Nozzle pressure is defined as what, and how is it chosen for an attack line?

• A. The pressure at the hydrant outlet
• B. The pressure at the pump discharge; chosen by the driver
• C. The pressure at the nozzle; chosen to achieve the desired GPM and reach without overpowering the line
• D. The pressure in the water main; decided by the city

Answer: (C)

Nozzle pressure is the pressure at the nozzle outlet—the pressure the water is exiting with to produce flow through the hose and nozzle. It’s chosen to achieve the desired gallons per minute (GPM) and enough reach to reach the fire, while staying within what the hose and nozzle can safely handle. In practice, the driver picks nozzle pressure based on the hose size, length, elevation changes, and the type of nozzle, balancing enough pressure to deliver the target flow and distance without creating excessive nozzle reaction or damaging the line. The pump discharge pressure is then set so that, after accounting for friction losses along the hose and any elevation differences, the nozzle ends up at that target nozzle pressure.