The smoke vents are of a louvred type to be situated on a raised 4 sided upstand. In a fire condition the louvred vents are motored open.The units close following resetting of the fire panel.
The louvres like any roof vent, have a coefficient factor of between 0.6 and 0.8. Therefore to achieve the free area required, the actual structural opening will need to be enlarged to take account of this.
The louvered roof vents are tested to the EN12101 standard for smoke control systems.