A valve system for controlling a flow of material includes a pipeline including an upstream portion a downstream portion. The system includes a variable flow restrictor configured for providing a restrictive orifice within the pipeline and creating a pressure differential in the flow of material high-pressure material in the upstream portion and low-pressure material in the downstream portion. The system includes a low-pressure tube connected to the downstream portion and a low-pressure chamber connected to the tube and receiving low-pressure material. The chamber includes a secondary flapper configured for selectively blocking the tube. The system includes a primary flapper disposed between the upstream portion and the low-pressure chamber and configured to be disposed in one of a first and second position. The flapper is held in the first position by the pressure differential. The flapper moves to the second position blocking the pipeline when a leak occurs.