An air curtain is a device that blows a controlled stream of air across an opening such as a doorway or window. The purpose of an air curtain is to create an invisible barrier of air that separates two different environments, typically an interior and exterior space. The air stream generated by the air curtain helps to prevent the entry of outside air, dust, insects, and other contaminants into the conditioned space, while also minimizing the loss of conditioned air from the space. Air curtains are commonly used in commercial and industrial settings, such as retail stores, supermarkets, restaurants, and manufacturing facilities, where maintaining indoor air quality and temperature control is important.