What device can automatically shut off gas supply in an overpressure situation?

The device that can automatically shut off the gas supply in an overpressure situation is the safety shutoff valve.

A safety shutoff valve is specifically designed to close off the gas supply when certain predetermined conditions are met, such as excessive pressure or irregularities in the system that could lead to dangerous situations. It acts as a critical safety mechanism by stopping the flow of gas to prevent hazards associated with overpressure, such as ruptures or explosions.

In contrast, the excess flow valve is designed to close when the flow of gas exceeds a set limit, which usually indicates a significant leakage or a break in the line, rather than a specific overpressure scenario. The pressure relief valve is meant to release excess pressure in the system to prevent damage, rather than shutting off the gas supply entirely. The control valve, while essential for regulating gas flow and pressure, does not automatically shut off the supply in the event of overpressure unless specifically designed to do so. Thus, the safety shutoff valve is the most appropriate device for the scenario described in the question.