Effects of Convective and Radiative Heat Sources on Thermal Response of Single- and Multiple-Layer Protective Fabrics in Benchtop Tests

摘要

Standard benchtop tests use a number of different heat sources for evaluating the performance of fabrics used in thermal protective clothing. These include convective sources (such as laboratory burners), radiative sources (such as quartz tubes), or a combination of convective and radiative sources. It is important to understand how the heat source used in a particular test will affect the thermal response and resulting test performance of fabrics due to factors such as the availability of oxygen to support thermal chemical reactions, the orientation of the heat source and fabric specimen, and the wavelength distribution of thermal radiation from the source. Temperatures at different locations within multiple-layer protective fabrics and benchtop test results were compared during 80-kW/m~2 exposures to a Meker laboratory burner and a cone calorimeter heater. In most locations within these specimens, temperatures in cone calorimeter tests were slightly higher than in the open flame tests, and the time to exceed the Stoll criterion was much shorter. Temperatures on the back of single-layer fabrics were compared during 10, 20, and 40-kW/m~2 exposures to the quartz tubes used in the Radiant Protective Performance (RPP) test and the cone calorimeter heater. Temperatures were higher in the cone calorimeter tests than in the RPP tests. These results are explained using a numerical heat transfer model and results of previous research. This paper also describes a cone calorimeter specimen holder that was developed to effectively test single- and multiple-layer fabrics in both horizontal and vertical orientations.