Fire Blankets for Munition Protection: Flame and Heat Blocking Properties of Advanced Materials

Abstract : This report examines the flame and heat penetration through layers of fabrics as blankets for thermally protecting stored munitions. Evaluated were 27 fabrics made of inorganic fibers (alumina, silica, and ceramic fibers) and organic fibers (Kevlar, Nomex, and carbon) varying in thickness from 3 to 25 mm. Two types of tests were performed. First, flame penetration tests were performed with an oxyacetylene flame. Visual observations and measured char depth into a wooden block at the back of the sample were used in the analysis. Second, heat penetration tests were performed in the heat penetration apparatus. A radiant heater was used for heat exposure. Temperatures were measured at the front and back surfaces of the inorganic fabrics and in each layer of the Kevlar fabric. The average steady-state temperatures were used for the analysis. Effective thermal diffusivity values for the sample "blankets" were estimated from the measured temperatures, sample thickness, and exposure duration using a simple heat conduction relationship for thermally thick materials. A procedure was developed to obtain effective thermal diffusivity of the sample "blankets" from the measured average steady-state temperatures at the front and back surfaces, thickness, and exposure time duration. This procedure, along with measurements in the heat penetration apparatus, can be used for routinely testing the various types and combinations of inorganic and organic fiber-based fabrics.