Description

For laboratories within the scheme of the voluntary surveillance system for technical insulation materials in Europe (VDI/Keymark), a proficiency test is the basis for obtaining a “registered laboratory.” The VDI/Keymark is a cooperation between the VDI, The Association of German Engineers, and the Keymark Group dealing with European voluntary product certification systems, within the scope of thermal insulation materials. Registered laboratories are allowed to conduct measurements to verify the declared thermal conductivity curve of technical insulation materials under the umbrella of the quality mark “VDI/Keymark”. The initial characterization work on a round robin material for the determination of thermal conductivity at higher temperatures led to the selection of an expanded glass granulate. With all the results of the round robin tests produced by five European laboratories, the expanded glass granulate has become a very important material for establishing a reliable European level of thermal conductivity at higher temperatures with a moderate uncertainty. The German expert group “AKThermophysik” of the Association of Thermal Analysis (GEFTA, Gesellschaft für Thermische Analyse e.V.) further initiated a round robin test for thermal conductivity in 2012. With this additional use of the expanded glass granulate, more experience with transient methods and thermal conductivity values in the extended temperature range could be obtained. A comparison with the reference curve of the VDI/Keymark indicates very good compliance for most cases. Since August 2012, comparative tests with the expanded glass granulate as a round robin material are very important. Furthermore, the European CE marking became mandatory for industrial insulation products and temperature-dependent thermal conductivity, declared by the manufacturer, was introduced as a limit value. The challenge to determine the thermal conductivity at higher temperatures for a material using different methods and apparatuses was also an important step to evaluate the level of “True Thermal Conductivity.”

Keywords

technical insulation material, VDI/Keymark, expanded glass granulate, high-temperature thermal conductivity, round robin, European level of thermal conductivity

DOI

10.5703/1288284315540

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Characterization Work and Comparative Testing of Expanded Glass Granulate as a Round Robin Material for Thermal Conductivity at Higher Temperatures

For laboratories within the scheme of the voluntary surveillance system for technical insulation materials in Europe (VDI/Keymark), a proficiency test is the basis for obtaining a “registered laboratory.” The VDI/Keymark is a cooperation between the VDI, The Association of German Engineers, and the Keymark Group dealing with European voluntary product certification systems, within the scope of thermal insulation materials. Registered laboratories are allowed to conduct measurements to verify the declared thermal conductivity curve of technical insulation materials under the umbrella of the quality mark “VDI/Keymark”. The initial characterization work on a round robin material for the determination of thermal conductivity at higher temperatures led to the selection of an expanded glass granulate. With all the results of the round robin tests produced by five European laboratories, the expanded glass granulate has become a very important material for establishing a reliable European level of thermal conductivity at higher temperatures with a moderate uncertainty. The German expert group “AKThermophysik” of the Association of Thermal Analysis (GEFTA, Gesellschaft für Thermische Analyse e.V.) further initiated a round robin test for thermal conductivity in 2012. With this additional use of the expanded glass granulate, more experience with transient methods and thermal conductivity values in the extended temperature range could be obtained. A comparison with the reference curve of the VDI/Keymark indicates very good compliance for most cases. Since August 2012, comparative tests with the expanded glass granulate as a round robin material are very important. Furthermore, the European CE marking became mandatory for industrial insulation products and temperature-dependent thermal conductivity, declared by the manufacturer, was introduced as a limit value. The challenge to determine the thermal conductivity at higher temperatures for a material using different methods and apparatuses was also an important step to evaluate the level of “True Thermal Conductivity.”