A setup consisting of elements serially produced by the industry and designed for the determination of the aggregate state of binary systems is described. Certain simple modification of the piston-type distributor of the UIPK-2 setup make it possible to utilize a visual method of control of the state of the phases. This speeds up and simplifies considerably the investigation. Diagrams of the phase state of the two-component system, nitrogen-carbon dioxide, at the temperatures from 0 to 10 degree C and at different pressures are obtained.