Analysis of Thermal-Conductivity Measurement Data from International Comparison of National Laboratories

Published

June 19, 2012

Author(s)

Bruno Hay, Robert R. Zarr, Clark Stacey, Leonel Lira Cortes, Ulf Hammerschmidt, Nikolay Sokolov, J.T. Zhang, Jean Remy Filtz

Abstract

For the first time under the auspices of the Bureau International des Poids et Mesures (BIPM), seven national metrology institutes (NMIs) participated in an international interlaboratory comparison on thermal-conductivity measurements by the guarded hot-plate method. Measurements were conducted successively by all participants on the same set of specimens of insulating materials (mineral wool and expanded polystyrene) at temperatures ranging from 10 °C to 40 °C, according to the International Standard ISO 8302. This protocol aims to minimize issues of material variability by circulating the same pairs of specimens among the laboratories following the strict format of a round-robin test program. This comparison is a pilot study which is intended as a first stage for future key comparisons between NMIs. The descriptive analysis of obtained results shows good agreement between laboratories for the mineral wool (MW) specimens and the thicker specimens of expanded polystyrene (EPS), with relative deviations within the uncertainties of measurement. A positive drift of thermal-conductivity values, which has appeared progressively during the comparison process, seems to be correlated with the size of the metering area of the guarded hot plates used. A statistical analysis was applied to repeated thermal conductivity measurements at 23 °C, to identify anomalous and outlying data, to assess the within- and between-laboratory variability, and to evaluate the participant laboratories' performance.

Citation

International Journal of Thermophysics

Volume

34

Pub Type

Journals

Download Paper

DOI Link

Keywords

guarded hot plate, insulating materials, inter-laboratory comparison, thermal conductivity

Citation

Hay, B. , Zarr, R. , Stacey, C. , Cortes, L. , Hammerschmidt, U. , Sokolov, N. , Zhang, J. and Filtz, J. (2012), Analysis of Thermal-Conductivity Measurement Data from International Comparison of National Laboratories, International Journal of Thermophysics, [online], https://doi.org/10.1007/s10765-012-1225-x (Accessed April 18, 2024)