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Oak Ridge National Laboratory with funding supplied by the Department of Energy sponsored the evaluation of a water calorimeter for thermal transmission testing of refractory fiber insulation using a ruggedness test. A round robin conducted on the calorimeter indicated that differences between laboratories are significant. The water calorimeter has several design characteristics that differ from other test methods. The energy transfer is measured by the increase in temperature of a constant water flow so the calorimeter is on the cold side and never exposed to high temperatures. With this test method the temperature difference across the sample is very large compared to some other instruments. In order to improve the test method a series of experiments was performed within a single laboratory to evaluate the sensitivity of the test method to deviations in standard practices. This experimental method is a ruggedness test, which is a statistical method of evaluating step changes while making multiple changes each test. Since this method is used for testing materials at different temperatures, essentially an independent ruggedness test was conducted at three temperatures. The factors evaluated included (1) emissivity of cold surface, (2) calorimeter to guard balance, (3) calorimeter to room temperature balance, (4) calorimeter water flow rate, (5) perimeter insulation, (6) type of hot side thermocouple, and (7) type of cold side thermocouple. Different factors were significant at different temperatures. Short and long term recommendations are given for improving the operation of the calorimeter.
calorimeter, ruggedness test, thermal conductivity, refractory fiber, emissivity
Section Manager of Research, Material Performance Evaluation, Manville Technology Section, Manville Corporation, Denver, CO