In this paper we present a simple differential thermal analysis cell designed for measurements in corrosive and volatile salt systems with vapour pressures exceeding ambient pressure. The DTA assembly consists of a sealed platinum capsule, made from a cylindrical Pt tube, welded to a Pt/Pt10%Rh thermocouple for measuring the temperature of the sample. The differential temperature is obtained by using a reference Pt/Pt10%Rh thermocouple for recording the furnace temperature. A reference cell used in conventional DTA assemblies is not necessary in the present set-up due to the small total heat capacity of the DTA assembly relative to the heat capacity of the furnace environments. Our simple DTA cell has been applied successfully to determine the phase diagrams of several binary and ternary ZrF4-based systems in the temperature region 200-1200 degrees C. The triple point of pure ZrF4, a compound which sublimes at ambient pressure, has also been obtained by the present method.