| 摘要 |
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. In the event of a break in a line downstream that permits the pressure to drop below the predetermined pressure threshold or permits the flow rate to exceed the nominal flow rate, the pressure sensitive switch will, respectively, deactivate the solenoid valve and shut off the fluid flow through the inlet port or the velocity fuse will shut off the fluid flow through the outlet port. If either the pressure sensitive valve or the velocity fuse fail, the device will still restrict the fluid flow.
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