With the objective of optimizing the process parameters of the R. H. Degassing Unit of USIMINAS (Brazil), the circulation rates in a 1: 5.3 scale model were evaluated for various gas injection rates and dimensionless correlations were obtained at for three different experimental conditions of static water level in the upleg. In general, the circulation velocity increases with increasing the gas injection rate and it shows a maximum when the water level in the upleg reaches the barometric height. The circulation velocities calculated from energy balance were close to the experimentally observed values. Application of the results of cold model experiments to the industrial installation has been discussed.