California ICC UST Inspector Practice Exam

Where is an emergency impact valve (shear valve) located in a UST system?

1. At the turbine piping termination

2. Base of the dispenser

3. Under the extractor tee

4. In the spill container

The correct answer is: Base of the dispenser

An emergency impact valve, also known as a shear valve, is specifically designed to minimize the risk of spills and leaks in the event of an accident or impact. Its primary function is to shut off the flow of product in case the fuel dispensing apparatus experiences a significant force, such as a vehicle collision. The correct location of the emergency impact valve is at the base of the dispenser, which is where the fuel is dispensed into vehicles. This placement allows the valve to immediately respond to any impact that might occur during typical operations, effectively isolating the underground storage tank (UST) from the dispensing equipment and minimizing the potential for product leakage into the environment. This functionality is critical for ensuring safety and compliance with environmental regulations. The other locations mentioned do not provide the same level of safety in the event of a collision or impact with the dispensing system. For example, the turbine piping termination, the extractor tee, and the spill container may not effectively prevent the flow of product in the event of a direct impact at the dispenser, where most accidents involving fuel dispensing occur. Therefore, the base of the dispenser is the most appropriate and effective location for the emergency impact valve.