NCCER Millwright Practice Exam

For optimal operation, what position should the suction line be plumbed to?

1. Below the equipment

2. In line with the flow direction

3. Perpendicular to the discharge

4. Parallel with the equipment base

The correct answer is: In line with the flow direction

The optimal position for the suction line to be plumbed in alignment with the flow direction is essential for efficient operation. When the suction line is aligned with the flow direction, it ensures that the liquid flows smoothly into the pump without causing turbulence. This alignment minimizes the risk of air entrapment, which can lead to cavitation—a condition that significantly hampers the performance of pumps and can cause mechanical damage. Proper alignment in the flow direction also helps in maintaining the necessary velocity of the fluid as it enters the pump, allowing for effective transfer and reducing the risk of pressure drops that could impair functionality. In contrast, configurations that are not in line with flow may create elbows or bends that hinder performance, reduce capacity, or increase wear on pump components. While other configurations might seem reasonable, such as being below the equipment or perpendicular to the discharge, these do not provide the same level of efficiency or protection against cavitation. For optimal operational performance, maintaining a position that aligns with the flow direction is critical.