The operating point of a pump is found at the intersection of which curves?

The operating point of a pump is found at the intersection of which curves?

• A. The pump's efficiency curve and its NPSH curve
• B. The pump's head-flow (performance) curve and the system resistance curve
• C. The system head curve and ambient temperature curve
• D. The motor torque curve and the impeller diameter curve

Answer: (B)

The operating point is found where the pump’s head‑flow curve intersects the system resistance curve. The pump curve shows how much head (pressure) the pump can deliver for every flow rate, while the system curve shows how much head the piping and fittings require at those same flow rates. The flow through the system adjusts until the head the pump can supply equals the head the system needs, and that matching point is the actual operating point—the corresponding flow rate and head. Other curves, like the efficiency curve or NPSH requirement, describe performance attributes at various points or cavitation considerations, but they don’t determine the operating point themselves.

The operating point is found where the pump’s head‑flow curve intersects the system resistance curve. The pump curve shows how much head (pressure) the pump can deliver for every flow rate, while the system curve shows how much head the piping and fittings require at those same flow rates. The flow through the system adjusts until the head the pump can supply equals the head the system needs, and that matching point is the actual operating point—the corresponding flow rate and head. Other curves, like the efficiency curve or NPSH requirement, describe performance attributes at various points or cavitation considerations, but they don’t determine the operating point themselves.