What type of shutoff valve shall be provided in the main supply line when the source valve is inaccessible from within the building?

The main supply line requires a specific type of shutoff valve to ensure safety and accessibility in the event of an emergency or maintenance situation. In cases where the source valve is not easily accessible within the building, a main shutoff valve should be installed in the main supply line. This valve allows for immediate control and isolation of the gas supply throughout the building, which is crucial for managing potential leaks or emergency situations effectively.

Having a dedicated main shutoff valve ensures that personnel can quickly and easily turn off the entire gas supply if necessary, regardless of the accessibility of the source valve. This practice is critical for maintaining safety standards and ensuring compliance with regulations governing medical gas systems. Other types of valves, such as supply, service, or zone valves, serve different purposes and are typically used for more localized control rather than providing a means to shut off the entire supply line.