An Air Curtain is a continuous broad stream of air circulated across a doorway serving a conditioned space. Air curtains are normally mounted horizontally over the door. They can also be mounted vertically at the side of the door or under the floor directed upwards
Air curtains are the best device to control the indoor climate in all the places where the doors cannot always be closed. The main purpose of Air Curtain is to disallow the influx of outside air through opening. Opening where an Air Curtain would typically be used are exterior shipping and receiving doors to plants and warehouses and interior doors between plant areas of different temperatures. These are used not only to prevent cold air from pushing its way in, but also prevent warm air from going outside the door.
In order to control climate an Air Curtain emits an air stream with enough velocity at the nozzle and the width of the nozzle. For different door sizes and different wind conditions, different air velocities at the nozzle are required.
To prevent the entry of outside winds the discharge nozzle is angled outward so that the air leaving it meets the wind trying to enter. The wind meet/strike the Air curtain stream in the doorway. Working principle is shown in the figure below;
When the vector representing the air stream and the vector representing the wind equalize they form a resultant which should meet the floor in the door plane for maximum efficiency.
The doors on industrial buildings are often open for long periods of time and can be extremely wide, in the case of warehouse doors. With people and delivery vehicles needing access, closing these doors to maintain the internal atmosphere is impractical. An industrial Air Curtain mounted above or to the side of these entrances will create a more comfortable and safer working environment.
For areas that are temperature controlled, Air Curtains act as an invisible barrier sealing in the chilled or heated air, providing unhindered access for staff and removing the inconvenience of fast-acting shutter doors or plastic slats.