Ventilating grille built into wall - has two sliding grilles between fixed grille and louvre

摘要

The ventilator has a fixed louvre (4) in a frame (3). A fixed grille (1) is fixed to the louvre and sandwiches two sliding grilles (7a,7b). There are operated by small handles. The grille (7a) is constrained between the outer frame and the angle stops (11) on the fixed grille (1). The width of the openings in the two sliding grilles is half that of the openings in the fixed grille. The ventilator is adjustable between fully closed and fully open in infinite stages by adjusting the two sliding grilles.