What should the set-points for overfill alerts not exceed?

The set-points for overfill alerts are critical in preventing overfilling of underground storage tanks, which can lead to environmental contamination and safety hazards. Setting these alerts at 90% of capacity is the industry standard because it provides a balance between allowing sufficient tank usage and ensuring that there is adequate room to accommodate any changes in liquid volume, such as temperature fluctuations that can cause expansion.

This threshold is also closely aligned with regulatory requirements and best practices, which emphasize the need for proactive measures to prevent spills and overflows. By alerting operators at 90%, it gives them time to take action and stop the filling process before reaching a critical level where an overfill could occur.

Establishing set-points at lower percentages than 90% could lead to unnecessary halts in operations, while setting them higher, such as at 95% or even 100%, could significantly increase the risk of overfilling and associated problems. Thus, 90% stands as the optimal choice to ensure safety and compliance in operating underground storage tanks.