The theory and practice of safe handling temperatures

Abstract

Many hot objects which may be touched or handled every day can cause either discomfort, pain or burning of the skin. The precise effect will depend on the Contact Temperature tc, an intermediate value between the hot object and the skin temperature. The value of tc varies with the material, and is governed by the Contact Coefficient b, a property of the material which has a wide range of values from metals to plastics. In the experiments with 48 female subjects, surface and contact temperatures for three materials were measured over a wide range, and subject reactions recorded on a five-point comfort scale. From the heat conduction theory outlined, and using the calculated values of b for the three materials, the predicted safe surface temperatures were determined. These predicted values were then compared with the observed temperatures and with those recommended in British Standards.