A new approach to evaluate the effect of moisture on heat transfer of thermal protective clothing under flashover

It’s urgent to investigate moisture effect on thermal protection of thermal protective clothing in simulated fire scene as accurately as possible. The current bench top tests can’t evaluate thermal protective performance (TPP) of fabrics under microclimate with high temperature and relative humidity (RH). In this paper, to well investigate effect of different RH under microclimate on thermal protective performance of flame-retardant fabrics exposed to flashover, a new modified TPP testing apparatus was developed. It consisted of a typical TPP tester and RH adjustable microclimate chamber. Three kinds of air gaps under fabrics were also employed to simulate different spaces between skin and clothing. The results showed that the temperature increment under microclimate of 35 % RH was highest, and that of 95 % RH was lowest. There was significant temperature difference found among above three adjusted environment. Time required of temperature rise to 12 oC highly prolonged as RH became higher. It could be deduced that the effect of RH on heat transfer became significant as air gap increasing; if the air gap width still increased, the moisture effect diminished. The newly developed testing apparatus could be well used to evaluate the moisture effect on thermal protective performance of flame-resistant fabrics.