Thermal energy transfer through heat protective clothing during a flame engulfment test

Abstract

The flame engulfment test according to ISO 13506 assesses the protective performance of ready-made heat and flame protective clothing when exposed to a flash fire condition using an instrumented manikin. It uses a thermal model of the human skin to predict the risk of skin burns. This evaluation method is based on a pass/fail criterion, as either a burn is predicted or not. Therefore, it provides only limited information about the transfer of heat through the protective clothing. In this study, we investigated the use of the total transferred energy as an improved characterization method of the performance of the garments. We defined an energy transmission factor as the quotient between the transferred energy on the clothed manikin divided by the transferred energy registered by the nude manikin during calibration. We analyzed the performance of seven garments and show that the energy transmission factors can be assessed with very high repeatability. When comparing the results of the right and left arms and legs, we found very high correlation coefficients of 0.96 and 0.98, respectively, showing that the thermal insulation of the garments tested was very symmetrical. This new assessment method will be proposed for the revision of ISO 13506.

Development of a multi‐layered skin simulant for burn injury evaluation of protective fabrics exposed to low radiant heat

“…12 In the most used models, the thermal properties of skin are supposed to remain constant during temperature rises. 13 Both ASTM F1930 and ISO 13506-2 provide further information on the thermal conductivity of each of the layers which varies with temperature due to the generalized thermo-physical characteristics of the layer components. However, the developed relationships were based on limited experimental data.…”

“…Therefore, the penetration of the radiation is limited, and it is assumed that heat conduction is the only mode of heat transfer in the skin and subcutaneous layers (adipose) . In the most used models, the thermal properties of skin are supposed to remain constant during temperature rises . Both ASTM F1930 and ISO 13506‐2 provide further information on the thermal conductivity of each of the layers which varies with temperature due to the generalized thermo‐physical characteristics of the layer components.…”

Prediction methods of skin burn for performance evaluation of thermal protective clothing

“…The traditional burn prediction methods are pass/fail criteria. This suggests that the method only indicates whether the burn degree is reached or not, without showing whether the energy transferred just induced the burn or whether it was far higher than the burn threshold [14]. An interlaboratory trial provided evidence of no uniform ranking of the institutes concerning the predicted burn area [7].…”

“…An interlaboratory trial provided evidence of no uniform ranking of the institutes concerning the predicted burn area [7]. Rossi have suggested that the total transferred energy be used; however, it is based on physical values instead of skin burn information [14]. Thus, better prediction methods are needed, with high repeatability and low coefficients of variation and at the same time indicating enough information of the potential skin burn risk.…”

“…Most of the benchtop tests use the temperature rise of a calorimeter and the Stoll criterion [10], while the manikin test uses the surface heat flux and a more complex mathematical model [11,12]. In recent years, many researchers have pointed out the limitation of traditional burn prediction methods, such as the uncertainty of the prediction results due to various skin properties in different body locations [13,14]. Moreover, the Pennes bio-heat transfer equation seems insufficient to simulate the heat transfer of human skin [15].…”