Abstract: A fluid detection and shutoff actuation apparatus includes a rotatable plate mountable over a shaft of a shutoff valve, a linear actuator spaced from the plate, a trigger disposed between the actuator and plate, a fluid detector, and a control mechanism connecting the fluid detector to the actuator for activating it in response to detection of a fluid at a location monitored by the detector. The actuator is movable between extended and retracted positions toward and away from the plate. The plate rotates with the shaft between first and second positions in which the shutoff valve is respectively in opened and closed conditions and the plate is biased by a coil spring to rotate from the first to second position and change the valve from the opened to closed condition. The trigger is connected to the actuator and is pivotally movable toward and away from the plate in respond to movement of the actuator between the extended and retracted positions.