Abstract <p>Perforated plates have found wide use in devices installed at thermal and nuclear power plants, and at chemical and petroleum and gas industry enterprises as submersed steam or gas distribution devices, and devices for gas phase dispersion into a low layer of liquid above them, in which processes of heat and mass transfer, or removal of finely dispersed droplet moisture from steam take place. For modeling the hydrodynamic processes occurring in a two-phase layer, it is important to be able to evaluate the average diameter of bubbles formed at the perforated plate holes and the bubble size distribution in terms of their sizes depending on the two-phase medium physical properties, perforated plate geometrical sizes, and two-phase layer height. However, despite numerous investigations, there are still no experimentally verified relationships for determining the sizes of bubbles formed at the perforated plate holes at the gas velocities typical for industrial installations and at a shall two-phase layer height. The article expands the application domain of their relationships for the detached bubbles formed at single submerged holes, also at a high steam pressure characteristic of devices used in the power industry. In addition, formulas have been proposed for the first time, using which it is possible to calculate the average sizes of detached bubbles and bubble size distributions for perforated plates having different geometrical parameters and with different heights of the two-phase layer above them. Experimental data deviate from the calculated values of detached bubble diameters for perforated plates by no more than 10%, and the average absolute deviations make no more than 3%.</p>