What is the maximum percentage full that an overfill device should activate to prevent tank overfilling?

The maximum percentage full that an overfill device should activate to prevent tank overfilling is 95%. This is a critical safety aspect in tank management to ensure that there is sufficient space left in the tank to accommodate any expansion of the liquid due to temperature changes or other factors.

In the context of vapor recovery systems and other related tanks, allowing 95% fullness provides a buffer zone that helps prevent accidental overfilling, which could lead to environmental hazards or safety risks. This threshold is widely accepted in industry standards to promote safe operating conditions and reliable system performance.

Opting for a lower percentage, such as 85% or 90%, does not provide that additional leeway that 95% offers and could result in premature activation of the overfill device, creating unnecessary operational interruptions. On the other hand, setting the activation at 100% does not allow any safety margin and poses a significant risk of overfilling when factors that affect liquid volume are considered. Therefore, 95% is the optimal threshold to ensure both safety and operational efficiency in vapor recovery systems.