What is the purpose of an Excess Flow Valve?

An Excess Flow Valve is designed to enhance safety in gas supply systems by automatically activating when gas flow exceeds a predetermined rate. This feature is crucial in preventing potential hazards such as leaks or ruptures in the gas line. When the flow rate surpasses the set threshold, the valve closes, effectively shutting off the gas supply and mitigating the risk of excessive gas being released into the environment, which could lead to dangerous situations such as explosions or fires.

The other options, while related to gas systems, do not accurately describe the primary function of an Excess Flow Valve. Reducing fuel gas pressure involves a different type of valve or regulator, deactivating when not in use is not a function of this specific valve, and monitoring gas levels typically involves sensors or gauges rather than an excess flow mechanism. Thus, the correct statement encompasses the essential safety role that the Excess Flow Valve plays in managing gas flow.