SEDL / STP / STP1116-EB / STP16369S

ASTM/DOE Hot Box Round Robin

Bales, E
Director and Research Professor, Buildings Engineering and Architectural Research Center, New Jersey Institute of Technology, Newark, New Jersey

Pages: 14    Published: Jan 1991

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Abstract

This paper presents the results of inviting the operators of all guarded and calibrated hot boxes in North America to participate in a round robin, an interlaboratory test program according to ASTM E 691, “Conducting an Interlaboratory Test Program to Determine the Precision of a Test Method”, to establish the precision and bias of the corresponding ASTM standard test methods: ASTM C 236, “Steady-State Thermal Performance of Building Assemblies by Means of a Guarded Hot Box”, and C 976, “Thermal Performance of Building Assemblies by Means of a Calibrated Hot Box”. The data and data analysis are reported from twenty-one laboratories that completed a series of tests on 4-inch thick specimens of cellular polystyrene thermal insulation. The data analysis resulted in two recommended statements of precision and bias.

Ninety-five per cent of the time measurements from two different laboratories on the same specimen would differ by up to +/-7.8% at a mean temperature of 75 F for the guarded hot box, and by up to +/-5.6% for the calibrated hot box. Based on guarded hot plate data for the specimen material, the reference value is 15.9 hr-F-ft sq/Btu. The mean of the thermal resistance reported for guarded hot boxes was 15.77 hr-F-ft sq/Btu, which differs by -1.2% from the reference value. The mean of the thermal resistance reported for calibrated hot boxes was 16.32 hr-F-ft sq/Btu, which differs by +2.6% from the reference value.