Variable-Volume View Cell with Ultra Low-Volume for the Measurements of High-Pressure Phase Equilibria

Phase equilibrium data are most important information for the process development with supercritical fluids. In these days, expensive and/or hazardous chemicals are frequently used in supercritical fluids processes especially for developing advanced materials. A safely and cost-effective measurements of the high-pressure phase equilibrium data with a small amount of samples are desired for an effective design of supercritical fluids process.

From this viewpoint, we have developed a variable-volume view cell with ultra low-volume for the high-pressure phase equilibrium data measurements. The cell consists of 60 mm in outer diameter and 6 mm in inner diameter. The maximum temperature and pressure of the cell are 473 K and 29 MPa, respectively. The piston is moved with geared motor and the piston speed is variable in the range of 0.1 to 185 mm/minute. The volume of the cell can be changed from 0.3 to 3 mL. The piston position is detected continuously with linear scale and inputted with the inside pressure data of the cell in the control system. The piston movement is strictly and automatically controlled by the sequence using both data for ensuring precise measurements.

Thus, the equipment developed gives us a useful tool for quick measurement of the high-pressure phase equilibrium data with a little bit of sample.