A model of explosion pressure build up in enclosures with translating inertial vent covers is presented. The previous approach, valid for inertia-free vents, is advanced by appending to it a new model of translating inertial vent cover displacement. The model and CINDY code are validated against experiments by Hochst and Leuckel (J. Loss Prev. Process Ind. 11 (1998) 89) in a 50-m(3) vessel with vertically translating covers with surface densities of 42 and 89 kg/m(2) at conditions of initially quiescent and turbulent mixtures. It is demonstrated for the first time that modelling of the vent cover jet effect is crucial for prediction of interdependent pressure-time and cover displacement-time transients, whereas air drag force and cushioning effects are negligible. The model was used further to investigate the influence of vent cover surface density on venting generated turbulence, via comparisons with experimental data of Cooper et al. (Combust. Flame 65 (1986) 1) in a 1-m(3) enclosure with vertically translating covers of various. The increase of the turbulence factor, i.e. total premixed flame front wrinkling factor, with cover surface densities up to 200 kg/m(2) inertia is obtained and explained. (C) 2003 Elsevier Ltd. All rights reserved.