Air Curtain

An air curtain is a long, slim blower unit mounted above a doorway. When it runs, it sends a steady sheet of air down across the whole opening, forming an invisible barrier that people and trolleys can walk straight through while dust, flying insects and outside air are held back.

Inside the stainless steel housing, a motor-driven blower draws air in through the intake grille and pushes it out through a long, narrow nozzle along the bottom. The air leaves at high velocity and travels down to the floor near the threshold. Anything trying to cross the opening, such as an insect, airborne dust or a draft of warm or humid air, meets this moving stream and is pushed back or down instead of drifting into the room.

Because the door can stay open while the barrier holds, an air curtain helps keep rooms cleaner without slowing down the movement of people and materials. It also reduces the exchange of air between the two sides, which helps air-conditioned areas hold their temperature and saves energy.

An air curtain is not a substitute for an airlock or air shower at the entry to a classified cleanroom. It is used at doorways where people and goods move often, such as entries to production halls, stores, dispatch bays and food areas, to cut down the dust and insects that come in with them.

Getting the air stream right matters more than the size of the motor. A unit narrower than the door leaves gaps at the sides, and one mounted too high for its air velocity loses force before it reaches the floor, letting insects and dust through at the bottom. Air curtains are normally mounted on the side you want to protect, as close to the top of the door frame as practical, with the intake grille kept clear.