What happens to the lead, second, and third refueling pumps when the issue venturi senses 1800 gpm and the return venturi senses 100 gpm for 15 seconds?

In this scenario, the lead, second, and third refueling pumps operate based on the flow readings sensed by the issue and return venturi systems. When the issue venturi detects a flow of 1800 gpm while the return venturi measures at 100 gpm, it indicates that there is a significant disparity between the fuel being delivered and what is being returned. Typically, the system is designed to maintain effective fuel delivery without overloading or underutilizing the available pumps.

When this specific flow rate configuration is sensed continuously for 15 seconds, it does not trigger the logic to turn off any of the active pumps. Instead, the continued operation of all three pumps ensures stable fuel delivery under high demand conditions. This means that the system is adequately designed to adjust pump operation based on real-time flow information to maintain operational efficiency and prevent any interruptions in the fuel supply.

While the other options suggest various manipulations of the pump operation (turning off certain pumps or activating a fourth), the readings indicate that the current setup is satisfactory, leading to the conclusion that all three pumps can continue to run without any issues. The understanding of the system's flow dynamics is crucial here, as it mitigates potential risks associated with fuel supply inconsistencies.