The main features of the Vangeli equilibrium still are discussed with respect to the literature apparatuses based on the use of the Cottrell pump. The Vangeli still is applied to study the binary and ternary systems formed bg: (a) cis-but-2-ene, (b) 1,3-butadiene and (c) N-formylmorpholine (CASRN 4394-85-0, supplied by author) at 40 degrees C, 60 degrees C, and 80 degrees C, respectively, in a range of pressure of 2 bar to 9 bar. The experimental data are correlated by using the NRTL equation.