Which of the following is NOT considered an overfill device?

• A. Ball float
• B. Spill bucket
• C. Tank overfill alarm
• D. Drop tube flapper valve

Answer: (B)

The spill bucket is not considered an overfill device because its primary function is to collect and contain any fuel that may spill during the refueling process rather than to prevent overfilling of the tank itself. Overfill devices are specifically designed to prevent the tank from exceeding its safe liquid capacity.

For example, a ball float, tank overfill alarm, and drop tube flapper valve all serve the purpose of alerting operators or mechanically preventing fuel from filling the tank too full. The ball float mechanism activates when the liquid level rises, triggering an alarm or stopping the flow. The tank overfill alarm alerts the operator when the tank is nearing its full capacity, providing an opportunity to stop the fuel transfer before overfilling occurs. The drop tube flapper valve helps to restrict flow based on the liquid level in the tank.

In contrast, the spill bucket plays a vital role in environmental protection by managing spills that may happen during the transfer process but does not monitor or prevent overfilling of the underground or aboveground tank itself.