Abstract
The Heat Flow Meter (HFM) Apparatus (ASTM C518) can be an ex tremely versatile test instrument used in a wide variety of conditions. Two special design HFM apparatuses are described here. They are Vacuum-Cryogenic and High Temperature (600°C) Heat Flow Meters. Calibration technique is the main key to obtaining useful information from testing under these unusual conditions. A few standards are available for use in these areas, however, others must be generated from Guarded Hot Plate (ASTM C177) tests under similar conditions. Mathematical modeling and statistical regression methods are employed to obtain calibration equa tions in order to calculate the coefficient or sensitivity under a variety of test condi tions. Error analysis is used to estimate the uncertainty of these test measurements which is usually greater than under standard conditions. These types of calibration methods have proven to be viable and useful for many years at the Manville-Schuller Mountain Technical Center thermal test labs. This allows the use of HFMs in testing conditions traditionally reserved for Guarded Hot Plates. The lower cost, simpler design, and easier operation of the HFM apparatus are significant advantages.
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