What is Friction Loss (FL) in regards to water flow?

Friction loss in the context of water flow refers specifically to the pressure loss that occurs as water moves through pipes, hoses, or any system containing water. When water flows through these conduits, it encounters resistance due to the internal surfaces of the piping or hose material, as well as any bends, fittings, or valves present in the system. This resistance converts some of the energy of the moving water into heat, resulting in a decrease in pressure, which is quantified as friction loss.

Understanding friction loss is crucial for firefighters and apparatus engineers when calculating the necessary pump pressure to ensure that adequate water reaches the nozzle or other firefighting equipment. It helps in determining how much pressure needs to be added to overcome the losses in the system, thereby ensuring efficient water delivery in fire suppression efforts.