California ICC UST Inspector Practice Exam

Which of the following is NOT an approved overfill protection device for a UST system with single wall vent or tank riser piping?

1. Alert the transfer operator when the tank is 90% full by restricting the flow into the tank.

2. Restrict delivery of flow to the tank at 95% of capacity, activating an alarm five minutes before overfilling.

3. Provide positive shut-off of flow to the tank at 95% of capacity.

4. Use a ball float to restrict flow when the tank is 95% full and activate an alarm at 98% full.

The correct answer is: Alert the transfer operator when the tank is 90% full by restricting the flow into the tank.

The correct answer is based on the function and requirements of overfill protection devices in underground storage tank (UST) systems. Overfill protection devices are designed to prevent the tank from overflowing during the filling process. For a UST system with single wall vent or tank riser piping, there are specific standards and mechanisms established to ensure safety and compliance with regulations. The option that suggests alerting the transfer operator when the tank is 90% full by restricting the flow into the tank does not meet the regulatory requirements for overfill protection. While this method indicates that the tank is nearing its capacity, it lacks an active mechanism to prevent an overflow, which is critical in the context of overfill protection. Essentially, while this approach may provide a warning, it does not actively stop the inflow or provide a method to contain any potential overfilling that may occur after reaching 90% capacity. In contrast, the other options describe methods that actively restrict the flow or provide shutdown mechanisms at specific thresholds (95% or higher), which are indeed approved strategies for preventing overfilling in UST systems, ensuring that the tanks do not exceed safe limits while being filled. These methods align with the necessary standards for performance, including providing alarms or automatic shut-off