Measurements of the vapor-liquid coexistence curve in the critical region for Refrigerant 13B1 (CBrF//3) were made by visual observation of the disappearance of the meniscus at the vapor-liquid interface within an optical cell. Twenty-two saturated densities for temperatures between 332 and 340 K were obtained in the range of densities 376 to 1108 kg/m**3. Based upon the results along the coexistence curve, the critical temperature T//c, the critical density P//c and the critical pressure P//c for R 13B1 were determined to be 340. 08 K, 764 kg/m**3 and 3. 956 MPa, respectively, in consideration of the disappearing meniscus level as well as the intensity of the critical opalescence. In addition, the critical exponent beta was determined to be 0. 340 and the correlation of the vapor-liquid coexistence curve for R 13B1 was established.
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