- Author
- Zarr, R. R. | Filliben, J. J.
- Title
- International Comparison of Guarded Hot Plate Apparatus Using National and Regional Reference Materials.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- NIST TN 1444; NIST Technical Note 1444, May 2002, 87 p.
- 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.