Journal of Scientific Instruments Editor: Dr H R Lang Vol 28 and Supplement No 1, 1951 Pp xvi + 388 + iii + 80 (London: Institute of Physics, 1951) Bound, £3 12s; unbound, £3

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A Review of Scientific Instruments

SUMMARY The National Institute of Standards and Technology (NIST) and the Center for Better Living have formed a collaboration to assess the performance and failure mechanisms of gypsum wall assemblies under real fires/furnace conditions. These measurements are being used to compile an experimental database necessary to validate models that could be used to predict their performance and ultimate failure under various design fires. A critical component of the database is thermal property data of gypsum board. The present paper describes the results of an effort to quantify thermal properties of gypsum board. The thermal conductivity specific heat mass loss and linear contraction for gypsum board types widely used in the U.S.A. and Japan were measured both at room temperature and at elevated temperatures. The gypsum board types tested include Type X and Type C from the U.S.A. and Type R and Type F from Japan. Results indicate that the difference in thermal properties of all gypsum board samples tested in the present study is not significant particularly at elevated temperatures. A large difference in linear contraction among gypsum board samples was observed at elevated temperatures, implying a significant difference in mechanical behavior at fire temperatures. The experimental data set provides valuable information that can be used to model the behavior of gypsum board at elevated temperatures. Copyright q 2009 John Wiley & Sons, Ltd.

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Determining thermal properties of gypsum board at elevated temperatures

Measurement of the through-plane thermal conductivity of carbon paper diffusion media for the temperature range from −50 to +120 °C

Fire resistive materials (FRMs) are currently qualified and certified based on lab-scale fire tests such as those described in the ASTM E119 Standard Test Methods for Fire Tests of Building Construction and Materials [1]. While these tests provide an “hourly” rating for the FRM, these ratings have no direct quantitative relationship to the performance of an FRM in an actual fire, e.g., a 2 h rating does not mean that the FRM will protect the steel (or other substrate) for 2 h in a real world fire. Computational heat transfer models offer the potential to bridge the gap between laboratory testing and field performance. However, these models, whether basic one-dimensional or more complex three-dimensional versions, depend critically on having accurate values for the thermophysical properties of the FRM (and substrate) as a function of temperature, to be used as inputs along with the system geometry and fire and heat transfer boundary conditions. Properties required include density, heat capacity, thermal conductivity, and enthalpies of reactions and phase changes. In this report, procedures for determining a consistent set of these input values are presented. Then, quantitative data for a variety of FRMs and several steel substrates that have been obtained from the literature or measured in the Building and Fire Research Laboratory are presented. The utilization of these properties to successfully simulate the thermal response of an FRM-steel layered system is demonstrated for the National Institute of Standards and Technology slug calorimeter experimental setup. Ultimately, similar performance simulations will be executed for E119-type tests and even real fires.

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Thermal Performance of Fire Resistive Materials I. Characterization With Respect to Thermal Performance Models | NIST

The thermal conductivity of a porous material is controlled by the thermal conductivities of its components and their spatial arrangement within the composite structure, e.g., the material’s microstructure. In this paper, the relationships between thermal conductivity and microstructural parameters such as porosity and pore size are examined for two calcium silicate boards of different densities. Thermal conductivities are measured from room temperature to 400 °C using a transient plane source technique, for both the as-received boards and for a corresponding set of boards that were first heated to and held at 1000 °C for at least 4 h. Microstructure is characterized by the measurement of the boards’ bulk and powder densities and an assessment of pore size based on scanning electron microscopy. The experimentally measured thermal conductivities are then compared to those predicted by three previously presented theories for porous materials. A better agreement is observed between the experimental values and two of the three theories. Aging the boards at 1000 °C has a small but significant effect on thermal conductivity, decreasing the room temperature values but increasing the 400 °C ones.

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Microstructure and Thermal Conductivity of Hydrated Calcium Silicate Board Materials

The 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 fumed-silica 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.

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J H. Kim

Papers

A slug calorimeter for evaluating the thermal performance of fire resistive materials