California ICC UST Service Technician Practice Exam

What percentage must a Positive shut-off device stop the flow at?

1. 90%

2. 92%

3. 95%

4. 98%

The correct answer is: 95%

A Positive shut-off device is a critical component in the safety and regulatory compliance of underground storage tank (UST) systems. The purpose of this device is to ensure that a significant portion of the fluid flow can be effectively stopped to prevent overfilling and potential spills, which can pose environmental hazards. The correct answer, which specifies a stopping flow percentage of 95%, aligns with regulatory standards outlined in key documents and technical guidelines for UST systems. A 95% shut-off ability means that the device must be able to halt the product flow with a high degree of reliability, creating a substantial buffer to ensure that even as the tank approaches full capacity, there is assurance that overfilling will not occur. This level of effectiveness is critical in maintaining compliance with environmental protection regulations. Other percentages like 90%, 92%, or 98% may not meet the established requirements necessary to adequately safeguard against spillage, which is why those options are not aligned with the regulatory expectation for effective operation of Positive shut-off devices. The 95% figure strikes the appropriate balance between operational efficiency and safety, ensuring that the system is robust enough to handle typical scenarios without failure.