Which valve is designed to automatically close at the rated flow specified by the manufacturer?

The excess flow valve is specifically designed to automatically close when the flow of gas exceeds a predetermined level, which is specified by the manufacturer. This function is crucial for safety in LP gas systems, as it helps to prevent excessive flow that could lead to unsafe conditions, such as leaks or potential explosions.

When the flow rate through the valve exceeds its rated limit, the internal mechanism activates to seal off the gas flow, ensuring that the system remains within safe operational parameters. This type of valve is typically installed in situations where high flow rates could pose a safety risk, serving as an essential component of the overall safety management system for gas installations.

In contrast, the other valves serve different purposes. A pressure relief valve is designed to open and relieve pressure to prevent overpressure situations; a check valve allows flow in one direction and prevents backflow, but does not monitor flow rates; and a vent valve is intended to allow gas to escape or vent to maintain safe pressure levels but does not function based on flow rates.