Line Heat-Source Guarded Hot Plate

The 1-meter guarded hot-plate apparatus measures thermal conductivity of building insulation. This facility provides for absolute measurement of thermal resistance of thick and low-density test specimens used as transfer standards. These standards are used to calibrate heat-flow-meter apparatus (ASTM C 518)or verify guarded-hot-plate apparatus (ASTM C177). This facility is the only one of its kind in the world that will permit low-density thick insulation to be measured with an expanded uncertainty of less 1%.

[History of the Guarded-Hot-Plate Apparatus at NIST]

Laboratory services for thermal resistance measurements (and related thermal properties) are provided for thermal insulation (and building materials) having thermal conductivities of 0.02 W·m -¹·K-¹ to 0. 15 W·m-¹·K-¹. In general, the highest accuracy is obtained for homogeneous specimens.; The preferred size for the test specimen is 1016 mm in diameter; the minimum size, 610 mm square. Customers can supply their own material for specimens, or request NIST to select specimens from an in-house inventory of fibrous-glass material. All tests are performed at an ambient atmospheric pressure of approximately 100 ± 20 kPa (site pressure at Gaithersburg, MD). Services at ambient pressures outside these limits or with other gases are not provided. A dry-air purge is available to reduce the relative humidity to less than 15 percent. Additional information on the apparatus is available in the reference, below. Laboratory capabilities are summarized below.