A glass concentric-tube-type thermal-diffusion column is used to study column operation for inert gases. The formal criteria of how to introduce column construction faults in the formulation is investigated. It seems that the relation lnQ̄0*exp=m̄ lnQ̄ 0*theoret holds for all inert gases, m being a geometric constant, independent of temperatures and gases in the column. Therefore, this relation provides us with a method of testing the gas interaction parameters which appear in literature.