Estimation of Uncertainty of Thermal Conductivity Measurement with Single Laboratory Validation Approach

Authors: Saowaluck Ukrisdawithid

Abstract:

The thermal conductivity of thermal insulation materials are measured by Heat Flow Meter (HFM) apparatus. The components of uncertainty are complex and difficult on routine measurement by modelling approach. In this study, uncertainty of thermal conductivity measurement was estimated by single laboratory validation approach. The within-laboratory reproducibility was 1.1%. The standard uncertainty of method and laboratory bias by using SRM1453 expanded polystyrene board was dominant at 1.4%. However, it was assessed that there was no significant bias. For sample measurement, the sources of uncertainty were repeatability, density of sample and thermal conductivity resolution of HFM. From this approach to sample measurements, the combined uncertainty was calculated. In summary, the thermal conductivity of sample, polystyrene foam, was reported as 0.03367 W/m·K ± 3.5% (k = 2) at mean temperature 23.5 °C. The single laboratory validation approach is simple key of routine testing laboratory for estimation uncertainty of thermal conductivity measurement by using HFM, according to ISO/IEC 17025-2017 requirements. These are meaningful for laboratory competent improvement, quality control on products, and conformity assessment.

Keywords: Single laboratory validation approach, within-laboratory reproducibility, method and laboratory bias, certified reference material.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3669256

References:

[1] The International Organization for Standardization, “ISO/IEC 17025:2017(E) General requirements for the competence of testing and calibration laboratories”, Geneva, Switzerland.
[2] JCGM member organizations, “Evaluation of measurement data — Guide to the expression of uncertainty in measurement,(GUM 1995 with Minor Correction),” JCGM 100, September 2008.
[3] The International Organization for Standardization, “ISO GUIDE 33:2015(E) Reference Materials – Good practice in using reference materials”, Geneva, Switzerland.
[4] European Federation of National Associations of Measurement, Testing and Analytical Laboratories, “Measurement uncertainty revisited: Alternative approaches to uncertainty evaluation,” Technical Report, August 2007.
[5] European Federation of National Associations of Measurement, Testing and Analytical Laboratories, “Guide to the evaluation of measurement uncertainty for quantitative test results” Technical Report, August 2006.
[6] Zarr, R.R., Pintar, A.L., “SRM 1453, Expanded Polystyrene Board, for Thermal Conductivity from 281 K to 313 K: NIST Special Publication 260-175; U.S. Government Printing Office: Washington, DC (2012).
[7] American Society for Testing and Materials, “Standard test method for steady-state thermal transmission properties by means of the heat flow meter apparatus,” ASTM C518-17, ASTM International, West Conshohocken, PA, 2017.
[8] H. Hovind, B. Magnusson, M. Krysell, U. Lund and I. Mäkinen, Internal Quality Controll – Handbook for Chemical Laboratories, NT TECHN REPORT 569 ed 4th Approved 2011-11, Nordic Innovation, 2011
[9] American Society for Testing and Materials, “Standard test method for apparent density of rigid cellular plastics,” ASTM D1622M/ D1622-14, ASTM International, West Conshohocken, PA, 2008.