Certification of Standard Reference Material® 1450e Fibrous Glass Board

Abstract

Thermal conductivity measurements at and near room temperature are presented as the basis for certified values of thermal conductivity for SRM 1450e, Fibrous Glass Board. The meas-urements have been conducted in accordance with a randomized full factorial experimental design with three variables (bulk density, mean temperature, and ambient pressure) using the NIST 500 mm guarded-hot-plate apparatus. The thermal conductivity of the SRM specimens was measured over a range of bulk densities from 110 kg∙m-3 to 154 kg∙m-3, mean tempera-tures from 280 K to 360 K, and ambient pressure of 60 kPa to 100 kPa. Uncertainties of the measurements, consistent in format with current international guidelines, have been prepared. Statistical analyses of the physical properties from the SRM are presented and include varia-tions between boards, as well as within board. Each unit of SRM 1450e is individually certified for bulk density, ρ, and batch certified for thermal conductivity with the following equation: where λ is the predicted thermal conductivity (W∙m-1∙K-1), ρ is the bulk density (kg∙m-3), and Tm is the mean temperature (K) valid over the temperature range of 280 K to 360 K. Certi-fied values of λ are valid for barometric pressures from 60 kPa to sea-level pressure (101.325 kPa). There is no pressure dependence on the thermal conductivity included in the certifica-tion equation above because no statistically significant relationship between  and pressure was determined over the limited range of 60 kPa to 100 kPa. The expanded uncertainty for λ values from the above equation is 1 % with a coverage factor of approximately k = 2.