If a centrifugal pump is vibrating excessively after start-up, what should be done?

When a centrifugal pump is vibrating excessively after start-up, the appropriate course of action is to shut it down and isolate the pump. Excessive vibration can indicate a range of problems, such as misalignment, imbalance, cavitation, or mechanical failure. Continuing to operate the pump in this state can lead to further damage not only to the pump itself but also to connected equipment and the overall system. Isolating the pump allows for a thorough inspection without risking safety or exacerbating any underlying issues. It is crucial to address the cause of the vibration before attempting to restart the pump to ensure safe and efficient operation.

The other options, while they may seem plausible in some contexts, do not directly address the urgent need to stop the pump when there is a clear sign of abnormal operation, which is critical for maintaining equipment integrity and safety.