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International Comparison of Guarded Hot Plate Apparatus Using National and Regional Reference Materials.


pdf icon International Comparison of Guarded Hot Plate Apparatus Using National and Regional Reference Materials. (6150 K)
Zarr, R. R.; Filliben, J. J.

NIST TN 1444; 87 p. May 2002.

Available from:

Government Printing Office, Washington, DC 20401-0003.
Telephone: 202-512-1800.
Fax: 202-512-2250.
Website: http://www.bookstore.gpo.gov
Order number: PB2002-108272

Keywords:

analysis of variance; comparison; density; certified reference material; expanded polystyrene; polystyrene; fibrous glass; guarded hot plate; data analysis; repeatability; thermal conductivity; thermal insulation; interlaboratory

Abstract:

As part of an international comparison of guarded-hot-plate apparatus, thermal conductivity measurements of four different thermal insulation materials are presented. The test program evaluates four national reference materials using a two-part experimental plan: five independent replicate measurements at fixed temperature (297.15 K) and single-point measurements from 280?K to 320 K. The analysis of the replicate data provides rankings for the primary factors - laboratory and material - based on descriptive statistics. The major finding of the replicate analysis reveals a laboratory-material interaction. In other words, there are changes in both location and variation in the data from material-to-material. Further analyses attempt to determine the sources (i.e., underlying causes) for the variability in the replicate data. Secondary laboratory factors are investigated both individually following a cause-and-effect chart, and collectively using correlation analysis and analysis of variance. The major finding of the multi-temperature (280 K to 320 K) data confirm the laboratory-material interaction finding of the fixed-temperature replicate data. The data reveal increasing scatter as the temperature departs from laboratory ambient conditions of 297.15 K.