Critical temperature and pressure tester LECPT200

The LECPT200 evaluates the critical point of pure compounds as well as binary mixtures. Critical temperature and critical pressure (Tc, Pc) are detected by critical opalescence in a transparent cell. The system encompasses two syringe pumps which store the pure compounds (liquid or liquefied gas) and synchronously operate to inject a constant composition mixture throughout the duration of the experiment. To prevent temperature and pressure fluctuations, pump cylinder temperature is regulated with an isothermal jacket and a refrigerant circulating bath.

The mixture is fed into a sapphire visualization cell located in a thermostatic air bath. An external image capturing system records the test fluid while high-resolution sensors continuously monitor temperature and pressure. Far above the critical point, only a supercritical transparent phase is observed while far below, two distinct phases can be distinguished. However in its nearby region, an opalescence phenomenon is observed as a result of density fluctuations and light scattering. The procedure is repeated several times to maximize the accuracy of the results.