Function — Louvers permit free air passage, controlling the volume by their size or design. They iffuse or control direction of air flow by blade design. Insert louvers — Louvers commonly used in standard steel doors are of the “insert” type designed to be mounted into a cutout in the door and an overlapping frame. Inverted “V” blade, “Z” blade, inverted “Y” or chevron-type blade, lightproof, adjustable blade, grille type, and fusible link self-closing fire door type are available in a wide range of sizes. Also available from some steel door manufacturers is a pierced louver design. Insert louvers intended for exterior doors or other doors where security is a consideration should have fasteners or materials specified accordingly. Note: If a louver door is required to provide security, the
steel door manufacturer should be consulted. Bird or insect screens are available with many of the
standard design louvers. Where specified, consult steel door manufacturer for availability. Weatherproof louvers — True weatherproof designs do not exist. Some louvers are manufactured to provide a certain degree of rain protection. Louver construction — Standard louver frames are a
minimum 20 gauge steel with louver blades of a minimum 24 gauge steel. The louver blades can be welded or tenoned to the frame and the entire assembly is generally fastened to the door with moldings. Generally, one molding will be an integral part of the louver, while the other molding will be detachable. When louvers are installed, the detachable moldings should be located on the room or non-security side of the door.
Inverted “V” blade and “Z” blade types allow maximum free air flow with minimum static pressure differential. Inverted “Y” or chevron blade louver, while offering less free air space, offers a higher strength factor for schools and other areas where vandalism or hard usage may occur. Lightproof louvers are used where light transmission must be avoided. These provide a minimal free air flow.