Abstract: A mounting device for mounting a reducer support beam of a sprinkler system to a ceiling support rail of a drop ceiling in a building. The mounting device comprises an adjustable clamp portion and a mount portion. The clamp portion has opposing ceiling support rail engagement portions separated by a clamping space sized and shaped for receiving a portion of the ceiling support rail of the drop ceiling. The clamp portion is adapted to adjustably move the rail engagement portions relative to one another between a loosened position and a clamped position to vary the clamping space separating the rail engagement portions. The clamping space is sized to receive the ceiling support rail when the rail engagement portions are in the loosened position. The rail engagement portions are adapted to securely engage the ceiling support rail when the rail engagement portions are in the clamped position.