When does the system close the motive flow line from the light tank?

The motive flow line from the light tank is closed when there is a 20 lb imbalance that persists for more than 30 seconds. This specific threshold is critical for ensuring the safety and stability of the system, as it helps prevent excessive discrepancies in pressure or flow that could lead to operational issues or hazards.

This choice is founded on operational protocols designed to maintain system balance and prevent overflow or spillage. By monitoring imbalances closely, the system can effectively manage the flow dynamics, ensuring that conditions remain within safe limits. The decision to use a 20 lb threshold indicates a calibration that balances responsiveness and operational safety, avoiding unnecessary disruptions while still being sensitive enough to potential issues.

Understanding this mechanism is essential for effective system operation and management, as it correlates directly to the broader principles of fluid dynamics and system safety within the context of the training material.