Friction loss occurs due to:

• A. Resistance to flow in hoses and fittings
• B. Change in water temperature
• C. Power loss in the pump motor
• D. Head loss due to elevation

Answer: (A)

Friction loss is the pressure drop that happens as water moves through hoses, fittings, and other components because of resistance against the flow. As water rubs along the inner surfaces, bends, and joints, energy is converted to heat and turbulence, reducing the pressure available at the end of the line. The amount of this loss grows with higher flow, longer hose runs, smaller diameter hoses, and rougher fittings, which is why it’s a key factor when calculating pump discharge pressure for the nozzle.

Other options don’t describe this pressure drop mechanism. Temperature changes can affect viscosity, which can influence friction a bit, but the direct cause of friction loss is the resistance inside hoses and fittings. Power loss in the pump motor concerns how efficiently the pump converts energy to flow, not the pressure drop in the hose. Elevation head is a static pressure change due to height, not a friction loss in the hose.