| 摘要 |
A non-return valve is described for use in a window with frame, where ventilation air is drawn into the building through slots between the frame and the fixed or openable window situated in the frame. The non-return valve is in the shape of an upside down U-section (19), whose inner leg (20), nearest the frame, is fixed to an upper crosspiece (1) of the window, and whose downward-pointing, lower leg (22), facing into the room, ends above the upper crosspiece (1) thus forming a slot (23) by the upper cross piece (1). The U-section (10) has airflow opening or a row of airflow openings (24) along the length of its inner leg (20). This or these airflow openings (24) are covered by a freely hanging flap (25) attached to the inner leg's (20) side, made of membrane foil material, in order to allow passage of external air from the surroundings into the building, and to prevent draughts caused by a reverse flow of air from the room through the opening or openings to the outside.<IMAGE> |
