Which valve should be closed first during the shut-down procedure of a centrifugal feed water pump?

The correct choice is to close the suction valve first during the shut-down procedure of a centrifugal feed water pump. This is important because closing the suction valve prevents the pump from drawing in more water, which could create a situation where the pump operates without fluid, known as "running dry." When a pump runs dry, it can lead to overheating and damage to the pump components.

By closing the suction valve first, you ensure that the pump is safely isolated from the water source, allowing the discharge side to be safely managed afterward. It effectively prevents backflow and allows for proper handling of any remaining fluid in the system after the suction is shut off.

Following this procedure helps maintain the integrity and longevity of the pump, ensuring safe operational practices are adhered to.