Isochoric p-ρ-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- rho -T relationships were measured for binary refrigerant mixtures by an isochoric method with gravimetric determinations of the amount of substance. 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, 0.3288 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- rho -T data are in good agreement with this study. The uncertainty is 0.03 K for temperature and is 0.01% for pressure at p > 3 MPa and 0.05% at p < 3 MPa. The principal source of uncertainty is the cell volume (approx. 28.5 cm super(3)), with a standard uncertainty of 0.003 cm super(3). When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k identical with 2 and, thus, a two-standard deviation estimate) of the density measurements is estimated to be 0.05%.