For pressure relief design, the thermodynamic properties of the involved substances are required. A test based on a thermodynamic stability criterion is proposed to check the thermodynamic consistency of values for the saturated liquid enthalpy, volume, and, respectively, the saturation vapor pressure or the enthalpy of evaporation and the saturated vapor volume in the proximity of the thermodynamic critical point. The effect of data inconsistencies is addressed exemplarily for propylene.