California ICC UST Service Technician Practice Exam

The primary function of overfill protection in underground storage tanks is to restrict product flow. Overfill protection systems are designed to prevent the tank from being filled beyond its capacity, which could lead to leaks, spills, and potential environmental contamination. When a tank reaches its designated fill level, the overfill protection device activates to impede further flow of the product into the tank, ensuring that it does not exceed its maximum capacity. This is crucial for maintaining safety and compliance with environmental regulations.

In an effective overfill protection system, various methods may be employed, such as automatic shut-off valves or alarms that alert operators when the tank is nearing its capacity. These measures not only protect the integrity of the tank and contents but also safeguard surrounding environments and communities from hazardous materials.

By contrast, other functions listed in the options do not align with the purpose of overfill protection. For instance, while preventing flow might sound similar, overfill protection specifically restricts the flow once a certain level is reached rather than aiming to stop flow altogether under all conditions. Increasing tank capacity is not relevant, nor is enhancing delivery speed, as overfill protection focuses on safety and compliance rather than operational efficiency.