Experimental studies on the hydraulics for six dumped and five structured packings under identical conditions were carried out. Technical data of the investigated packings were determined experimentally (Table 1). The investigations were carried out in the column of 250 mm in diameter and 1 m heigh of packed bed for the air-water system at normal pressure. The experiments included measurements of pressure drop on dry and wetted packings and column flooding. Pressure drop on dry packing is described by Eq. (11) where the wall factor K has been calculated from Eq. (10) and the friction factor psi has been calculated from Eq. (13). The Reynolds number Re-g was calculated from Eq. (12). The constant c and exponent A in Eq. (13) were determined on the basis of experimental data and (Table 2). In Figure 3 there are presented pressure drops on dry packings as a function of gas velocities for the investigated metallic packings. Basing on the form of the equation for pressure drop on wetted packing [10, 24] correlational equation (20) was developed. The values of estimated parameters a(0)-a(4) in Eq. (20) are listed in Table 3. The dimensionless numbers Re-g, Re-c, Fr-c are defined by Eqs. (12), (18) and (19). The agreement between the calculated values of Delta P/H (Eq. (20)) and the experimental ones can be considered as satisfactory. By way of illustration the comparison between the calculated pressure drop using eq. (20) and the experimental data for PSL-25 packing is shown in Fig. 5. The flooding line can be calculated according to Eq. (22) for all investigated packings except for Raschig-25 rings, for which Eq. (23) is valid. In Figure 6 there are compared the values calculated from Eq. (22) with the experimental data for investigated packings. The agreement between the calculated results and those obtained by measurement is satisfactory. The investigations showed that pressure drops on construction packings are much lower and limiting loads of gas and liquid phases much higher than those on dumped packings. It was found that the most desirable properties had construction packing X-30-100.