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.
(6150 K)
Zarr, R. R.; Filliben, J. J.
NIST TN 1444; 87 p. May 2002.
Available from:
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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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899