Installation of which device is critical for preventing overfilling during product delivery?

The installation of a flow shut-off device is crucial in preventing overfilling during product delivery into underground storage tanks. This device actively monitors the flow of the liquid being delivered and is designed to automatically stop the flow when the tank reaches a predetermined level. By interrupting the product flow at a critical point, the flow shut-off device helps to prevent spills and potential environmental contamination, which can occur if a tank is filled beyond its capacity.

While other devices, like the emergency shut-off valve and pressure relief valve, serve important safety and operational functions, they do not specifically address the prevention of overfilling during the filling process. The emergency shut-off valve typically addresses emergency situations where there is a need to quickly stop the flow of product in case of a significant failure or leak, but it is not designed for routine overfill prevention. Similarly, a pressure relief valve is intended to release excess pressure in the tank to prevent structural failure but does not have a direct role in monitoring or controlling the fill level during product delivery. The vapor recovery unit is aimed at capturing vapors that could escape during filling and does not prevent overfilling.

In summary, the flow shut-off device is specifically designed to monitor and control the filling of the tank, making it a