In the event of a fire, doors and roller shutters act as a barrier to smoke. It ensures that the other side of the door is kept as far as possible from the fire. The pressure on the fire surface of the door will change, and the pressure difference between the two sides of the door will make the smoke flow to all possible gaps. Most doors are asymmetrical, with smoke performance dependent on the side with the higher pressure. Therefore, the determination of the smoke resistance performance o