What is the basic formula for determining pump discharge pressure (PDP)?

The basic formula for determining pump discharge pressure (PDP) is indeed represented as PDP = NP + FL. This equation illustrates how the total discharge pressure at the pump outlet is affected by the net pump pressure (NP) and the friction loss (FL) incurred in the hose, fittings, and other components in the system.

Net pump pressure (NP) refers to the pressure produced by the pump, usually measured in pounds per square inch (psi) at the pump discharge when the pump is operating under specific conditions. Friction loss (FL) is the pressure loss due to the internal resistance of the hose and fittings as water is transported through them.

By adding these two pressures together, you can determine the total pressure that is available at the discharge nozzle. This is critical for ensuring that there is enough pressure to effectively deliver water to the required location and overcome any resistance in the system.

Understanding this formula is essential for fire service operations, as it helps operators determine whether they have enough pressure for specific firefighting situations or for supplying water to various fireground operations.