At 1700 kPa, the pumper is rated at what percentage of its rated capacity?

• A. 50%
• B. 40%
• C. 60%
• D. 70%

Answer: (A)

The key idea is how a pump’s capacity changes as discharge pressure increases. A pump has a performance curve that shows how many gallons per minute it can move (flow) at different discharge pressures (head) while running at a given speed. The “rated capacity” is the maximum flow the pump can deliver under standard test conditions. As you push more pressure against the discharge, the flow the pump can deliver drops along that curve.

At about 1700 kPa (roughly 246 psi), typical NFPA-tested pump curves show the flow already reduced to about half of the rated maximum. So the pumper is operating at roughly 50% of its rated capacity at that pressure. The other percentages would occur at different points on the curve (lower head gives higher flow, higher head would push it lower, but at 1700 kPa the characteristic point is near 50%).