In the scenario where a pump draws 700 kPa from its tank and is connected to a hydrant at 350 kPa with no relief valve set, the statement 'the maximum discharge pressure equals the sum of the tank pressure and hydrant pressure' is:

• A. True
• B. False
• C. Cannot be determined
• D. Only the larger pressure counts

Answer: (A)

The idea being tested is how a pump adds pressure to what is already present in the system. A pump increases the pressure of the fluid as it moves from suction to discharge. If the suction side (the tank) is at 700 kPa and the downstream hydrant presents 350 kPa against the flow, and there’s no relief valve to limit it, the pump can raise the discharge pressure by its own head on top of the existing pressures. In a scenario where flow is blocked or effectively at a maximum, the discharge pressure can reach the sum of the two pressures: 700 kPa + 350 kPa = 1050 kPa.

So the statement is true because the pump’s pressure rise adds to the pressure already on the suction side, yielding a theoretical maximum discharge pressure equal to the sum of the two pressures. In real pumping with flow, friction and other losses will prevent you from always hitting that exact sum, but the additive concept explains why the maximum can approach 1050 kPa. The other options don’t fit because they ignore the pump’s additive effect, rely on ambiguity, or incorrectly discount the influence of the downstream pressure.