Positive pressure air supply outlets are designed to boost air flow during fires, continuously supplying fresh air to the entrance lobby. When a fire occurs on the current floor, all outlets adjacent to the upper and lower floors are opened to maintain positive pressure in the lobby, ensuring smoke doesn't spread in the area and provides an escape route. Stairwells should have a positive pressure air supply outlet every 2-3 floors. Each floor of the entrance lobby should have a normally closed positive pressure air supply outlet, which is activated by the fire control center during a fire. If the lobby uses a fire door with an opening signal, a normally open positive pressure air supply outlet is recommended. If mechanical positive pressure air supply is only installed in the lobby, a top-discharge outlet or an air curtain system is suggested as a solution.