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Thermal conductivity measurements of insulating materials: results of a round-robin test between laboratories and manufacturers
Sylvie Quin, Jacques Hameury

A round-robin test on thermal conductivity measurements of insulating materials was carried out between 50 industrial laboratories involved in the French Association pour la Certification des Matériaux Isolants (ACERMI) and four nationally-recognised European laboratories. The aim was the assessment of the consistency of all measurements. The participants performed tests on transfer standards with their apparatus (guarded hot plate or heat-flow meter). The transfer standards were machined from a batch of 25 mm thick and 35 kg m-3 expanded polystyrene boards which were fully characterised by the Laboratoire National d’Essais. A total of about 300 thermal conductivity measurements were obtained on sample thicknesses from 25 mm single boards up to 200 mm thick stacks of boards and at mean test temperatures from 5 °C up to 35 °C. The analysis of results shows a satisfactory outcome from this round-robin test with relative differences between the individual measurements lower than 3% in the range of thicknesses from 25 mm to 100 mm, covered by most of the participants.

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