A continuously weighed pycnometer providing densities for carbon dioxide+ethane mixtures between 240 and 350 K at pressures up to 35 MPa / by

Typescript (photocopy).A new, continuously weighed pycnometer has been constructed for fast and accurate density measurements. This apparatus consists of a sample cell that is suspended from an electronic balance at all times. The sample cell is filled and evacuated through a flexible capillary that remains attached to the sample cell without affecting the precision of the balance. Data collection occurs at a rate of one measurement every twenty minutes along an isotherm. The precision of liquid density measurement is 0.2 kg/m^3, and the accuracy has been shown to be better than 0.1%. With this apparatus, we have measured densities of pure carbon dioxide, ethane, and four of their mixtures at six temperatures between 240 and 350 K, and at pressures up to 35 MPa. Measurements outside these ranges are currently limited by the pressure transducer inside the isothermal bath. With a suitable pressure measurement device, this apparatus can be used for density measurements between 200 and 500 K and at pressures up to 170 MPa