An uncertainty analysis for steady-state thermal transmission properties determined by the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented for fibrous-glass blanket and expanded polystyrene board. The uncertainties are presented for the guarded-hot-plate apparatus in the single-sided mode of operation covering specimen heat flows from 0.5 W to 5 W. The relative expanded uncertainties for thermal resistance increase from 1 % to 3.5 % for thicknesses of 25.4 mm to 254 mm, respectively. Although these uncertainties have been developed for two thermal insulation materials, the results are indicative of other insulation materials measured at a mean temperature near 297 K (23.9 °C). This assessment of uncertainties is of particular interest for users of Test Method C 177 that operate similar apparatus at low heat flows (i.e., near or less than 1 W). Implications for laboratories that develop secondary standards from NIST calibrations are discussed.
Citation: Journal of Testing and Evaluation
Pub Type: Journals
building technology, calibration, expanded polystyrene board, fibrous glass blanket, guarded hot plate, heat flow, thermal conductivity, thermal insulation, thermal resistance, standard uncertainty, expanded uncertainty