Which situation can cause a seal to change from negative to positive pressure?

A change from negative to positive pressure within a seal can occur due to fluctuations in the surrounding barometric pressure. When barometric pressure increases, it exerts more force on the seal, potentially shifting the internal pressure from a lower value (negative) to a higher value (positive). This is particularly relevant in mining or sealed environments where the differentiation between internal and external pressures is critical for controlling ventilation and ensuring safety.

While other factors like temperature changes, humidity, and inventory adjustments may impact the overall conditions within a mine, they do not directly cause a switch from negative to positive pressure within a seal in the same consistent and controlled manner as barometric pressure changes.