Abstract: A flow and pressure responsive valve which blocks upstream flow in the event of a break in a downstream line. Included is a solenoid valve positioned adjacent an inlet port, a pressure sensitive switch, and a velocity fuse positioned adjacent the outlet port. The pressure sensitive switch is tied to a cavity in common with the solenoid valve. The pressure sensitive switch activates the solenoid valve at a predetermined pressure threshold to permit the fluid to flow through the inlet port. The velocity fuse is calibrated to permit the fluid to flow at a nominal flow rate and when the fluid flow exceeds this rate, the velocity fuse shuts off fluid flow through the outlet port.