International Comparison of Guarded Hot Plate Apparatus Using National and Regional Reference Materials.
International Comparison of Guarded Hot Plate Apparatus
Using National and Regional Reference Materials.
Zarr, R. R.; Filliben, J. J.
NIST TN 1444; 87 p. May 2002.
Available from: Government Printing Office, Washington,
Order number: PB2002-108272
analysis of variance; comparison; density; certified
reference material; expanded polystyrene; polystyrene;
fibrous glass; guarded hot plate; data analysis;
repeatability; thermal conductivity; thermal insulation;
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.