Which statement best describes the effect of friction loss on nozzle pressure?

• A. Friction loss reduces nozzle pressure, so discharge pressure must be increased to maintain nozzle pressure.
• B. Nozzle pressure is unaffected by friction loss.
• C. Friction loss automatically adjusts discharge valves.
• D. Friction loss only occurs at high temperatures.

Answer: (A)

Friction loss in hose lines reduces the pressure that actually reaches the nozzle. As water is pushed through hose, resistance from the hose walls and fittings causes a drop in pressure along the length. The longer and narrower the hose, and the higher the flow, the greater the loss. To keep the nozzle at the desired, specified pressure, you must raise the pump discharge pressure to compensate for that drop. This is why friction loss means nozzle pressure falls unless you increase discharge pressure.

Why the other ideas don’t fit: friction loss does affect nozzle pressure, so it isn’t “unaffected.” It isn’t something that automatically adjusts discharge valves; valves don’t change on their own to compensate. And friction loss isn’t limited to high temperatures—it's a function of flow, hose length, diameter, and fittings, occurring under normal operating conditions.