The Study Of Thermal Comfort And Thermal Protective Performance Of Flame Retardant Fabrics

Flame retardant fabric is one of the modern social security essentials, especially in the field of thermal protective clothing, it’s the guarantee of fire fighters’ life safety and operation security.Under low radiation condition, while fabric system hinders the heat transferring from outside to the human body to reduce the possibility of skin burns, the human body internal heat dissipating to outside is also hindered by the fabric system, then heat stress occurs, even worse, after long time’s exposure, lot of energy was stored in the fabric system, it can continually be transferred to the body as a secondary heat source and cause potential skin burn. All of these require that fabric system should have good thermal comfort performance combined with excellent thermal protective performance after taking account of stored energy.This study focused on the performances of thermal comfort and thermal protection and the relationship between them. By using SGHP(Sweating Guarded Hotplate)and SET(Stored Energy Tester), data of Rcf, Ref, THL(Total Heat Lose)can be acquired as well as data of thermal protection times(TN and TY)both with consideration of stored energy or not under five different air gaps. Based on these data, four aspects were analyzed including the relationship between influential factors and the fabric performance of both thermal protection and thermal comfort; the influence of stored energy on thermal protective performance and related factors analysis; the effects of air gaps on both two performances of fabric and the relationship between performances of thermal protection and thermal comfort.Total Heat Lose was used to represent the thermal comfort of the clothing, in combination with Rcf and Ref, the correlation analysis between the fabric physical properties and THL under different air gaps were tested by using SPSS. The results show that grammage and thickness of fabrics had significant effects on the THL when there’s no air gaps, the effect of thickness tended to be larger than grammage’s; the bigger the grammage and thickness are, the lower THL will reach, and the worse the thermal comfort will be; but with the increasing of air layer thickness, air layer gradually become the main factor influencing the thermal comfort, and THL gradually decreases, but the decline rate decreases.A comparison was made between thermal protection times TN and TY, the result shows thatTN is much higher than TY which is with consideration of stored energy, grammage and thickness of fabrics had an obvious negative effect on thermal protection time, but this result comes to the opposite when stored energy is out of consideration; By using the concept of stored energy index IY, factors affecting IY were discussed, results showed that IY is positively related to the fabric grammage and thickness, exposure time also strongly effects IY, the longer the exposure time is,the faster the second skin burning happens, and shorter the total protection time will be, air gaps played a complex role in IY, while thermal protection time with stored energy consideration increases with the increasing of the air gap thickness, especially when air gap is 12 mm, the thermal protection time is much longer than 9mm.Combined with THL and TN and TY, the relationships under different air gaps were discussed.THL had a negative relationship with TN, while this relationship becomes obscure when it comes to THL and TY, the relationship between THL and TY changes when air gaps change, an index Ci from Economics is referred to combine THL and TY to value the comprehensive performance of fabrics, the best fabric can be easily selected under each air gap by this method, it’s a good reference when making some comprehensive evaluation.In conclusion, the basic physical properties of the fabric system has a significant effect on both thermal comfort and thermal protective performance, stored energy had a significant influence on the thermal protective performance and it relationship with thermal comfort, while decreasing the thermal comfort, air gap can strength thermal protective performance the with increasement of its thickness, the IY differs from each other when air gap changes, so is the relationship of thermal comfort and thermal protective performance.