Isochoric p-rho-T measurements for binary refrigerant mixtures containing difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), and 1,1,1-trifluoroethane (R143a) from 200 to 400 K at pressures to 35 MPa

The p p T relationships were measured for binary refrigerant mixtures by an isochoric method with gravimetric determinations of the amount of substanc e. Temperatures ranged from 200 to 400 K, while pressures extended up to 35 MPa. Measurements were conducted on compressed gas and liquid samples with the following mole Fraction compositions: 0.4997 R32 + 0.5003 R134a, 0.328 8 R32 + 0.6712 R134a, 0.4996 R32+0.5004 R125, 0.5001 R125+0.4999 R134a, and 0.5000 R125 + 0.5000 R143a. Most published p-p-T data are in good agreemen t with this study. The uncertainty is 0.03 K for temperature and is 0.01% f or pressure at p > 3 M Pa and 0.05% at p < 3 M Pa. The principal source of uncertainty is the cell volume ( similar to 28.5 cm(3)), with a standard un certainty of 0.003 cm(3) When all components of experimental uncertainty ar e considered, the expanded relative uncertainty (with a coverage factor k=2 and, thus, a two-standard deviation estimate of the density measurements i s estimated to be 0.05 %.