SUMMARYThe utilization of a slug calorimeter to evaluate the thermal performance of fire resistive materials (FRMs) is presented. The basic specimen configuration consists of a 'sandwich', with a square central stainless-steel plate (slug) surrounded on two sides by the FRM. This sandwich configuration provides an adiabatic boundary condition at the central axis of the slug plate that greatly simplifies the analysis. The other four (thin) sides of the steel plate (and FRM specimens) are insulated using a low thermal conductivity fumedsilica board. Two metal plates manufactured from a high temperature alloy provide a frame for placing the entire sandwich specimen slightly in compression. The entire configuration is centrally placed at the bottom of an electrically heated box furnace and the temperatures of the metal slug and exterior FRM surfaces are monitored during multiple heating and cooling cycles. Knowing the heat capacities and densities of the steel slug and the FRM, an effective thermal conductivity for the FRM can be estimated. The effective thermal conductivity of the FRM will be influenced by its true thermal conductivity and by any endothermic or exothermic reactions or phase changes occurring within the FRM. Preliminary tests have been conducted on two commonly used FRMs and on a non-reactive fumed-silica board to demonstrate the feasibility of the method. Published in 2005 by John Wiley & Sons, Ltd.

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An assessment of uncertainties for the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented. The uncertainties are reported in a format consistent with current NIST policy on the expression of measurement uncertainty. The report describes a procedure for determination of component uncertainties for thermal conductivity and thermal resistance for the apparatus under operation in either the double-sided or single-sided mode of operation. An extensive example for computation of uncertainties for the single-sided mode of operation is provided for a low-density fibrous-glass blanket thermal insulation. For this material, the relative expanded uncertainty for thermal resistance increases from 1 % for a thickness of 25.4 mm to 3 % for a thickness of 228.6 mm. Although these uncertainties have been developed for a particular insulation material, the procedure and, to a lesser extent, the results are applicable to other insulation materials measured at a mean temperature close to 297 K (23.9 °C, 75 °F). The analysis identifies dominant components of uncertainty and, thus, potential areas for future improvement in the measurement process. For the NIST 1016 mm Guarded-Hot-Plate apparatus, considerable improvement, especially at higher values of thermal resistance, may be realized by developing better control strategies for guarding that include better measurement techniques for the guard gap thermopile voltage and the temperature sensors.

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