What is the approximate nozzle pressure for a smooth bore 1¾-inch handline?

• A. Approximately 50 psi
• B. Approximately 25 psi
• C. Approximately 75 psi
• D. Approximately 100 psi

Answer: (A)

Smooth bore handlines are designed to operate at a fixed nozzle pressure to produce a solid, coherent spray. For a 1¾-inch smooth bore, that nozzle pressure is about 50 psi. This value is chosen because it provides an effective stream, good reach, and manageable velocity without needing higher pressures that are used for fog or adjustable nozzles. The other numbers would correspond to different nozzle types or patterns (such as fog nozzles that require higher nozzle pressures), but for a smooth bore 1¾-inch line, roughly 50 psi is the standard target at the nozzle. In practice, you add friction losses and any elevation to that nozzle pressure to set the pump discharge pressure, so if friction losses total, say, 20 psi, you’d aim for about 70 psi at the pump to keep the nozzle at 50 psi.