, on fabric TPP. When the sample S-3-D (aramid 1313 and flame-retardant viscose-blended fabric, moisture barrier and the thin thermal liner) was both wetted in the outer shell and thermal liner, its second-degree burn time was improved by 12.8% over performance in dry conditions. These findings may have important applications for the design and manufacture of optimal protective performance clothing systems.

Effect of moisture content on thermal protective performance of fabric assemblies by a stored energy approach under flash exposure

“…In order to simulate the scenario of moisture in the outer shell and sweating in the thermal liner (two-layer wetness), two levels in the outer shell were selected. According to the previous study 15 for wetness only in the outer shell, the TPP of the level of 60% wetness was better than other levels' and thus was selected as a base for the two-layer wetness. That is, when the outer shell was in dry condition and 60% wetness, respectively, the thermal liners (T1 and T2) at the four levels of wetness as stated above were selected.…”

“…The definition of water addition (60% wetness) in this study was 60% of 100% saturated wetness (the maximum water absorbability of O1 and O2, 3.70 g and 6.04 g, respectively). 15 The mass of water needed in 60% wetness was calculated and sprayed evenly on the surface of the outer shell by a 10 mL sprinkling can. The other steps were consistent with the wetness in the thermal liner, as described in Table 3.…”

“…These factors each have a direct influence on thermal protection and comfort. 15 The heat and mass transfer of the moisture within thermal protective clothing is very complex and can affect the temperature and heat flux from surrounding environment to human skin. Many studies concerning the effect of moisture on TPP have been conducted by different methods.…”

An exploration of enhancing thermal protective clothing performance by incorporating aerogel and phase change materials

“…A modified TPP tester was used to simulate the heat hazards and evaluate the TPP in this study, included a heat source, sample holder, skin simulant sensor, data acquisition system, and skin burn prediction software, as shown in Figure . The heat source consisted of 2 Meker burners and a bank of 9 electrically heated quartz tubes.…”

Automatization of individual anti-thermal protection of rescuers in the initial period of fire suppression

“…For this purpose, a tester with the change in heat protection characteristic was used [11]. Individual simulation of thermal protection at various wind velocity was carried out on a life-size mannequin.…”