Isobaric vapor-liquid equilibrium (VLE) data for the two binary systems of {propane-1,2-diol + ethane-1,2-diol and propane-1,2-diol + butane-1,2-diol} at p = (10.0, 20.0, and 40.0) kPa have been determined using a modified Rose-Williams still with continuous circulation of both vapor and liquid phases in this work. The thermodynamic consistency tests of the experimental VLE data were performed according to the methods of the Herington area test and Van Ness point test. The experimental isobaric VLE data were then correlated using the universal quasichemical (UNIQUAC), nonrandom two-liquid (NRTL), Margules, and Wilson activity coefficient models. Consequently, the calculation values showed good agreements with the experimental data measured in this study.