What is an Air Curtain?

An Air Curtain is a device specifically designed to provide a resistance to air flow through an opening, without having any physical barrier there. Simply put, an Air Curtain is a fan that is designed with an air outlet that has a low turbulent air stream (high laminarity) that can be angled towards the incoming air stream in such a manner that the inflow of air can be prevented, and thereby creates a seal. Different types of Air Curtains

Air curtains can either be re-circulating types, or non re-circulating types.

Re-circulating Air Curtains emit air from a discharge grill on one side of the door opening and collect the air on the opposite side. It is then filtered, sometimes heated, and then is returned to the discharge grille. These units are essentially a modified heating system and uses large amounts of air. They are usually associated with high initial costs and high operating costs. Also, because the air has to be filtered, the maintenance costs are also quite high. The feature is that they use low velocity air streams, which is desirable in some commercial entrances. They are usually used in supermarkets and store entrances.

Non re-circulating Air Curtains are much more widely used. They are characterized by much lower initial and operating costs. As they are not re-using the air, it does not normally have to be filtered and thereby they can be made essentially maintenance free. They are also more effective, as the air streams are narrower and of higher velocities. These are the types that we manufacture.

Why use Air Curtains

Interior:- Air Curtain are often used at interior doorways of industrial and commercial facilities to seperate environments and to proivide an invisible barrier for protection against drafts, dust, dirt, odors and fumes.

Exterior:- Air Curtains are not designed for security purposes. They are secondary doors that allow unristricted access to the outside while conserving energy. Also, special types of Air Curtains protect against flying insects, dust and dirt.

Principles of A Non-Recirculating Air Curtain

The Air Curtain operates on a very simple law of physics. One force will change direction if it is subjected to another force. The force is air mass and the velocity at which it travels. The outside wind has a certain mass and a certain velocity, so does the air curtain stream. If the Air Curtain force is equal and opposed to the force form the draft through the door then the draft is prevented from entering. If the draft is much stronger than the Air Curtain it will break through and some will enter. However, even in this circumstance, the Air Curtain will prevent some of the outside wind from entering at all times. If the Air Curtain is much stronger than the draft some of the air will go outside. The strength of the Air Curtain follows the formula: mass times the velocity squared. Therefore an Air Curtain that blows at twice the speed has four times the wind stopping power at the same air volume.

Air Curtain can be mounted above, on one side, or on both sides of a door. The most common way is to mount the Air Curtain above the door. The feature with this is that the unit is out of the way and is not likely to be damaged by, for example, forklifts. It is also the most economical way of installing an Air Curtain. The drawback is that a small amount of air at the extreme bottom of the doorway may enter due to the height of Air Curtain.

The Air Curtain can also be mounted vertically on one side of the door. There are some disadvantages to this however. If, for example, a truck is parked in the door way then the entire doorway is unprotected because the truck will break the air stream. With the unit mounted on one side of the door it is more likely to be damaged. Also, if there is no equal force on the other side of the door to stop the stream then the flow will follow the wall for some distance and may disturb people who are standing in the air stream.

The final way of mounting an Air Curtain is on both side of the door with the air stream flowing towards each other. This is the most comfortable way of installing an Air Curtain as it eliminates the above drawbacks, except the damage.

Principals of Motion of Air Curtains

Air Curtains creates an invisible barrier of air, generated by high efficiency, direct driven centrifugal fans, that compress the air inside the unit and release the air through a directional nozzle with a pressure powerful enough to stop strong winds.