A valve comprises a valve body and a shutoff assembly. The valve body includes an inlet, an outlet, and a fluid flow passage therebetween. The shutoff assembly includes a poppet and a piston. The poppet is movable between a closed position, a partially open position, and a full open position. The piston is disposed in the valve body adjacent to the poppet, and is moveable between a first position, in which the piston at least inhibits movement of the poppet from the closed position to the full open position, and a second position, in which the piston allows movement of the poppet from the closed position to the full open position.