What action should be taken if the pressure in a tank being discharged drops below the allowable limit?

When the pressure in a tank being discharged drops below the allowable limit, the most prudent action is to reduce the pumping rate. This measure helps to stabilize the pressure within the tank, preventing the risk of negative pressure that could result in potential structural damage or undesirable cargo behavior. Maintaining an adequate pressure is crucial for safety, as it ensures that the liquid remains in a stable state and prevents air from entering the tank, which could lead to hazardous situations such as vapor release or the possibility of a fire.

Increasing the pumping rate would exacerbate the issue by further lowering the tank pressure and increasing the risk of tank collapse. Shutting down the inert gas system could also lead to dangerous conditions, as it might allow air to enter the tank. Beginning to discharge from a different tank would not address the immediate pressure issue in the tank currently being discharged, and could complicate the operation further. Thus, reducing the pumping rate is the most effective and safe response in this scenario.