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High-Temperature Guarded Hot Plate Apparatus Optimal Locations of Circular Heaters



Daniel R. Flynn, William M. Healy, Robert R. Zarr


The National Bureau of Standards (now the National Institute of Standards and Technology (NIST)) pioneered the use of circular line-heat-sources in guarded hot plate (GHP) apparatus, the most common type of absolute apparatus for measurement of the thermal transmission properties of thermal insulation. The prototype 305-mm GHP apparatus used one circular line-heat-source in the meter plate and one in the guard plate. The later one-meter GHP apparatus used a single circular line-heat-source in the meter plate but two such heaters in the guard plate. NIST is now completing the fabrication of a third GHP apparatus, to cover a much broader temperature range than achievable by the previous designs, that utilizes multiple line-heat-sources in the meter plate, the guard plate, and the cold plates. The purposes of the present paper are to (1) describe various strategies for locating these heaters so as to obtain the desired temperature distribution on the plates, (2) provide analytical solutions for computing the circular heater locations for the various strategies, (3) provide tabulated values for the desired circular heater locations, (4) present computed temperature variations for various circular heater layouts, and (5) provide representative temperature variations, obtained using finite element analyses, for heater layouts that are more complex than circular line-heat-sources.
Proceedings Title
Proceedings| 28th Symposium
Conference Dates
June 26-29, 2005
Conference Location
St. Andrews, New Brunswick, CA
Conference Title
International Thermal Conductivity Conference


305-mm guarded hot plate, circular line-heat-source, guarded hot plate, one-meter guarded hot plate


Flynn, D. , Healy, W. and Zarr, R. (2005), High-Temperature Guarded Hot Plate Apparatus Optimal Locations of Circular Heaters, Proceedings| 28th Symposium, St. Andrews, New Brunswick, CA, [online], (Accessed April 15, 2024)
Created June 1, 2005, Updated February 19, 2017