How does friction loss affect the pressure the pump must supply?

• A. It reduces the required discharge pressure.
• B. It has no effect on nozzle pressure.
• C. It adds pressure loss along hose and fittings, requiring higher discharge pressure to maintain nozzle pressure.
• D. It only affects flow if the hose is damaged.

Answer: (C)

Friction loss is the pressure drop that happens as water moves through hose, fittings, and equipment. Because this loss occurs along the hose run, the pump has to supply extra pressure to compensate. To keep the nozzle operating at the desired pressure, you must overcome that loss, so the discharge pressure from the pump must be higher by the amount of friction loss. For example, if you want 50 psi at the nozzle and the hose and fittings cause 20 psi of friction loss, you’d need about 70 psi at the pump discharge. Friction loss increases with longer hose, smaller diameter, higher flow, and more fittings. So friction loss does affect nozzle pressure and the pump discharge requirement; it isn’t reduced by itself, it isn’t zero, and it isn’t conditional only on hose damage.