Which factors contribute to friction loss in a hose line?

• A. Longer hose length
• B. Smaller diameter
• C. Higher flow (GPM)
• D. All of the above

Answer: (D)

Friction loss comes from the water rubbing along the hose wall as it moves. It increases with longer hose runs because each extra foot adds more surface area for that wall friction to act on, so the total loss grows with length. A smaller diameter worsens this because the same flow must pass through a tighter opening, raising the water’s velocity and the wall shear, which dramatically increases friction loss. Higher flow also raises friction loss since more water moving faster against the walls creates more resistance and turbulence. All three factors—length, diameter, and flow—raise friction loss, so the overall loss is greatest when all are increased.