The draining crucible (DC) technique was used for measurements on AZ91D under Ar and SF 6 . The DC technique is a new method developed to simultaneously measure the physical properties of fluids, the density, surface tension, and viscosity. Based on the relationship between the height of a metal in a crucible and the outgoing flow rate, a multi-variable regression is used to calculate the values of these fluid properties. Experiments performed with AZ91D at temperatures from 923 K to 1173 K indicate that under argon, the surface tension (N · m −1 ) and density (kg · m −3 ) are [0.63 − 2.13 × 10 −4 (T − T L )] and [1656 − 0.158(T − T L )], respectively. The viscosity (Pa · s) has been determined to be [1.455 × 10 −3 − 1.209 × 10 −5 (T − T L )] over the temperature range from 921 K to 967 K superheat. Above 967 K, the viscosity of the alloy under argon seems to be constant at (2.66 × 10 −4 ± 8.67 × 10 −5 ) Pa · s. SF 6 reduces the surface tension of AZ91D.