During an operation, the turnout gear for firefighters must meet two important requirements: thermal protection and comfort. As comfort and protection are inherently incompatible, it is impossible to satisfy both. As part of this study, the outer layer of multilayered turnout suits was analyzed under the influence of various factors such as intensity of heat flux, pick density, and air space between the fabric and the sensor. Choosing Nomex IIIA was based on its inherent properties that are conductive to thermal protection. To simulate the environment encountered during firefighting, benchtop experiments were designed. A system equation for the prediction of the protection time (t-protection) was developed based on a three-factor and three-level Box–Behnken model. The predicted values of t-protection obtained for all the experimental blocks in the design space were subjected to ANOVA analysis which showed that the system equation, as well as the coefficients of linear interactive and square terms, is significant, so the system equation can be efficiently used for predicting t-protection. The validity of the system equation was verified by using the same experimental blocks and estimating t-protection using the Stoll criteria. The accuracy of the system equation was checked by comparing t-protection and t*-protection which revealed a linear relationship with a high correlation coefficient (R² = 0.975). To analyze the effects of the independent variables on protection time, 3D surface response curves were created. The nature of the surfaces was critically analyzed by developing regression equations for the contours and the diagonals.

Firefighters rely heavily on their firefighter’s protective clothing (FPC) for their safety. The effectiveness of an appropriately engineered turnout suit decreases over time when repeatedly exposed to radiative heat and flame. A measure of durability is the radiative protective performance (RPP) rating, which is influenced by properties like thickness, surface area, and areal density (mass per unit area) of outer shell fabric in multilayered ensembles. Four independent variables were considered: fabric material, pick density, exposure cycles and heat flux intensity. In addition to RPP, changes in the thickness, shrinkage, and mass loss was also tracked. An evaluation of properties was conducted at the end of each cycle to determine the effects of the heat flux (21, 42 and 63 kW/m ² ), number of exposure cycles (from one to five) and effects of each attribute. Two types of fabrics were used in this study, one made with meta aramid (Nomex® IIIA) yarns in both warp and weft (type-A fabric), and the other made with Nomex® IIIA (warp) and para aramid (Kevlar ^® ) (weft) (type-B fabric). Type-A fabrics displayed a greater degree of differentiation in their properties than type-B fabrics. With the same exposure conditions, the thickness, shrinkage, mass loss and RPP gradually increased. A regression analysis conclusively established that pick density significantly affects the performance of the outer-shell fabric used in FPCs. Textile designers may find the results useful for creating more thermo-stable and durable turnout suits in the future.

A study was designed to determine the effect of basic construction parameters of woven fabric on the thermal protection and comfort performance of the fabric. Thermal protection performance may be calculated using thermal protective performance (TPP) rating. The thermal resistance and water vapour transmission rate (WVTR) of different fabric woven patterns were used to evaluate their comfort performance. The current research is primarily concerned with determining the influence of fabric weaving pattern (plain, twill 2/2, twill 3/1, satin and honeycomb), picks per inch (40, 50 and 60), ply of yarn (2 ply and 3 ply) and type of material (meta aramid and para aramid). We measured the TPP rating of fabrics against 50:50 combination of radiant heat and flame exposures at high level of heat flux (80 ± 2 kW/m² or ∼2 cal/cm²/s). It was found that the TPP rating of honeycomb weave was very good for the same picks per inch compare to other weaves. The change in ply of yarn (from 3 ply to 2 ply) reduce the TPP rating and areal density of fabric but % loss in areal density is higher compare to TPP rating. Comparing honeycomb woven fabrics to fabrics with different weaving pattern, thermal resistance of honeycomb woven fabrics were good. As the number of fabric picks per inch increased for each type of woven structure examined, the TPP rating and thermal resistance improved, while WVTR declined. The multiple linear regression equation (model) is significant for TPP rating.

In this study, stainless steel/viscose blended yarn was prepared and different structured woven fabrics were prepared for studying the moisture transmission and electromagnetic shielding behaviour. By doubling viscose spun yarn with SS filament yarn, the SS/viscose blended yarn was prepared. The woven fabrics were made in a sample loom using viscose yarn and SS/viscose blended yarn. By changing the metal content, thread density and conductive fibre proportions at different levels, the developed fabrics were analyzed for maximum shielding effectiveness in the frequency of 300 kHz to 1.5 GHz. The fabric having conductive threads in warp and weft directions showed larger shielding effectiveness (SE) compared to fabric having conductive threads in one direction. The increase in weft density, proportions of conductive threads (in weft direction) and metal content increases the shielding level of fabric. The highest SE of 56 dB was observed for plain woven fabric compared to 3/1 twill, 2/2 twill and 2/2 basket fabrics in the frequency of 700 MHz. The influence of environmental factors such as relative humidity and pH on shielding behaviour of fabrics were also studied. As the relative humidity was increased, the SE was also increased. The fabric treated with acidic (or) basic condition exhibited better SE than the fabric in neutral condition. Similarly, air permeability and water vapour transmission characteristics of the developed conductive fabrics were also analyzed. The air permeability of the fabric was higher when the metal content in the fabric was low. The fabric having more floats showed higher air permeability compared to fabrics with less floats. Similarly, the water vapour transmission rate was also high for long float fabrics. The developed conductive fabrics could be used as wall covering and personal protective clothing in defense industry.

The present study considers a multilayer fire protective ensemble consisting of Nomex IIIA fabric with a honeycomb weave structure as an outer layer, aramid batting quilted to Nomex as a moisture barrier, and Teijin Conex as an inner layer, and cotton as face fabric. The performance of the multilayer ensemble (in vertical orientation) is analysed numerically for different exposure conditions, namely flame (convective) exposure, radiant heat exposure, and combined convective-radiant exposures with varying airgap widths. A coupled conduction-radiative heat transfer model is presented and solved numerically using an in-house developed code to evaluate the protective performance of ensembles subjected to a higher heat flux. The model and code are validated with the experimental data obtained using the bench top tests (Vertical Thermal Protective Performance (TPP) Tester) for lower heat flux. From the model results, the highest burn time for the protective ensemble is observed under flame exposure and the lowest under radiant exposure.

The study examined the fire protection performance of several woven products. Given that the comfort and fire protection properties of fire protective clothing (FPC) are opposite, it is important to consider the specific needs of firefighters when selecting the most suitable structure from various plain-woven derivatives, such as plain, basket, and ripstop. The yarn used was Nomex IIIA, which is a type of meta-aramid fibre. To achieve different thread densities, the pick density was adjusted while keeping the end density constant. The physical characteristics, thermal protective performance, thermal resistance, thermal conductivity, water vapour transmission rate and air permeability of all samples were assessed according to the appropriate standards. The goal was to identify the weave structure with the highest performance and the most optimal thread density. The basket weave structure was proposed as a fire protective clothing (FPC) having comfort qualities at a moderate level. Furthermore, increased density provided enhanced fire resistance, however, comfort must be sacrificed. Thus, to achieve a balance between fire protection and comfort, it was recommended to choose a thread density that is of an average level and the suggestion made by this research is to use the fabric as a basket weave design with an ends per inch of approximately 42, it is recommended to retain the pick density within the range of 46 with 44 tex Nomex IIIA yarn. The results of this study may be replicated in other designs using Nomex IIIA and comparable types of cloth and weave specifications.