What device is used to prevent overfilling a UST?

An overfill alarm serves as a critical safety device in the operation of underground storage tanks (USTs). Its primary function is to alert operators that the tank is approaching its maximum capacity during the filling process. This proactive warning is crucial because it helps prevent spillage and possible environmental contamination, which can occur if a tank is filled beyond its capacity.

When the tank is nearing full, the overfill alarm activates, providing a clear indication to the operator. This allows the operator to take immediate action to stop the filling process before an overfill condition occurs. The proper use of an overfill alarm contributes to compliance with safety regulations and best practices for UST operations.

In contrast, while other devices mentioned play important roles in UST management, they serve different purposes. For example, a spill bucket is designed to catch any spills that may occur during transfer to prevent them from reaching the ground. A leak detection system monitors the tank for product losses, while a vent pipe allows for the release of vapors to prevent pressure build-up during filling. However, none of these directly serve the primary function of preventing overfilling like the overfill alarm does.