A support bracket for use in installing a sprinkler fitting for a fire protection sprinkler in a building. The support bracket includes a support beam and a center bracket. The center bracket has a body that defines an opening to receive a sprinkler fitting, and a closure assembly, including a closure member having a first end rotatably connected to the body, and a second end having a handle. The closure assembly is movable between an open position and a closed position. When in the closed position, the closure assembly presses the sprinkler fitting against one of the body and the support beam, thereby urging the center bracket against the support beam to maintain the center bracket stationary relative to the support beam. In addition, the closure assembly includes a lock that engages with the closure assembly when the closure member moves from the open position to the closed position, and that prevents the closure member from returning from the closed position to the open position.