During pantograph flushing, how many seconds does the operator have to press the deadman control on the refueling control valve before pumps shut off due to high pressure?

The correct answer of 10 seconds for pressing the deadman control on the refueling control valve during pantograph flushing is based on operational safety and equipment design principles. The deadman control is a critical safety feature designed to automatically shut off the pumps if excessive pressure is detected to prevent potential over-pressurization and equipment damage.

In this context, the 10-second duration is established as a balance: it allows the operator sufficient time to ensure that the flushing process is engaged effectively without risking overpressurization. Pressing the deadman control for too short a duration may result in insufficient flushing of the system, while excessive pressure builds up if the control is not released in time.

This timeframe helps maintain operational efficiency while prioritizing safety, ensuring that operators can effectively manage the process. The choice of 10 seconds reflects design standards and procedures that ensure both equipment integrity and safe operation during maintenance activities.