VAPOR-PRESSURE OF 2-(DIFLUOROMETHOXY)-1,1,1-TRIFLUOROETHANE CHF2-O-CH2CF3 (HFE-245)

The vapor pressure of 2-(difluoromethoxy)-1,1,1-trifluoroethane, a can didate alternative refrigerant that is also known as HFE-245, has been measured. The vapor pressure was determined at temperatures between 2 61 K and 369 K by two ebulliometric techniques. The differences in the se two methods arise from the method used to determine pressure. Atp < 200 kPa, a comparative instrument was used and pressures were obtaine d from the temperature at which water boiled at the same pressure. At pressures up to 747 kPa, the pressures were measured directly. A corre lation for the vapor pressure from 261 K to the critical temperature i s provided. The comparative ebulliometric measurements have an expande d uncertainty (k = 2) of less than 0.0005.p, while the direct ebulliom etric measurements have an expanded uncertainty (k = 2) of 0.002.p.