What must happen if a tank reaches a full capacity of 90%?

When a tank reaches a full capacity of 90%, it indicates that it is nearing its maximum fill level, which poses a risk for possible overfills if further deliveries are made. To ensure safety and compliance with regulations, the overfill alarm should trigger at this threshold. This system is designed to alert personnel that the tank is approaching its capacity limit, allowing for corrective action to prevent an overflow situation which can lead to hazardous spills and environmental contamination.

The overfill alarm serves as a critical safety mechanism in the operations of storage tanks, highlighting the system's purpose to protect both property and the surrounding environment by preventing overfilling incidents. Therefore, understanding the operational guidelines of such alarms is essential for UST service technicians to maintain safety standards and adhere to regulatory requirements.