The closure operator assembly is intended to be used as a shutoff device to prevent the spread of fire, smoke, and flooding via HVAC ductwork from a watertight subdivision, compartment, or deck to another watertight subdivision, compartment, or deck. The closure is also intended to survive a 1500 °F fire and be capable of manual operation. It is intended that the closure, operator, and operator fasteners be provided as a package to ensure proper mounting and operation under conditions set forth in 3 and 4.