An investigation of the applicability of the flash heating of a three-layered cell for determining the thermal diffusivity of a central liquid layer at temperatures between its melting and boiling points is described. Two different cell designs were developed. In one, the outside layers were brazed to a ring-shaped central spacer; in the other, bolted flanges held the outside layers against a central spacer. Test units were fabricated from type 304 stainless steel. Thermal diffusivity results for water obtained with two brazed cells and one bolted cell were all within ±1 of standard reference values. Results obtained with a high temperature salt (Hitec) with two brazed cells were within ±2.5 of each other over the temperature range of 149–427°C. In contrast, bolted cell measurements were inconsis
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