Friction loss is affected by flow rate.

• A. Friction loss is affected by flow rate
• B. Friction loss is independent of flow rate
• C. Friction loss depends only on temperature
• D. Friction loss depends only on pipe material

Answer: (A)

Friction loss in piping is tied directly to how much water is moving through the pipe. When flow rate goes up, water travels faster, increasing shear against the pipe walls and creating more turbulence. That extra motion converts more of the pumped energy into losses along the pipe, so the pressure drop due to friction rises. In common fire-protection calculations, this relationship is shown by formulas where head loss increases with flow rate (roughly with a power greater than one), meaning higher flow produces disproportionately larger friction losses. Temperature and pipe material can influence friction only indirectly (through viscosity and roughness), but they don’t set the friction loss on their own—the flow rate is the primary factor. So, friction loss is affected by flow rate.