Previous studies on vented gaseous deflagrations with inertial vent covers and related regulatory aspects are examined. The model of turbulent deflagration dynamics, built on energy and mass conservation principles, is developed further to take into account the influence of vent cover inertia. An engineering formula for conservative estimation of the upper limit of vent cover inertia is presented. Similarity analysis has shown that the scaling relationship between the surface density of the cover, w, and the turbulence factor, chi, is wchi(3) = const, indicating a significant interrelationship between vent cover inertia and venting-generated turbulence. Results confirm that turbulence gradually increases after vent opening begins, so that it is possible to increase vent cover inertia significantly. It is demonstrated that instead of widely accepted surface density limits of about 10 kg/m(2) values of one/two orders higher, depending on the conditions, could be used for explosion protection with 100% efficiency for large-scale enclosures. (C) 2004 American Institute of Chemical Engineers.