To activate rated capacity of a pump it must be operated in the blank position.

• A. Series
• B. Tandem
• C. Stack
• D. Parallel

Answer: (D)

To get the pump’s rated capacity you need to maximize how much water can be delivered at the same discharge pressure, which is achieved by connecting pumps in parallel. In a parallel setup, each pump contributes its own flow, and these flows add together, so the total gallons per minute increases while the system pressure (head) stays essentially the same. That combination lets you reach the pump’s rated capacity at the given pressure.

In contrast, connecting pumps in series (or stacked/tandem) increases the pressure output but does not increase the overall flow; the output is governed by the pump curves and tends to be lower than the combined parallel flow. So the rated capacity is effectively activated through the parallel arrangement because that configuration yields the higher flow required to meet the rated capacity at the specified pressure.