For installations with a capacity of 4,000 gallons or more, what must be installed with a common manifold liquid line of 1.5 inches or larger?

For installations with a capacity of 4,000 gallons or more, the requirement for a back check valve or emergency shut-off valve is crucial for ensuring safety and operational integrity within the propane system. A back check valve prevents the backflow of propane, which could otherwise lead to unsafe conditions or system contamination. The emergency shut-off valve adds an important layer of safety, allowing for the immediate cessation of flow in the event of a malfunction or emergency situation. This is particularly vital in large installations where the potential for significant propane release exists.

While components such as a pressure regulator, safety relief valve, and visual flow indicator are all important in their own right, the specific requirement for a back check valve or emergency shut-off valve in combination with a common manifold liquid line of 1.5 inches or larger is designed to directly manage safety and control over the entire system, especially in larger-scale operations where the stakes are significantly higher.