What does net pump pressure refer to when pumping at draft?

Net pump pressure, when pumping at draft, refers to the overall pressure being applied to the water being pumped, which is critical for understanding how effectively the system will operate. In this context, it specifically represents the sum of the discharge pressure and the suction lift. Discharge pressure is the pressure at which water is being pushed out of the pump, while suction lift indicates the vertical distance and atmospheric pressure necessary to draw water into the pump from a draft source. By adding both of these pressures, you gain insight into the actual pressure that is available for delivering water to the desired location, factoring in the challenges presented by drawing water from a lower elevation.

The other choices do not accurately describe net pump pressure in this scenario. One might consider the total pressure output alone without adding other relevant factors, which does not provide a complete picture of pump performance while drafting. The concept of fuel tank pressure is unrelated to the hydraulic performance of a water pump, as it pertains to a completely different system. Finally, the pressure required to refill the tank focuses on filling rather than the actual performance metrics of the water being pumped. Understanding net pump pressure in this way is essential for effective operation and troubleshooting during firefighting or other emergency responses.