Principles of Fire Hose Friction Loss
Friction loss is the conversion of mechanical energy into heat as water molecules rub against each other and against the internal rubber lining of the fire hose. Under the 4th Law of Hydraulics, friction loss increases with the square of flow velocity—doubling flow quadruples friction resistance.
Standard Friction Loss Coefficients (C)
- 1.75" Attack Hose: C = 15.5
- 2.0" Attack Line: C = 8.0
- 2.5" Line: C = 2.0
- 3.0" Supply Line (with 2.5" couplings): C = 0.8
- 4.0" Large Diameter Hose (LDH): C = 0.2
- 5.0" Large Diameter Hose (LDH): C = 0.08