California UST System Operator Practice Test

The purpose of an automatic shutoff device in underground storage tank (UST) systems is primarily to prevent spills and overflows during the delivery of fuel or other liquids. This device is crucial in ensuring that the tank does not overfill, which can lead to environmental hazards and compliance violations. When the delivery process is taking place, the automatic shutoff device serves as a safeguard, detecting when the tank has reached its maximum capacity and promptly stopping the flow of the liquid. This function helps mitigate risks associated with spills that could contaminate soil and groundwater.

While the monitoring of levels, temperature control, and leak detection are important components of UST management, they do not directly address the immediate risk of spills during the filling process like the automatic shutoff device does. This distinction in purpose emphasizes the device's role in maintaining safety and environmental integrity during liquid deliveries to USTs.