What is defined as the sum of the discharge pressure and the suction lift when pumping at draft?

The sum of the discharge pressure and the suction lift when pumping at draft is referred to as net pump pressure. This term takes into account both the pressure created by the pump (discharge pressure) and the impact of atmospheric conditions that can affect water sourcing (suction lift). When a pump is drawing water from a source that is lower than the pump itself, the suction lift indicates how much pressure is needed to lift the water to the pump. By adding this suction lift to the discharge pressure, you derive the net pressure that the pump can supply to the system. This metric is crucial for ensuring that the pump operates effectively within its designed capacities and is able to deliver the required flow rates under varying conditions.

Static pressure, hydrant pressure, and discharge pressure are related concepts, but they do not encapsulate the full dynamics of pressure involved when lifting and discharging water at height. Understanding net pump pressure is essential for proper hydraulic calculations and ensuring successful water delivery in various firefighting scenarios.