The dynamics of hydrogen gas explosions in a typical industrial building were investigated using computational fluid dynamics (CFD) with different vent opening times. The purpose of this study was to elucidate the mechanisms by which the opening time of typical explosion-venting surfaces such as light walls, doors, and windows affect the danger posed by hydrogen explosions in industrial settings. It was found that inside the room the maximum peak overpressure and its incidence time increase exponentially and linearly, respectively, with an increase in opening time. If the opening time exceeds a certain threshold, the opening of the explosion-venting surface will induce secondary external explosions, where the intensity of the secondary explosions initially increases and then decreases with an increase in opening time. The peak dynamic pressure and peak wind speed outside the explosion chamber varied significantly when the vent opening time was varied between 0 and 0.1 s; the differences between the maximum and minimum values were 122% and 43% for the peak dynamic pressure and peak wind speed, respectively. The high-temperature area and flame area produced by the explosion progressively decreased in size with an increase in opening time, and the high-temperature area and flame area were, at their largest, 4.3-times and 1.9-times the length of the room, respectively. The findings of this study will provide a useful theoretical basis for the design of explosion-venting features, accident investigations, and disaster risk assessments in factories that use hydrogen gas. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.