People commonly recognize gates, windows, and doors as barriers. Yet, few are likely to name air if asked to recommend an effective barrier. However, a barrier is exactly what an air curtain, also known as an air door, is designed to be. Factors that affect whether or not air curtains are effective include the quantity of air, the velocity of the air, and the height at which the machine is placed.
An air curtain is a blower designed to create a barrier between two spaces. Air curtains can be found in places such as at the entrance of a building, at the entrance of a refrigerated room, or in some industrial spaces. These machines are usually installed to prevent the flow of certain things without inhibiting the flow of other things.
In food establishments, for example, air barriers are used to repel bugs. In many industrial settings they are used to prevent the spread of dust to a cleaner area. In office buildings, they are often used for climate control. However, in all of these instances, it may be counterproductive if the barrier inhibited the flow of people.
It is most common to find air curtains as downward flows of air. These are usually recommended for spaces that are more than a couple feet wide. There are instances, however, when air curtains are placed at the sides of an opening. This provides a horizontal air barrier. These are generally best for narrow and tall spaces.
An air curtain may blow continuously, but it is common for the machines to have triggers. For example, they may be activated by the opening of a door. To be effective in either case, such a machine requires a strong blowing component. Factors such as the items the air curtain is designed to repel and the air pressure on each side affect the amount of air needed and the speed at which it is required to travel.
These machines may be built into a building’s structure or they may be attached to the structure. They are generally placed on the side of the entrance where there is material that needs to be repelled. For example, when the machines are used as climate control, it is advisable to place them on the outer side of the entrance. To be effective, they must also be installed along the entire length of the area where they are placed. Otherwise, the unprotected areas are likely to be vulnerable to the entrance of unwanted items.
